Imported from libpng-0.99a.tar

CHANGES

@@ -167,3 +167,52 @@ version 0.96 [May, 1997]
    added read of CRC after IEND chunk for embedded PNGs (Laszlo Nyul)
    added typecasts to quiet compiler errors
    added more debugging info
+version 0.97 [January, 1998]
+   removed PNG_USE_OWN_CRC capability
+   relocated png_set_crc_action from pngrutil.c to pngrtran.c
+   fixed typecasts of "new_key", etc. (Andreas Dilger)
+   added RFC 1152 [sic] date support
+   fixed bug in gamma handling of 4-bit grayscale
+   added 2-bit grayscale gamma handling (Glenn R-P)
+   added more typecasts. 65536L becomes (png_uint_32)65536L, etc. (Glenn R-P)
+   minor corrections in libpng.txt
+   added simple sRGB support (Glenn R-P)
+   easier conditional compiling, e.g. define PNG_READ/WRITE_NOT_FULLY_SUPPORTED;
+      all configurable options can be selected from command-line instead
+      of having to edit pngconf.h (Glenn R-P)
+   fixed memory leak in pngwrite.c (free info_ptr->text) (Glenn R-P)
+   added more conditions for png_do_background, to avoid changing
+      black pixels to background when a background is supplied and
+      no pixels are transparent
+   repaired PNG_NO_STDIO behaviour
+   tested NODIV support and made it default behaviour (Greg Roelofs)
+   added "-m" option and PNGTEST_DEBUG_MEMORY to pngtest (John Bowler)
+   regularized version numbering scheme and bumped shared-library major
+      version number to 2 to avoid problems with libpng 0.89 apps (Greg Roelofs)
+version 0.98 [January, 1998]
+   cleaned up some typos in libpng.txt and in code documentation
+   fixed memory leaks in pCAL chunk processing (Glenn R-P and John Bowler)
+   cosmetic change "display_gamma" to "screen_gamma" in pngrtran.c
+   changed recommendation about file_gamma for PC images to .51 from .45,
+      in example.c and libpng.txt, added comments to distinguish between
+      screen_gamma, viewing_gamma, and display_gamma.
+   changed all references to RFC1152 to read RFC1123 and changed the
+      PNG_TIME_RFC1152_SUPPORTED macro to PNG_TIME_RFC1123_SUPPORTED
+   added png_invert_alpha capability (Glenn R-P -- suggestion by Jon Vincent)
+   changed srgb_intent from png_byte to int to avoid compiler bugs
+version 0.99 [January 30, 1998]
+   free info_ptr->text instead of end_info_ptr->text in pngread.c (John Bowler)
+   fixed a longstanding "packswap" bug in pngtrans.c
+   fixed some inconsistencies in pngconf.h that prevented compiling with
+      PNG_READ_GAMMA_SUPPORTED and PNG_READ_hIST_SUPPORTED undefined
+   fixed some typos and made other minor rearrangement of libpng.txt (Andreas)
+   changed recommendation about file_gamma for PC images to .50 from .51 in
+      example.c and libpng.txt, and changed file_gamma for sRGB images to .45
+   added a number of functions to access information from the png structure
+      png_get_image_height(), etc. (Glenn R-P, suggestion by Brad Pettit)
+   added TARGET_MACOS similar to zlib-1.0.8
+   define PNG_ALWAYS_EXTERN when __MWERKS__ && WIN32 are defined
+   added type casting to all png_malloc() function calls
+version 0.99a [January 31, 1998]
+   added type casts and parentheses to all returns that return a value.(Tim W.)
+

README

@@ -1,16 +1,22 @@
-README for libpng 0.96
+[NOTE:  this is still beta version 0.99a; the text below has already
+ been updated in anticipation of the imminent 1.0 release.]
 
-This is the sixth (and hopefully last) beta release of libpng 1.0.
-The changes from libpng-0.90 include bug fixes, a C++ wrapper for
-png.h, some additions to the API, as well as internal changes to
-the library.  See "CHANGES" for a detailed list of differences.
+
+README for libpng 1.0
+
+This is the first official release of libpng.  Don't let the fact that
+it's the first release fool you.  The libpng library has been in
+extensive use and testing for about two and a half years.  However, it's
+finally gotten to the stage where there haven't been significant
+changes to the API in some time, and people have a bad feeling about
+libraries with versions < 1.0.
 
 ****
 Note that some of the changes to the png_info structure render this
 version of the library binary incompatible with libpng-0.89 or
 earlier versions if you are using a shared library.  The type of the
 "filler" parameter for png_set_filler() has changed from png_byte to
-png_uint_32, which will affect shared-library applications which use
+png_uint_32, which will affect shared-library applications that use
 this function.
 
 To avoid problems with changes to the internals of png_info_struct,
@@ -19,6 +25,12 @@ access to info_ptr.  These functions are the png_set_<chunk> and
 png_get_<chunk> functions.  These functions should be used when
 accessing/storing the info_struct data, rather than manipulating it
 directly, to avoid such problems in the future.
+
+It is important to note that the APIs do not make current programs
+that access the info struct directly incompatible with the new
+library.  However, it is strongly suggested that new programs use
+the new APIs (as shown in example.c), and older programs be converted
+to the new format, to facilitate upgrades in the future.
 ****
 
 Additions since 0.90 include the ability to compile libpng as a
@@ -65,7 +77,7 @@ If not, it should be at ftp.uu.net in /graphics/png
 Eventually, it will be at ftp.uu.net in /pub/archiving/zip/zlib
 
 You may also want a copy of the PNG specification.  It is available
-as an Internet Draft, and RFC, and a W3C Recommendation.  Failing
+as an RFC and a W3C Recommendation.  Failing
 these resources you can try ftp.uu.net in the /graphics/png directory.
 
 This code is currently being archived at ftp.uu.net in the
@@ -85,19 +97,19 @@ Finally, if you get any warning messages when compiling libpng
 fix.  Please mention "libpng" somewhere in the subject line.  Thanks.
 
 This release was created and will be supported by myself (of course
-based in a large way on Guy's earlier work), and the PNG group.
+based in a large way on Guy's and Andreas' earlier work), and the PNG group.
 
-adilger@enel.ucalgary.ca
+randeg@alumni.rpi.edu
 png-implement@dworkin.wustl.edu
 
-You can reach Guy, the original libpng author, at (internet preferred):
-
-internet: schalnat@group42.com
-CompuServe: 75501,1625
+You can't reach Guy, the original libpng author, at the addresses
+given in previous versions of this document.  He and Andreas will read mail
+addressed to the png-implement list, however.
 
 Please do not send general questions about PNG.  Send them to
-the address in the specification.  At the same time, please do
-not send libpng questions to that address, send them to me.  I'll
+the address in the specification (png-group@w3.org).  At the same
+time, please do not send libpng questions to that address, send them to me
+or to png-implement@dworkin.wustl.edu.  I'll
 get them in the end anyway.  If you have a question about something
 in the PNG specification that is related to using libpng, send it
 to me.  Send me any questions that start with "I was using libpng,
@@ -120,18 +132,20 @@ Files in this distribution:
       descrip.mms   =>  VMS project file
       example.c     =>  Example code for using libpng functions
       libpng.txt    =>  Description of libpng and its functions
-      makefile      =>  Default Unixish makefile
       makefile.aco  =>  ACORN makefile
       makefile.ama  =>  Amiga makefile
       makefile.atr  =>  Atari makefile
       makefile.bor  =>  Borland makefile
+      makefile.dec  =>  DEC makefile
       makefile.dj2  =>  DJGPP 2 makefile
       makefile.elf  =>  Unix ELF makefile
       makefile.knr  =>  Makefile which calls ansi2knr to convert files
       makefile.mip  =>  MIPS makefile
       makefile.msc  =>  Microsoft C makefile
+      makefile.sgi  =>  Silicon Graphics Irix makefile
       makefile.std  =>  Standard Unix makefile
-      makefile.tc   =>  Turbo C makefile
+      makefile.sun  =>  SUN makefile
+      makefile.tc3  =>  Turbo C 3.0 makefile
       makevms.com   =>  VMS make program
       png.c         =>  Basic interface functions common to library
       png.h         =>  Library function and interface declarations
@@ -154,13 +168,15 @@ Files in this distribution:
 
 Good luck, and happy coding.
 
+-Glenn Randers-Pehrson
+ Internet: randeg@alumni.rpi.edu
+ Web: http://www.rpi.edu/~randeg/index.html
+
 -Andreas Eric Dilger
  Internet: adilger@enel.ucalgary.ca
  Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/
 
 -Guy Eric Schalnat
- Group 42, Inc.
- Internet: schalnat@group42.com
- CompuServe: 75501,1625
+ (formerly of Group 42, Inc)
  Web: http://www.group42.com/
 

TODO

@@ -3,8 +3,9 @@ pngtodo.txt - list of things to do for libpng
 add "grayscale->palette" transformation and "palette->grayscale" detection
 improved dithering
 multi-lingual error and warning message support
+sPLT chunk handling
 cHRM transformation
-sRGB chunk handling
+complete sRGB transformation (presently it simply uses gamma=0.45)
 man pages for function calls
 high-level API for reading images
 final bug fixes

example.c

@@ -1,36 +1,36 @@
 /* example.c - an example of using libpng */
 
 /* This is an example of how to use libpng to read and write PNG files.
-   The file libpng.txt is much more verbose then this.  If you have not
-   read it, do so first.  This was designed to be a starting point of an
-   implementation.  This is not officially part of libpng, and therefore
-   does not require a copyright notice.
-
-   This file does not currently compile, because it is missing certain
-   parts, like allocating memory to hold an image.  You will have to
-   supply these parts to get it to compile.  For an example of a minimal
-   working PNG reader/writer, see pngtest.c, included in this distribution.
-*/
+ * The file libpng.txt is much more verbose then this.  If you have not
+ * read it, do so first.  This was designed to be a starting point of an
+ * implementation.  This is not officially part of libpng, and therefore
+ * does not require a copyright notice.
+ *
+ * This file does not currently compile, because it is missing certain
+ * parts, like allocating memory to hold an image.  You will have to
+ * supply these parts to get it to compile.  For an example of a minimal
+ * working PNG reader/writer, see pngtest.c, included in this distribution.
+ */
 
 #include <png.h>
 
 /* Check to see if a file is a PNG file using png_check_sig().  Returns
-   non-zero if the image is a PNG, and 0 if it isn't a PNG.
-
-   If this call is successful, and you are going to keep the file open,
-   you should call png_set_sig_bytes(png_ptr, PNG_BYTES_TO_CHECK); once
-   you have created the png_ptr, so that libpng knows your application
-   has read that many bytes from the start of the file.  Make sure you
-   don't call png_set_sig_bytes() with more than 8 bytes read or give it
-   an incorrect number of bytes read, or you will either have read too
-   many bytes (your fault), or you are telling libpng to read the wrong
-   number of magic bytes (also your fault).
-
-   Many applications already read the first 2 or 4 bytes from the start
-   of the image to determine the file type, so it would be easiest just
-   to pass the bytes to png_check_sig() or even skip that if you know
-   you have a PNG file, and call png_set_sig_bytes().
-*/
+ * non-zero if the image is a PNG, and 0 if it isn't a PNG.
+ *
+ * If this call is successful, and you are going to keep the file open,
+ * you should call png_set_sig_bytes(png_ptr, PNG_BYTES_TO_CHECK); once
+ * you have created the png_ptr, so that libpng knows your application
+ * has read that many bytes from the start of the file.  Make sure you
+ * don't call png_set_sig_bytes() with more than 8 bytes read or give it
+ * an incorrect number of bytes read, or you will either have read too
+ * many bytes (your fault), or you are telling libpng to read the wrong
+ * number of magic bytes (also your fault).
+ *
+ * Many applications already read the first 2 or 4 bytes from the start
+ * of the image to determine the file type, so it would be easiest just
+ * to pass the bytes to png_check_sig() or even skip that if you know
+ * you have a PNG file, and call png_set_sig_bytes().
+ */
 #define PNG_BYTES_TO_CHECK 4
 int check_if_png(char *file_name, FILE **fp)
 {
@@ -49,10 +49,11 @@ int check_if_png(char *file_name, FILE **fp)
 }
 
 /* Read a PNG file.  You may want to return an error code if the read
-   fails (depending upon the failure).  There are two "prototypes" given
-   here - one where we are given the filename, and we need to open the
-   file, and the other where we are given an open file (possibly with
-   some or all of the magic bytes read - see comments above). */
+ * fails (depending upon the failure).  There are two "prototypes" given
+ * here - one where we are given the filename, and we need to open the
+ * file, and the other where we are given an open file (possibly with
+ * some or all of the magic bytes read - see comments above).
+ */
 **** prototype 1 ****
 void read_png(char *file_name)  /* We need to open the file */
 {
@@ -118,7 +119,8 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
 
 **** PNG file I/O method 2 ****
    /* If you are using replacement read functions, instead of calling
-    * png_init_io() here you would call */
+    * png_init_io() here you would call:
+    */
    png_set_read_fn(png_ptr, (void *)user_io_ptr, user_read_fn);
    /* where user_io_ptr is a structure you want available to the callbacks */
 **** Use only one I/O method! ****
@@ -143,29 +145,31 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
    /* tell libpng to strip 16 bit/color files down to 8 bits/color */
    png_set_strip_16(png_ptr);
 
-   /* strip alpha bytes from the input data without combining with th
-    * background (not recommended) */
+   /* Strip alpha bytes from the input data without combining with th
+    * background (not recommended).
+    */
    png_set_strip_alpha(png_ptr);
 
-   /* extract multiple pixels with bit depths of 1, 2, and 4 from a single
+   /* Extract multiple pixels with bit depths of 1, 2, and 4 from a single
     * byte into separate bytes (useful for paletted and grayscale images).
     */
    png_set_packing(png_ptr);
 
-   /* change the order of packed pixels to least significant bit first
+   /* Change the order of packed pixels to least significant bit first
     * (not useful if you are using png_set_packing). */
    png_set_packswap(png_ptr);
 
-   /* expand paletted colors into true RGB triplets */
+   /* Expand paletted colors into true RGB triplets */
    if (color_type == PNG_COLOR_TYPE_PALETTE)
       png_set_expand(png_ptr);
 
-   /* expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */
+   /* Expand grayscale images to the full 8 bits from 1, 2, or 4 bits/pixel */
    if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
       png_set_expand(png_ptr);
 
-   /* expand paletted or RGB images with transparency to full alpha channels
-    * so the data will be available as RGBA quartets */
+   /* Expand paletted or RGB images with transparency to full alpha channels
+    * so the data will be available as RGBA quartets.
+    */
    if (png_get_valid(png_ptr, info_ptr, PNG_INFO_tRNS))
       png_set_expand(png_ptr);
 
@@ -186,19 +190,22 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
                          PNG_BACKGROUND_GAMMA_SCREEN, 0, 1.0);
 
    /* Some suggestions as to how to get a screen gamma value */
+
+   /* Note that screen gamma is (display_gamma/viewing_gamma)
    if (/* We have a user-defined screen gamma value */)
    {
       screen_gamma = user-defined screen_gamma;
    }
    /* This is one way that applications share the same screen gamma value */
-   else if ((gamma_str = getenv("DISPLAY_GAMMA")) != NULL)
+   else if ((gamma_str = getenv("SCREEN_GAMMA")) != NULL)
    {
       screen_gamma = atof(gamma_str);
    }
    /* If we don't have another value */
    else
    {
-      screen_gamma = 2.2;  /* A good guess for PC monitors */
+      screen_gamma = 2.2;  /* A good guess for a PC monitors in a dimly
+                              lit room */
       screen_gamma = 1.7 or 1.0;  /* A good guess for Mac systems */
    }
 
@@ -207,13 +214,20 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
     * by the user at run time by the user.  It is strongly suggested that
     * your application support gamma correction.
     */
-   if (png_get_gAMA(png_ptr, info_ptr, &image_gamma);
-      png_set_gamma(png_ptr, screen_gamma, image_gamma);
-   else
-      png_set_gamma(png_ptr, screen_gamma, 0.45);
+
+   int intent;
+
+   if (png_get_sRGB(png_ptr, info_ptr, &intent)
+      png_set_sRGB(png_ptr, intent, 0);
+   else 
+      if (png_get_gAMA(png_ptr, info_ptr, &image_gamma)
+         png_set_gamma(png_ptr, screen_gamma, image_gamma);
+      else
+         png_set_gamma(png_ptr, screen_gamma, 0.50);
 
    /* Dither RGB files down to 8 bit palette or reduce palettes
-      to the number of colors available on your screen */
+    * to the number of colors available on your screen.
+    */
    if (color_type & PNG_COLOR_MASK_COLOR)
    {
       png_uint_32 num_palette;
@@ -241,7 +255,7 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
    }
 
    /* invert monocrome files to have 0 as white and 1 as black */
-   png_set_invert(png_ptr);
+   png_set_invert_mono(png_ptr);
 
    /* If you want to shift the pixel values from the range [0,255] or
     * [0,65535] to the original [0,7] or [0,31], or whatever range the
@@ -269,19 +283,19 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
 
    /* Turn on interlace handling.  REQUIRED if you are not using
     * png_read_image().  To see how to handle interlacing passes,
-    * see the png_read_row() method below.
+    * see the png_read_row() method below:
     */
    number_passes = png_set_interlace_handling(png_ptr);
 
-   /* optional call to gamma correct and add the background to the palette
+   /* Optional call to gamma correct and add the background to the palette
     * and update info structure.  REQUIRED if you are expecting libpng to
     * update the palette for you (ie you selected such a transform above).
     */
    png_read_update_info(png_ptr, info_ptr);
 
-   /* allocate the memory to hold the image using the fields of info_ptr. */
+   /* Allocate the memory to hold the image using the fields of info_ptr. */
 
-   /* the easiest way to read the image */
+   /* The easiest way to read the image: */
    png_bytep row_pointers[height];
 
    for (row = 0; row < height; row++)
@@ -294,7 +308,7 @@ void read_png(FILE *fp, unsigned int sig_read)  /* file is already open */
    png_read_image(png_ptr, row_pointers);
 
 **** Read the image one or more scanlines at a time ****
-   /* the other way to read images - deal with interlacing */
+   /* The other way to read images - deal with interlacing: */
 
    for (pass = 0; pass < number_passes; pass++)
    {
@@ -535,7 +549,7 @@ void write_png(char *file_name, ... other image information ...)
       PNG_INTERLACE_????, PNG_COMPRESSION_TYPE_BASE, PNG_FILTER_TYPE_BASE);
 
    /* set the palette if there is one.  REQUIRED for indexed-color images */
-   palette = png_malloc(png_ptr, 256 * sizeof (png_color));
+   palette = (png_colorp)png_malloc(png_ptr, 256 * sizeof (png_color));
    ... set palette colors ...
    png_set_PLTE(png_ptr, info_ptr, palette, 256);
 
@@ -552,7 +566,8 @@ void write_png(char *file_name, ... other image information ...)
 
   
    /* Optional gamma chunk is strongly suggested if you have any guess
-    * as to the correct gamma of the image. */
+    * as to the correct gamma of the image.
+    */
    png_set_gAMA(png_ptr, info_ptr, gamma);
 
    /* Optionally write comments into the image */
@@ -568,6 +583,8 @@ void write_png(char *file_name, ... other image information ...)
    png_set_text(png_ptr, info_ptr, text_ptr, 2);
 
    /* other optional chunks like cHRM, bKGD, tRNS, tIME, oFFs, pHYs, */
+   /* note that if sRGB is present the cHRM chunk must be ignored
+    * on read and must be written in accordance with the sRGB profile */
 
    /* Write the file header information.  REQUIRED */
    png_write_info(png_ptr, info_ptr);
@@ -579,13 +596,15 @@ void write_png(char *file_name, ... other image information ...)
     */
 
    /* set up the transformations you want.  Note that these are
-    * all optional.  Only call them if you want them. */
+    * all optional.  Only call them if you want them.
+    */
 
    /* invert monocrome pixels */
-   png_set_invert(png_ptr);
+   png_set_invert_mono(png_ptr);
 
    /* Shift the pixels up to a legal bit depth and fill in
-    * as appropriate to correctly scale the image */
+    * as appropriate to correctly scale the image.
+    */
    png_set_shift(png_ptr, &sig_bit);
 
    /* pack pixels into bytes */
@@ -595,7 +614,8 @@ void write_png(char *file_name, ... other image information ...)
    png_set_swap_alpha(png_ptr);
 
    /* Get rid of filler (OR ALPHA) bytes, pack XRGB/RGBX/ARGB/RGBA into
-    * RGB (4 channels -> 3 channels). The second parameter is not used. */
+    * RGB (4 channels -> 3 channels). The second parameter is not used.
+    */
    png_set_filler(png_ptr, 0, PNG_FILLER_BEFORE);
 
    /* flip BGR pixels to RGB */

libpng.txt

@@ -1,11 +1,17 @@
 libpng.txt - a description on how to use and modify libpng
 
-   libpng 1.0 beta 5 - version 0.95
-   Updated and distributed by Andreas Dilger <adilger@enel.ucalgary.ca>,
-   Copyright (c) 1996, 1997 Andreas Dilger
-   March 15, 1997
+   libpng version 0.99a
+   Updated and distributed by Glenn Randers-Pehrson <randeg@alumni.rpi.edu>
+   Copyright (c) 1998, Glenn Randers-Pehrson
+   January 31, 1998
+
       based on:
 
+   libpng 1.0 beta 6  version 0.96
+   Updated and distributed by Andreas Dilger 
+   Copyright (c) 1996, 1997 Andreas Dilger
+   May 28, 1997
+
    libpng 1.0 beta 2 - version 0.88
    For conditions of distribution and use, see copyright notice in png.h
    Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
@@ -26,12 +32,19 @@ it is heavily commented and should include everything most people
 will need.
 
 Libpng was written as a companion to the PNG specification, as a way
-to reduce the amount of time and effort it takes to support the PNG
-file format in application programs.  Most users will not have to
-modify the library significantly; advanced users may want to modify it
-more.  All attempts were made to make it as complete as possible,
-while keeping the code easy to understand.  Currently, this library
-only supports C.  Support for other languages is being considered.
+of reducing the amount of time and effort it takes to support the PNG
+file format in application programs.  The PNG specification is available
+as RFC 2083 <ftp://ftp.uu.net/graphics/png/documents/> and as a
+W3C Recommendation <http://www.w3.org/pub/WWW/TR/REC.png.html>. Some
+additional chunks are described in the special-purpose public chunks
+documents at <ftp://ftp.uu.net/graphics/png/documents/>.  Other information
+about PNG can be found at the PNG home page, <http://www.cdrom.com/pub/png/>.
+
+Most users will not have to modify the library significantly; advanced
+users may want to modify it more.  All attempts were made to make it as
+complete as possible, while keeping the code easy to understand.
+Currently, this library only supports C.  Support for other languages
+is being considered.
 
 Libpng has been designed to handle multiple sessions at one time,
 to be easily modifiable, to be portable to the vast majority of
@@ -39,12 +52,14 @@ machines (ANSI, K&R, 16-, 32-, and 64-bit) available, and to be easy
 to use.  The ultimate goal of libpng is to promote the acceptance of
 the PNG file format in whatever way possible.  While there is still
 work to be done (see the TODO file), libpng should cover the
-majority of the needs of it's users.
+majority of the needs of its users.
 
 Libpng uses zlib for its compression and decompression of PNG files.
 The zlib compression utility is a general purpose utility that is
 useful for more than PNG files, and can be used without libpng.
 See the documentation delivered with zlib for more details.
+You can usually find the source files for the zlib utility wherever you
+find the libpng source files.
 
 Libpng is thread safe, provided the threads are using different
 instances of the structures.  Each thread should have its own
@@ -59,13 +74,15 @@ II. Structures
 There are two main structures that are important to libpng, png_struct
 and png_info.  The first, png_struct, is an internal structure that
 will not, for the most part, be used by a user except as the first
-variable passed to every libpng function call.
+variable passed to every libpng function call.  It is not actually
+used in many of the functions; do not be alarmed about compiler
+warnings that say something to the effect that "png_ptr is not used."
 
 The png_info structure is designed to provide information about the
 PNG file.  At one time, the fields of png_info were intended to be
 directly accessible to the user.  However, this tended to cause problems
 with applications using dynamically loaded libraries, and as a result
-a set of interface functions for png_info were delevoped.  The fields
+a set of interface functions for png_info was developed.  The fields
 of png_info are still available for older applications, but it is
 suggested that applications use the new interfaces if at all possible.
 
@@ -183,6 +200,19 @@ libpng know that there are some bytes missing from the start of the file.
 
     png_set_sig_bytes(png_ptr, number);
 
+In PNG files, the alpha channel in an image is the level of opacity.
+If you need the alpha channel in an image to be the level of transparency
+instead of opacity, you can invert the alpha channel (or the tRNS chunk
+data) after it's read, so that 0 is fully opaque and 255 (in 8-bit or
+paletted images) or 65535 (in 16-bit images) is fully transparent, with
+
+    png_set_invert_alpha(png_ptr);
+
+This has to appear here rather than later with the other transformations
+because the tRNS chunk data must be modified in the case of paletted images.
+If your image is not a paletted image, the tRNS data (which in such cases
+represents a single color to be rendered as transparent) won't be changed.
+
 You are now ready to read all the file information up to the actual
 image data.  You do this with a call to png_read_info().
 
@@ -209,9 +239,11 @@ Functions are used to get the information from the info_ptr:
                      PNG_COLOR_MASK_COLOR
                      PNG_COLOR_MASK_ALPHA
 
-    interlace_type - PNG_INTERLACE_TYPE_NONE or PNG_INTERLACE_TYPE_ADAM7
-    compression_type - (must be PNG_COMPRESSION_TYPE_BASE for PNG 1.0)
     filter_type    - (must be PNG_FILTER_TYPE_BASE for PNG 1.0)
+    compression_type - (must be PNG_COMPRESSION_TYPE_BASE for PNG 1.0)
+    interlace_type - (PNG_INTERLACE_TYPE_NONE or PNG_INTERLACE_TYPE_ADAM7)
+    Any or all of interlace_type, compression_type, of filter_type can be
+    NULL if you are not interested in their values.
 
     channels = png_get_channels(png_ptr, info_ptr);
     channels       - number of channels of info for the color type
@@ -227,6 +259,17 @@ Functions are used to get the information from the info_ptr:
                      already read in 4 bytes of signature before staring
                      libpng, the remaining 4 bytes would be in signature[4]
                      through signature[7] (see png_set_sig_bytes())).
+    
+Information from each if the IHDR fields can be retrieve separately as well:
+
+    width            = png_get_image_width(png_ptr, info_ptr);
+    height           = png_get_image_height(png_ptr, info_ptr);
+    bit_depth        = png_get_bit_depth(png_ptr, info_ptr);
+    color_type       = png_get_color_type(png_ptr, info_ptr);
+    filter_type      = png_get_filter_type(png_ptr, info_ptr);
+    compression_type = png_get_compression_type(png_ptr, info_ptr);
+    interlace_type   = png_get_interlace_type(png_ptr, info_ptr);
+
 
 These are also important, but their validity depends on whether the chunk
 has been read.  The png_get_valid(png_ptr, info_ptr, PNG_INFO_<chunk>) and
@@ -242,6 +285,12 @@ into the info_ptr is returned for any complex types.
     png_get_gAMA(png_ptr, info_ptr, &gamma);
     gamma          - the gamma the file is written at (PNG_INFO_gAMA)
 
+    png_get_sRGB(png_ptr, info_ptr, &srgb_intent);
+    srgb_intent    - the rendering intent (PNG_INFO_sRGB)
+                     The presence of the sRGB chunk means that the pixel
+                     data is in the sRGB color space.  This chunk also
+                     implies specific values of gAMA and cHRM.
+
     png_get_sBIT(png_ptr, info_ptr, &sig_bit);
     sig_bit        - the number of significant bits for (PNG_INFO_sBIT)
                      the gray, red, green, and blue channels, whichever
@@ -280,6 +329,15 @@ into the info_ptr is returned for any complex types.
     res_y          - pixels/unit physical resolution in x direction
     unit_type      - PNG_RESOLUTION_UNKOWN, PNG_RESOLUTION_METER
 
+The data from the pHYs chunk can be retrieved in several convenient
+forms:
+
+    res_x_and_y = png_get_pixels_per_meter(png_ptr, info_ptr)
+    aspect_ratio = png_get_pixel_aspect_ratio(png_ptr, info_ptr)
+
+   (Each of these returns 0 [signifying "unknown"] if the data is not
+     present or if res_x is 0; res_x_and_y is 0 if res_x != res_y)
+
 For more information, see the png_info definition in png.h and the
 PNG specification for chunk contents.  Be careful with trusting
 rowbytes, as some of the transformations could increase the space
@@ -291,9 +349,9 @@ keyword/text pairs, one pair per chunk, with no limit on the number
 of text chunks, and a 2^31 byte limit on their size.  While there are
 suggested keywords, there is no requirement to restrict the use to these
 strings.  It is strongly suggested that keywords and text be sensible
-to humans (that's the point), so don't use abbreviations or non-printing
-symbols.  See the PNG specification for more details.  There is also
-no requirement to have text after the keyword.
+to humans (that's the point), so don't use abbreviations.  Non-printing
+symbols are not allowed.  See the PNG specification for more details.
+There is also no requirement to have text after the keyword.
 
 Keywords should be limited to 79 Latin-1 characters without leading or
 trailing spaces, but non-consecutive spaces are allowed within the
@@ -341,7 +399,7 @@ transparency information in a tRNS chunk.  This is most useful on
 grayscale images with bit depths of 2 or 4 or if there is a multiple-image
 viewing application that wishes to treat all images in the same way.
 
-    if (color_type == PNG_COLOR_TYPE_PALETTE && bit_depth < 8)
+    if (color_type == PNG_COLOR_TYPE_PALETTE && bit_depth <= 8)
         png_set_expand(png_ptr);
 
     if (color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8)
@@ -356,8 +414,21 @@ PNG can have files with 16 bits per channel.  If you only can handle
     if (bit_depth == 16)
         png_set_strip_16(png_ptr);
 
+The png_set_background() function tells libpng to composite images
+with alpha or simple transparency against the supplied background
+color.  If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
+you may use this color, or supply another color more suitable for
+the current display (e.g., the background color from a web page).  You
+need to tell libpng whether the color is in the gamma space of the
+display (PNG_BACKGROUND_GAMMA_SCREEN for colors you supply), the file
+(PNG_BACKGROUND_GAMMA_FILE for colors from the bKGD chunk), or one
+that is neither of these gammas (PNG_BACKGROUND_GAMMA_UNIQUE - I don't
+know why anyone would use this, but it's here).
+
 If, for some reason, you don't need the alpha channel on an image,
-and you want to remove it rather than combining it with the background:
+and you want to remove it rather than combining it with the background
+(but the image author certainly had in mind that you *would* combine
+it with the background, so that's what you should probably do):
 
     if (color_type & PNG_COLOR_MASK_ALPHA)
         png_set_strip_alpha(png_ptr);
@@ -371,7 +442,7 @@ values of the pixels:
         png_set_packing(png_ptr);
 
 PNG files have possible bit depths of 1, 2, 4, 8, and 16.  All pixels
-stored in a PNG image whave been "scaled" or "shifted" up to the next
+stored in a PNG image have been "scaled" or "shifted" up to the next
 higher possible bit depth (eg from 5 bits/sample in the range [0,31] to
 8 bits/sample in the range [0, 255]).  However, it is also possible to
 convert the PNG pixel data back to the original bit depth of the image.
@@ -413,17 +484,6 @@ RGB.  This code will do that conversion:
         color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
           png_set_gray_to_rgb(png_ptr);
 
-The png_set_background() function tells libpng to composite images
-with alpha or simple transparency against the supplied background
-color.  If the PNG file contains a bKGD chunk (PNG_INFO_bKGD valid),
-you may use this color, or supply another color more suitable for
-the current display (e.g., the background color from a web page).  You
-need to tell libpng whether the color is in the gamma space of the
-dispay (PNG_BACKGROUND_GAMMA_SCREEN for colors you supply), the file
-(PNG_BACKGROUND_GAMMA_FILE for colors from the bKGD chunk), or one
-that is neither of these gammas (PNG_BACKGROUND_GAMMA_UNIQUE - I don't
-know why anyone would use this, but it's here).
-
 If you have a grayscale and you are using png_set_expand() to change to
 a higher bit-depth you must indicate if the supplied background gray
 is supplied in the original file bit depth (need_expand = 1) or in the
@@ -447,28 +507,40 @@ To properly display PNG images on any kind of system, the application needs
 to know what the display gamma is.  Ideally, the user will know this, and
 the application will allow them to set it.  One method of allowing the user
 to set the display gamma separately for each system is to check for the
-DISPLAY_GAMMA environment variable, which will hopefully be correctly set.
+DISPLAY_GAMMA and VIEWING_GAMMA environment variables or for a SCREEN_GAMMA
+environment variable, which will hopefully be correctly set.
+
+Note that display_gamma is the gamma of your display, while screen_gamma is
+the overall gamma correction required to produce pleasing results,
+which depends on the lighting conditions in the surrounding environment.
+Screen_gamma is display_gamma/viewing_gamma, where viewing_gamma is
+the amount of additional gamma correction needed to compensate for
+a dim (viewing_gamma=1.125) or dark (viewing_gamma=1.25) environment.
+In a brightly lit room, no compensation other than the display_gamma
+is needed (viewing_gamma=1.0).
 
    if (/* We have a user-defined screen gamma value */)
    {
       screen_gamma = user_defined_screen_gamma;
    }
    /* One way that applications can share the same screen gamma value */
-   else if ((gamma_str = getenv("DISPLAY_GAMMA")) != NULL)
+   else if ((gamma_str = getenv("SCREEN_GAMMA")) != NULL)
    {
       screen_gamma = atof(gamma_str);
    }
    /* If we don't have another value */
    else
    {
-      screen_gamma = 2.2;  /* A good guess for PC monitors */
+      screen_gamma = 2.5; /* A good guess for a PC monitor in a bright office */
+      screen_gamma = 2.2; /* A good guess for a PC monitor in a dim room */
+      screen_gamma = 2.0; /* A good guess for a PC monitor in a dark room */
       screen_gamma = 1.7 or 1.0;  /* A good guess for Mac systems */
    }
 
 The png_set_gamma() function handles gamma transformations of the data.
 Pass both the file gamma and the current screen_gamma.  If the file does
 not have a gamma value, you can pass one anyway if you have an idea what
-it is (usually 0.45 is a good guess for GIF images on PCs).  Note
+it is (usually 0.50 is a good guess for GIF images on PCs).  Note
 that file gammas are inverted from screen gammas.  See the discussions
 on gamma in the PNG specification for an excellent description of what
 gamma is, and why all applications should support it.  It is strongly
@@ -477,7 +549,7 @@ recommended that PNG viewers support gamma correction.
    if (png_get_gAMA(png_ptr, info_ptr, &gamma))
       png_set_gamma(png_ptr, screen_gamma, gamma);
    else
-      png_set_gamma(png_ptr, screen_gamma, 0.45);
+      png_set_gamma(png_ptr, screen_gamma, 0.50);
 
 If you need to reduce an RGB file to a paletted file, or if a paletted
 file has more entries then will fit on your screen, png_set_dither()
@@ -532,15 +604,16 @@ need to change the order the pixels are packed into bytes, you can use:
        png_set_packswap(png_ptr);
 
 The last thing to handle is interlacing; this is covered in detail below,
-but you must call the function here.
+but you must call the function here if you want libpng to handle expansion
+of the interlaced image.
 
-    number_passes = png_set_interlace_handling(png_ptr);
+    number_of_passes = png_set_interlace_handling(png_ptr);
 
 After setting the transformations, libpng can update your png_info
 structure to reflect any transformations you've requested with this
 call.  This is most useful to update the info structure's rowbytes
 field so you can use it to allocate your image memory.  This function
-will also update your palette with the correct display gamma and
+will also update your palette with the correct screen_gamma and
 background if these have been given with the calls above.
 
     png_read_update_info(png_ptr, info_ptr);
@@ -572,7 +645,7 @@ where row_pointers is:
 
 You can point to void or char or whatever you use for pixels.
 
-If you don't want to read int the whole image at once, you can
+If you don't want to read in the whole image at once, you can
 use png_read_rows() instead.  If there is no interlacing (check
 interlace_type == PNG_INTERLACE_TYPE_NONE), this is simple:
 
@@ -589,24 +662,24 @@ row_pointers:
 If the file is interlaced (info_ptr->interlace_type != 0), things get
 somewhat harder.  The only current (PNG Specification version 1.0)
 interlacing type for PNG is (interlace_type == PNG_INTERLACE_TYPE_ADAM7)
-is a someewhat complicated 2D interlace scheme, known as Adam7, that
+is a somewhat complicated 2D interlace scheme, known as Adam7, that
 breaks down an image into seven smaller images of varying size, based
 on an 8x8 grid.
 
 libpng can fill out those images or it can give them to you "as is".
 If you want them filled out, there are two ways to do that.  The one
 mentioned in the PNG specification is to expand each pixel to cover
-those pixels that have not been read yet.  This results in a blocky
-image for the first pass, which gradually smoothes out as more pixels
-are read.  The other method is the "sparkle" method, where pixels are
-draw only in their final locations, with the rest of the image remaining
-whatever colors they were initialized to before the start of the read.
-The first method usually looks better, but tends to be slower, as there
-are more pixels to put in the rows.
+those pixels that have not been read yet (the "rectangle" method).
+This results in a blocky image for the first pass, which gradually
+smooths out as more pixels are read.  The other method is the "sparkle"
+method, where pixels are drawn only in their final locations, with the
+rest of the image remaining whatever colors they were initialized to
+before the start of the read.  The first method usually looks better,
+but tends to be slower, as there are more pixels to put in the rows.
 
 If you don't want libpng to handle the interlacing details, just call
 png_read_rows() seven times to read in all seven images.  Each of the
-images are valid images by themselves, or they can be combined on an
+images is a valid image by itself, or they can all be combined on an
 8x8 grid to form a single image (although if you intend to combine them
 you would be far better off using the libpng interlace handling).
 
@@ -614,7 +687,7 @@ The first pass will return an image 1/8 as wide as the entire image
 (every 8th column starting in column 0) and 1/8 as high as the original
 (every 8th row starting in row 0), the second will be 1/8 as wide
 (starting in column 4) and 1/8 as high (also starting in row 0).  The
-third pass will be 1/4 as wide (every 4th pixel starting in row 0) and
+third pass will be 1/4 as wide (every 4th pixel starting in column 0) and
 1/8 as high (every 8th row starting in row 4), and the fourth pass will
 be 1/4 as wide and 1/4 as high (every 4th column starting in column 2,
 and every 4th row starting in row 0).  The fifth pass will return an
@@ -628,7 +701,7 @@ If you want libpng to expand the images, call this before calling
 png_start_read_image() or png_read_update_info():
 
     if (interlace_type == PNG_INTERLACE_TYPE_ADAM7)
-        number_passes = png_set_interlace_handling(png_ptr);
+        number_of_passes = png_set_interlace_handling(png_ptr);
 
 This will return the number of passes needed.  Currently, this
 is seven, but may change if another interlace type is added.
@@ -639,12 +712,12 @@ If you are not going to display the image after each pass, but are
 going to wait until the entire image is read in, use the sparkle
 effect.  This effect is faster and the end result of either method
 is exactly the same.  If you are planning on displaying the image
-after each pass, the rectangle effect is generally considered the
+after each pass, the "rectangle" effect is generally considered the
 better looking one.
 
 If you only want the "sparkle" effect, just call png_read_rows() as
 normal, with the third parameter NULL.  Make sure you make pass over
-the image number_passes times, and you don't change the data in the
+the image number_of_passes times, and you don't change the data in the
 rows between calls.  You can change the locations of the data, just
 not the data.  Each pass only writes the pixels appropriate for that
 pass, and assumes the data from previous passes is still valid.
@@ -923,7 +996,7 @@ contain, see the PNG specification.
 Some of the more important parts of the png_info are:
 
     png_set_IHDR(png_ptr, info_ptr, width, height, bit_depth, color_type,
-       interlace_type,
+       interlace_type, compression_type, filter_type)
     width          - holds the width of the image in pixels (up to 2^31).
     height         - holds the height of the image in pixels (up to 2^31).
     bit_depth      - holds the bit depth of one of the image channels.
@@ -940,11 +1013,9 @@ Some of the more important parts of the png_info are:
                      PNG_COLOR_MASK_COLOR
                      PNG_COLOR_MASK_ALPHA
 
-    interlace_type - PNG_INTERLACE_TYPE_NONE or PNG_INTER_LACE_TYPE_ADAM7
+    interlace_type - PNG_INTERLACE_TYPE_NONE or PNG_INTERLACE_TYPE_ADAM7
     compression_type - (must be PNG_COMPRESSION_TYPE_DEFAULT for PNG 1.0)
     filter_type    - (must be PNG_FILTER_TYPE_DEFAULT for PNG 1.0)
-    Any or all of interlace_type, compression_type, of filter_type can be
-    NULL if you are not interested in their values.
 
     png_set_PLTE(png_ptr, info_ptr, palette, num_palette);
     palette        - the palette for the file (array of png_color)
@@ -953,6 +1024,25 @@ Some of the more important parts of the png_info are:
     png_set_gAMA(png_ptr, info_ptr, gamma);
     gamma          - the gamma the image was created at (PNG_INFO_gAMA)
 
+    png_set_sRGB(png_ptr, info_ptr, srgb_intent);
+    srgb_intent    - the rendering intent (PNG_INFO_sRGB)
+                     The presence of the sRGB chunk means that the pixel
+                     data is in the sRGB color space.  This chunk also
+                     implies specific values of gAMA and cHRM.
+                     Rendering intent is the CSS-1 property that has been
+                     defined by the International Color Consortium
+                     (http://www.color.org).  It can be one of
+                     PNG_SRGB_INTENT_SATURATION, PNG_SRGB_INTENT_PERCEPTUAL,
+                     PNG_SRGB_INTENT_ABSOLUTE, or PNG_SRGB_INTENT_RELATIVE.
+                        
+
+    png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr, srgb_intent);
+    srgb_intent    - the rendering intent (PNG_INFO_sRGB)
+                     The presence of the sRGB chunk means that the pixel
+                     data is in the sRGB color space.  This chunk also
+                     causes gAMA and cHRM chunks with the specific values
+                     that are consistent with sRGB to be written.
+
     png_set_sBIT(png_ptr, info_ptr, sig_bit);
     sig_bit        - the number of significant bits for (PNG_INFO_sBIT)
                      the gray, red, green, and blue channels, whichever
@@ -986,11 +1076,25 @@ Some of the more important parts of the png_info are:
     offset_y       - positive offset from the top edge of the screen
     unit_type      - PNG_OFFSET_PIXEL, PNG_OFFSET_MICROMETER
 
-    png_get_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type);
+    png_set_pHYs(png_ptr, info_ptr, res_x, res_y, unit_type);
     res_x          - pixels/unit physical resolution in x direction
     res_y          - pixels/unit physical resolution in x direction
     unit_type      - PNG_RESOLUTION_UNKOWN, PNG_RESOLUTION_METER
 
+In PNG files, the alpha channel in an image is the level of opacity.
+If your data is supplied as a level of transparency, you can invert the
+alpha channel before you write it, so that 0 is fully transparent and 255
+(in 8-bit or paletted images) or 65535 (in 16-bit images) is fully opaque,
+with
+
+    png_set_invert_alpha(png_ptr);
+
+This must appear here instead of later with the other transformations
+because in the case of paletted images the tRNS chunk data has to
+be inverted before the tRNS chunk is written.  If your image is not a
+paletted image, the tRNS data (which in such cases represents a single
+color to be rendered as transparent) won't be changed.
+
 A quick word about text and num_text.  text is an array of png_text
 structures.  num_text is the number of valid structures in the array.
 If you want, you can use max_text to hold the size of the array, but
@@ -1013,7 +1117,8 @@ The keywords that are given in the PNG Specification are:
             Author           Name of image's creator
             Description      Description of image (possibly long)
             Copyright        Copyright notice
-            Creation Time    Time of original image creation
+            Creation Time    Time of original image creation (usually
+                             RFC 1123 format, see below)
             Software         Software used to create the image
             Disclaimer       Legal disclaimer
             Warning          Warning of nature of content
@@ -1050,6 +1155,20 @@ instead of your local time.  Note that the year number is the full
 year (ie 1996, rather than 96 - PNG is year 2000 compliant!), and
 that months start with 1.
 
+If you want to store the time of the original image creation, you should
+use a plain tEXt chunk with the "Creation Time" keyword.  This is
+necessary because the "creation time" of a PNG image is somewhat vague,
+depending on whether you mean the PNG file, the time the image was
+created in a non-PNG format, a still photo from which the image was
+scanned, or possibly the subject matter itself.  In order to facilitate
+machine-readable dates, it is recommended that the "Creation Time"
+tEXt chunk use RFC 1123 format dates (eg 22 May 1997 18:07:10 GMT"),
+although this isn't a requirement.  Unlike the tIME chunk, the
+"Creation Time" tEXt chunk is not expected to be automatically changed
+by the software.  To facilitate the use of RFC 1123 dates, a function
+png_convert_to_rfc1123(png_timep) is provided to convert from PNG
+time to an RFC 1123 format string.
+
 You are now ready to write all the file information up to the actual
 image data.  You do this with a call to png_write_info().
 
@@ -1133,7 +1252,7 @@ PNG files describe monochrome as black being zero and white being
 one. This code would be used if the pixels are supplied with this reversed
 (black being one and white being zero):
 
-    png_set_invert(png_ptr);
+    png_set_invert_mono(png_ptr);
 
 It is possible to have libpng flush any pending output, either manually,
 or automatically after a certain number of lines have been written.  To
@@ -1204,12 +1323,12 @@ correct number of times to write all seven sub-images.
 If you want libpng to build the sub-images, call this before you start
 writing any rows:
 
-    number_passes = png_set_interlace_handling(png_ptr);
+    number_of_passes = png_set_interlace_handling(png_ptr);
 
 This will return the number of passes needed.  Currently, this
 is seven, but may change if another interlace type is added.
 
-Then write the complete image number_passes times.
+Then write the complete image number_of_passes times.
 
     png_write_rows(png_ptr, row_pointers, number_of_rows);
 
@@ -1219,8 +1338,8 @@ and only update the rows that are actually used.
 
 After you are finished writing the image, you should finish writing
 the file.  If you are interested in writing comments or time, you should
-pass the an appropriately filled png_info pointer.  If you
-are not interested, you can pass NULL.
+pass an appropriately filled png_info pointer.  If you are not interested,
+you can pass NULL.
 
     png_write_end(png_ptr, info_ptr);
 
@@ -1255,7 +1374,7 @@ MAXSEG_64K in zlib.h.  Since it is unlikely that the method of handling
 memory allocation on a platform will change between applications, these
 functions must be modified in the library at compile time.
 
-Input/Output in libpng is done throught png_read() and png_write(),
+Input/Output in libpng is done through png_read() and png_write(),
 which currently just call fread() and fwrite().  The FILE * is stored in
 png_struct and is initialized via png_init_io().  If you wish to change
 the method of I/O, the library supplies callbacks that you can set
@@ -1307,8 +1426,8 @@ default function will be used, calling fprintf() and/or longjmp() if a
 problem is encountered.  The replacement error functions should have
 parameters as follows:
 
-    void user_error_fn(png_struct png_ptr, png_const_charp error_msg);
-    void user_warning_fn(png_struct png_ptr, png_const_charp warning_msg);
+    void user_error_fn(png_structp png_ptr, png_const_charp error_msg);
+    void user_warning_fn(png_structp png_ptr, png_const_charp warning_msg);
 
 The motivation behind using setjmp() and longjmp() is the C++ throw and
 catch exception handling methods.  This makes the code much easier to write,
@@ -1353,7 +1472,7 @@ call.  See zlib.h or zconf.h in the zlib library for more information.
 Configuring for Medium Model:
 
 Libpng's support for medium model has been tested on most of the popular
-complers.  Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
+compilers.  Make sure MAXSEG_64K gets defined, USE_FAR_KEYWORD gets
 defined, and FAR gets defined to far in pngconf.h, and you should be
 all set.  Everything in the library (except for zlib's structure) is
 expecting far data.  You must use the typedefs with the p or pp on
@@ -1385,8 +1504,8 @@ most useful one changes the compression level, which currently uses
 input compression values in the range 0 - 9.  The library normally
 uses the default compression level (Z_DEFAULT_COMPRESSION = 6).  Tests
 have shown that for a large majority of images, compression values in
-the range 3-6 compress as well as higher levels, and do so much faster.
-For online applications it may be desirable to have maximum speed
+the range 3-6 compress nearly as well as higher levels, and do so much
+faster.  For online applications it may be desirable to have maximum speed
 (Z_BEST_SPEED = 1).  With versions of zlib after v0.99, you can also
 specify no compression (Z_NO_COMPRESSION = 0), but this would create
 files larger than just storing the raw bitmap.  You can specify the
@@ -1412,14 +1531,19 @@ Controlling row filtering:
 
 If you want to control whether libpng uses filtering or not, which
 filters are used, and how it goes about picking row filters, you
-can call one of these functions.  Filtering is enabled by default for
-RGB and grayscale images (with and without alpha), and for 8-bit
-paletted images, but not for paletted images with bit depths less
-than 8 bits/pixel.  The 'method' parameter sets the main filtering
-method, which is currently only '0' in the PNG 1.0 specification.
-The 'filters' parameter sets which filter(s), if any, should be
-used for each scanline.  Possible values are PNG_ALL_FILTERS and
-PNG_NO_FILTERS to turn filtering on and off, respectively.
+can call one of these functions.  The selection and configuration
+of row filters can have a significant impact on the size and
+encoding speed and a somewhat lesser impact on the decoding speed
+of an image.  Filtering is enabled by default for RGB and grayscale
+images (with and without alpha), and for 8-bit paletted images, but
+not for paletted images with bit depths less than 8 bits/pixel.
+
+The 'method' parameter sets the main filtering method, which is
+currently only '0' in the PNG 1.0 specification.  The 'filters'
+parameter sets which filter(s), if any, should be used for each
+scanline.  Possible values are PNG_ALL_FILTERS and PNG_NO_FILTERS
+to turn filtering on and off, respectively.
+
 Individual filter types are PNG_FILTER_NONE, PNG_FILTER_SUB,
 PNG_FILTER_UP, PNG_FILTER_AVG, PNG_FILTER_PAETH, which can be bitwise
 ORed together '|' to specify one or more filters to use.  These
@@ -1470,8 +1594,18 @@ Removing unwanted object code:
 There are a bunch of #define's in pngconf.h that control what parts of
 libpng are compiled.  All the defines end in _SUPPORTED.  If you are
 never going to use an ability, you can change the #define to #undef
-before recompiling libpng and save yourself code and data space.  All
-the reading and writing specific code are in seperate files, so the
+before recompiling libpng and save yourself code and data space.
+You can also turn them off en masse with a compiler directive that
+defines PNG_READ[or WRITE]_NOT_FULLY_SUPPORTED, or
+PNG_READ[or WRITE]_ANCILLARY_CHUNKS_NOT_SUPPORTED, or all four,
+along with directives to turn on any of the capabilities that you do
+want.  The NOT_FULLY_SUPPORTED directives disable the extra
+transformations but still leave the library fully capable of reading
+and writing PNG files with all known public chunks [except for sPLT].
+Use of the PNG_READ[or WRITE]_ANCILLARY_CHUNKS_NOT_SUPPORTED directive
+produces a library that is incapable of reading or writing ancillary chunks.
+
+All the reading and writing specific code are in separate files, so the
 linker should only grab the files it needs.  However, if you want to
 make sure, or if you are building a stand alone library, all the
 reading files start with pngr and all the writing files start with
@@ -1489,10 +1623,12 @@ those sections which are actually used will be loaded into memory.
 
 Changes to Libpng from version 0.88
 
-It should be noted that versions of libpng later than 0.88 are not
-distributed by the original libpng author, Guy Schalnat, but rather
-another member of the original PNG Group, Andreas Dilger.  Guy is still
-alive and well, but he has moved on to other things.
+It should be noted that versions of libpng later than 0.96 are not
+distributed by the original libpng author, Guy Schalnat, nor by
+Andreas Dilger, who had taken over from Guy during 1996 and 1997, and
+distributed versions 0.89 through 0.96, but rather by another member
+of the original PNG Group, Glenn Randers-Pehrson.  Guy and Andreas are
+still alive and well, but they have moved on to other things.
 
 The old libpng functions png_read_init(), png_write_init(),
 png_info_init(), png_read_destroy(), and png_write_destory() have been

makefile.dec

@@ -0,0 +1,68 @@
+# makefile for libpng on DEC Alpha Unix
+# Copyright (C) 1995 Guy Eric Schalnat, Group 42, Inc.
+# For conditions of distribution and use, see copyright notice in png.h
+
+# Where the zlib library and include files are located
+#ZLIBLIB=/usr/local/lib
+#ZLIBINC=/usr/local/include
+ZLIBLIB=../zlib
+ZLIBINC=../zlib
+
+CC=cc
+CFLAGS=-std -w1 -I$(ZLIBINC) -O # -g -DPNG_DEBUG=1
+LDFLAGS=-L. -L$(ZLIBLIB) -lpng -lz -lm
+
+#RANLIB=echo
+RANLIB=ranlib
+
+# where make install puts libpng.a and png.h
+prefix=/usr/local
+
+OBJS = png.o pngset.o pngget.o pngrutil.o pngtrans.o pngwutil.o \
+	pngread.o pngrio.o pngwio.o pngwrite.o pngrtran.o \
+	pngwtran.o pngmem.o pngerror.o pngpread.o
+
+all: libpng.a pngtest
+
+libpng.a: $(OBJS)
+	ar rc $@  $(OBJS)
+	$(RANLIB) $@
+
+pngtest: pngtest.o libpng.a
+	$(CC) -o pngtest $(CCFLAGS) pngtest.o $(LDFLAGS)
+
+test: pngtest
+	./pngtest
+
+install: libpng.a
+	-@mkdir $(prefix)/include
+	-@mkdir $(prefix)/lib
+	cp png.h $(prefix)/include
+	cp pngconf.h $(prefix)/include
+	chmod 644 $(prefix)/include/png.h
+	chmod 644 $(prefix)/include/pngconf.h
+	cp libpng.a $(prefix)/lib
+	chmod 644 $(prefix)/lib/libpng.a
+
+clean:
+	rm -f *.o libpng.a pngtest pngout.png
+
+# DO NOT DELETE THIS LINE -- make depend depends on it.
+
+png.o: png.h pngconf.h
+pngerror.o: png.h pngconf.h
+pngrio.o: png.h pngconf.h
+pngwio.o: png.h pngconf.h
+pngmem.o: png.h pngconf.h
+pngset.o: png.h pngconf.h
+pngget.o: png.h pngconf.h
+pngread.o: png.h pngconf.h
+pngrtran.o: png.h pngconf.h
+pngrutil.o: png.h pngconf.h
+pngtest.o: png.h pngconf.h
+pngtrans.o: png.h pngconf.h
+pngwrite.o: png.h pngconf.h
+pngwtran.o: png.h pngconf.h
+pngwutil.o: png.h pngconf.h
+pngpread.o: png.h pngconf.h
+

makefile.elf

@@ -1,5 +1,6 @@
-# makefile for libpng on (linux) ELF
+# makefile for libpng on Linux ELF with gcc
 # Copyright (C) 1996, 1997 Andreas Dilger
+# Copyright (C) 1998 Greg Roelofs
 # For conditions of distribution and use, see copyright notice in png.h
 
 CC=gcc
@@ -13,14 +14,15 @@ ZLIBINC=../zlib
 WARNMORE=-Wwrite-strings -Wpointer-arith -Wshadow \
          -Wmissing-declarations -Wtraditional -Wcast-align \
          -Wstrict-prototypes -Wmissing-prototypes #-Wconversion
-CFLAGS=-I$(ZLIBINC) -Wall -O2 -fPIC # $(WARNMORE) # -g -DPNG_DEBUG=3
+CFLAGS=-I$(ZLIBINC) -Wall -O3 -funroll-loops -malign-loops=2 \
+       -malign-functions=2 #$(WARNMORE) -g -DPNG_DEBUG=5
 LDFLAGS=-L. -Wl,-rpath,. -L$(ZLIBLIB) -Wl,-rpath,$(ZLIBLIB) -lpng -lz -lm
 
 RANLIB=ranlib
 #RANLIB=echo
 
-PNGMAJ = 0
-PNGMIN = 96
+PNGMAJ = 2
+PNGMIN = 0.99
 PNGVER = $(PNGMAJ).$(PNGMIN)
 
 # where make install puts libpng.a, libpng.so*, and png.h
@@ -32,10 +34,17 @@ OBJS = png.o pngset.o pngget.o pngrutil.o pngtrans.o pngwutil.o \
        pngread.o pngrio.o pngwio.o pngwrite.o pngrtran.o \
        pngwtran.o pngmem.o pngerror.o pngpread.o
 
-all: libpng.so pngtest
+OBJSDLL = $(OBJS:.o=.pic.o)
+
+.SUFFIXES:      .c .o .pic.o
+
+.c.pic.o:
+	$(CC) -c $(CFLAGS) -fPIC -o $@ $*.c
+
+all: libpng.a libpng.so pngtest
 
 libpng.a: $(OBJS)
-	ar rc $@  $(OBJS)
+	ar rc $@ $(OBJS)
 	$(RANLIB) $@
 
 libpng.so: libpng.so.$(PNGMAJ)
@@ -44,43 +53,45 @@ libpng.so: libpng.so.$(PNGMAJ)
 libpng.so.$(PNGMAJ): libpng.so.$(PNGVER)
 	ln -sf libpng.so.$(PNGVER) libpng.so.$(PNGMAJ)
 
-libpng.so.$(PNGVER): $(OBJS)
-	gcc -shared -Wl,-soname,libpng.so.$(PNGMAJ) -o libpng.so.$(PNGVER) $(OBJS)
+libpng.so.$(PNGVER): $(OBJSDLL)
+	gcc -shared -Wl,-soname,libpng.so.$(PNGMAJ) -o libpng.so.$(PNGVER) \
+	 $(OBJSDLL)
 
 pngtest: pngtest.o libpng.so
-	$(CC) -o pngtest pngtest.o $(LDFLAGS)
+	$(CC) -o pngtest $(CFLAGS) pngtest.o $(LDFLAGS)
 
 test: pngtest
 	./pngtest
 
-install: libpng.so.$(PNGVER)
+install: libpng.a libpng.so.$(PNGVER)
 	-@mkdir $(INCPATH) $(LIBPATH)
 	cp png.h pngconf.h $(INCPATH)
 	chmod 644 $(INCPATH)/png.h $(INCPATH)/pngconf.h
-	cp libpng.so.$(PNGVER) $(LIBPATH)
+	cp libpng.a libpng.so.$(PNGVER) $(LIBPATH)
 	chmod 755 $(LIBPATH)/libpng.so.$(PNGVER)
-	-@/bin/rm $(LIBPATH)/libpng.so.$(PNGMAJ) $(LIBPATH)/libpng.so
+	-@/bin/rm -f $(LIBPATH)/libpng.so.$(PNGMAJ) $(LIBPATH)/libpng.so
 	(cd $(LIBPATH); ln -sf libpng.so.$(PNGVER) libpng.so.$(PNGMAJ); \
 	 ln -sf libpng.so.$(PNGMAJ) libpng.so)
 
 clean:
-	rm -f *.o libpng.a libpng.so* pngtest pngout.png
+	/bin/rm -f *.o libpng.a libpng.so* pngtest pngout.png
 
 # DO NOT DELETE THIS LINE -- make depend depends on it.
 
-png.o: png.h pngconf.h
-pngerror.o: png.h pngconf.h
-pngrio.o: png.h pngconf.h
-pngwio.o: png.h pngconf.h
-pngmem.o: png.h pngconf.h
-pngset.o: png.h pngconf.h
-pngget.o: png.h pngconf.h
-pngread.o: png.h pngconf.h
-pngrtran.o: png.h pngconf.h
-pngrutil.o: png.h pngconf.h
+png.o png.pic.o: png.h pngconf.h
+pngerror.o pngerror.pic.o: png.h pngconf.h
+pngrio.o pngrio.pic.o: png.h pngconf.h
+pngwio.o pngwio.pic.o: png.h pngconf.h
+pngmem.o pngmem.pic.o: png.h pngconf.h
+pngset.o pngset.pic.o: png.h pngconf.h
+pngget.o pngget.pic.o: png.h pngconf.h
+pngread.o pngread.pic.o: png.h pngconf.h
+pngrtran.o pngrtran.pic.o: png.h pngconf.h
+pngrutil.o pngrutil.pic.o: png.h pngconf.h
+pngtrans.o pngtrans.pic.o: png.h pngconf.h
+pngwrite.o pngwrite.pic.o: png.h pngconf.h
+pngwtran.o pngwtran.pic.o: png.h pngconf.h
+pngwutil.o pngwutil.pic.o: png.h pngconf.h
+pngpread.o pngpread.pic.o: png.h pngconf.h
+
 pngtest.o: png.h pngconf.h
-pngtrans.o: png.h pngconf.h
-pngwrite.o: png.h pngconf.h
-pngwtran.o: png.h pngconf.h
-pngwutil.o: png.h pngconf.h
-pngpread.o: png.h pngconf.h

makefile.min

@@ -0,0 +1,80 @@
+# makefile for libpng
+# Copyright (C) 1995 Guy Eric Schalnat, Group 42, Inc.
+# For conditions of distribution and use, see copyright notice in png.h
+
+# Where the zlib library and include files are located
+#ZLIBLIB=/usr/local/lib
+#ZLIBINC=/usr/local/include
+ZLIBLIB=../zlib
+ZLIBINC=../zlib
+
+CC=cc
+
+# CFLAGS=-I$(ZLIBINC) -O -fullwarn \
+#    -DPNG_NO_EASY_ACCESS
+
+CFLAGS=-I$(ZLIBINC) -O -fullwarn  \
+    -DPNG_READ_NOT_FULLY_SUPPORTED -DPNG_WRITE_NOT_FULLY_SUPPORTED
+
+#CFLAGS=-I$(ZLIBINC) -O -fullwarn -DPNGTEST_MEMORY_DEBUG \
+#    -DPNG_READ_NOT_FULLY_SUPPORTED -DPNG_WRITE_NOT_FULLY_SUPPORTED \
+#    -DPNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED \
+#    -DPNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED \
+#    -DPNG_NO_STDIO
+
+LDFLAGS=-L. -L$(ZLIBLIB) -lpng -lz -lm
+
+RANLIB=echo
+#RANLIB=ranlib
+
+# where make install puts libpng.a and png.h
+prefix=/usr/local
+
+OBJS = png.o pngset.o pngget.o pngrutil.o pngtrans.o pngwutil.o \
+	pngread.o pngrio.o pngwio.o pngwrite.o pngrtran.o \
+	pngwtran.o pngmem.o pngerror.o pngpread.o
+
+all: libpng.a pngtest
+
+libpng.a: $(OBJS)
+	ar rc $@  $(OBJS)
+	$(RANLIB) $@
+
+pngtest: pngtest.o libpng.a
+	$(CC) -o pngtest $(CCFLAGS) pngtest.o $(LDFLAGS)
+
+test: pngtest
+	./pngtest
+
+install: libpng.a
+	-@mkdir $(prefix)/include
+	-@mkdir $(prefix)/lib
+	cp png.h $(prefix)/include
+	cp pngconf.h $(prefix)/include
+	chmod 644 $(prefix)/include/png.h
+	chmod 644 $(prefix)/include/pngconf.h
+	cp libpng.a $(prefix)/lib
+	chmod 644 $(prefix)/lib/libpng.a
+
+clean:
+	rm -f *.o libpng.a pngtest pngout.png
+
+# DO NOT DELETE THIS LINE -- make depend depends on it.
+
+png.o: png.h pngconf.h
+pngerror.o: png.h pngconf.h
+pngrio.o: png.h pngconf.h
+pngwio.o: png.h pngconf.h
+pngmem.o: png.h pngconf.h
+pngset.o: png.h pngconf.h
+pngget.o: png.h pngconf.h
+pngread.o: png.h pngconf.h
+pngrtran.o: png.h pngconf.h
+pngrutil.o: png.h pngconf.h
+pngtest.o: png.h pngconf.h
+pngtrans.o: png.h pngconf.h
+pngwrite.o: png.h pngconf.h
+pngwtran.o: png.h pngconf.h
+pngwutil.o: png.h pngconf.h
+pngpread.o: png.h pngconf.h
+

makefile.sgi

@@ -9,11 +9,12 @@ ZLIBLIB=../zlib
 ZLIBINC=../zlib
 
 CC=cc
-CFLAGS=-I$(ZLIBINC) -O # -g -DPNG_DEBUG=1
+
+CFLAGS=-I$(ZLIBINC) -O -fullwarn # -g -DPNG_DEBUG=1
 LDFLAGS=-L. -L$(ZLIBLIB) -lpng -lz -lm
 
-#RANLIB=echo
-RANLIB=ranlib
+RANLIB=echo
+#RANLIB=ranlib
 
 # where make install puts libpng.a and png.h
 prefix=/usr/local

makefile.tc3

@@ -1,7 +1,7 @@
 # Makefile for libpng
 # TurboC++ 3.0 (Note: All modules are compiled in C mode)
 
-# To use, do "make -fmakefile.tc"
+# To use, do "make -fmakefile.tc3"
 
 # ------------- Turbo C++ 3.0 -------------
 MODEL=-ml

png.c

@@ -1,27 +1,30 @@
 
-/* png.c - location for general purpose png functions
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-   */
+/* png.c - location for general purpose libpng functions
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ */
 
 #define PNG_INTERNAL
 #define PNG_NO_EXTERN
 #include "png.h"
 
 /* Version information for C files.  This had better match the version
-   string defined in png.h */
-char png_libpng_ver[] = "0.95";
+ * string defined in png.h.
+ */
+char png_libpng_ver[6] = "0.99";
 
-/* Place to hold the signiture string for a PNG file. */
+/* Place to hold the signature string for a PNG file. */
 png_byte FARDATA png_sig[8] = {137, 80, 78, 71, 13, 10, 26, 10};
 
-/* constant strings for known chunk types.  If you need to add a chunk,
-   add a string holding the name here.  If you want to make the code
-   portable to EBCDIC machines, use ASCII numbers, not characters. */
+/* Constant strings for known chunk types.  If you need to add a chunk,
+ * add a string holding the name here.  If you want to make the code
+ * portable to EBCDIC machines, use ASCII numbers, not characters.
+ */
 png_byte FARDATA png_IHDR[5] = { 73,  72,  68,  82, '\0'};
 png_byte FARDATA png_IDAT[5] = { 73,  68,  65,  84, '\0'};
 png_byte FARDATA png_IEND[5] = { 73,  69,  78,  68, '\0'};
@@ -34,6 +37,7 @@ png_byte FARDATA png_oFFs[5] = {111,  70,  70, 115, '\0'};
 png_byte FARDATA png_pCAL[5] = {112,  67,  65,  76, '\0'};
 png_byte FARDATA png_pHYs[5] = {112,  72,  89, 115, '\0'};
 png_byte FARDATA png_sBIT[5] = {115,  66,  73,  84, '\0'};
+png_byte FARDATA png_sRGB[5] = {115,  82,  71,  66, '\0'};
 png_byte FARDATA png_tEXt[5] = {116,  69,  88, 116, '\0'};
 png_byte FARDATA png_tIME[5] = {116,  73,  77,  69, '\0'};
 png_byte FARDATA png_tRNS[5] = {116,  82,  78,  83, '\0'};
@@ -53,22 +57,20 @@ int FARDATA png_pass_ystart[] = {0, 0, 4, 0, 2, 0, 1};
 /* offset to next interlace block in the y direction */
 int FARDATA png_pass_yinc[] = {8, 8, 8, 4, 4, 2, 2};
 
-/* width of interlace block */
-/* this is not currently used - if you need it, uncomment it here and
-   in png.h
+/* Width of interlace block.  This is not currently used - if you need
+ * it, uncomment it here and in png.h
 int FARDATA png_pass_width[] = {8, 4, 4, 2, 2, 1, 1};
 */
 
-/* height of interlace block */
-/* this is not currently used - if you need it, uncomment it here and
-   in png.h
+/* Height of interlace block.  This is not currently used - if you need
+ * it, uncomment it here and in png.h
 int FARDATA png_pass_height[] = {8, 8, 4, 4, 2, 2, 1};
 */
 
-/* mask to determine which pixels are valid in a pass */
+/* Mask to determine which pixels are valid in a pass */
 int FARDATA png_pass_mask[] = {0x80, 0x08, 0x88, 0x22, 0xaa, 0x55, 0xff};
 
-/* mask to determine which pixels to overwrite while displaying */
+/* Mask to determine which pixels to overwrite while displaying */
 int FARDATA png_pass_dsp_mask[] = {0xff, 0x0f, 0xff, 0x33, 0xff, 0x55, 0xff};
 
 
@@ -101,24 +103,25 @@ png_sig_cmp(png_bytep sig, png_size_t start, png_size_t num_to_check)
    if (num_to_check > 8)
       num_to_check = 8;
    else if (num_to_check < 1)
-      return 0;
+      return (0);
 
    if (start > 7)
-      return 0;
+      return (0);
 
    if (start + num_to_check > 8)
       num_to_check = 8 - start;
 
-   return (png_memcmp(&sig[start], &png_sig[start], num_to_check));
+   return ((int)(png_memcmp(&sig[start], &png_sig[start], num_to_check)));
 }
 
 /* (Obsolete) function to check signature bytes.  It does not allow one
-   to check a partial signature.  This function will be removed in the
-   future - use png_sig_cmp(). */
+ * to check a partial signature.  This function will be removed in the
+ * future - use png_sig_cmp().
+ */
 int
 png_check_sig(png_bytep sig, int num)
 {
-  return !png_sig_cmp(sig, (png_size_t)0, (png_size_t)num);
+  return ((int)!png_sig_cmp(sig, (png_size_t)0, (png_size_t)num));
 }
 
 /* Function to allocate memory for zlib. */
@@ -129,7 +132,7 @@ png_zalloc(voidpf png_ptr, uInt items, uInt size)
    png_uint_32 num_bytes;
 
    num_bytes = (png_uint_32)items * size;
-   ptr = png_malloc((png_structp)png_ptr, num_bytes);
+   ptr = (png_voidp)png_malloc((png_structp)png_ptr, num_bytes);
    if (num_bytes > (png_uint_32)0x8000)
    {
       png_memset(ptr, 0, (png_size_t)0x8000L);
@@ -140,7 +143,7 @@ png_zalloc(voidpf png_ptr, uInt items, uInt size)
    {
       png_memset(ptr, 0, (png_size_t)num_bytes);
    }
-   return (voidpf)(ptr);
+   return ((voidpf)ptr);
 }
 
 /* function to free memory for zlib */
@@ -151,78 +154,19 @@ png_zfree(voidpf png_ptr, voidpf ptr)
 }
 
 /* Reset the CRC variable to 32 bits of 1's.  Care must be taken
-   in case CRC is > 32 bits to leave the top bits 0. */
+ * in case CRC is > 32 bits to leave the top bits 0.
+ */
 void
 png_reset_crc(png_structp png_ptr)
 {
-   /* set CRC to all 1's */
-#ifdef PNG_USE_OWN_CRC
-   png_ptr->crc = 0xffffffffL;
-#else
    png_ptr->crc = crc32(0, Z_NULL, 0);
-#endif
 }
 
-#ifdef PNG_USE_OWN_CRC
-/* Table of CRCs of all 8-bit messages.  By default, we use the tables made
-   by zlib, to save some memory.  If you wish to png_malloc() this
-   table, turn this into a pointer, and png_malloc() it in make_crc_table().
-   You may then want to hook it into png_struct and free it with the
-   destroy functions.  Another alternative is to pre-fill the table.  */
-static png_uint_32 crc_table[256];
-
-/* Flag: has the table been computed? Initially false. */
-static int crc_table_computed = 0;
-
-/* make the table for a fast crc */
-static void
-make_crc_table(void)
-{
-  png_uint_32 c;
-  int n, k;
-
-  for (n = 0; n < 256; n++)
-  {
-   c = (png_uint_32)n;
-   for (k = 0; k < 8; k++)
-     c = c & 1 ? 0xedb88320L ^ (c >> 1) : c >> 1;
-   crc_table[n] = c;
-  }
-  crc_table_computed = 1;
-}
-
-/* Update a running CRC with the bytes buf[0..len-1] - the CRC should be
-   initialized to all 1's, and the transmitted value is the 1's complement
-   of the final running CRC. */
-static png_uint_32
-update_crc(png_uint_32 crc, png_bytep buf, png_size_t len)
-{
-  png_uint_32 c;
-  png_bytep p;
-  png_uint_32 n;
-
-  c = crc;
-  p = buf;
-  n = len;
-
-  if (!crc_table_computed)
-  {
-   make_crc_table();
-  }
-
-  if (n > 0) do
-  {
-   c = crc_table[(png_byte)((c ^ (*p++)) & 0xff)] ^ (c >> 8);
-  } while (--n);
-
-  return c;
-}
-#endif /* PNG_USE_OWN_CRC */
-
 /* Calculate the CRC over a section of data.  We can only pass as
-   much data to this routine as the largest single buffer size.  We
-   also check that this data will actually be used before going to the
-   trouble of calculating it. */
+ * much data to this routine as the largest single buffer size.  We
+ * also check that this data will actually be used before going to the
+ * trouble of calculating it.
+ */
 void
 png_calculate_crc(png_structp png_ptr, png_bytep ptr, png_size_t length)
 {
@@ -241,18 +185,15 @@ png_calculate_crc(png_structp png_ptr, png_bytep ptr, png_size_t length)
    }
 
    if (need_crc)
-#ifdef PNG_USE_OWN_CRC
-      png_ptr->crc = update_crc(png_ptr->crc, ptr, length);
-#else
       png_ptr->crc = crc32(png_ptr->crc, ptr, length);
-#endif
 }
 
 /* Allocate the memory for an info_struct for the application.  We don't
-   really need the png_ptr, but it could potentially be useful in the
-   future.  This should be used in favour of malloc(sizeof(png_info))
-   and png_info_init() so that applications that want to use a shared
-   libpng don't have to be recompiled if png_info changes size. */
+ * really need the png_ptr, but it could potentially be useful in the
+ * future.  This should be used in favour of malloc(sizeof(png_info))
+ * and png_info_init() so that applications that want to use a shared
+ * libpng don't have to be recompiled if png_info changes size.
+ */
 png_infop
 png_create_info_struct(png_structp png_ptr)
 {
@@ -264,13 +205,14 @@ png_create_info_struct(png_structp png_ptr)
       png_info_init(info_ptr);
    }
 
-   return info_ptr;
+   return (info_ptr);
 }
 
 /* This function frees the memory associated with a single info struct.
-   Normally, one would use either png_destroy_read_struct() or
-   png_destroy_write_struct() to free an info struct, but this may be
-   useful for some applications. */
+ * Normally, one would use either png_destroy_read_struct() or
+ * png_destroy_write_struct() to free an info struct, but this may be
+ * useful for some applications.
+ */
 void
 png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr)
 {
@@ -290,8 +232,9 @@ png_destroy_info_struct(png_structp png_ptr, png_infopp info_ptr_ptr)
 }
 
 /* Initialize the info structure.  This is now an internal function (0.89)
-   and applications using it are urged to use png_create_info_struct()
-   instead. */
+ * and applications using it are urged to use png_create_info_struct()
+ * instead.
+ */
 void
 png_info_init(png_infop info_ptr)
 {
@@ -337,18 +280,20 @@ png_info_destroy(png_structp png_ptr, png_infop info_ptr)
 }
 
 /* This function returns a pointer to the io_ptr associated with the user
-   functions.  The application should free any memory associated with this
-   pointer before png_write_destroy() or png_read_destroy() are called. */
+ * functions.  The application should free any memory associated with this
+ * pointer before png_write_destroy() or png_read_destroy() are called.
+ */
 png_voidp
 png_get_io_ptr(png_structp png_ptr)
 {
-   return png_ptr->io_ptr;
+   return (png_ptr->io_ptr);
 }
 
 #if !defined(PNG_NO_STDIO)
 /* Initialize the default input/output functions for the PNG file.  If you
-   use your own read or write routines, you can call either png_set_read_fn()
-   or png_set_write_fn() instead of png_init_io(). */
+ * use your own read or write routines, you can call either png_set_read_fn()
+ * or png_set_write_fn() instead of png_init_io().
+ */
 void
 png_init_io(png_structp png_ptr, FILE *fp)
 {

png.h

@@ -1,67 +1,98 @@
 
 /* png.h - header file for PNG reference library
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-
-   BETA NOTICE:
-      This is a beta version.  It reads and writes valid files on the
-      platforms I have, and has had a wide testing program.  You may
-      have to modify the includes below to get it to work on your
-      system, and you may have to supply the correct compiler flags in
-      the makefile if you can't find a makefile suitable for your
-      operating system/compiler combination.  Read libpng.txt for more
-      information, including how to contact the authors if you have any
-      problems, or if you want your compiler/platform to be supported in
-      the next official libpng release.
-
-   See libpng.txt for more information.
-
-   Contributing Authors:
-      John Bowler
-      Sam Bushell
-      Kevin Bracey
-      Andreas Dilger
-      Magnus Holmgren
-      Dave Martindale
-      Greg Roelofs
-      Guy Eric Schalnat
-      Paul Schmidt
-      Tom Tanner
-      Tim Wegner
-
-   The contributing authors would like to thank all those who helped
-   with testing, bug fixes, and patience.  This wouldn't have been
-   possible without all of you.
-
-   Thanks to Frank J. T. Wojcik for helping with the documentation.
-
-   The PNG Reference Library is supplied "AS IS".  The Contributing Authors
-   and Group 42, Inc. disclaim all warranties, expressed or implied,
-   including, without limitation, the warranties of merchantability and of
-   fitness for any purpose.  The Contributing Authors and Group 42, Inc.
-   assume no liability for direct, indirect, incidental, special, exemplary,
-   or consequential damages, which may result from the use of the PNG
-   Reference Library, even if advised of the possibility of such damage.
-
-   Permission is hereby granted to use, copy, modify, and distribute this
-   source code, or portions hereof, for any purpose, without fee, subject
-   to the following restrictions:
-   1. The origin of this source code must not be misrepresented.
-   2. Altered versions must be plainly marked as such and must not be
-      misrepresented as being the original source.
-   3. This Copyright notice may not be removed or altered from any source or
-      altered source distribution.
-
-   The Contributing Authors and Group 42, Inc. specifically permit, without
-   fee, and encourage the use of this source code as a component to
-   supporting the PNG file format in commercial products.  If you use this
-   source code in a product, acknowledgment is not required but would be
-   appreciated.
-*/
+ *
+ * libpng 0.99a beta
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998 Glenn Randers-Pehrson
+ * January 31, 1998
+ *
+ * Note about libpng version numbers:
+ *
+ *    Due to various miscommunications, unforeseen code incompatibilities
+ *    and occasional factors outside the authors' control, version numbering
+ *    on the library has not always been consistent and straightforward.
+ *    The following table summarizes matters since version 0.89c, which was
+ *    the first widely used release:
+ *
+ *      source                    png.h     shared-lib
+ *      version                   string    version
+ *      -------                   ------    ----------
+ *      0.89c ("1.0 beta 3")      0.89      1.0.89
+ *      0.90  ("1.0 beta 4")      0.90      0.90  [should have been 2.0.90]
+ *      0.95  ("1.0 beta 5")      0.95      0.95  [should have been 2.0.95]
+ *      0.96  ("1.0 beta 6")      0.96      0.96  [should have been 2.0.96]
+ *      0.97b ("1.00.97 beta 7")  1.00.97   1.0.0 [should have been 2.0.97]
+ *      0.97c                     0.97      2.0.97
+ *      0.98                      0.98      2.0.98
+ *      0.99                      0.99      2.0.99
+ *      0.99a                     0.99      2.0.99
+ *      1.0                       1.00      2.1.0
+ *
+ *    Henceforth the source version will match the shared-library minor
+ *    and patch numbers; the shared-library major version number will be
+ *    used for changes in backward compatibility, as it is intended.
+ *
+ * BETA NOTICE:
+ *    This is a beta version.  It reads and writes valid files on the
+ *    platforms I have, and has had a wide testing program.  You may
+ *    have to modify the includes below to get it to work on your
+ *    system, and you may have to supply the correct compiler flags in
+ *    the makefile if you can't find a makefile suitable for your
+ *    operating system/compiler combination.  Read libpng.txt for more
+ *    information, including how to contact the authors if you have any
+ *    problems, or if you want your compiler/platform to be supported in
+ *    the next official libpng release.
+ *
+ * See libpng.txt for more information.  The PNG specification is available
+ * as RFC 2083 <ftp://ftp.uu.net/graphics/png/documents/>
+ * and as a W3C Recommendation <http://www.w3.org/pub/WWW/TR/REC.png.html>
+ *
+ * Contributing Authors:
+ *    John Bowler
+ *    Sam Bushell
+ *    Kevin Bracey
+ *    Andreas Dilger
+ *    Magnus Holmgren
+ *    Tom Lane
+ *    Dave Martindale
+ *    Glenn Randers-Pehrson
+ *    Greg Roelofs
+ *    Guy Eric Schalnat
+ *    Paul Schmidt
+ *    Tom Tanner
+ *    Tim Wegner
+ *
+ * The contributing authors would like to thank all those who helped
+ * with testing, bug fixes, and patience.  This wouldn't have been
+ * possible without all of you.
+ *
+ * Thanks to Frank J. T. Wojcik for helping with the documentation.
+ *
+ * The PNG Reference Library is supplied "AS IS".  The Contributing Authors
+ * and Group 42, Inc. disclaim all warranties, expressed or implied,
+ * including, without limitation, the warranties of merchantability and of
+ * fitness for any purpose.  The Contributing Authors and Group 42, Inc.
+ * assume no liability for direct, indirect, incidental, special, exemplary,
+ * or consequential damages, which may result from the use of the PNG
+ * Reference Library, even if advised of the possibility of such damage.
+ *
+ * Permission is hereby granted to use, copy, modify, and distribute this
+ * source code, or portions hereof, for any purpose, without fee, subject
+ * to the following restrictions:
+ * 1. The origin of this source code must not be misrepresented.
+ * 2. Altered versions must be plainly marked as such and must not be
+ *    misrepresented as being the original source.
+ * 3. This Copyright notice may not be removed or altered from any source or
+ *    altered source distribution.
+ *
+ * The Contributing Authors and Group 42, Inc. specifically permit, without
+ * fee, and encourage the use of this source code as a component to
+ * supporting the PNG file format in commercial products.  If you use this
+ * source code in a product, acknowledgment is not required but would be
+ * appreciated.
+ */
 
 #ifndef _PNG_H
 #define _PNG_H
@@ -89,30 +120,30 @@ extern "C" {
  */
 
 /* Version information for png.h - this should match the version in png.c */
-#define PNG_LIBPNG_VER_STRING "0.96"
+#define PNG_LIBPNG_VER_STRING "0.99"
 
 /* careful here.  At one time, I wanted to use 082, but that would be octal.
  * Version 1.0 will be 100 here, etc.
  */
-#define PNG_LIBPNG_VER 96
+#define PNG_LIBPNG_VER  99
 
 /* variables declared in png.c - only it needs to define PNG_NO_EXTERN */
-#ifndef PNG_NO_EXTERN
+#if !defined(PNG_NO_EXTERN) || defined(PNG_ALWAYS_EXTERN)
 /* Version information for C files, stored in png.c.  This had better match
  * the version above.
  */
-extern char png_libpng_ver[];
+extern char png_libpng_ver[5];
 
 /* Structures to facilitate easy interlacing.  See png.c for more details */
-extern int FARDATA png_pass_start[];
-extern int FARDATA png_pass_inc[];
-extern int FARDATA png_pass_ystart[];
-extern int FARDATA png_pass_yinc[];
-extern int FARDATA png_pass_mask[];
-extern int FARDATA png_pass_dsp_mask[];
+extern int FARDATA png_pass_start[7];
+extern int FARDATA png_pass_inc[7];
+extern int FARDATA png_pass_ystart[7];
+extern int FARDATA png_pass_yinc[7];
+extern int FARDATA png_pass_mask[7];
+extern int FARDATA png_pass_dsp_mask[7];
 /* These aren't currently used.  If you need them, see png.c for more details
-extern int FARDATA png_pass_width[];
-extern int FARDATA png_pass_height[];
+extern int FARDATA png_pass_width[7];
+extern int FARDATA png_pass_height[7];
 */
 #endif /* PNG_NO_EXTERN */
 
@@ -172,10 +203,11 @@ typedef png_text FAR * FAR * png_textpp;
 #define PNG_TEXT_COMPRESSION_LAST     1  /* Not a valid value */
 
 /* png_time is a way to hold the time in an machine independent way.
-   Two conversions are provided, both from time_t and struct tm.  There
-   is no portable way to convert to either of these structures, as far
-   as I know.  If you know of a portable way, send it to me.  As a side
-   note - PNG is Year 2000 compliant! */
+ * Two conversions are provided, both from time_t and struct tm.  There
+ * is no portable way to convert to either of these structures, as far
+ * as I know.  If you know of a portable way, send it to me.  As a side
+ * note - PNG is Year 2000 compliant!
+ */
 typedef struct png_time_struct
 {
    png_uint_16 year; /* full year, as in, 1995 */
@@ -237,13 +269,21 @@ typedef struct png_info_struct
     * and initialize the appropriate fields below.
     */
 
-#if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_WRITE_gAMA_SUPPORTED)
+#if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_WRITE_gAMA_SUPPORTED) || \
+    defined(PNG_READ_GAMMA_SUPPORTED)
    /* The gAMA chunk describes the gamma characteristics of the system
     * on which the image was created, normally in the range [1.0, 2.5].
     * Data is valid if (valid & PNG_INFO_gAMA) is non-zero.
     */
    float gamma; /* gamma value of image, if (valid & PNG_INFO_gAMA) */
 #endif /* PNG_READ_gAMA_SUPPORTED || PNG_WRITE_gAMA_SUPPORTED */
+
+#if defined(PNG_READ_sRGB_SUPPORTED) || defined(PNG_WRITE_sRGB_SUPPORTED)
+    /* GR-P, 0.96a */
+    /* Data valid if (valid & PNG_INFO_sRGB) non-zero. */
+   png_byte srgb_intent; /* sRGB rendering intent [0, 1, 2, or 3] */
+#endif /* PNG_READ_sRGB_SUPPORTED || PNG_WRITE_sRGB_SUPPORTED */
+
 #if defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_WRITE_tEXt_SUPPORTED) || \
     defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
    /* The tEXt and zTXt chunks contain human-readable textual data in
@@ -285,7 +325,8 @@ typedef struct png_info_struct
    png_bytep trans; /* transparent values for paletted image */
    png_color_16 trans_values; /* transparent color for non-palette image */
 #endif /* PNG_READ_tRNS_SUPPORTED || PNG_WRITE_tRNS_SUPPORTED */
-#if defined(PNG_READ_bKGD_SUPPORTED) || defined(PNG_WRITE_bKGD_SUPPORTED)
+#if defined(PNG_READ_bKGD_SUPPORTED) || defined(PNG_WRITE_bKGD_SUPPORTED) || \
+    defined(PNG_READ_BACKGROUND_SUPPORTED)
    /* The bKGD chunk gives the suggested image background color if the
     * display program does not have its own background color and the image
     * is needs to composited onto a background before display.  The colors
@@ -406,6 +447,15 @@ typedef png_info FAR * FAR * png_infopp;
 #define PNG_RESOLUTION_METER      1 /* pixels/meter */
 #define PNG_RESOLUTION_LAST       2 /* Not a valid value */
 
+/* These are for the sRGB chunk.  These values should NOT be changed. */
+#define PNG_sRGB_INTENT_SATURATION 0
+#define PNG_sRGB_INTENT_PERCEPTUAL 1
+#define PNG_sRGB_INTENT_ABSOLUTE   2
+#define PNG_sRGB_INTENT_RELATIVE   3
+#define PNG_sRGB_INTENT_LAST       4 /* Not a valid value */
+                        
+
+
 /* These determine if an ancillary chunk's data has been successfully read
  * from the PNG header, or if the application has filled in the corresponding
  * data in the info_struct to be written into the output file.  The values
@@ -422,6 +472,7 @@ typedef png_info FAR * FAR * png_infopp;
 #define PNG_INFO_oFFs 0x0100
 #define PNG_INFO_tIME 0x0200
 #define PNG_INFO_pCAL 0x0400
+#define PNG_INFO_sRGB 0x0800   /* GR-P, 0.96a */
 
 /* This is used for the transformation routines, as some of them
  * change these values for the row.  It also should enable using
@@ -524,7 +575,6 @@ struct png_struct_def
    png_byte usr_channels;     /* channels at start of write */
    png_byte sig_bytes;        /* magic bytes read/written from start of file */
 
-
 #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
    png_byte filler;           /* filler byte for 24->32-bit pixel expansion */
 #endif /* PNG_READ_FILLER_SUPPORTED */
@@ -542,9 +592,9 @@ struct png_struct_def
    png_uint_32 flush_rows;    /* number of rows written since last flush */
 #endif /* PNG_WRITE_FLUSH_SUPPORTED */
 #if defined(PNG_READ_GAMMA_SUPPORTED)
-   int gamma_shift;           /* number of "insignificant" bits 16-bit gamma */
-   float gamma;               /* file gamma value */
-   float display_gamma;       /* display gamma value */
+   int gamma_shift;      /* number of "insignificant" bits 16-bit gamma */
+   float gamma;          /* file gamma value */
+   float screen_gamma;   /* screen gamma value (display_gamma/viewing_gamma */
 #endif /* PNG_READ_GAMMA_SUPPORTED */
 #if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_READ_BACKGROUND_SUPPORTED)
    png_bytep gamma_table;     /* gamma table for 8 bit depth files */
@@ -586,6 +636,7 @@ struct png_struct_def
    png_charp current_text;           /* current text chunk buffer */
    png_charp current_text_ptr;       /* current location in current_text */
 #endif /* PNG_PROGRESSIVE_READ_SUPPORTED && PNG_READ_tEXt/zTXt_SUPPORTED */
+#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
 #if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
 /* for the Borland special 64K segment handler */
    png_bytepp offset_table_ptr;
@@ -593,13 +644,14 @@ struct png_struct_def
    png_uint_16 offset_table_number;
    png_uint_16 offset_table_count;
    png_uint_16 offset_table_count_free;
-#endif /* PNG_PROGRESSIVE_READ_SUPPORTED&&__TURBOC__&&!_Windows&&!__FLAT__ */
-#endif /* PNG_PROGRESSIVE_READ_SUPPORTED */
+#endif /* __TURBOC__&&!_Windows&&!__FLAT__ */
 #if defined(PNG_READ_DITHER_SUPPORTED)
    png_bytep palette_lookup;         /* lookup table for dithering */
    png_bytep dither_index;           /* index translation for palette files */
-   png_uint_16p hist;                /* histogram */
 #endif /* PNG_READ_DITHER_SUPPORTED */
+#if defined(PNG_READ_DITHER_SUPPORTED) || defined(PNG_READ_hIST_SUPPORTED)
+   png_uint_16p hist;                /* histogram */
+#endif
 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
    png_byte heuristic_method;        /* heuristic for row filter selection */
    png_byte num_prev_filters;        /* number of weights for previous rows */
@@ -609,6 +661,9 @@ struct png_struct_def
    png_uint_16p filter_costs;        /* relative filter calculation cost */
    png_uint_16p inv_filter_costs;    /* 1/relative filter calculation cost */
 #endif /* PNG_WRITE_WEIGHTED_FILTER_SUPPORTED */
+#if defined(PNG_TIME_RFC1123_SUPPORTED)
+   png_charp time_buffer;            /* String to hold RFC 1123 time text */
+#endif /* PNG_TIME_RFC1123_SUPPORTED */
 };
 
 typedef png_struct FAR * FAR * png_structpp;
@@ -640,8 +695,8 @@ extern PNG_EXPORT(int,png_check_sig) PNGARG((png_bytep sig, int num));
 
 /* Allocate and initialize png_ptr struct for reading, and any other memory. */
 extern PNG_EXPORT(png_structp,png_create_read_struct)
-   PNGARG((png_charp user_png_ver, voidp error_ptr, png_error_ptr error_fn,
-   png_error_ptr warn_fn));
+   PNGARG((png_const_charp user_png_ver, voidp error_ptr,
+   png_error_ptr error_fn, png_error_ptr warn_fn));
 
 /* Allocate and initialize png_ptr struct for reading, and any other memory */
 extern PNG_EXPORT(png_structp,png_create_write_struct)
@@ -663,6 +718,11 @@ extern PNG_EXPORT(void,png_write_info) PNGARG((png_structp png_ptr,
 extern PNG_EXPORT(void,png_read_info) PNGARG((png_structp png_ptr,
    png_infop info_ptr));
 
+#if defined(PNG_TIME_RFC1123_SUPPORTED)
+extern PNG_EXPORT(png_charp,png_convert_to_rfc1123)
+   PNGARG((png_structp png_ptr, png_timep ptime));
+#endif /* PNG_TIME_RFC1123_SUPPORTED */
+
 #if defined(PNG_WRITE_tIME_SUPPORTED)
 /* convert from a struct tm to png_time */
 extern PNG_EXPORT(void,png_convert_from_struct_tm) PNGARG((png_timep ptime,
@@ -705,6 +765,11 @@ extern PNG_EXPORT(void,png_set_strip_alpha) PNGARG((png_structp png_ptr));
 extern PNG_EXPORT(void,png_set_swap_alpha) PNGARG((png_structp png_ptr));
 #endif /* PNG_READ_SWAP_ALPHA_SUPPORTED || PNG_WRITE_SWAP_ALPHA_SUPPORTED */
 
+#if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
+    defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
+extern PNG_EXPORT(void,png_set_invert_alpha) PNGARG((png_structp png_ptr));
+#endif /* PNG_READ_INVERT_ALPHA_SUPPORTED || PNG_WRITE_INVERT_ALPHA_SUPPORTED */
+
 #if defined(PNG_READ_FILLER_SUPPORTED) || defined(PNG_WRITE_FILLER_SUPPORTED)
 /* Add a filler byte to 24-bit RGB images. */
 extern PNG_EXPORT(void,png_set_filler) PNGARG((png_structp png_ptr,
@@ -771,7 +836,7 @@ extern PNG_EXPORT(void,png_set_dither) PNGARG((png_structp png_ptr,
 #endif /* PNG_READ_DITHER_SUPPORTED */
 
 #if defined(PNG_READ_GAMMA_SUPPORTED)
-/* Handle gamma correction. */
+/* Handle gamma correction. Screen_gamma=(display_gamma/viewing_gamma) */
 extern PNG_EXPORT(void,png_set_gamma) PNGARG((png_structp png_ptr,
    double screen_gamma, double default_file_gamma));
 #endif /* PNG_READ_GAMMA_SUPPORTED */
@@ -840,6 +905,9 @@ extern void png_read_destroy PNGARG((png_structp png_ptr, png_infop info_ptr,
 extern PNG_EXPORT(void,png_destroy_write_struct)
    PNGARG((png_structpp png_ptr_ptr, png_infopp info_ptr_ptr));
 
+/* free any memory used in info_ptr struct (old method - NOT DLL EXPORTED) */
+extern void png_write_destroy_info PNGARG((png_infop info_ptr));
+
 /* free any memory used in png_ptr struct (old method - NOT DLL EXPORTED) */
 extern void png_write_destroy PNGARG((png_structp png_ptr));
 
@@ -868,10 +936,12 @@ extern PNG_EXPORT(void,png_set_crc_action) PNGARG((png_structp png_ptr,
  * mainly useful for testing, as the defaults should work with most users.
  * Those users who are tight on memory or want faster performance at the
  * expense of compression can modify them.  See the compression library
- * header file (zlib.h) for an explination of the compression functions. */
+ * header file (zlib.h) for an explination of the compression functions.
+ */
 
 /* set the filtering method(s) used by libpng.  Currently, the only valid
- * value for "method" is 0 */
+ * value for "method" is 0.
+ */
 extern PNG_EXPORT(void,png_set_filter) PNGARG((png_structp png_ptr, int method,
    int filters));
 
@@ -972,8 +1042,10 @@ extern PNG_EXPORT(void,png_set_compression_method) PNGARG((png_structp png_ptr,
  * more information.
  */
 
+#if !defined(PNG_NO_STDIO)
 /* Initialize the input/output for the PNG file to the default functions. */
 extern PNG_EXPORT(void,png_init_io) PNGARG((png_structp png_ptr, FILE *fp));
+#endif
 
 /* Replace the (error and abort), and warning functions with user
  * supplied functions.  If no messages are to be printed you must still
@@ -1030,9 +1102,16 @@ extern PNG_EXPORT(void,png_progressive_combine_row) PNGARG((png_structp png_ptr,
 extern PNG_EXPORT(png_voidp,png_malloc) PNGARG((png_structp png_ptr,
    png_uint_32 size));
 
-/* free's a pointer allocated by png_malloc() */
+/* frees a pointer allocated by png_malloc() */
 extern PNG_EXPORT(void,png_free) PNGARG((png_structp png_ptr, png_voidp ptr));
 
+#ifdef PNGTEST_MEMORY_DEBUG
+/* debugging versions of png_malloc() and png_free() */
+extern PNG_EXPORT(png_voidp,png_debug_malloc) PNGARG((png_structp png_ptr,
+   png_uint_32 size));
+extern PNG_EXPORT(void,png_debug_free) PNGARG((png_structp png_ptr,
+   png_voidp ptr));
+#endif
 #if defined(USE_FAR_KEYWORD)  /* memory model conversion function */
 extern void *far_to_near PNGARG((png_structp png_ptr,png_voidp ptr,int check));
 #endif /* USE_FAR_KEYWORD */
@@ -1041,10 +1120,18 @@ extern void *far_to_near PNGARG((png_structp png_ptr,png_voidp ptr,int check));
 extern PNG_EXPORT(void,png_error) PNGARG((png_structp png_ptr,
    png_const_charp error));
 
+/* The same, but the chunk name is prepended to the error string. */
+extern PNG_EXPORT(void,png_chunk_error) PNGARG((png_structp png_ptr,
+   png_const_charp error));
+
 /* Non-fatal error in libpng.  Can continue, but may have a problem. */
 extern PNG_EXPORT(void,png_warning) PNGARG((png_structp png_ptr,
    png_const_charp message));
 
+/* Non-fatal error in libpng, chunk name is prepended to message. */
+extern PNG_EXPORT(void,png_chunk_warning) PNGARG((png_structp png_ptr,
+   png_const_charp message));
+
 /* The png_set_<chunk> functions are for storing values in the png_info_struct.
  * Similarly, the png_get_<chunk> calls are used to read values from the
  * png_info_struct, either storing the parameters in the passed variables, or
@@ -1057,18 +1144,67 @@ extern PNG_EXPORT(void,png_warning) PNGARG((png_structp png_ptr,
  * to avoid problems with future changes in the size and internal layout of
  * png_info_struct.
  */
-/* Returns "flag" if chunk data is valid in info_ptr */
+/* Returns "flag" if chunk data is valid in info_ptr. */
 extern PNG_EXPORT(png_uint_32,png_get_valid) PNGARG((png_structp png_ptr,
 png_infop info_ptr, png_uint_32 flag));
 
-/* Returns number of bytes needed to hold a transformed row */
+/* Returns number of bytes needed to hold a transformed row. */
 extern PNG_EXPORT(png_uint_32,png_get_rowbytes) PNGARG((png_structp png_ptr,
 png_infop info_ptr));
 
-/* Returns number of color channels in image */
+/* Returns number of color channels in image. */
 extern PNG_EXPORT(png_byte,png_get_channels) PNGARG((png_structp png_ptr,
 png_infop info_ptr));
 
+#ifdef PNG_EASY_ACCESS_SUPPORTED
+/* Returns image width in pixels. */
+extern PNG_EXPORT(png_uint_32, png_get_image_width) PNGARG((png_structp
+png_ptr, png_infop info_ptr));
+
+/* Returns image height in pixels. */
+extern PNG_EXPORT(png_uint_32, png_get_image_height) PNGARG((png_structp
+png_ptr, png_infop info_ptr));
+
+/* Returns image bit_depth. */
+extern PNG_EXPORT(png_byte, png_get_bit_depth) PNGARG((png_structp
+png_ptr, png_infop info_ptr));
+
+/* Returns image color_type. */
+extern PNG_EXPORT(png_byte, png_get_color_type) PNGARG((png_structp
+png_ptr, png_infop info_ptr));
+
+/* Returns image filter_type. */
+extern PNG_EXPORT(png_byte, png_get_filter_type) PNGARG((png_structp
+png_ptr, png_infop info_ptr));
+
+/* Returns image interlace_type. */
+extern PNG_EXPORT(png_byte, png_get_interlace_type) PNGARG((png_structp
+png_ptr, png_infop info_ptr));
+
+/* Returns image compression_type. */
+extern PNG_EXPORT(png_byte, png_get_compression_type) PNGARG((png_structp
+png_ptr, png_infop info_ptr));
+
+/* Returns image resolution in pixels per meter, from pHYs chunk data. */
+extern PNG_EXPORT(png_uint_32, png_get_pixels_per_meter) PNGARG((png_structp
+png_ptr, png_infop info_ptr));
+
+/* Returns pixel aspect ratio, computed from pHYs chunk data.  */
+extern PNG_EXPORT(float, png_get_pixel_aspect_ratio) PNGARG((png_structp
+png_ptr, png_infop info_ptr));
+
+/* Returns image x, y offset in pixels or microns, from oFFs chunk data. */
+extern PNG_EXPORT(png_uint_32, png_get_x_offset_pixels) PNGARG((png_structp
+png_ptr, png_infop info_ptr));
+extern PNG_EXPORT(png_uint_32, png_get_y_offset_pixels) PNGARG((png_structp
+png_ptr, png_infop info_ptr));
+extern PNG_EXPORT(png_uint_32, png_get_x_offset_microns) PNGARG((png_structp
+png_ptr, png_infop info_ptr));
+extern PNG_EXPORT(png_uint_32, png_get_y_offset_microns) PNGARG((png_structp
+png_ptr, png_infop info_ptr));
+
+#endif /* PNG_EASY_ACCESS_SUPPORTED */
+
 /* Returns pointer to signature string read from PNG header */
 extern PNG_EXPORT(png_bytep,png_get_signature) PNGARG((png_structp png_ptr,
 png_infop info_ptr));
@@ -1175,6 +1311,18 @@ extern PNG_EXPORT(void,png_set_sBIT) PNGARG((png_structp png_ptr,
    png_infop info_ptr, png_color_8p sig_bit));
 #endif /* PNG_READ_sBIT_SUPPORTED || PNG_WRITE_sBIT_SUPPORTED */
 
+#if defined(PNG_READ_sRGB_SUPPORTED)
+extern PNG_EXPORT(png_uint_32,png_get_sRGB) PNGARG((png_structp png_ptr,
+   png_infop info_ptr, int *intent));
+#endif /* PNG_READ_sRGB_SUPPORTED */
+
+#if defined(PNG_READ_sRGB_SUPPORTED) || defined(PNG_WRITE_sRGB_SUPPORTED)
+extern PNG_EXPORT(void,png_set_sRGB) PNGARG((png_structp png_ptr,
+   png_infop info_ptr, int intent));
+extern PNG_EXPORT(void,png_set_sRGB_gAMA_and_cHRM) PNGARG((png_structp png_ptr,
+   png_infop info_ptr, int intent));
+#endif /* PNG_READ_sRGB_SUPPORTED || PNG_WRITE_sRGB_SUPPORTED */
+
 #if defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_READ_zTXt_SUPPORTED)
 /* png_get_text also returns the number of text chunks in text_ptr */
 extern PNG_EXPORT(png_uint_32,png_get_text) PNGARG((png_structp png_ptr,
@@ -1216,6 +1364,9 @@ extern PNG_EXPORT(void,png_set_tRNS) PNGARG((png_structp png_ptr,
  * libpng yet, but more support will be added as needed.
  */
 #if (PNG_DEBUG > 0)
+#ifdef PNG_NO_STDIO
+#include <stdio.h>
+#endif
 #ifndef PNG_DEBUG_FILE
 #define PNG_DEBUG_FILE stderr
 #endif /* PNG_DEBUG_FILE */
@@ -1244,13 +1395,17 @@ extern PNG_EXPORT(void,png_set_tRNS) PNGARG((png_structp png_ptr,
 #if defined(PNG_INTERNAL)
 
 /* Various modes of operation.  Note that after an init, mode is set to
-   zero automatically when the structure is created. */
+ * zero automatically when the structure is created.
+ */
 #define PNG_BEFORE_IHDR       0x00
 #define PNG_HAVE_IHDR         0x01
 #define PNG_HAVE_PLTE         0x02
 #define PNG_HAVE_IDAT         0x04
 #define PNG_AFTER_IDAT        0x08
 #define PNG_HAVE_IEND         0x10
+#define PNG_HAVE_gAMA         0x20
+#define PNG_HAVE_cHRM         0x40
+#define PNG_HAVE_sRGB         0x80
 
 /* push model modes */
 #define PNG_READ_SIG_MODE   0
@@ -1282,6 +1437,7 @@ extern PNG_EXPORT(void,png_set_tRNS) PNGARG((png_structp png_ptr,
 #define PNG_PACKSWAP          0x10000
 #define PNG_SWAP_ALPHA        0x20000
 #define PNG_STRIP_ALPHA       0x40000
+#define PNG_INVERT_ALPHA      0x80000
 
 /* flags for png_create_struct */
 #define PNG_STRUCT_PNG   0x0001
@@ -1328,29 +1484,31 @@ extern PNG_EXPORT(void,png_set_tRNS) PNGARG((png_structp png_ptr,
 
 /* variables declared in png.c - only it needs to define PNG_NO_EXTERN */
 #ifndef PNG_NO_EXTERN
-/* place to hold the signiture string for a PNG file. */
-extern png_byte FARDATA png_sig[];
+/* place to hold the signature string for a PNG file. */
+extern png_byte FARDATA png_sig[8];
 
-/* constant strings for known chunk types.  If you need to add a chunk,
-   add a string holding the name here.  See png.c for more details.  We
-   can't selectively include these, since we still check for chunk in the
-   wrong locations with these labels. */
-extern png_byte FARDATA png_IHDR[];
-extern png_byte FARDATA png_IDAT[];
-extern png_byte FARDATA png_IEND[];
-extern png_byte FARDATA png_PLTE[];
-extern png_byte FARDATA png_bKGD[];
-extern png_byte FARDATA png_cHRM[];
-extern png_byte FARDATA png_gAMA[];
-extern png_byte FARDATA png_hIST[];
-extern png_byte FARDATA png_oFFs[];
-extern png_byte FARDATA png_pCAL[];
-extern png_byte FARDATA png_pHYs[];
-extern png_byte FARDATA png_sBIT[];
-extern png_byte FARDATA png_tEXt[];
-extern png_byte FARDATA png_tIME[];
-extern png_byte FARDATA png_tRNS[];
-extern png_byte FARDATA png_zTXt[];
+/* Constant strings for known chunk types.  If you need to add a chunk,
+ * add a string holding the name here.  See png.c for more details.  We
+ * can't selectively include these, since we still check for chunk in the
+ * wrong locations with these labels.
+ */
+extern png_byte FARDATA png_IHDR[5];
+extern png_byte FARDATA png_IDAT[5];
+extern png_byte FARDATA png_IEND[5];
+extern png_byte FARDATA png_PLTE[5];
+extern png_byte FARDATA png_bKGD[5];
+extern png_byte FARDATA png_cHRM[5];
+extern png_byte FARDATA png_gAMA[5];
+extern png_byte FARDATA png_hIST[5];
+extern png_byte FARDATA png_oFFs[5];
+extern png_byte FARDATA png_pCAL[5];
+extern png_byte FARDATA png_pHYs[5];
+extern png_byte FARDATA png_sBIT[5];
+extern png_byte FARDATA png_sRGB[5];
+extern png_byte FARDATA png_tEXt[5];
+extern png_byte FARDATA png_tIME[5];
+extern png_byte FARDATA png_tRNS[5];
+extern png_byte FARDATA png_zTXt[5];
 
 #endif /* PNG_NO_EXTERN */
 
@@ -1376,12 +1534,14 @@ PNG_EXTERN png_uint_32 png_get_uint_32 PNGARG((png_bytep buf));
 PNG_EXTERN png_uint_16 png_get_uint_16 PNGARG((png_bytep buf));
 #endif /* PNG_BIG_ENDIAN_GET_SUPPORTED */
 
-/* Initialize png_ptr struct for reading, and allocate any other memory
- * (old interface - NOT DLL EXPORTED) */
+/* Initialize png_ptr struct for reading, and allocate any other memory.
+ * (old interface - NOT DLL EXPORTED).
+ */
 extern void png_read_init PNGARG((png_structp png_ptr));
 
-/* Initialize png_ptr struct for writing, and allocate any other memory
- * (old interface - NOT DLL EXPORTED) */
+/* Initialize png_ptr struct for writing, and allocate any other memory.
+ * (old interface - NOT DLL EXPORTED).
+ */
 extern void png_write_init PNGARG((png_structp png_ptr));
 
 /* allocate memory for an internal libpng struct */
@@ -1433,7 +1593,7 @@ PNG_EXTERN void png_flush PNGARG((png_structp png_ptr));
 #endif
 
 /* Place a 32-bit number into a buffer in PNG byte order (big-endian).
- * The only currently known PNG chunk that uses unsigned numbers is
+ * The only currently known PNG chunk that uses signed numbers is
  * the ancillary extension chunk, pCAL.
  */
 PNG_EXTERN void png_save_uint_32 PNGARG((png_bytep buf, png_uint_32 i));
@@ -1442,8 +1602,11 @@ PNG_EXTERN void png_save_uint_32 PNGARG((png_bytep buf, png_uint_32 i));
 PNG_EXTERN void png_save_int_32 PNGARG((png_bytep buf, png_int_32 i));
 #endif
 
-/* place a 16 bit number into a buffer in PNG byte order */
-PNG_EXTERN void png_save_uint_16 PNGARG((png_bytep buf, png_uint_16 i));
+/* Place a 16 bit number into a buffer in PNG byte order.
+ * The parameter is declared unsigned int, not png_uint_16,
+ * just to avoid potential problems on pre-ANSI C compilers.
+ */
+PNG_EXTERN void png_save_uint_16 PNGARG((png_bytep buf, unsigned int i));
 
 /* Write a PNG chunk - size, type, (optional) data, CRC. */
 PNG_EXTERN void png_write_chunk PNGARG((png_structp png_ptr,
@@ -1460,13 +1623,14 @@ PNG_EXTERN void png_write_chunk_data PNGARG((png_structp png_ptr,
 /* Finish a chunk started with png_write_chunk_start() (includes CRC). */
 PNG_EXTERN void png_write_chunk_end PNGARG((png_structp png_ptr));
 
-/* simple function to write the signiture */
+/* simple function to write the signature */
 PNG_EXTERN void png_write_sig PNGARG((png_structp png_ptr));
 
 /* write various chunks */
 
 /* Write the IHDR chunk, and update the png_struct with the necessary
-   information. */
+ * information.
+ */
 PNG_EXTERN void png_write_IHDR PNGARG((png_structp png_ptr, png_uint_32 width,
    png_uint_32 height,
    int bit_depth, int color_type, int compression_type, int filter_type,
@@ -1496,6 +1660,11 @@ PNG_EXTERN void png_write_cHRM PNGARG((png_structp png_ptr,
    double blue_x, double blue_y));
 #endif
 
+#if defined(PNG_WRITE_sRGB_SUPPORTED)
+PNG_EXTERN void png_write_sRGB PNGARG((png_structp png_ptr,
+   int intent));
+#endif
+
 #if defined(PNG_WRITE_tRNS_SUPPORTED)
 PNG_EXTERN void png_write_tRNS PNGARG((png_structp png_ptr, png_bytep trans,
    png_color_16p values, int number, int color_type));
@@ -1513,7 +1682,7 @@ PNG_EXTERN void png_write_hIST PNGARG((png_structp png_ptr, png_uint_16p hist,
 
 #if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
 PNG_EXTERN png_size_t png_check_keyword PNGARG((png_structp png_ptr,
-   png_charp key, png_bytepp new_key));
+   png_charp key, png_charpp new_key));
 #endif
 
 #if defined(PNG_WRITE_tEXt_SUPPORTED)
@@ -1610,6 +1779,16 @@ PNG_EXTERN void png_do_write_swap_alpha PNGARG((png_row_infop row_info,
    png_bytep row));
 #endif
 
+#if defined(PNG_READ_INVERT_ALPHA_SUPPORTED)
+PNG_EXTERN void png_do_read_invert_alpha PNGARG((png_row_infop row_info,
+   png_bytep row));
+#endif
+
+#if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
+PNG_EXTERN void png_do_write_invert_alpha PNGARG((png_row_infop row_info,
+   png_bytep row));
+#endif
+
 #if defined(PNG_WRITE_FILLER_SUPPORTED) || \
     defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
 PNG_EXTERN void png_do_strip_filler PNGARG((png_row_infop row_info,
@@ -1698,7 +1877,8 @@ PNG_EXTERN void png_do_expand PNGARG((png_row_infop row_info,
 #endif
 
 /* The following decodes the appropriate chunks, and does error correction,
- * then calls the appropriate callback for the chunk if it is valid */
+ * then calls the appropriate callback for the chunk if it is valid.
+ */
 
 /* decode the IHDR chunk */
 PNG_EXTERN void png_handle_IHDR PNGARG((png_structp png_ptr, png_infop info_ptr,
@@ -1723,6 +1903,11 @@ PNG_EXTERN void png_handle_cHRM PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));
 #endif
 
+#if defined(PNG_READ_sRGB_SUPPORTED)
+PNG_EXTERN void png_handle_sRGB PNGARG((png_structp png_ptr, png_infop info_ptr,
+   png_uint_32 length));
+#endif
+
 #if defined(PNG_READ_tRNS_SUPPORTED)
 PNG_EXTERN void png_handle_tRNS PNGARG((png_structp png_ptr, png_infop info_ptr,
    png_uint_32 length));

pngconf.h

@@ -1,66 +1,71 @@
 
 /* pngconf.c - machine configurable file for libpng
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-   */
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ */
 
 /* Any machine specific code is near the front of this file, so if you
-   are configuring libpng for a machine, you may want to read the section
-   starting here down to where it starts to typedef png_color, png_text,
-   and png_info */
+ * are configuring libpng for a machine, you may want to read the section
+ * starting here down to where it starts to typedef png_color, png_text,
+ * and png_info.
+ */
 
 #ifndef PNGCONF_H
 #define PNGCONF_H
 
 /* This is the size of the compression buffer, and thus the size of
-   an IDAT chunk.  Make this whatever size you feel is best for your
-   machine.  One of these will be allocated per png_struct.  When this
-   is full, it writes the data to the disk, and does some other
-   calculations.  Making this an extreamly small size will slow
-   the library down, but you may want to experiment to determine
-   where it becomes significant, if you are concerned with memory
-   usage.  Note that zlib allocates at least 32Kb also.  For readers,
-   this describes the size of the buffer available to read the data in.
-   Unless this gets smaller then the size of a row (compressed),
-   it should not make much difference how big this is.  */
+ * an IDAT chunk.  Make this whatever size you feel is best for your
+ * machine.  One of these will be allocated per png_struct.  When this
+ * is full, it writes the data to the disk, and does some other
+ * calculations.  Making this an extremely small size will slow
+ * the library down, but you may want to experiment to determine
+ * where it becomes significant, if you are concerned with memory
+ * usage.  Note that zlib allocates at least 32Kb also.  For readers,
+ * this describes the size of the buffer available to read the data in.
+ * Unless this gets smaller than the size of a row (compressed),
+ * it should not make much difference how big this is.
+ */
 
+#ifndef PNG_ZBUF_SIZE
 #define PNG_ZBUF_SIZE 8192
+#endif
 
 /* If you are running on a machine where you cannot allocate more
-   than 64K of memory at once, uncomment this.  While libpng will not
-   normally need that much memory in a chunk (unless you load up a very
-   large file), zlib needs to know how big of a chunk it can use, and
-   libpng thus makes sure to check any memory allocation to verify it
-   will fit into memory.
+ * than 64K of memory at once, uncomment this.  While libpng will not
+ * normally need that much memory in a chunk (unless you load up a very
+ * large file), zlib needs to know how big of a chunk it can use, and
+ * libpng thus makes sure to check any memory allocation to verify it
+ * will fit into memory.
 #define PNG_MAX_MALLOC_64K
-*/
+ */
 #if defined(MAXSEG_64K) && !defined(PNG_MAX_MALLOC_64K)
 #define PNG_MAX_MALLOC_64K
 #endif
 
 /* This protects us against compilers which run on a windowing system
-   and thus don't have or would rather us not use the stdio types:
-   stdin, stdout, and stderr.  The only one currently used is stderr
-   in png_error() and png_warning().  #defining PNG_NO_STDIO will
-   prevent these from being compiled and used. */
+ * and thus don't have or would rather us not use the stdio types:
+ * stdin, stdout, and stderr.  The only one currently used is stderr
+ * in png_error() and png_warning().  #defining PNG_NO_STDIO will
+ * prevent these from being compiled and used.
+ * #define PNG_NO_STDIO
+ */
 
-/* #define PNG_NO_STDIO */
-
-/* for FILE.  If you are not using standard io, you don't need this */
-#ifndef PNG_NO_STDIO
+#ifndef PNG_NO_STDIO 
 #include <stdio.h>
 #endif
 
 /* This macro protects us against machines that don't have function
-   prototypes (ie K&R style headers).  If your compiler does not handle
-   function prototypes, define this macro and use the included ansi2knr.
-   I've always been able to use _NO_PROTO as the indicator, but you may
-   need to drag the empty declaration out in front of here, or change the
-   ifdef to suit your own needs. */
+ * prototypes (ie K&R style headers).  If your compiler does not handle
+ * function prototypes, define this macro and use the included ansi2knr.
+ * I've always been able to use _NO_PROTO as the indicator, but you may
+ * need to drag the empty declaration out in front of here, or change the
+ * ifdef to suit your own needs.
+ */
 #ifndef PNGARG
 
 #ifdef OF /* zlib prototype munger */
@@ -77,10 +82,16 @@
 
 #endif /* PNGARG */
 
-/* Try to determine if we are compiling on a Mac */
-#if defined(__MWERKS__) ||defined(applec) ||defined(THINK_C) ||defined(__SC__)
+/* Try to determine if we are compiling on a Mac.  Note that testing for
+ * just __MWERKS__ is not good enough, because the Codewarrior is now used
+ * on non-Mac platforms.
+ */
+#ifndef MACOS
+#if (defined(__MWERKS__) && defined(macintosh)) || defined(applec) || \
+    defined(THINK_C) || defined(__SC__) || defined(TARGET_OS_MAC)
 #define MACOS
 #endif
+#endif
 
 /* enough people need this for various reasons to include it here */
 #if !defined(MACOS) && !defined(RISCOS)
@@ -88,27 +99,28 @@
 #endif
 
 /* This is an attempt to force a single setjmp behaviour on Linux.  If
-   the X config stuff didn't define _BSD_SOURCE we wouldn't need this. */
-#ifdef linux
+ * the X config stuff didn't define _BSD_SOURCE we wouldn't need this.
+ */
+#ifdef __linux__
 #ifdef _BSD_SOURCE
 #define _PNG_SAVE_BSD_SOURCE
 #undef _BSD_SOURCE
 #endif
 #ifdef _SETJMP_H
-#error  __png_h_already_includes_setjmp_h__
-#error  __dont_include_it_again__
+__png.h__ already includes setjmp.h
+__dont__ include it again
 #endif
-#endif /* linux */
+#endif /* __linux__ */
 
 /* include setjmp.h for error handling */
 #include <setjmp.h>
 
-#ifdef linux
+#ifdef __linux__
 #ifdef _PNG_SAVE_BSD_SOURCE
 #define _BSD_SOURCE
 #undef _PNG_SAVE_BSD_SOURCE
 #endif
-#endif /* linux */
+#endif /* __linux__ */
 
 #ifdef BSD
 #include <strings.h>
@@ -119,9 +131,6 @@
 /* Other defines for things like memory and the like can go here.  */
 #ifdef PNG_INTERNAL
 #include <stdlib.h>
-/* Where do we need this???
-#include <ctype.h>
-*/
 
 /* The functions exported by PNG_EXTERN are PNG_INTERNAL functions, which
  * aren't usually used outside the library (as far as I know), so it is
@@ -133,12 +142,14 @@
 #define PNG_EXTERN
 
 /* Other defines specific to compilers can go here.  Try to keep
-   them inside an appropriate ifdef/endif pair for portability */
+ * them inside an appropriate ifdef/endif pair for portability.
+ */
 
 #if defined(MACOS)
 /* We need to check that <math.h> hasn't already been included earlier
-   as it seems it doesn't agree with <fp.h>, yet we should really use
-   <fp.h> if possible. */
+ * as it seems it doesn't agree with <fp.h>, yet we should really use
+ * <fp.h> if possible.
+ */
 #if !defined(__MATH_H__) && !defined(__MATH_H) && !defined(__cmath__)
 #include <fp.h>
 #endif
@@ -146,9 +157,15 @@
 #include <math.h>
 #endif
 
+/* Codewarrior on NT has linking problems without this. */
+#if defined(__MWERKS__) && defined(WIN32)
+#define PNG_ALWAYS_EXTERN
+#endif
+
 /* For some reason, Borland C++ defines memcmp, etc. in mem.h, not
-   stdlib.h like it should (I think).  Or perhaps this is a C++
-   "feature"? */
+ * stdlib.h like it should (I think).  Or perhaps this is a C++
+ * "feature"?
+ */
 #ifdef __TURBOC__
 #include <mem.h>
 #include "alloc.h"
@@ -159,58 +176,81 @@
 #endif
 
 /* This controls how fine the dithering gets.  As this allocates
-   a largish chunk of memory (32K), those who are not as concerned
-   with dithering quality can decrease some or all of these. */
+ * a largish chunk of memory (32K), those who are not as concerned
+ * with dithering quality can decrease some or all of these.
+ */
+#ifndef PNG_DITHER_RED_BITS
 #define PNG_DITHER_RED_BITS 5
+#endif
+#ifndef PNG_DITHER_GREEN_BITS
 #define PNG_DITHER_GREEN_BITS 5
+#endif
+#ifndef PNG_DITHER_BLUE_BITS
 #define PNG_DITHER_BLUE_BITS 5
+#endif
 
 /* This controls how fine the gamma correction becomes when you
-   are only interested in 8 bits anyway.  Increasing this value
-   results in more memory being used, and more pow() functions
-   being called to fill in the gamma tables.  Don't set this
-   value less then 8, and even that may not work (I haven't tested
-   it). */
+ * are only interested in 8 bits anyway.  Increasing this value
+ * results in more memory being used, and more pow() functions
+ * being called to fill in the gamma tables.  Don't set this value
+ * less then 8, and even that may not work (I haven't tested it).
+ */
 
+#ifndef PNG_MAX_GAMMA_8
 #define PNG_MAX_GAMMA_8 11
+#endif
 
 /* This controls how much a difference in gamma we can tolerate before
-   we actually start doing gamma conversion.  */
+ * we actually start doing gamma conversion.
+ */
+#ifndef PNG_GAMMA_THRESHOLD
 #define PNG_GAMMA_THRESHOLD 0.05
+#endif
 
 #endif /* PNG_INTERNAL */
 
 /* The following uses const char * instead of char * for error
-   and warning message functions, so some compilers won't complain.
-   If you want to use const, define PNG_USE_CONST here.  It is not
-   normally defined to make configuration easier, as it is not a
-   critical part of the code.
-   */
-#undef PNG_USE_CONST
+ * and warning message functions, so some compilers won't complain.
+ * If you do not want to use const, define PNG_NO_CONST here.
+ */
 
-#ifdef PNG_USE_CONST
+#ifndef PNG_NO_CONST
 #  define PNG_CONST const
 #else
 #  define PNG_CONST
 #endif
 
 /* The following defines give you the ability to remove code from the
-   library that you will not be using.  I wish I could figure out how to
-   automate this, but I can't do that without making it seriously hard
-   on the users.  So if you are not using an ability, change the #define
-   to and #undef, and that part of the library will not be compiled.  If
-   your linker can't find a function, you may want to make sure the
-   ability is defined here.  Some of these depend upon some others being
-   defined.  I haven't figured out all the interactions here, so you may
-   have to experiment awhile to get everything to compile.  If you are
-   creating or using a shared library, you probably shouldn't touch this,
-   as it will affect the size of the structures, and this will cause bad
-   things to happen if the library and/or application ever change. */
+ * library that you will not be using.  I wish I could figure out how to
+ * automate this, but I can't do that without making it seriously hard
+ * on the users.  So if you are not using an ability, change the #define
+ * to and #undef, and that part of the library will not be compiled.  If
+ * your linker can't find a function, you may want to make sure the
+ * ability is defined here.  Some of these depend upon some others being
+ * defined.  I haven't figured out all the interactions here, so you may
+ * have to experiment awhile to get everything to compile.  If you are
+ * creating or using a shared library, you probably shouldn't touch this,
+ * as it will affect the size of the structures, and this will cause bad
+ * things to happen if the library and/or application ever change.
+ */
 
 /* Any transformations you will not be using can be undef'ed here */
+
+/* GR-P, 0.96a: Set "*FULLY_SUPPORTED as default but allow user
+   to turn it off with "*NOT_FULLY_SUPPORTED" on the compile line,
+   then pick and choose which ones to define without having to edit
+   this file.
+ */
+
+#ifndef PNG_READ_NOT_FULLY_SUPPORTED
+#define PNG_READ_FULLY_SUPPORTED
+#endif
+#ifndef PNG_WRITE_NOT_FULLY_SUPPORTED
+#define PNG_WRITE_FULLY_SUPPORTED
+#endif
+
+#ifdef PNG_READ_FULLY_SUPPORTED
 #define PNG_PROGRESSIVE_READ_SUPPORTED
-#define PNG_READ_OPT_PLTE_SUPPORTED
-#define PNG_READ_INTERLACING_SUPPORTED
 #define PNG_READ_EXPAND_SUPPORTED
 #define PNG_READ_SHIFT_SUPPORTED
 #define PNG_READ_PACK_SUPPORTED
@@ -225,9 +265,14 @@
 #define PNG_READ_GAMMA_SUPPORTED
 #define PNG_READ_GRAY_TO_RGB_SUPPORTED
 #define PNG_READ_SWAP_ALPHA_SUPPORTED
+#define PNG_READ_INVERT_ALPHA_SUPPORTED
 #define PNG_READ_STRIP_ALPHA_SUPPORTED
+#define PNG_READ_COMPOSITE_NODIV_SUPPORTED        /* well tested on Intel */
+#endif /* PNG_READ_FULLY_SUPPORTED */
 
-#define PNG_WRITE_INTERLACING_SUPPORTED
+#define PNG_READ_INTERLACING_SUPPORTED  /* required for PNG-compliant decoders */
+
+#ifdef PNG_WRITE_FULLY_SUPPORTED
 #define PNG_WRITE_SHIFT_SUPPORTED
 #define PNG_WRITE_PACK_SUPPORTED
 #define PNG_WRITE_BGR_SUPPORTED
@@ -237,27 +282,71 @@
 #define PNG_WRITE_FILLER_SUPPORTED  /* This is the same as WRITE_STRIP_ALPHA */
 #define PNG_WRITE_FLUSH_SUPPORTED
 #define PNG_WRITE_SWAP_ALPHA_SUPPORTED
+#define PNG_WRITE_INVERT_ALPHA_SUPPORTED
 #define PNG_WRITE_WEIGHTED_FILTER_SUPPORTED
+#endif /* PNG_WRITE_FULLY_SUPPORTED */
 
-/* These are currently experimental features */
-#undef PNG_READ_16_TO_8_ACCURATE_SHIFT_SUPPORTED /* very little testing */
-#undef PNG_READ_COMPOSITE_NODIV_SUPPORTED        /* very little testing */
+#define PNG_WRITE_INTERLACING_SUPPORTED  /* not required for PNG-compliant */
+                                         /* encoders, but can cause trouble
+                                            if left undefined */
+
+#if !defined(PNG_NO_STDIO)
+#define PNG_TIME_RFC1123_SUPPORTED
+#endif
+
+/* This adds extra functions in pngget.c for accessing data from the
+ * info pointer (added in version 0.99)
+ * png_get_image_width()
+ * png_get_image_height()
+ * png_get_bit_depth()
+ * png_get_color_type()
+ * png_get_compression_type()
+ * png_get_filter_type()
+ * png_get_interlace_type()
+ * png_get_pixel_aspect_ratio()
+ * png_get_pixels_per_meter()
+ * png_get_x_offset_pixels()
+ * png_get_y_offset_pixels()
+ * png_get_x_offset_microns()
+ * png_get_y_offset_microns()
+ */
+#if !defined(PNG_NO_EASY_ACCESS)
+#define PNG_EASY_ACCESS_SUPPORTED
+#endif
+
+/* These are currently experimental features, define them if you want */
+
+/* very little testing */
+/*
+#define PNG_READ_16_TO_8_ACCURATE_SHIFT_SUPPORTED
+*/
 
 /* This is only for PowerPC big-endian and 680x0 systems */
-#undef PNG_READ_BIG_ENDIAN_SUPPORTED             /* some testing */
+/* some testing */
+/*
+#define PNG_READ_BIG_ENDIAN_SUPPORTED
+*/
 
 /* These functions are turned off by default, as they will be phased out. */
-#undef  PNG_USE_OWN_CRC
-#undef  PNG_USELESS_TESTS_SUPPORTED
-#undef  PNG_CORRECT_PALETTE_SUPPORTED
+/*
+#define  PNG_USELESS_TESTS_SUPPORTED
+#define  PNG_CORRECT_PALETTE_SUPPORTED
+*/
 
 /* Any chunks you are not interested in, you can undef here.  The
  * ones that allocate memory may be expecially important (hIST,
  * tEXt, zTXt, tRNS, pCAL).  Others will just save time and make png_info
- * a bit smaller.  OPT_PLTE only disables the optional palette in RGB
- * and RGBA images.
+ * a bit smaller.
  */
 
+#ifndef PNG_READ_ANCILLARY_CHUNKS_NOT_SUPPORTED
+#define PNG_READ_ANCILLARY_CHUNKS_SUPPORTED
+#endif
+#ifndef PNG_WRITE_ANCILLARY_CHUNKS_NOT_SUPPORTED
+#define PNG_WRITE_ANCILLARY_CHUNKS_SUPPORTED
+#endif
+
+#ifdef PNG_READ_ANCILLARY_CHUNKS_SUPPORTED
 #define PNG_READ_bKGD_SUPPORTED
 #define PNG_READ_cHRM_SUPPORTED
 #define PNG_READ_gAMA_SUPPORTED
@@ -266,11 +355,16 @@
 #define PNG_READ_pCAL_SUPPORTED
 #define PNG_READ_pHYs_SUPPORTED
 #define PNG_READ_sBIT_SUPPORTED
+#define PNG_READ_sRGB_SUPPORTED
 #define PNG_READ_tEXt_SUPPORTED
 #define PNG_READ_tIME_SUPPORTED
 #define PNG_READ_tRNS_SUPPORTED
 #define PNG_READ_zTXt_SUPPORTED
+#define PNG_READ_OPT_PLTE_SUPPORTED /* only affects support of the optional */
+                                    /* PLTE chunk in RGB and RGBA images */
+#endif /* PNG_READ_ANCILLARY_CHUNKS_SUPPORTED */
 
+#ifdef PNG_WRITE_ANCILLARY_CHUNKS_SUPPORTED
 #define PNG_WRITE_bKGD_SUPPORTED
 #define PNG_WRITE_cHRM_SUPPORTED
 #define PNG_WRITE_gAMA_SUPPORTED
@@ -279,10 +373,12 @@
 #define PNG_WRITE_pCAL_SUPPORTED
 #define PNG_WRITE_pHYs_SUPPORTED
 #define PNG_WRITE_sBIT_SUPPORTED
+#define PNG_WRITE_sRGB_SUPPORTED
 #define PNG_WRITE_tEXt_SUPPORTED
 #define PNG_WRITE_tIME_SUPPORTED
 #define PNG_WRITE_tRNS_SUPPORTED
 #define PNG_WRITE_zTXt_SUPPORTED
+#endif /* PNG_WRITE_ANCILLARY_CHUNKS_SUPPORTED */
 
 /* need the time information for reading tIME chunks */
 #if defined(PNG_READ_tIME_SUPPORTED) || defined(PNG_WRITE_tIME_SUPPORTED)
@@ -336,18 +432,19 @@ typedef size_t png_size_t;
 #endif   /* LDATA != 1 */
 
 /* Possibly useful for moving data out of default segment.
-   Uncomment it if you want. Could also define FARDATA as
-   const if your compiler supports it. (SJT)
+ * Uncomment it if you want. Could also define FARDATA as
+ * const if your compiler supports it. (SJT)
 #  define FARDATA FAR
-*/
+ */
 #endif  /* __WIN32__, __FLAT__ */
 
 #endif   /* __BORLANDC__ */
 
 
 /* Suggest testing for specific compiler first before testing for
-   FAR.  The Watcom compiler defines both __MEDIUM__ and M_I86MM,
-   making reliance oncertain keywords suspect. (SJT) */
+ * FAR.  The Watcom compiler defines both __MEDIUM__ and M_I86MM,
+ * making reliance oncertain keywords suspect. (SJT)
+ */
 
 /* MSC Medium model */
 #if defined(FAR)
@@ -400,18 +497,29 @@ typedef charf *         png_zcharp;
 typedef charf * FAR *   png_zcharpp;
 typedef z_stream FAR *  png_zstreamp; 
 
-/* allow for compilation as dll under windows */
+/* allow for compilation as dll under MS Windows */
 #ifdef __WIN32DLL__
 #define PNG_EXPORT(type,symbol) __declspec(dllexport) type symbol
 #endif
 
+/* allow for compilation as dll with BORLAND C++ 5.0 */
+#if defined(__BORLANDC__) && defined(_Windows) && defined(__DLL__)
+#   define PNG_EXPORT(type,symbol) type _export symbol
+#endif
+
+/* allow for compilation as shared lib under BeOS */
+#ifdef __BEOSDLL__
+#define PNG_EXPORT(type,symbol) __declspec(export) type symbol
+#endif
+
 #ifndef PNG_EXPORT
-#define PNG_EXPORT(t,s) t s
+#define PNG_EXPORT(type,symbol) type symbol
 #endif
 
 
 /* User may want to use these so not in PNG_INTERNAL. Any library functions
-   that are passed far data must be model independent. */
+ * that are passed far data must be model independent.
+ */
 
 #if defined(USE_FAR_KEYWORD)  /* memory model independent fns */
 /* use this to make far-to-near assignments */

pngerror.c

@@ -1,16 +1,18 @@
 
 /* pngerror.c - stub functions for i/o and memory allocation
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-
-   This file provides a location for all error handling.  Users which
-   need special error handling are expected to write replacement functions
-   and use png_set_error_fn() to use those functions.  See the instructions
-   at each function. */
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ *
+ * This file provides a location for all error handling.  Users which
+ * need special error handling are expected to write replacement functions
+ * and use png_set_error_fn() to use those functions.  See the instructions
+ * at each function.
+ */
 
 #define PNG_INTERNAL
 #include "png.h"
@@ -21,9 +23,10 @@ static void png_default_warning PNGARG((png_structp png_ptr,
                                         png_const_charp message));
 
 /* This function is called whenever there is a fatal error.  This function
-   should not be changed.  If there is a need to handle errors differently,
-   you should supply a replacement error function and use png_set_error_fn()
-   to replace the error function at run-time. */
+ * should not be changed.  If there is a need to handle errors differently,
+ * you should supply a replacement error function and use png_set_error_fn()
+ * to replace the error function at run-time.
+ */
 void
 png_error(png_structp png_ptr, png_const_charp message)
 {
@@ -36,9 +39,10 @@ png_error(png_structp png_ptr, png_const_charp message)
 }
 
 /* This function is called whenever there is a non-fatal error.  This function
-   should not be changed.  If there is a need to handle warnings differently,
-   you should supply a replacement warning function and use
-   png_set_error_fn() to replace the warning function at run-time. */
+ * should not be changed.  If there is a need to handle warnings differently,
+ * you should supply a replacement warning function and use
+ * png_set_error_fn() to replace the warning function at run-time.
+ */
 void
 png_warning(png_structp png_ptr, png_const_charp message)
 {
@@ -48,10 +52,65 @@ png_warning(png_structp png_ptr, png_const_charp message)
       png_default_warning(png_ptr, message);
 }
 
+/* These utilities are used internally to build an error message which relates
+ * to the current chunk.  The chunk name comes from png_ptr->chunk_name,
+ * this is used to prefix the message.  The message is limited in length
+ * to 63 bytes, the name characters are output as hex digits wrapped in []
+ * if the character is invalid.
+ */
+#define isnonalpha(c) ((c) < 41 || (c) > 122 || ((c) > 90 && (c) < 97))
+static const char png_digit[16] = {
+   '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
+};
+
+static void
+png_format_buffer(png_structp png_ptr, png_charp buffer, png_const_charp message)
+{
+   int iout = 0, iin = 0;
+
+   while (iin < 4) {
+      int c = png_ptr->chunk_name[iin++];
+      if (isnonalpha(c)) {
+         buffer[iout++] = '[';
+         buffer[iout++] = png_digit[(c & 0xf0) >> 4];
+         buffer[iout++] = png_digit[c & 0xf];
+         buffer[iout++] = ']';
+      } else {
+         buffer[iout++] = c;
+      }
+   }
+
+   if (message == NULL)
+      buffer[iout++] = 0;
+   else {
+      buffer[iout++] = ':';
+      buffer[iout++] = ' ';
+      png_memcpy(buffer+iout, message, 64);
+      buffer[iout+63] = 0;
+   }
+}
+
+void
+png_chunk_error(png_structp png_ptr, png_const_charp message)
+{
+   char msg[16+64];
+   png_format_buffer(png_ptr, msg, message);
+   png_error(png_ptr, msg);
+}
+
+void
+png_chunk_warning(png_structp png_ptr, png_const_charp message)
+{
+   char msg[16+64];
+   png_format_buffer(png_ptr, msg, message);
+   png_warning(png_ptr, msg);
+}
+
 /* This is the default error handling function.  Note that replacements for
-   this function MUST NOT RETURN, or the program will likely crash.  This
-   function is used by default, or if the program supplies NULL for the
-   error function pointer in png_set_error_fn(). */
+ * this function MUST NOT RETURN, or the program will likely crash.  This
+ * function is used by default, or if the program supplies NULL for the
+ * error function pointer in png_set_error_fn().
+ */
 static void
 png_default_error(png_structp png_ptr, png_const_charp message)
 {
@@ -71,9 +130,10 @@ png_default_error(png_structp png_ptr, png_const_charp message)
 }
 
 /* This function is called when there is a warning, but the library thinks
-   it can continue anyway.  Replacement functions don't have to do anything
-   here if you don't want to.  In the default configuration, png_ptr is
-   not used, but it is passed in case it may be useful. */
+ * it can continue anyway.  Replacement functions don't have to do anything
+ * here if you don't want to.  In the default configuration, png_ptr is
+ * not used, but it is passed in case it may be useful.
+ */
 static void
 png_default_warning(png_structp png_ptr, png_const_charp message)
 {
@@ -86,9 +146,10 @@ png_default_warning(png_structp png_ptr, png_const_charp message)
 }
 
 /* This function is called when the application wants to use another method
-   of handling errors and warnings.  Note that the error function MUST NOT
-   return to the calling routine or serious problems will occur.  The return
-   method used in the default routine calls longjmp(png_ptr->jmpbuf, 1) */
+ * of handling errors and warnings.  Note that the error function MUST NOT
+ * return to the calling routine or serious problems will occur.  The return
+ * method used in the default routine calls longjmp(png_ptr->jmpbuf, 1)
+ */
 void
 png_set_error_fn(png_structp png_ptr, png_voidp error_ptr,
    png_error_ptr error_fn, png_error_ptr warning_fn)
@@ -100,12 +161,13 @@ png_set_error_fn(png_structp png_ptr, png_voidp error_ptr,
 
 
 /* This function returns a pointer to the error_ptr associated with the user
-   functions.  The application should free any memory associated with this
-   pointer before png_write_destroy and png_read_destroy are called. */
+ * functions.  The application should free any memory associated with this
+ * pointer before png_write_destroy and png_read_destroy are called.
+ */
 png_voidp
 png_get_error_ptr(png_structp png_ptr)
 {
-   return png_ptr->error_ptr;
+   return ((png_voidp)png_ptr->error_ptr);
 }
 
 

pngget.c

@@ -1,12 +1,13 @@
 
 /* pngget.c - retrieval of values from info struct
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-   */
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ */
 
 #define PNG_INTERNAL
 #include "png.h"
@@ -29,6 +30,179 @@ png_get_rowbytes(png_structp png_ptr, png_infop info_ptr)
       return(0);
 }
 
+#ifdef PNG_EASY_ACCESS_SUPPORTED
+/* easy access to info, added in libpng-0.99 */
+png_uint_32
+png_get_image_width(png_structp png_ptr, png_infop info_ptr)
+{
+   if (info_ptr != NULL)
+   {
+      return info_ptr->width;
+   }
+   return (0);
+}
+
+png_uint_32
+png_get_image_height(png_structp png_ptr, png_infop info_ptr)
+{
+   if (info_ptr != NULL)
+   {
+      return info_ptr->height;
+   }
+   return (0);
+}
+
+png_byte
+png_get_bit_depth(png_structp png_ptr, png_infop info_ptr)
+{
+   if (info_ptr != NULL)
+   {
+      return info_ptr->bit_depth;
+   }
+   return (0);
+}
+
+png_byte
+png_get_color_type(png_structp png_ptr, png_infop info_ptr)
+{
+   if (info_ptr != NULL)
+   {
+      return info_ptr->color_type;
+   }
+   return (0);
+}
+
+png_byte
+png_get_filter_type(png_structp png_ptr, png_infop info_ptr)
+{
+   if (info_ptr != NULL)
+   {
+      return info_ptr->filter_type;
+   }
+   return (0);
+}
+
+png_byte
+png_get_interlace_type(png_structp png_ptr, png_infop info_ptr)
+{
+   if (info_ptr != NULL)
+   {
+      return info_ptr->interlace_type;
+   }
+   return (0);
+}
+
+png_byte
+png_get_compression_type(png_structp png_ptr, png_infop info_ptr)
+{
+   if (info_ptr != NULL)
+   {
+      return info_ptr->compression_type;
+   }
+   return (0);
+}
+
+png_uint_32
+png_get_pixels_per_meter(png_structp png_ptr, png_infop info_ptr)
+{
+#if defined(PNG_READ_pHYs_SUPPORTED) || defined(PNG_WRITE_pHYs_SUPPORTED)
+   if (info_ptr != NULL && info_ptr->valid & PNG_INFO_pHYs)
+   {
+      png_debug1(1, "in %s retrieval function\n", "png_get_pixels_per_meter");
+      if(info_ptr->phys_unit_type != PNG_RESOLUTION_METER)
+          return (0);
+      else return (info_ptr->x_pixels_per_unit);
+   }
+   else
+#endif
+   return (0);
+}
+
+float
+png_get_pixel_aspect_ratio(png_structp png_ptr, png_infop info_ptr)
+   {
+#if defined(PNG_READ_pHYs_SUPPORTED) || defined(PNG_WRITE_pHYs_SUPPORTED)
+   if (info_ptr != NULL && info_ptr->valid & PNG_INFO_pHYs)
+   {
+      png_debug1(1, "in %s retrieval function\n", "png_get_aspect_ratio");
+      if (info_ptr->x_pixels_per_unit == 0)
+         return (0.0);
+      else
+         return ((float)info_ptr->y_pixels_per_unit
+            /(float)info_ptr->x_pixels_per_unit);
+   }
+   else
+#endif
+      return (0.0);
+}
+
+png_uint_32
+png_get_x_offset_microns(png_structp png_ptr, png_infop info_ptr)
+{
+#if defined(PNG_READ_oFFs_SUPPORTED) || defined(PNG_WRITE_oFFs_SUPPORTED)
+   if (info_ptr != NULL && info_ptr->valid & PNG_INFO_oFFs)
+   {
+      png_debug1(1, "in %s retrieval function\n", "png_get_x_offset_microns");
+      if(info_ptr->offset_unit_type != PNG_OFFSET_MICROMETER)
+          return (0);
+      else return (info_ptr->x_offset);
+   }
+   else
+#endif
+   return (0);
+}
+
+png_uint_32
+png_get_y_offset_microns(png_structp png_ptr, png_infop info_ptr)
+{
+#if defined(PNG_READ_oFFs_SUPPORTED) || defined(PNG_WRITE_oFFs_SUPPORTED)
+   if (info_ptr != NULL && info_ptr->valid & PNG_INFO_oFFs)
+   {
+      png_debug1(1, "in %s retrieval function\n", "png_get_y_offset_microns");
+      if(info_ptr->offset_unit_type != PNG_OFFSET_MICROMETER)
+          return (0);
+      else return (info_ptr->y_offset);
+   }
+   else
+#endif
+   return (0);
+}
+
+png_uint_32
+png_get_x_offset_pixels(png_structp png_ptr, png_infop info_ptr)
+{
+#if defined(PNG_READ_oFFs_SUPPORTED) || defined(PNG_WRITE_oFFs_SUPPORTED)
+   if (info_ptr != NULL && info_ptr->valid & PNG_INFO_oFFs)
+   {
+      png_debug1(1, "in %s retrieval function\n", "png_get_x_offset_microns");
+      if(info_ptr->offset_unit_type != PNG_OFFSET_PIXEL)
+          return (0);
+      else return (info_ptr->x_offset);
+   }
+   else
+#endif
+   return (0);
+}
+
+png_uint_32
+png_get_y_offset_pixels(png_structp png_ptr, png_infop info_ptr)
+{
+#if defined(PNG_READ_oFFs_SUPPORTED) || defined(PNG_WRITE_oFFs_SUPPORTED)
+   if (info_ptr != NULL && info_ptr->valid & PNG_INFO_oFFs)
+   {
+      png_debug1(1, "in %s retrieval function\n", "png_get_y_offset_microns");
+      if(info_ptr->offset_unit_type != PNG_OFFSET_PIXEL)
+          return (0);
+      else return (info_ptr->y_offset);
+   }
+   else
+#endif
+   return (0);
+}
+
+/* png_get_channels really belongs in here, too, but it's been around longer */
+#endif
+
 png_byte
 png_get_channels(png_structp png_ptr, png_infop info_ptr)
 {
@@ -109,6 +283,21 @@ png_get_gAMA(png_structp png_ptr, png_infop info_ptr, double *file_gamma)
 }
 #endif
 
+#if defined(PNG_READ_sRGB_SUPPORTED)
+png_uint_32
+png_get_sRGB(png_structp png_ptr, png_infop info_ptr, int *file_srgb_intent)
+{
+   if (info_ptr != NULL && info_ptr->valid & PNG_INFO_sRGB &&
+      file_srgb_intent != NULL)
+   {
+      png_debug1(1, "in %s retrieval function\n", "sRGB");
+      *file_srgb_intent = (int)info_ptr->srgb_intent;
+      return (PNG_INFO_sRGB);
+   }
+   return (0);
+}
+#endif
+
 #if defined(PNG_READ_hIST_SUPPORTED)
 png_uint_32
 png_get_hIST(png_structp png_ptr, png_infop info_ptr, png_uint_16p *hist)
@@ -196,14 +385,23 @@ png_uint_32
 png_get_pHYs(png_structp png_ptr, png_infop info_ptr,
    png_uint_32 *res_x, png_uint_32 *res_y, int *unit_type)
 {
-   if (info_ptr != NULL && info_ptr->valid & PNG_INFO_pHYs &&
-      res_x != NULL && res_y != NULL && unit_type != NULL)
+   png_uint_32 retval = 0;
+
+   if (info_ptr != NULL && info_ptr->valid & PNG_INFO_pHYs)
    {
       png_debug1(1, "in %s retrieval function\n", "pHYs");
-      *res_x = info_ptr->x_pixels_per_unit;
-      *res_y = info_ptr->y_pixels_per_unit;
-      *unit_type = (int)info_ptr->phys_unit_type;
-      return (PNG_INFO_pHYs);
+      if (res_x != NULL && res_y != NULL)
+      {
+         *res_x = info_ptr->x_pixels_per_unit;
+         *res_y = info_ptr->y_pixels_per_unit;
+         retval |= PNG_INFO_pHYs;
+      }
+      if (unit_type != NULL)
+      {
+         *unit_type = (int)info_ptr->phys_unit_type;
+         retval |= PNG_INFO_pHYs;
+      }
+      return (retval);
    }
    return (0);
 }
@@ -246,12 +444,13 @@ png_get_text(png_structp png_ptr, png_infop info_ptr, png_textp *text_ptr,
    if ((info_ptr != NULL) || (info_ptr->num_text > 0))
    {
       png_debug1(1, "in %s retrieval function\n",
-         (png_ptr->chunk_name[0] == '\0' ? "text" : png_ptr->chunk_name));
+         (png_ptr->chunk_name[0] == '\0' ? "text"
+             : (png_const_charp)png_ptr->chunk_name));
       if (text_ptr != NULL)
          *text_ptr = info_ptr->text;
       if (num_text != NULL)
          *num_text = info_ptr->num_text;
-      return (info_ptr->num_text);
+      return ((png_uint_32)info_ptr->num_text);
    }
    return(0);
 }

pngmem.c

@@ -1,19 +1,30 @@
-
 /* pngmem.c - stub functions for memory allocation
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-
-   This file provides a location for all memory allocation.  Users which
-   need special memory handling are expected to modify the code in this file
-   to meet their needs.  See the instructions at each function. */
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ *
+ * This file provides a location for all memory allocation.  Users which
+ * need special memory handling are expected to modify the code in this file
+ * to meet their needs.  See the instructions at each function.
+ */
 
 #define PNG_INTERNAL
 #include "png.h"
 
+/* The following "hides" PNG_MALLOC and PNG_FREE thus allowing the pngtest
+   application to put a wrapper on top of them. */
+#ifdef PNGTEST_MEMORY_DEBUG
+   #define PNG_MALLOC png_debug_malloc
+   #define PNG_FREE   png_debug_free
+#else
+   #define PNG_MALLOC png_malloc
+   #define PNG_FREE   png_free
+#endif
+
 /* Borland DOS special memory handler */
 #if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
 /* if you change this, be sure to change the one in png.h also */
@@ -31,7 +42,7 @@ png_create_struct(int type)
    else if (type == PNG_STRUCT_PNG)
      size = sizeof(png_struct);
    else
-     return (png_voidp)NULL;
+     return ((png_voidp)NULL);
 
    if ((struct_ptr = (png_voidp)farmalloc(size)) != NULL)
    {
@@ -47,7 +58,10 @@ void
 png_destroy_struct(png_voidp struct_ptr)
 {
    if (struct_ptr != NULL)
+   {
       farfree (struct_ptr);
+      struct_ptr = NULL;
+   }
 }
 
 /* Allocate memory.  For reasonable files, size should never exceed
@@ -70,18 +84,18 @@ png_destroy_struct(png_voidp struct_ptr)
  * (which should cause a fatal error) and introducing major problems.
  */
 png_voidp
-png_malloc(png_structp png_ptr, png_uint_32 size)
+PNG_MALLOC(png_structp png_ptr, png_uint_32 size)
 {
    png_voidp ret;
    if (png_ptr == NULL || size == 0)
-      return ((voidp)NULL);
+      return ((png_voidp)NULL);
 
 #ifdef PNG_MAX_MALLOC_64K
    if (size > (png_uint_32)65536L)
       png_error(png_ptr, "Cannot Allocate > 64K");
 #endif
 
-   if (size == (png_uint_32)(65536L))
+   if (size == (png_uint_32)65536L)
    {
       if (png_ptr->offset_table == NULL)
       {
@@ -96,8 +110,10 @@ png_malloc(png_structp png_ptr, png_uint_32 size)
             png_byte huge * hptr;
 
             if (ret != NULL)
+            {
                farfree(ret);
-            ret = NULL;
+               ret = NULL;
+            }
 
             num_blocks = (int)(1 << (png_ptr->zlib_window_bits - 14));
             if (num_blocks < 1)
@@ -113,7 +129,7 @@ png_malloc(png_structp png_ptr, png_uint_32 size)
 
             if (table == NULL)
             {
-               png_error(png_ptr, "Out of Memory");
+               png_error(png_ptr, "Out Of Memory."); /* Note "O" and "M" */
             }
 
             if ((png_size_t)table & 0xfff0)
@@ -127,7 +143,7 @@ png_malloc(png_structp png_ptr, png_uint_32 size)
 
             if (png_ptr->offset_table_ptr == NULL)
             {
-               png_error(png_ptr, "Out of memory");
+               png_error(png_ptr, "Out Of memory.");
             }
 
             hptr = (png_byte huge *)table;
@@ -139,7 +155,7 @@ png_malloc(png_structp png_ptr, png_uint_32 size)
             for (i = 0; i < num_blocks; i++)
             {
                png_ptr->offset_table_ptr[i] = (png_bytep)hptr;
-               hptr += 65536L;
+               hptr += (png_uint_32)65536L;
             }
 
             png_ptr->offset_table_number = num_blocks;
@@ -149,7 +165,7 @@ png_malloc(png_structp png_ptr, png_uint_32 size)
       }
 
       if (png_ptr->offset_table_count >= png_ptr->offset_table_number)
-         png_error(png_ptr, "Out of Memory");
+         png_error(png_ptr, "Out of Memory.");
 
       ret = png_ptr->offset_table_ptr[png_ptr->offset_table_count++];
    }
@@ -158,17 +174,17 @@ png_malloc(png_structp png_ptr, png_uint_32 size)
 
    if (ret == NULL)
    {
-      png_error(png_ptr, "Out of Memory");
+      png_error(png_ptr, "Out of memory."); /* Note "o" and "m" */
    }
 
-   return ret;
+   return (ret);
 }
 
-/* free a pointer allocated by png_malloc().  In the default
+/* free a pointer allocated by PNG_MALLOC().  In the default
    configuration, png_ptr is not used, but is passed in case it
    is needed.  If ptr is NULL, return without taking any action. */
 void
-png_free(png_structp png_ptr, png_voidp ptr)
+PNG_FREE(png_structp png_ptr, png_voidp ptr)
 {
    if (png_ptr == NULL || ptr == NULL)
       return;
@@ -196,7 +212,10 @@ png_free(png_structp png_ptr, png_voidp ptr)
    }
 
    if (ptr != NULL)
+   {
       farfree(ptr);
+      ptr = NULL;
+   }
 }
 
 #else /* Not the Borland DOS special memory handler */
@@ -215,7 +234,7 @@ png_create_struct(int type)
    else if (type == PNG_STRUCT_PNG)
       size = sizeof(png_struct);
    else
-      return (png_voidp)NULL;
+      return ((png_voidp)NULL);
 
 #if defined(__TURBOC__) && !defined(__FLAT__)
    if ((struct_ptr = (png_voidp)farmalloc(size)) != NULL)
@@ -239,15 +258,20 @@ void
 png_destroy_struct(png_voidp struct_ptr)
 {
    if (struct_ptr != NULL)
+   {
 #if defined(__TURBOC__) && !defined(__FLAT__)
       farfree(struct_ptr);
+      struct_ptr = NULL;
 #else
 # if defined(_MSC_VER) && defined(MAXSEG_64K)
       hfree(struct_ptr);
+      struct_ptr = NULL;
 # else
       free(struct_ptr);
+      struct_ptr = NULL;
 # endif
 #endif
+   }
 }
 
 
@@ -258,11 +282,11 @@ png_destroy_struct(png_voidp struct_ptr)
    have the ability to do that. */
 
 png_voidp
-png_malloc(png_structp png_ptr, png_uint_32 size)
+PNG_MALLOC(png_structp png_ptr, png_uint_32 size)
 {
    png_voidp ret;
    if (png_ptr == NULL || size == 0)
-      return (NULL);
+      return ((png_voidp)NULL);
 
 #ifdef PNG_MAX_MALLOC_64K
    if (size > (png_uint_32)65536L)
@@ -284,25 +308,28 @@ png_malloc(png_structp png_ptr, png_uint_32 size)
       png_error(png_ptr, "Out of Memory");
    }
 
-   return ret;
+   return (ret);
 }
 
-/* Free a pointer allocated by png_malloc().  In the default
+/* Free a pointer allocated by PNG_MALLOC().  In the default
   configuration, png_ptr is not used, but is passed in case it
   is needed.  If ptr is NULL, return without taking any action. */
 void
-png_free(png_structp png_ptr, png_voidp ptr)
+PNG_FREE(png_structp png_ptr, png_voidp ptr)
 {
    if (png_ptr == NULL || ptr == NULL)
       return;
 
 #if defined(__TURBOC__) && !defined(__FLAT__)
    farfree(ptr);
+   ptr = NULL;
 #else
 # if defined(_MSC_VER) && defined(MAXSEG_64K)
    hfree(ptr);
+   ptr = NULL;
 # else
    free(ptr);
+   ptr = NULL;
 # endif
 #endif
 }

pngpread.c

@@ -1,12 +1,13 @@
 
 /* pngpread.c - read a png file in push mode
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-   */
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ */
 
 #define PNG_INTERNAL
 #include "png.h"
@@ -116,10 +117,11 @@ void
 png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
 {
    /* First we make sure we have enough data for the 4 byte chunk name
-      and the 4 byte chunk length before proceeding with decoding the
-      chunk data.  To fully decode each of these chunks, we also make
-      sure we have enough data in the buffer for the 4 byte CRC at the
-      end of every chunk (except IDAT, which is handled separately). */
+    * and the 4 byte chunk length before proceeding with decoding the
+    * chunk data.  To fully decode each of these chunks, we also make
+    * sure we have enough data in the buffer for the 4 byte CRC at the
+    * end of every chunk (except IDAT, which is handled separately).
+    */
    if (!(png_ptr->flags & PNG_FLAG_HAVE_CHUNK_HEADER))
    {
       png_byte chunk_length[4];
@@ -160,8 +162,9 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
    else if (!png_memcmp(png_ptr->chunk_name, png_IDAT, 4))
    {
       /* If we reach an IDAT chunk, this means we have read all of the
-         header chunks, and we can start reading the image (or if this
-         is called after the image has been read - we have an error). */
+       * header chunks, and we can start reading the image (or if this
+       * is called after the image has been read - we have an error).
+       */
       if (png_ptr->mode & PNG_HAVE_IDAT)
       {
          if (png_ptr->push_length == 0)
@@ -227,6 +230,18 @@ png_push_read_chunk(png_structp png_ptr, png_infop info_ptr)
       png_handle_cHRM(png_ptr, info_ptr, png_ptr->push_length);
    }
 #endif
+#if defined(PNG_READ_sRGB_SUPPORTED)
+   else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))
+   {
+      if (png_ptr->push_length + 4 > png_ptr->buffer_size)
+      {
+         png_push_save_buffer(png_ptr);
+         return;
+      }
+
+      png_handle_sRGB(png_ptr, info_ptr, png_ptr->push_length);
+   }
+#endif
 #if defined(PNG_READ_tRNS_SUPPORTED)
    else if (!png_memcmp(png_ptr->chunk_name, png_tRNS, 4))
    {
@@ -783,11 +798,11 @@ png_push_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length
 #ifdef PNG_MAX_MALLOC_64K
    png_ptr->skip_length = 0;  /* This may not be necessary */
 
-   if (length > 65535L)  /* We can't hold the entire string in memory */
+   if (length > (png_uint_32)65535L) /* Can't hold the entire string in memory */
    {
       png_warning(png_ptr, "tEXt chunk too large to fit in memory");
-      png_ptr->skip_length = length - 65535L;
-      length = 65535L;
+      png_ptr->skip_length = length - (png_uint_32)65535L;
+      length = (png_uint_32)65535L;
    }
 #endif
 
@@ -866,7 +881,7 @@ png_push_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length
     * to be able to store the uncompressed data.  Actually, the threshold
     * is probably around 32K, but it isn't as definite as 64K is.
     */
-   if (length > 65535L)
+   if (length > (png_uint_32)65535L)
    {
       png_warning(png_ptr, "zTXt chunk too large to fit in memory");
       png_push_crc_skip(png_ptr, length);
@@ -977,7 +992,7 @@ png_push_read_zTXt(png_structp png_ptr, png_infop info_ptr)
                png_charp tmp;
 
                tmp = text;
-               text = png_malloc(png_ptr, text_size +
+               text = (png_charp)png_malloc(png_ptr, text_size +
                   png_ptr->zbuf_size - png_ptr->zstream.avail_out + 1);
                png_memcpy(text, tmp, text_size);
                png_free(png_ptr, tmp);
@@ -1029,11 +1044,12 @@ png_push_read_zTXt(png_structp png_ptr, png_infop info_ptr)
 #endif
 
 /* This function is called when we haven't found a handler for this
-   chunk.  In the future we will have code here which can handle
-   user-defined callback functions for unknown chunks before they are
-   ignored or cause an error.  If there isn't a problem with the
-   chunk itself (ie a bad chunk name or a critical chunk), the chunk
-   is (currently) silently ignored. */
+ * chunk.  In the future we will have code here which can handle
+ * user-defined callback functions for unknown chunks before they are
+ * ignored or cause an error.  If there isn't a problem with the
+ * chunk itself (ie a bad chunk name or a critical chunk), the chunk
+ * is (currently) silently ignored.
+ */
 void
 png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 {
@@ -1041,10 +1057,7 @@ png_push_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 len
 
    if (!(png_ptr->chunk_name[0] & 0x20))
    {
-      char msg[40];
-
-      sprintf(msg, "Unknown critical chunk %s", png_ptr->chunk_name);
-      png_error(png_ptr, msg);
+      png_chunk_error(png_ptr, "unknown critical chunk");
    }
 
    png_push_crc_skip(png_ptr, length);

pngread.c

@@ -1,19 +1,23 @@
 
 /* pngread.c - read a PNG file
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-   */
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ *
+ * This file contains routines that an application calls directly to
+ * read a PNG file or stream.
+ */
 
 #define PNG_INTERNAL
 #include "png.h"
 
 /* Create a PNG structure for reading, and allocate any memory needed. */
 png_structp
-png_create_read_struct(png_charp user_png_ver, png_voidp error_ptr,
+png_create_read_struct(png_const_charp user_png_ver, png_voidp error_ptr,
    png_error_ptr error_fn, png_error_ptr warn_fn)
 {
    png_structp png_ptr;
@@ -54,7 +58,7 @@ png_create_read_struct(png_charp user_png_ver, png_voidp error_ptr,
 
    /* initialize zbuf - compression buffer */
    png_ptr->zbuf_size = PNG_ZBUF_SIZE;
-   png_ptr->zbuf = png_malloc(png_ptr, png_ptr->zbuf_size);
+   png_ptr->zbuf = (png_bytep)png_malloc(png_ptr, png_ptr->zbuf_size);
    png_ptr->zstream.zalloc = png_zalloc;
    png_ptr->zstream.zfree = png_zfree;
    png_ptr->zstream.opaque = (voidpf)png_ptr;
@@ -76,7 +80,6 @@ png_create_read_struct(png_charp user_png_ver, png_voidp error_ptr,
    return (png_ptr);
 }
 
-
 /* Initialize PNG structure for reading, and allocate any memory needed.
    This interface is depreciated in favour of the png_create_read_struct(),
    and it will eventually disappear. */
@@ -97,7 +100,7 @@ png_read_init(png_structp png_ptr)
 
    /* initialize zbuf - compression buffer */
    png_ptr->zbuf_size = PNG_ZBUF_SIZE;
-   png_ptr->zbuf = png_malloc(png_ptr, png_ptr->zbuf_size);
+   png_ptr->zbuf = (png_bytep)png_malloc(png_ptr, png_ptr->zbuf_size);
    png_ptr->zstream.zalloc = png_zalloc;
    png_ptr->zstream.zfree = png_zfree;
    png_ptr->zstream.opaque = (voidpf)png_ptr;
@@ -215,6 +218,10 @@ png_read_info(png_structp png_ptr, png_infop info_ptr)
       else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))
          png_handle_sBIT(png_ptr, info_ptr, length);
 #endif
+#if defined(PNG_READ_sRGB_SUPPORTED)
+      else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))
+         png_handle_sRGB(png_ptr, info_ptr, length);
+#endif
 #if defined(PNG_READ_tEXt_SUPPORTED)
       else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))
          png_handle_tEXt(png_ptr, info_ptr, length);
@@ -247,10 +254,11 @@ png_read_update_info(png_structp png_ptr, png_infop info_ptr)
    png_read_transform_info(png_ptr, info_ptr);
 }
 
-/* initialize palette, background, etc, after transformations
-   are set, but before any reading takes place.  This allows
-   the user to obtail a gamma corrected palette, for example.
-   If the user doesn't call this, we will do it ourselves. */
+/* Initialize palette, background, etc, after transformations
+ * are set, but before any reading takes place.  This allows
+ * the user to obtail a gamma corrected palette, for example.
+ * If the user doesn't call this, we will do it ourselves.
+ */
 void
 png_start_read_image(png_structp png_ptr)
 {
@@ -439,23 +447,26 @@ png_read_row(png_structp png_ptr, png_bytep row, png_bytep dsp_row)
 }
 
 /* Read one or more rows of image data.  If the image is interlaced,
-   and png_set_interlace_handling() has been called, the rows need to
-   to contain the contents of the rows from the previous pass.  If
-   the image has alpha or transparency, and png_handle_alpha() has been
-   called, the rows contents must be initialized to the contents of the
-   screen.  "row" holds the actual image, and pixels are placed in it
-   as they arrive.  If the image is displayed after each pass, it will
-   appear to "sparkle" in.  "display_row" can be used to display a
-   "chunky" progressive image, with finer detail added as it becomes
-   available.  If you do not want this "chunky" display, you may pass
-   NULL for display_row.  If you do not want the sparkle display, and
-   you have not called png_handle_alpha(), you may pass NULL for rows.
-   If you have called png_handle_alpha(), and the image has either an
-   alpha channel or a transparency chunk, you must provide a buffer for
-   rows.  In this case, you do not have to provide a display_row buffer
-   also, but you may.  If the image is not interlaced, or if you have
-   not called png_set_interlace_handling(), the display_row buffer will
-   be ignored, so pass NULL to it. */
+ * and png_set_interlace_handling() has been called, the rows need to
+ * contain the contents of the rows from the previous pass.  If the
+ * image has alpha or transparency, and png_handle_alpha() has been
+ * called, the rows contents must be initialized to the contents of the
+ * screen.
+ * 
+ * "row" holds the actual image, and pixels are placed in it
+ * as they arrive.  If the image is displayed after each pass, it will
+ * appear to "sparkle" in.  "display_row" can be used to display a
+ * "chunky" progressive image, with finer detail added as it becomes
+ * available.  If you do not want this "chunky" display, you may pass
+ * NULL for display_row.  If you do not want the sparkle display, and
+ * you have not called png_handle_alpha(), you may pass NULL for rows.
+ * If you have called png_handle_alpha(), and the image has either an
+ * alpha channel or a transparency chunk, you must provide a buffer for
+ * rows.  In this case, you do not have to provide a display_row buffer
+ * also, but you may.  If the image is not interlaced, or if you have
+ * not called png_set_interlace_handling(), the display_row buffer will
+ * be ignored, so pass NULL to it.
+ */
 
 void
 png_read_rows(png_structp png_ptr, png_bytepp row,
@@ -491,14 +502,15 @@ png_read_rows(png_structp png_ptr, png_bytepp row,
 }
 
 /* Read the entire image.  If the image has an alpha channel or a tRNS
-   chunk, and you have called png_handle_alpha(), you will need to
-   initialize the image to the current image that PNG will be overlaying.
-   We set the num_rows again here, in case it was incorrectly set in
-   png_read_start_row() by a call to png_read_update_info() or
-   png_start_read_image() if png_set_interlace_handling() wasn't called
-   prior to either of these functions like it should have been.  You can
-   only call this function once.  If you desire to have an image for
-   each pass of a interlaced image, use png_read_rows() instead */
+ * chunk, and you have called png_handle_alpha(), you will need to
+ * initialize the image to the current image that PNG will be overlaying.
+ * We set the num_rows again here, in case it was incorrectly set in
+ * png_read_start_row() by a call to png_read_update_info() or
+ * png_start_read_image() if png_set_interlace_handling() wasn't called
+ * prior to either of these functions like it should have been.  You can
+ * only call this function once.  If you desire to have an image for
+ * each pass of a interlaced image, use png_read_rows() instead.
+ */
 void
 png_read_image(png_structp png_ptr, png_bytepp image)
 {
@@ -524,8 +536,9 @@ png_read_image(png_structp png_ptr, png_bytepp image)
 }
 
 /* Read the end of the PNG file.  Will not read past the end of the
-   file, will verify the end is accurate, and will read any comments
-   or time information at the end of the file, if info is not NULL. */
+ * file, will verify the end is accurate, and will read any comments
+ * or time information at the end of the file, if info is not NULL.
+ */
 void
 png_read_end(png_structp png_ptr, png_infop info_ptr)
 {
@@ -594,6 +607,10 @@ png_read_end(png_structp png_ptr, png_infop info_ptr)
       else if (!png_memcmp(png_ptr->chunk_name, png_sBIT, 4))
          png_handle_sBIT(png_ptr, info_ptr, length);
 #endif
+#if defined(PNG_READ_sRGB_SUPPORTED)
+      else if (!png_memcmp(png_ptr->chunk_name, png_sRGB, 4))
+         png_handle_sRGB(png_ptr, info_ptr, length);
+#endif
 #if defined(PNG_READ_tEXt_SUPPORTED)
       else if (!png_memcmp(png_ptr->chunk_name, png_tEXt, 4))
          png_handle_tEXt(png_ptr, info_ptr, length);
@@ -638,12 +655,18 @@ png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
 
    if (info_ptr != NULL)
    {
+#if defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_READ_zTXt_SUPPORTED)
+      png_free(png_ptr, info_ptr->text);
+#endif
       png_destroy_struct((png_voidp)info_ptr);
       *info_ptr_ptr = (png_infop)NULL;
    }
 
    if (end_info_ptr != NULL)
    {
+#if defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_READ_zTXt_SUPPORTED)
+      png_free(png_ptr, end_info_ptr->text);
+#endif
       png_destroy_struct((png_voidp)end_info_ptr);
       *end_info_ptr_ptr = (png_infop)NULL;
    }
@@ -659,7 +682,6 @@ png_destroy_read_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr,
 void
 png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr)
 {
-   int i;
    jmp_buf tmp_jmp;
    png_error_ptr error_fn;
    png_error_ptr warning_fn;
@@ -688,7 +710,7 @@ png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr
    png_free(png_ptr, png_ptr->gamma_to_1);
 #endif
    if (png_ptr->flags & PNG_FLAG_FREE_PALETTE)
-      png_free(png_ptr, png_ptr->palette);
+      png_zfree(png_ptr, png_ptr->palette);
 #if defined(PNG_READ_BACKGROUND_SUPPORTED) && defined(PNG_READ_bKGD_SUPPORTED)
    if (png_ptr->flags & PNG_FLAG_FREE_TRANS)
       png_free(png_ptr, png_ptr->trans);
@@ -700,6 +722,7 @@ png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr
 #if defined(PNG_READ_GAMMA_SUPPORTED)
    if (png_ptr->gamma_16_table != NULL)
    {
+      int i;
       for (i = 0; i < (1 << (8 - png_ptr->gamma_shift)); i++)
       {
          png_free(png_ptr, png_ptr->gamma_16_table[i]);
@@ -710,6 +733,7 @@ png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr
    png_free(png_ptr, png_ptr->gamma_16_table);
    if (png_ptr->gamma_16_from_1 != NULL)
    {
+      int i;
       for (i = 0; i < (1 << (8 - png_ptr->gamma_shift)); i++)
       {
          png_free(png_ptr, png_ptr->gamma_16_from_1[i]);
@@ -718,6 +742,7 @@ png_read_destroy(png_structp png_ptr, png_infop info_ptr, png_infop end_info_ptr
    png_free(png_ptr, png_ptr->gamma_16_from_1);
    if (png_ptr->gamma_16_to_1 != NULL)
    {
+      int i;
       for (i = 0; i < (1 << (8 - png_ptr->gamma_shift)); i++)
       {
          png_free(png_ptr, png_ptr->gamma_16_to_1[i]);

pngrio.c

@@ -1,18 +1,20 @@
 
 /* pngrio.c - functions for data input
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-
-   This file provides a location for all input.  Users which need
-   special handling are expected to write a function which has the same
-   arguments as this, and perform a similar function, but possibly has
-   a different input method.  Note that you shouldn't change this
-   function, but rather write a replacement function and then make
-   libpng use it at run time with png_set_read_fn(...) */
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ *
+ * This file provides a location for all input.  Users which need
+ * special handling are expected to write a function which has the same
+ * arguments as this, and perform a similar function, but possibly has
+ * a different input method.  Note that you shouldn't change this
+ * function, but rather write a replacement function and then make
+ * libpng use it at run time with png_set_read_fn(...).
+ */
 
 #define PNG_INTERNAL
 #include "png.h"
@@ -32,6 +34,7 @@ png_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
       png_error(png_ptr, "Call to NULL read function");
 }
 
+#if !defined(PNG_NO_STDIO)
 /* This is the function which does the actual reading of data.  If you are
    not reading from a standard C stream, you should create a replacement
    read_data function and use it at run time with png_set_read_fn(), rather
@@ -102,6 +105,7 @@ png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
    }
 }
 #endif
+#endif
 
 /* This function allows the application to supply a new input function
    for libpng if standard C streams aren't being used.
@@ -122,10 +126,14 @@ png_set_read_fn(png_structp png_ptr, png_voidp io_ptr,
 {
    png_ptr->io_ptr = io_ptr;
 
+#if !defined(PNG_NO_STDIO)
    if (read_data_fn != NULL)
       png_ptr->read_data_fn = read_data_fn;
    else
       png_ptr->read_data_fn = png_default_read_data;
+#else
+   png_ptr->read_data_fn = read_data_fn;
+#endif
 
    /* It is an error to write to a read device */
    png_ptr->write_data_fn = NULL;

pngrtran.c

@@ -1,49 +1,114 @@
 
 /* pngrtran.c - transforms the data in a row for PNG readers
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-   */
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ *
+ * This file contains functions optionally called by an application 
+ * in order to tell libpng how to handle data when reading a PNG.
+ * Transformations which are used in both reading and writing are
+ * in pngtrans.c.
+ */
 
 #define PNG_INTERNAL
 #include "png.h"
 
 #ifdef PNG_READ_COMPOSITE_NODIV_SUPPORTED
 /* With these routines, we avoid an integer divide, which will be slower on
-   many machines.  However, it does take more operations than the corresponding
-   divide method, so it may be slower on some RISC systems.  There are two
-   shifts (by 8 or 16 bits) and an addition, versus a single integer divide.
-   The results may also be off by one for certain values. */
+ * many machines.  However, it does take more operations than the corresponding
+ * divide method, so it may be slower on some RISC systems.  There are two
+ * shifts (by 8 or 16 bits) and an addition, versus a single integer divide.
+ *
+ * Note that the rounding factors are NOT supposed to be the same!  128 and
+ * 32768 are correct for the NODIV code; 127 and 32767 are correct for the
+ * standard method.
+ *
+ * [Optimized code by Greg Roelofs and Mark Adler...blame us for bugs. :-) ]
+ */
 
-/* pixel and background should be in gamma 1.0 space */
-#define png_composite(composite, pixel, trans, background) \
-   { png_uint_16 temp = ((png_uint_16)(pixel) * (png_uint_16)(trans) + \
-                      (png_uint_16)(background)*(png_uint_16)(255 - \
-                      (png_uint_16)(trans)) + (png_uint_16)127); \
-     (composite) = (png_byte)(((temp >> 8) + temp) >> 8); }
+   /* fg and bg should be in `gamma 1.0' space; alpha is the opacity */
+#  define png_composite(composite, fg, alpha, bg) \
+     { png_uint_16 temp = ((png_uint_16)(fg) * (png_uint_16)(alpha) + \
+                        (png_uint_16)(bg)*(png_uint_16)(255 - \
+                        (png_uint_16)(alpha)) + (png_uint_16)128); \
+       (composite) = (png_byte)((temp + (temp >> 8)) >> 8); }
+#  define png_composite_16(composite, fg, alpha, bg) \
+     { png_uint_32 temp = ((png_uint_32)(fg) * (png_uint_32)(alpha) + \
+                        (png_uint_32)(bg)*(png_uint_32)(65535L - \
+                        (png_uint_32)(alpha)) + (png_uint_32)32768L); \
+       (composite) = (png_uint_16)((temp + (temp >> 16)) >> 16); }
 
-/* pixel and background should be in gamma 1.0 space */
-#define png_composite_16(composite, pixel, trans, background) \
-   { png_uint_32 temp = ((png_uint_32)(pixel) * (png_uint_32)(trans) + \
-                      (png_uint_32)(background)*(png_uint_32)(65535L - \
-                      (png_uint_32)(trans)) + (png_uint_32)32767); \
-     (composite) = (png_uint_16)(((temp >> 16) + temp) >> 16); }
-#else
-/* pixel and background should be in gamma 1.0 space */
-#define png_composite(composite, pixel, trans, background) \
-   (composite) = (png_byte)(((png_uint_16)(pixel) * (png_uint_16)(trans) + \
-     (png_uint_16)(background) * (png_uint_16)(255 - (png_uint_16)(trans)) + \
-     (png_uint_16)127) / 255)
- 
-/* pixel and background should be in gamma 1.0 space */
-#define png_composite_16(composite, pixel, trans, background) \
-   (composite) = (png_uint_16)(((png_uint_32)(pixel) * (png_uint_32)(trans) + \
-     (png_uint_32)(background)*(png_uint_32)(65535L - (png_uint_32)(trans)) + \
-     (png_uint_32)32767) / 65535L)
-#endif
+#else  /* standard method using integer division */
+
+   /* fg and bg should be in `gamma 1.0' space; alpha is the opacity */
+#  define png_composite(composite, fg, alpha, bg) \
+     (composite) = (png_byte)(((png_uint_16)(fg) * (png_uint_16)(alpha) + \
+       (png_uint_16)(bg) * (png_uint_16)(255 - (png_uint_16)(alpha)) + \
+       (png_uint_16)127) / 255)
+#  define png_composite_16(composite, fg, alpha, bg) \
+     (composite) = (png_uint_16)(((png_uint_32)(fg) * (png_uint_32)(alpha) + \
+       (png_uint_32)(bg)*(png_uint_32)(65535L - (png_uint_32)(alpha)) + \
+       (png_uint_32)32767) / (png_uint_32)65535L)
+
+#endif /* ?PNG_READ_COMPOSITE_NODIV_SUPPORTED */
+
+
+/* Set the action on getting a CRC error for an ancillary or critical chunk. */
+void
+png_set_crc_action(png_structp png_ptr, int crit_action, int ancil_action)
+{
+   png_debug(1, "in png_set_crc_action\n");
+   /* Tell libpng how we react to CRC errors in critical chunks */
+   switch (crit_action)
+   {
+      case PNG_CRC_NO_CHANGE:                        /* leave setting as is */
+         break;
+      case PNG_CRC_WARN_USE:                               /* warn/use data */
+         png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
+         png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE;
+         break;
+      case PNG_CRC_QUIET_USE:                             /* quiet/use data */
+         png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
+         png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE |
+                           PNG_FLAG_CRC_CRITICAL_IGNORE;
+         break;
+      case PNG_CRC_WARN_DISCARD:    /* not a valid action for critical data */
+         png_warning(png_ptr, "Can't discard critical data on CRC error.");
+      case PNG_CRC_ERROR_QUIT:                                /* error/quit */
+      case PNG_CRC_DEFAULT:
+      default:
+         png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
+         break;
+   }
+
+   switch (ancil_action)
+   {
+      case PNG_CRC_NO_CHANGE:                       /* leave setting as is */
+         break;
+      case PNG_CRC_WARN_USE:                              /* warn/use data */
+         png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
+         png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE;
+         break;
+      case PNG_CRC_QUIET_USE:                            /* quiet/use data */
+         png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
+         png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE |
+                           PNG_FLAG_CRC_ANCILLARY_NOWARN;
+         break;
+      case PNG_CRC_ERROR_QUIT:                               /* error/quit */
+         png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
+         png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN;
+         break;
+      case PNG_CRC_WARN_DISCARD:                      /* warn/discard data */
+      case PNG_CRC_DEFAULT:
+      default:
+         png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
+         break;
+   }
+}
 
 #if defined(PNG_READ_BACKGROUND_SUPPORTED)
 /* handle alpha and tRNS via a background color */
@@ -89,12 +154,13 @@ png_set_strip_alpha(png_structp png_ptr)
 
 #if defined(PNG_READ_DITHER_SUPPORTED)
 /* Dither file to 8 bit.  Supply a palette, the current number
-   of elements in the palette, the maximum number of elements
-   allowed, and a histogram if possible.  If the current number
-   of colors is greater then the maximum number, the palette will be
-   modified to fit in the maximum number.  "full_dither" indicates
-   whether we need a dithering cube set up for RGB images, or if we
-   simply are reducing the number of colors in a paletted image. */
+ * of elements in the palette, the maximum number of elements
+ * allowed, and a histogram if possible.  If the current number
+ * of colors is greater then the maximum number, the palette will be
+ * modified to fit in the maximum number.  "full_dither" indicates
+ * whether we need a dithering cube set up for RGB images, or if we
+ * simply are reducing the number of colors in a paletted image.
+ */
 
 typedef struct png_dsort_struct
 {
@@ -306,7 +372,7 @@ png_set_dither(png_structp png_ptr, png_colorp palette,
                   {
                      png_dsortp t;
 
-                     t = png_malloc(png_ptr, sizeof (png_dsort));
+                     t = (png_dsortp)png_malloc(png_ptr, sizeof (png_dsort));
                      t->next = hash[d];
                      t->left = (png_byte)i;
                      t->right = (png_byte)j;
@@ -478,24 +544,26 @@ png_set_dither(png_structp png_ptr, png_colorp palette,
 
 #if defined(PNG_READ_GAMMA_SUPPORTED)
 /* Transform the image from the file_gamma to the screen_gamma.  We
-   only do transformations on images where the file_gamma and screen_gamma
-   are not close reciprocals, otherwise it slows things down slightly, and
-   also needlessly introduces small errors. */
+ * only do transformations on images where the file_gamma and screen_gamma
+ * are not close reciprocals, otherwise it slows things down slightly, and
+ * also needlessly introduces small errors.
+ */
 void
-png_set_gamma(png_structp png_ptr, double screen_gamma, double file_gamma)
+png_set_gamma(png_structp png_ptr, double scrn_gamma, double file_gamma)
 {
    png_debug(1, "in png_set_gamma\n");
-   if (fabs(screen_gamma * file_gamma - 1.0) > PNG_GAMMA_THRESHOLD)
+   if (fabs(scrn_gamma * file_gamma - 1.0) > PNG_GAMMA_THRESHOLD)
       png_ptr->transformations |= PNG_GAMMA;
    png_ptr->gamma = (float)file_gamma;
-   png_ptr->display_gamma = (float)screen_gamma;
+   png_ptr->screen_gamma = (float)scrn_gamma;
 }
 #endif
 
 #if defined(PNG_READ_EXPAND_SUPPORTED)
 /* Expand paletted images to rgb, expand grayscale images of
-   less then 8 bit depth to 8 bit depth, and expand tRNS chunks
-   to alpha channels. */
+ * less then 8 bit depth to 8 bit depth, and expand tRNS chunks
+ * to alpha channels.
+ */
 void
 png_set_expand(png_structp png_ptr)
 {
@@ -515,19 +583,22 @@ png_set_gray_to_rgb(png_structp png_ptr)
 
 #if defined(PNG_READ_RGB_TO_GRAY_SUPPORTED)
 /* Convert a RGB image to a grayscale of the given width.  This would
-   allow us, for example, to convert a 24 bpp RGB image into an 8 or
-   16 bpp grayscale image. (Not yet implemented.) */
+ * allow us, for example, to convert a 24 bpp RGB image into an 8 or
+ * 16 bpp grayscale image. (Not yet implemented.)
+ */
 void
 png_set_rgb_to_gray(png_structp png_ptr, int gray_bits)
 {
    png_debug(1, "in png_set_rgb_to_gray\n");
    png_ptr->transformations |= PNG_RGB_TO_GRAY;
    /* Need to do something with gray_bits here. */
+   png_warning(png_ptr, "RGB to GRAY transformation is not yet implemented.");
 }
 #endif
 
 /* Initialize everything needed for the read.  This includes modifying
-   the palette */
+ * the palette.
+ */
 void
 png_init_read_transformations(png_structp png_ptr)
 {
@@ -574,6 +645,23 @@ png_init_read_transformations(png_structp png_ptr)
             png_ptr->palette[png_ptr->background.index].green;
          png_ptr->background.blue  =
             png_ptr->palette[png_ptr->background.index].blue;
+
+#if defined(PNG_READ_INVERT_ALPHA_SUPPORTED)
+        if (png_ptr->transformations & PNG_INVERT_ALPHA)
+        {
+#if defined(PNG_READ_EXPAND_SUPPORTED)
+           if (png_ptr->transformations & !PNG_EXPAND)
+#endif
+           {
+           /* invert the alpha channel (in tRNS) unless the pixels are 
+              going to be expanded, in which case leave it for later */
+              int i;
+              for (i=0; i<png_ptr->num_trans; i++)
+                 png_ptr->trans[i] = 255 - png_ptr->trans[i];
+           }
+        }
+#endif
+
       }
    }
 #endif
@@ -611,7 +699,7 @@ png_init_read_transformations(png_structp png_ptr)
             {
                double g;
 
-               g = 1.0 / (png_ptr->background_gamma * png_ptr->display_gamma);
+               g = 1.0 / (png_ptr->background_gamma * png_ptr->screen_gamma);
 
                if (png_ptr->background_gamma_type==PNG_BACKGROUND_GAMMA_SCREEN||
                    fabs(g - 1.0) < PNG_GAMMA_THRESHOLD)
@@ -691,17 +779,17 @@ png_init_read_transformations(png_structp png_ptr)
             switch (png_ptr->background_gamma_type)
             {
                case PNG_BACKGROUND_GAMMA_SCREEN:
-                  g = (png_ptr->display_gamma);
+                  g = (png_ptr->screen_gamma);
                   gs = 1.0;
                   break;
                case PNG_BACKGROUND_GAMMA_FILE:
                   g = 1.0 / (png_ptr->gamma);
-                  gs = 1.0 / (png_ptr->gamma * png_ptr->display_gamma);
+                  gs = 1.0 / (png_ptr->gamma * png_ptr->screen_gamma);
                   break;
                case PNG_BACKGROUND_GAMMA_UNIQUE:
                   g = 1.0 / (png_ptr->background_gamma);
                   gs = 1.0 / (png_ptr->background_gamma *
-                     png_ptr->display_gamma);
+                     png_ptr->screen_gamma);
                   break;
             }
 
@@ -810,8 +898,9 @@ png_init_read_transformations(png_structp png_ptr)
 }
 
 /* Modify the info structure to reflect the transformations.  The
-   info should be updated so a PNG file could be written with it,
-   assuming the transformations result in valid PNG data. */
+ * info should be updated so a PNG file could be written with it,
+ * assuming the transformations result in valid PNG data.
+ */
 void
 png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
 {
@@ -883,7 +972,7 @@ png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
    else
       info_ptr->channels = 1;
 
-#if defined(PNG_STRIP_ALPHA_SUPPORTED)
+#if defined(PNG_READ_STRIP_ALPHA_SUPPORTED)
    if ((png_ptr->transformations & PNG_STRIP_ALPHA) &&
        info_ptr->color_type & PNG_COLOR_MASK_ALPHA)
    {
@@ -910,9 +999,10 @@ png_read_transform_info(png_structp png_ptr, png_infop info_ptr)
       (png_size_t)((info_ptr->width * info_ptr->pixel_depth + 7) >> 3);
 }
 
-/* transform the row.  The order of transformations is significant,
-   and is very touchy.  If you add a transformation, take care to
-   decide how it fits in with the other transformations here. */
+/* Transform the row.  The order of transformations is significant,
+ * and is very touchy.  If you add a transformation, take care to
+ * decide how it fits in with the other transformations here.
+ */
 void
 png_do_read_transformations(png_structp png_ptr)
 {
@@ -920,11 +1010,15 @@ png_do_read_transformations(png_structp png_ptr)
 #if !defined(PNG_USELESS_TESTS_SUPPORTED)
    if (png_ptr->row_buf == NULL)
    {
+#if !defined(PNG_NO_STDIO)
       char msg[50];
 
       sprintf(msg, "NULL row buffer for row %ld, pass %d", png_ptr->row_number,
          png_ptr->pass);
       png_error(png_ptr, msg);
+#else
+      png_error(png_ptr, "NULL row buffer");
+#endif
    }
 #endif
 
@@ -955,7 +1049,9 @@ png_do_read_transformations(png_structp png_ptr)
 #endif
 
 #if defined(PNG_READ_BACKGROUND_SUPPORTED)
-   if (png_ptr->transformations & PNG_BACKGROUND)
+   if ((png_ptr->transformations & PNG_BACKGROUND) &&
+      ((png_ptr->num_trans != 0 ) ||
+      (png_ptr->color_type & PNG_COLOR_MASK_ALPHA)))
       png_do_background(&(png_ptr->row_info), png_ptr->row_buf + 1,
          &(png_ptr->trans_values), &(png_ptr->background),
          &(png_ptr->background_1),
@@ -1034,6 +1130,11 @@ png_do_read_transformations(png_structp png_ptr)
       png_do_read_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
 
+#if defined(PNG_READ_INVERT_ALPHA_SUPPORTED)
+   if (png_ptr->transformations & PNG_INVERT_ALPHA)
+      png_do_read_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
+#endif
+
 #if defined(PNG_READ_SWAP_SUPPORTED)
    if (png_ptr->transformations & PNG_SWAP_BYTES)
       png_do_swap(&(png_ptr->row_info), png_ptr->row_buf + 1);
@@ -1041,11 +1142,12 @@ png_do_read_transformations(png_structp png_ptr)
 }
 
 #if defined(PNG_READ_PACK_SUPPORTED)
-/* unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
-   without changing the actual values.  Thus, if you had a row with
-   a bit depth of 1, you would end up with bytes that only contained
-   the numbers 0 or 1.  If you would rather they contain 0 and 255, use
-   png_do_shift() after this. */
+/* Unpack pixels of 1, 2, or 4 bits per pixel into 1 byte per pixel,
+ * without changing the actual values.  Thus, if you had a row with
+ * a bit depth of 1, you would end up with bytes that only contained
+ * the numbers 0 or 1.  If you would rather they contain 0 and 255, use
+ * png_do_shift() after this.
+ */
 void
 png_do_unpack(png_row_infop row_info, png_bytep row)
 {
@@ -1131,10 +1233,11 @@ png_do_unpack(png_row_infop row_info, png_bytep row)
 #endif
 
 #if defined(PNG_READ_SHIFT_SUPPORTED)
-/* reverse the effects of png_do_shift.  This routine merely shifts the
-   pixels back to their significant bits values.  Thus, if you have
-   a row of bit depth 8, but only 5 are significant, this will shift
-   the values back to 0 through 31 */
+/* Reverse the effects of png_do_shift.  This routine merely shifts the
+ * pixels back to their significant bits values.  Thus, if you have
+ * a row of bit depth 8, but only 5 are significant, this will shift
+ * the values back to 0 through 31.
+ */
 void
 png_do_unshift(png_row_infop row_info, png_bytep row, png_color_8p sig_bits)
 {
@@ -1268,7 +1371,17 @@ png_do_chop(png_row_infop row_info, png_bytep row)
           *
           * What the ideal calculation should be:
          *dp = (((((png_uint_32)(*sp) << 8) |
-                   (png_uint_32)(*(sp + 1))) * 255 + 127) / 65535;
+                   (png_uint_32)(*(sp + 1))) * 255 + 127) / (png_uint_32)65535L;
+
+
+          * GRR: no, I think this is what it really should be:
+         *dp = (((((png_uint_32)(*sp) << 8) |
+                   (png_uint_32)(*(sp + 1))) + 128L) / (png_uint_32)257L;
+
+          * GRR: here's the exact calculation with shifts:
+         temp = (((png_uint_32)(*sp) << 8) | (png_uint_32)(*(sp + 1))) + 128L;
+         *dp = (temp - (temp >> 8)) >> 8;
+
 
           * Approximate calculation with shift/add instead of multiply/divide:
          *dp = ((((png_uint_32)(*sp) << 8) |
@@ -1378,6 +1491,87 @@ png_do_read_swap_alpha(png_row_infop row_info, png_bytep row)
 }
 #endif
 
+#if defined(PNG_READ_INVERT_ALPHA_SUPPORTED)
+void
+png_do_read_invert_alpha(png_row_infop row_info, png_bytep row)
+{
+   png_debug(1, "in png_do_read_invert_alpha\n");
+#if defined(PNG_USELESS_TESTS_SUPPORTED)
+   if (row != NULL && row_info != NULL)
+#endif
+   {
+      if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+      {
+         /* This inverts the alpha channel in RGBA */
+         if (row_info->bit_depth == 8)
+         {
+            png_bytep sp, dp;
+            png_uint_32 i;
+
+            for (i = 0, sp = dp = row + row_info->rowbytes;
+               i < row_info->width; i++)
+            {
+               *(--dp) = *(--sp);
+               *(--dp) = *(--sp);
+               *(--dp) = *(--sp);
+               *(--dp) = 255 - *(--sp);
+            }
+         }
+         /* This inverts the alpha channel in RRGGBBAA */
+         else
+         {
+            png_bytep sp, dp;
+            png_uint_32 i;
+
+            for (i = 0, sp = dp = row + row_info->rowbytes;
+               i < row_info->width; i++)
+            {
+               *(--dp) = *(--sp);
+               *(--dp) = *(--sp);
+               *(--dp) = *(--sp);
+               *(--dp) = *(--sp);
+               *(--dp) = *(--sp);
+               *(--dp) = *(--sp);
+               *(--dp) = 255 - *(--sp);
+               *(--dp) = 255 - *(--sp);
+            }
+         }
+      }
+      else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+      {
+         /* This inverts the alpha channel in AG */
+         if (row_info->bit_depth == 8)
+         {
+            png_bytep sp, dp;
+            png_uint_32 i;
+
+            for (i = 0, sp = dp = row + row_info->rowbytes;
+               i < row_info->width; i++)
+            {
+               *(--dp) = *(--sp);
+               *(--dp) = 255 - *(--sp);
+            }
+         }
+         /* This inverts the alpha channel in AAGG */
+         else
+         {
+            png_bytep sp, dp;
+            png_uint_32 i;
+
+            for (i = 0, sp = dp = row + row_info->rowbytes;
+               i < row_info->width; i++)
+            {
+               *(--dp) = *(--sp);
+               *(--dp) = *(--sp);
+               *(--dp) = 255 - *(--sp);
+               *(--dp) = 255 - *(--sp);
+            }
+         }
+      }
+   }
+}
+#endif
+
 #if defined(PNG_READ_FILLER_SUPPORTED)
 /* Add filler channel if we have RGB color */
 void
@@ -1527,10 +1721,11 @@ png_do_gray_to_rgb(png_row_infop row_info, png_bytep row)
 }
 #endif
 
-/* build a grayscale palette.  Palette is assumed to be 1 << bit_depth
-   large of png_color.  This lets grayscale images be treated as
-   paletted.  Most useful for gamma correction and simplification
-   of code. */
+/* Build a grayscale palette.  Palette is assumed to be 1 << bit_depth
+ * large of png_color.  This lets grayscale images be treated as
+ * paletted.  Most useful for gamma correction and simplification
+ * of code.
+ */
 void
 png_build_grayscale_palette(int bit_depth, png_colorp palette)
 {
@@ -1602,7 +1797,7 @@ png_correct_palette(png_structp png_ptr, png_colorp palette,
       {
          double g;
 
-         g = 1.0 / (png_ptr->background_gamma * png_ptr->display_gamma);
+         g = 1.0 / (png_ptr->background_gamma * png_ptr->screen_gamma);
 
          if (png_ptr->background_gamma_type == PNG_BACKGROUND_GAMMA_SCREEN ||
              fabs(g - 1.0) < PNG_GAMMA_THRESHOLD)
@@ -1762,8 +1957,9 @@ png_correct_palette(png_structp png_ptr, png_colorp palette,
 
 #if defined(PNG_READ_BACKGROUND_SUPPORTED)
 /* Replace any alpha or transparency with the supplied background color.
-   "background" is already in the screen gamma, while "background_1" is
-   at a gamma of 1.0.  Paletted files have already been taken care of. */
+ * "background" is already in the screen gamma, while "background_1" is
+ * at a gamma of 1.0.  Paletted files have already been taken care of.
+ */
 void
 png_do_background(png_row_infop row_info, png_bytep row,
    png_color_16p trans_values, png_color_16p background,
@@ -2330,7 +2526,7 @@ png_do_background(png_row_infop row_info, png_bytep row,
                         png_composite_16(v, g, a, background->green);
                         *(dp + 2) = (png_byte)((v >> 8) & 0xff);
                         *(dp + 3) = (png_byte)(v & 0xff);
-                        png_composite_16(v, g, a, background->green);
+                        png_composite_16(v, b, a, background->blue);
                         *(dp + 4) = (png_byte)((v >> 8) & 0xff);
                         *(dp + 5) = (png_byte)(v & 0xff);
                      }
@@ -2356,10 +2552,11 @@ png_do_background(png_row_infop row_info, png_bytep row,
 
 #if defined(PNG_READ_GAMMA_SUPPORTED)
 /* Gamma correct the image, avoiding the alpha channel.  Make sure
-   you do this after you deal with the trasparency issue on grayscale
-   or rgb images. If your bit depth is 8, use gamma_table, if it
-   is 16, use gamma_16_table and gamma_shift.  Build these with
-   build_gamma_table(). */
+ * you do this after you deal with the trasparency issue on grayscale
+ * or rgb images. If your bit depth is 8, use gamma_table, if it
+ * is 16, use gamma_16_table and gamma_shift.  Build these with
+ * build_gamma_table().
+ */
 void
 png_do_gamma(png_row_infop row_info, png_bytep row,
    png_bytep gamma_table, png_uint_16pp gamma_16_table,
@@ -2481,6 +2678,22 @@ png_do_gamma(png_row_infop row_info, png_bytep row,
          }
          case PNG_COLOR_TYPE_GRAY:
          {
+            if (row_info->bit_depth == 2)
+            {
+               for (i = 0, sp = row; i < row_info->width; i += 4)
+               {
+                  int a = *sp & 0xc0;
+                  int b = *sp & 0x30;
+                  int c = *sp & 0x0c;
+                  int d = *sp & 0x03;
+
+                  *sp = ((((int)gamma_table[a|(a>>2)|(a>>4)|(a>>6)])   ) & 0xc0)|
+                        ((((int)gamma_table[(b<<2)|b|(b>>2)|(b>>4)])>>2) & 0x30)|
+                        ((((int)gamma_table[(c<<4)|(c<<2)|c|(c>>2)])>>4) & 0x0c)|
+                        ((((int)gamma_table[(d<<6)|(d<<4)|(d<<2)|d])>>6)       );
+                  sp++;
+               }
+            }
             if (row_info->bit_depth == 4)
             {
                for (i = 0, sp = row; i < row_info->width; i += 2)
@@ -2488,8 +2701,8 @@ png_do_gamma(png_row_infop row_info, png_bytep row,
                   int msb = *sp & 0xf0;
                   int lsb = *sp & 0x0f;
 
-                  *sp = (((int)gamma_table[msb | msb >> 4] + 8) & 0xf0) |
-                        (((int)gamma_table[lsb << 4 | lsb] + 8) >> 4);
+                  *sp = (((int)gamma_table[msb | (msb >> 4)]) & 0xf0) |
+                        (((int)gamma_table[(lsb << 4) | lsb]) >> 4);
                   sp++;
                }
             }
@@ -2521,8 +2734,9 @@ png_do_gamma(png_row_infop row_info, png_bytep row,
 #endif
 
 #if defined(PNG_READ_EXPAND_SUPPORTED)
-/* expands a palette row to an rgb or rgba row depending
-   upon whether you supply trans and num_trans */
+/* Expands a palette row to an rgb or rgba row depending
+ * upon whether you supply trans and num_trans.
+ */
 void
 png_do_expand_palette(png_row_infop row_info, png_bytep row,
    png_colorp palette, png_bytep trans, int num_trans)
@@ -2662,8 +2876,9 @@ png_do_expand_palette(png_row_infop row_info, png_bytep row,
    }
 }
 
-/* if the bit depth < 8, it is expanded to 8.  Also, if the
-   transparency value is supplied, an alpha channel is built. */
+/* If the bit depth < 8, it is expanded to 8.  Also, if the
+ * transparency value is supplied, an alpha channel is built.
+ */
 void
 png_do_expand(png_row_infop row_info, png_bytep row,
    png_color_16p trans_value)
@@ -2958,9 +3173,10 @@ static int png_gamma_shift[] =
    {0x10, 0x21, 0x42, 0x84, 0x110, 0x248, 0x550, 0xff0};
 
 /* We build the 8- or 16-bit gamma tables here.  Note that for 16-bit
-   tables, we don't make a full table if we are reducing to 8-bit in
-   the future.  Note also how the gamma_16 tables are segmented so that
-   we don't need to allocate > 64K chunks for a full 16-bit table. */
+ * tables, we don't make a full table if we are reducing to 8-bit in
+ * the future.  Note also how the gamma_16 tables are segmented so that
+ * we don't need to allocate > 64K chunks for a full 16-bit table.
+ */
 void
 png_build_gamma_table(png_structp png_ptr)
 {
@@ -2970,7 +3186,7 @@ png_build_gamma_table(png_structp png_ptr)
       int i;
       double g;
 
-      g = 1.0 / (png_ptr->gamma * png_ptr->display_gamma);
+      g = 1.0 / (png_ptr->gamma * png_ptr->screen_gamma);
 
       png_ptr->gamma_table = (png_bytep)png_malloc(png_ptr,
          (png_uint_32)256);
@@ -2995,7 +3211,7 @@ png_build_gamma_table(png_structp png_ptr)
                g) * 255.0 + .5);
          }
 
-         g = 1.0 / (png_ptr->display_gamma);
+         g = 1.0 / (png_ptr->screen_gamma);
 
          png_ptr->gamma_from_1 = (png_bytep)png_malloc(png_ptr,
             (png_uint_32)256);
@@ -3048,7 +3264,7 @@ png_build_gamma_table(png_structp png_ptr)
 
       num = (1 << (8 - shift));
 
-      g = 1.0 / (png_ptr->gamma * png_ptr->display_gamma);
+      g = 1.0 / (png_ptr->gamma * png_ptr->screen_gamma);
 
       png_ptr->gamma_16_table = (png_uint_16pp)png_malloc(png_ptr,
          num * sizeof (png_uint_16p));
@@ -3126,7 +3342,7 @@ png_build_gamma_table(png_structp png_ptr)
                      65535.0, g) * 65535.0 + .5);
             }
          }
-         g = 1.0 / (png_ptr->display_gamma);
+         g = 1.0 / (png_ptr->screen_gamma);
 
          png_ptr->gamma_16_from_1 = (png_uint_16pp)png_malloc(png_ptr,
             num * sizeof (png_uint_16p));

pngrutil.c

@@ -1,12 +1,16 @@
 
 /* pngrutil.c - utilities to read a PNG file
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-   */
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ *
+ * This file contains routines which are only called from within
+ * libpng itself during the course of reading an image.
+ */
 
 #define PNG_INTERNAL
 #include "png.h"
@@ -23,7 +27,7 @@ png_get_uint_32(png_bytep buf)
       ((png_uint_32)(*(buf + 2)) << 8) +
       (png_uint_32)(*(buf + 3));
 
-   return i;
+   return (i);
 }
 
 #if defined(PNG_READ_pCAL_SUPPORTED)
@@ -40,7 +44,7 @@ png_get_int_32(png_bytep buf)
       ((png_int_32)(*(buf + 2)) << 8) +
       (png_int_32)(*(buf + 3));
 
-   return i;
+   return (i);
 }
 #endif /* PNG_READ_pCAL_SUPPORTED */
 
@@ -53,63 +57,10 @@ png_get_uint_16(png_bytep buf)
    i = (png_uint_16)(((png_uint_16)(*buf) << 8) +
       (png_uint_16)(*(buf + 1)));
 
-   return i;
+   return (i);
 }
 #endif /* PNG_READ_BIG_ENDIAN_SUPPORTED */
 
-/* Set the action on getting a CRC error for an ancillary or critical chunk. */
-void
-png_set_crc_action(png_structp png_ptr, int crit_action, int ancil_action)
-{
-   png_debug(1, "in png_set_crc_action\n");
-   /* Tell libpng how we react to CRC errors in critical chunks */
-   switch (crit_action)
-   {
-      case PNG_CRC_NO_CHANGE:                        /* leave setting as is */
-         break;
-      case PNG_CRC_WARN_USE:                               /* warn/use data */
-         png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
-         png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE;
-         break;
-      case PNG_CRC_QUIET_USE:                             /* quiet/use data */
-         png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
-         png_ptr->flags |= PNG_FLAG_CRC_CRITICAL_USE |
-                           PNG_FLAG_CRC_CRITICAL_IGNORE;
-         break;
-      case PNG_CRC_WARN_DISCARD:    /* not a valid action for critical data */
-         png_warning(png_ptr, "Can't discard critical data on CRC error.");
-      case PNG_CRC_ERROR_QUIT:                                /* error/quit */
-      case PNG_CRC_DEFAULT:
-      default:
-         png_ptr->flags &= ~PNG_FLAG_CRC_CRITICAL_MASK;
-         break;
-   }
-
-   switch (ancil_action)
-   {
-      case PNG_CRC_NO_CHANGE:                       /* leave setting as is */
-         break;
-      case PNG_CRC_WARN_USE:                              /* warn/use data */
-         png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
-         png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE;
-         break;
-      case PNG_CRC_QUIET_USE:                            /* quiet/use data */
-         png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
-         png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_USE |
-                           PNG_FLAG_CRC_ANCILLARY_NOWARN;
-         break;
-      case PNG_CRC_ERROR_QUIT:                               /* error/quit */
-         png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
-         png_ptr->flags |= PNG_FLAG_CRC_ANCILLARY_NOWARN;
-         break;
-      case PNG_CRC_WARN_DISCARD:                      /* warn/discard data */
-      case PNG_CRC_DEFAULT:
-      default:
-         png_ptr->flags &= ~PNG_FLAG_CRC_ANCILLARY_MASK;
-         break;
-   }
-}
-
 /* Read data, and (optionally) run it through the CRC. */
 void
 png_crc_read(png_structp png_ptr, png_bytep buf, png_size_t length)
@@ -138,28 +89,24 @@ png_crc_finish(png_structp png_ptr, png_uint_32 skip)
 
    if (png_crc_error(png_ptr))
    {
-      char msg[80];
-
-      sprintf(msg,"CRC error in %s", png_ptr->chunk_name);
-
       if ((png_ptr->chunk_name[0] & 0x20 &&                /* Ancillary */
            !(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)) ||
           (!(png_ptr->chunk_name[0] & 0x20) &&             /* Critical  */
            png_ptr->flags & PNG_FLAG_CRC_CRITICAL_USE))
       {
-         png_warning(png_ptr, msg);
+         png_chunk_warning(png_ptr, "CRC error");
       }
       else
       {
-         png_error(png_ptr, msg);
+         png_chunk_error(png_ptr, "CRC error");
       }
-      return 1;
+      return (1);
    }
 
-   return 0;
+   return (0);
 }
 
-/* Compare the CRC stored in the PNG file with that calulated by libpng from
+/* Compare the CRC stored in the PNG file with that calculated by libpng from
    the data it has read thus far. */
 int
 png_crc_error(png_structp png_ptr)
@@ -185,14 +132,10 @@ png_crc_error(png_structp png_ptr)
    if (need_crc)
    {
       crc = png_get_uint_32(crc_bytes);
-#ifdef PNG_USE_OWN_CRC
-      return (((crc^0xffffffffL)&0xffffffffL) != (png_ptr->crc&0xffffffffL));
-#else
-      return (crc != png_ptr->crc);
-#endif
+      return ((int)(crc != png_ptr->crc));
    }
    else
-      return 0;
+      return (0);
 }
 
 
@@ -228,7 +171,8 @@ png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    interlace_type = buf[12];
 
    /* check for width and height valid values */
-   if (width == 0 || width > 2147483647 || height == 0 || height > 2147483647)
+   if (width == 0 || width > (png_uint_32)2147483647L || height == 0 ||
+        height > (png_uint_32)2147483647L)
       png_error(png_ptr, "Invalid image size in IHDR");
 
    /* check other values */
@@ -246,7 +190,7 @@ png_handle_IHDR(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
          color_type == PNG_COLOR_TYPE_RGB_ALPHA) && bit_depth < 8))
       png_error(png_ptr, "Invalid color type/bit depth combination in IHDR");
 
-   if (interlace_type > PNG_INTERLACE_ADAM7)
+   if (interlace_type >= PNG_INTERLACE_LAST)
       png_error(png_ptr, "Unknown interlace method in IHDR");
 
    if (compression_type != PNG_COMPRESSION_TYPE_BASE)
@@ -337,7 +281,7 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    }
 
    num = (int)length / 3;
-   palette = (png_colorp)png_malloc(png_ptr, num * sizeof (png_color));
+   palette = (png_colorp)png_zalloc(png_ptr, (uInt)num, sizeof (png_color));
    png_ptr->flags |= PNG_FLAG_FREE_PALETTE;
    for (i = 0; i < num; i++)
    {
@@ -354,16 +298,15 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       whatever the normal CRC configuration tells us.  However, if we
       have an RGB image, the PLTE can be considered ancillary, so
       we will act as though it is. */
+#if !defined(PNG_READ_OPT_PLTE_SUPPORTED)
    if (png_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+#endif
    {
       png_crc_finish(png_ptr, 0);
    }
+#if !defined(PNG_READ_OPT_PLTE_SUPPORTED)
    else if (png_crc_error(png_ptr))  /* Only if we have a CRC error */
    {
-      char msg[80];
-
-      sprintf(msg,"CRC error in %s", png_ptr->chunk_name);
-
       /* If we don't want to use the data from an ancillary chunk,
          we have two options: an error abort, or a warning and we
          ignore the data in this chunk (which should be OK, since
@@ -372,23 +315,23 @@ png_handle_PLTE(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       {
          if (png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN)
          {
-            png_error(png_ptr, msg);
+            png_chunk_error(png_ptr, "CRC error");
          }
          else
          {
-            png_warning(png_ptr, msg);
+            png_chunk_warning(png_ptr, "CRC error");
             png_ptr->flags &= ~PNG_FLAG_FREE_PALETTE;
-            png_free(png_ptr, palette);
+            png_zfree(png_ptr, palette);
             return;
          }
       }
       /* Otherwise, we (optionally) emit a warning and use the chunk. */
       else if (!(png_ptr->flags & PNG_FLAG_CRC_ANCILLARY_NOWARN))
       {
-         png_warning(png_ptr, msg);
+         png_chunk_warning(png_ptr, "CRC error");
       }
    }
-
+#endif
    png_ptr->palette = palette;
    png_ptr->num_palette = (png_uint_16)num;
    png_set_PLTE(png_ptr, info_ptr, palette, num);
@@ -434,7 +377,12 @@ png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    else if (png_ptr->mode & PNG_HAVE_PLTE)
       /* Should be an error, but we can cope with it */
       png_warning(png_ptr, "Out of place gAMA chunk");
-   else if (info_ptr != NULL && info_ptr->valid & PNG_INFO_gAMA)
+
+   else if (info_ptr != NULL && info_ptr->valid & PNG_INFO_gAMA
+#if defined(PNG_READ_sRGB_SUPPORTED)
+      && !(info_ptr->valid & PNG_INFO_sRGB)
+#endif
+      )
    {
       png_warning(png_ptr, "Duplicate gAMA chunk");
       png_crc_finish(png_ptr, length);
@@ -457,8 +405,23 @@ png_handle_gAMA(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    if (igamma == 0)
       return;
 
+#if defined(PNG_READ_sRGB_SUPPORTED)
+   if (info_ptr->valid & PNG_INFO_sRGB)
+      if(igamma != (png_uint_32)45000L)
+      {
+         png_warning(png_ptr,
+           "Ignoring incorrect gAMA value when sRGB is also present");
+#ifndef PNG_NO_STDIO
+         fprintf(stderr, "igamma = %lu\n", igamma);
+#endif
+         return;
+      }
+#endif /* PNG_READ_sRGB_SUPPORTED */
+
    file_gamma = (float)igamma / (float)100000.0;
+#ifdef PNG_READ_GAMMA_SUPPORTED
    png_ptr->gamma = file_gamma;
+#endif
    png_set_gAMA(png_ptr, info_ptr, file_gamma);
 }
 #endif
@@ -483,8 +446,10 @@ png_handle_sBIT(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       return;
    }
    else if (png_ptr->mode & PNG_HAVE_PLTE)
+   {
       /* Should be an error, but we can cope with it */
       png_warning(png_ptr, "Out of place sBIT chunk");
+   }
    else if (info_ptr != NULL && info_ptr->valid & PNG_INFO_sBIT)
    {
       png_warning(png_ptr, "Duplicate sBIT chunk");
@@ -545,7 +510,12 @@ png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    else if (png_ptr->mode & PNG_HAVE_PLTE)
       /* Should be an error, but we can cope with it */
       png_warning(png_ptr, "Missing PLTE before cHRM");
-   else if (info_ptr != NULL && info_ptr->valid & PNG_INFO_cHRM)
+
+   else if (info_ptr != NULL && info_ptr->valid & PNG_INFO_cHRM
+#if defined(PNG_READ_sRGB_SUPPORTED)
+      && !(info_ptr->valid & PNG_INFO_sRGB)
+#endif
+      )
    {
       png_warning(png_ptr, "Duplicate cHRM chunk");
       png_crc_finish(png_ptr, length);
@@ -615,8 +585,8 @@ png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    val = png_get_uint_32(buf);
    blue_y = (float)val / (float)100000.0;
 
-   if (blue_x < 0 || blue_x > 0.8 || blue_y < 0 || blue_y > 0.8 ||
-       blue_x + blue_y > 1.0)
+   if (blue_x < (float)0 || blue_x > (float)0.8 || blue_y < (float)0 ||
+       blue_y > (float)0.8 || blue_x + blue_y > (float)1.0)
    {
       png_warning(png_ptr, "Invalid cHRM blue point");
       png_crc_finish(png_ptr, 0);
@@ -626,11 +596,116 @@ png_handle_cHRM(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    if (png_crc_finish(png_ptr, 0))
       return;
 
+#if defined(PNG_READ_sRGB_SUPPORTED)
+   if (info_ptr->valid & PNG_INFO_sRGB)
+      {
+      if (fabs(white_x - (float).3127) > (float).001 ||
+          fabs(white_y - (float).3290) > (float).001 ||
+          fabs(  red_x - (float).6400) > (float).001 ||
+          fabs(  red_y - (float).3300) > (float).001 ||
+          fabs(green_x - (float).3000) > (float).001 ||
+          fabs(green_y - (float).6000) > (float).001 ||
+          fabs( blue_x - (float).1500) > (float).001 ||
+          fabs( blue_y - (float).0600) > (float).001)
+         {
+
+            png_warning(png_ptr,
+              "Ignoring incorrect cHRM value when sRGB is also present");
+#ifndef PNG_NO_STDIO
+            fprintf(stderr,"wx=%f, wy=%f, rx=%f, ry=%f\n",
+               white_x, white_y, red_x, red_y);
+            fprintf(stderr,"gx=%f, gy=%f, bx=%f, by=%f\n",
+               green_x, green_y, blue_x, blue_y);
+#endif
+         }
+         return;
+      }
+#endif /* PNG_READ_sRGB_SUPPORTED */
+
    png_set_cHRM(png_ptr, info_ptr,
       white_x, white_y, red_x, red_y, green_x, green_y, blue_x, blue_y);
 }
 #endif
 
+#if defined(PNG_READ_sRGB_SUPPORTED)
+void
+png_handle_sRGB(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
+{
+   int intent;
+   png_byte buf[1];
+
+   png_debug(1, "in png_handle_sRGB\n");
+
+   if (!(png_ptr->mode & PNG_HAVE_IHDR))
+      png_error(png_ptr, "Missing IHDR before sRGB");
+   else if (png_ptr->mode & PNG_HAVE_IDAT)
+   {
+      png_warning(png_ptr, "Invalid sRGB after IDAT");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+   else if (png_ptr->mode & PNG_HAVE_PLTE)
+      /* Should be an error, but we can cope with it */
+      png_warning(png_ptr, "Out of place sRGB chunk");
+
+   else if (info_ptr != NULL && info_ptr->valid & PNG_INFO_sRGB)
+   {
+      png_warning(png_ptr, "Duplicate sRGB chunk");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   if (length != 1)
+   {
+      png_warning(png_ptr, "Incorrect sRGB chunk length");
+      png_crc_finish(png_ptr, length);
+      return;
+   }
+
+   png_crc_read(png_ptr, buf, 1);
+   if (png_crc_finish(png_ptr, 0))
+      return;
+
+   intent = buf[0];
+   /* check for bad intent */
+   if (intent >= PNG_sRGB_INTENT_LAST)
+   {
+      png_warning(png_ptr, "Unknown sRGB intent");
+      return;
+   }
+
+#if defined(PNG_READ_gAMA_SUPPORTED) && defined(PNG_READ_GAMMA_SUPPORTED)
+   if ((info_ptr->valid & PNG_INFO_gAMA))
+      if((png_uint_32)(png_ptr->gamma*(float)100000.+.5) != (png_uint_32)45000L)
+      {
+         png_warning(png_ptr,
+           "Ignoring incorrect gAMA value when sRGB is also present");
+#ifndef PNG_NO_STDIO
+           fprintf(stderr,"gamma=%f\n",png_ptr->gamma);
+#endif
+      }
+#endif /* PNG_READ_gAMA_SUPPORTED */
+
+#ifdef PNG_READ_cHRM_SUPPORTED
+   if (info_ptr->valid & PNG_INFO_cHRM)
+      if (fabs(info_ptr->x_white - (float).3127) > (float).001 ||
+          fabs(info_ptr->y_white - (float).3290) > (float).001 ||
+          fabs(  info_ptr->x_red - (float).6400) > (float).001 ||
+          fabs(  info_ptr->y_red - (float).3300) > (float).001 ||
+          fabs(info_ptr->x_green - (float).3000) > (float).001 ||
+          fabs(info_ptr->y_green - (float).6000) > (float).001 ||
+          fabs( info_ptr->x_blue - (float).1500) > (float).001 ||
+          fabs( info_ptr->y_blue - (float).0600) > (float).001)
+         {
+            png_warning(png_ptr,
+              "Ignoring incorrect cHRM value when sRGB is also present");
+         }
+#endif /* PNG_READ_cHRM_SUPPORTED */
+
+   png_set_sRGB_gAMA_and_cHRM(png_ptr, info_ptr, intent);
+}
+#endif /* PNG_READ_sRGB_SUPPORTED */
+
 #if defined(PNG_READ_tRNS_SUPPORTED)
 void
 png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
@@ -683,7 +758,7 @@ png_handle_tRNS(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       }
 
       png_crc_read(png_ptr, buf, (png_size_t)length);
-      png_ptr->num_trans = 3;
+      png_ptr->num_trans = 1;
       png_ptr->trans_values.red = png_get_uint_16(buf);
       png_ptr->trans_values.green = png_get_uint_16(buf + 2);
       png_ptr->trans_values.blue = png_get_uint_16(buf + 4);
@@ -1113,11 +1188,11 @@ png_handle_tEXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
       png_ptr->mode |= PNG_AFTER_IDAT;
 
 #ifdef PNG_MAX_MALLOC_64K
-   if (length > 65535L)
+   if (length > (png_uint_32)65535L)
    {
       png_warning(png_ptr, "tEXt chunk too large to fit in memory");
-      skip = length - 65535L;
-      length = 65535L;
+      skip = length - (png_uint_32)65535L;
+      length = (png_uint_32)65535L;
    }
 #endif
 
@@ -1171,7 +1246,7 @@ png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 #ifdef PNG_MAX_MALLOC_64K
    /* We will no doubt have problems with chunks even half this size, but
       there is no hard and fast rule to tell us where to stop. */
-   if (length > 65535L)
+   if (length > (png_uint_32)65535L)
    {
      png_warning(png_ptr,"zTXt chunk too large to fit in memory");
      png_crc_finish(png_ptr, length);
@@ -1259,7 +1334,7 @@ png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
                png_charp tmp;
 
                tmp = text;
-               text = png_malloc(png_ptr, text_size +
+               text = (png_charp)png_malloc(png_ptr, text_size +
                   png_ptr->zbuf_size - png_ptr->zstream.avail_out + 1);
                png_memcpy(text, tmp, text_size);
                png_free(png_ptr, tmp);
@@ -1291,10 +1366,14 @@ png_handle_zTXt(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
    else /* if (comp_type >= PNG_TEXT_COMPRESSION_LAST) */
    {
       png_size_t text_size;
+#if !defined(PNG_NO_STDIO)
       char umsg[50];
 
       sprintf(umsg, "Unknown zTXt compression type %d", comp_type);
       png_warning(png_ptr, umsg);
+#else
+      png_warning(png_ptr, "Unknown zTXt compression type");
+#endif
 
       /* Copy what we can of the error message into the text chunk */
       text_size = (png_size_t)length - (text - key) - 1;
@@ -1329,10 +1408,7 @@ png_handle_unknown(png_structp png_ptr, png_infop info_ptr, png_uint_32 length)
 
    if (!(png_ptr->chunk_name[0] & 0x20))
    {
-      char msg[40];
-
-      sprintf(msg, "Unknown critical chunk %s", png_ptr->chunk_name);
-      png_error(png_ptr, msg);
+      png_chunk_error(png_ptr, "unknown critical chunk");
    }
 
    if (png_ptr->mode & PNG_HAVE_IDAT)
@@ -1356,11 +1432,7 @@ png_check_chunk_name(png_structp png_ptr, png_bytep chunk_name)
    if (isnonalpha(chunk_name[0]) || isnonalpha(chunk_name[1]) ||
        isnonalpha(chunk_name[2]) || isnonalpha(chunk_name[3]))
    {
-      char msg[45];
-
-      sprintf(msg, "Invalid chunk type 0x%02X 0x%02X 0x%02X 0x%02X",
-         chunk_name[0], chunk_name[1], chunk_name[2], chunk_name[3]);
-      png_error(png_ptr, msg);
+      png_chunk_error(png_ptr, "invalid chunk type");
    }
 }
 
@@ -2113,13 +2185,13 @@ png_read_start_row(png_structp png_ptr)
    rowbytes = ((rowbytes * (png_uint_32)max_pixel_depth + 7) >> 3) +
       1 + ((max_pixel_depth + 7) >> 3);
 #ifdef PNG_MAX_MALLOC_64K
-   if (rowbytes > 65536L)
+   if (rowbytes > (png_uint_32)65536L)
       png_error(png_ptr, "This image requires a row greater than 64KB");
 #endif
    png_ptr->row_buf = (png_bytep)png_malloc(png_ptr, rowbytes);
 
 #ifdef PNG_MAX_MALLOC_64K
-   if (png_ptr->rowbytes + 1 > 65536L)
+   if ((png_uint_32)png_ptr->rowbytes + 1 > (png_uint_32)65536L)
       png_error(png_ptr, "This image requires a row greater than 64KB");
 #endif
    png_ptr->prev_row = (png_bytep)png_malloc(png_ptr, png_ptr->rowbytes + 1);

pngset.c

@@ -1,12 +1,18 @@
 
 /* pngset.c - storage of image information into info struct
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-   */
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ *
+ * The functions here are used during reads to store data from the file
+ * into the info struct, and during writes to store application data
+ * into the info struct for writing into the file.  This abstracts the
+ * info struct and allows us to change the structure in the future.
+ */
 
 #define PNG_INTERNAL
 #include "png.h"
@@ -205,8 +211,57 @@ png_set_sBIT(png_structp png_ptr, png_infop info_ptr,
 }
 #endif
 
-#if defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED) || \
-    defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
+#if defined(PNG_READ_sRGB_SUPPORTED) || defined(PNG_WRITE_sRGB_SUPPORTED)
+void
+png_set_sRGB(png_structp png_ptr, png_infop info_ptr, int intent)
+{
+   png_debug1(1, "in %s storage function\n", "sRGB");
+   if (info_ptr == NULL)
+      return;
+
+   info_ptr->srgb_intent = (png_byte)intent;
+   info_ptr->valid |= PNG_INFO_sRGB;
+}
+void
+png_set_sRGB_gAMA_and_cHRM(png_structp png_ptr, png_infop info_ptr,
+   int intent)
+{
+#if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_WRITE_gAMA_SUPPORTED)
+   float file_gamma;
+#endif
+#if defined(PNG_READ_cHRM_SUPPORTED) || defined(PNG_WRITE_cHRM_SUPPORTED)
+   float white_x, white_y, red_x, red_y, green_x, green_y, blue_x, blue_y;
+#endif
+   png_debug1(1, "in %s storage function\n", "sRGB_gAMA_and_cHRM");
+   if (info_ptr == NULL)
+      return;
+
+   png_set_sRGB(png_ptr, info_ptr, intent);
+
+#if defined(PNG_READ_gAMA_SUPPORTED) || defined(PNG_WRITE_gAMA_SUPPORTED)
+   file_gamma = (float).45;
+   png_set_gAMA(png_ptr, info_ptr, file_gamma);
+#endif
+
+#if defined(PNG_READ_cHRM_SUPPORTED) || defined(PNG_WRITE_cHRM_SUPPORTED)
+   white_x = (float).3127;
+   white_y = (float).3290;
+   red_x   = (float).64;
+   red_y   = (float).33;
+   green_x = (float).30;
+   green_y = (float).60;
+   blue_x  = (float).15;
+   blue_y  = (float).06;
+
+   png_set_cHRM(png_ptr, info_ptr,
+      white_x, white_y, red_x, red_y, green_x, green_y, blue_x, blue_y);
+
+#endif
+}
+#endif
+
+#if defined(PNG_READ_tEXt_SUPPORTED) || defined(PNG_WRITE_tEXt_SUPPORTED) || \
+    defined(PNG_READ_zTXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
 void
 png_set_text(png_structp png_ptr, png_infop info_ptr, png_textp text_ptr,
    int num_text)
@@ -214,7 +269,7 @@ png_set_text(png_structp png_ptr, png_infop info_ptr, png_textp text_ptr,
    int i;
 
    png_debug1(1, "in %s storage function\n", (png_ptr->chunk_name[0] == '\0' ?
-      "text" : png_ptr->chunk_name));
+      "text" : (png_const_charp)png_ptr->chunk_name));
 
    if (info_ptr == NULL || num_text == 0)
       return;
@@ -253,7 +308,7 @@ png_set_text(png_structp png_ptr, png_infop info_ptr, png_textp text_ptr,
       png_textp textp = &(info_ptr->text[info_ptr->num_text]);
 
       if (text_ptr[i].text == NULL)
-         text_ptr[i].text = "";
+         text_ptr[i].text = (png_charp)"";
 
       if (text_ptr[i].text[0] == '\0')
       {
@@ -304,6 +359,8 @@ png_set_tRNS(png_structp png_ptr, png_infop info_ptr,
    {
       png_memcpy(&(info_ptr->trans_values), trans_values,
          sizeof(png_color_16));
+      if (num_trans == 0)
+        num_trans = 1;
    }
    info_ptr->num_trans = (png_uint_16)num_trans;
    info_ptr->valid |= PNG_INFO_tRNS;

pngtest.c

@@ -1,12 +1,31 @@
 
 /* pngtest.c - a simple test program to test libpng
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-   */
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ *
+ * This program reads in a PNG image, writes it out again, and then
+ * compares the two files.  If the files are identical, this shows that
+ * the basic chunk handling, filtering, and (de)compression code is working
+ * properly.  It does not currently test all of the transforms, although
+ * it probably should.
+ *
+ * The program will fail in certain legitimate cases:
+ * 1) when the compression level or filter selection method is changed.
+ * 2) when the chunk size is smaller than 8K.
+ * 3) unknown ancillary chunks exist in the input file.
+ * 4) others not listed here...
+ * In these cases, it is best to check with another tool such as "pngcheck"
+ * to see what the differences between the two images are.
+ *
+ * If a filename is given on the command-line, then this file is used
+ * for the input, rather than the default "pngtest.png".  This allows
+ * testing a wide variety of files easily.
+ */
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -18,6 +37,13 @@
 
 #include "png.h"
 
+#ifdef PNGTEST_MEMORY_DEBUG
+#include <unistd.h>
+void *sbrk (ssize_t incr);
+#endif
+
+int test_one_file(PNG_CONST char *inname, PNG_CONST char *outname);
+
 #ifdef __TURBOC__
 #include <mem.h>
 #endif
@@ -26,21 +52,305 @@
 /*  #define STDERR stderr  */
 #define STDERR stdout   /* for DOS */
 
-/* input and output filenames */
-#ifdef RISCOS
-char *inname = "pngtest_png";
-char *outname = "pngout_png";
+static int verbose = 0;
+
+#if defined(PNG_NO_STDIO)
+/* START of code to validate stdio-free compilation */
+/* These copies of the default read/write functions come from pngrio.c and */
+/* pngwio.c.  They allow "don't include stdio" testing of the library. */
+/* This is the function which does the actual reading of data.  If you are
+   not reading from a standard C stream, you should create a replacement
+   read_data function and use it at run time with png_set_read_fn(), rather
+   than changing the library. */
+#ifndef USE_FAR_KEYWORD
+static void
+png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length);
+static void
+png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
+{
+   png_size_t check;
+
+   /* fread() returns 0 on error, so it is OK to store this in a png_size_t
+    * instead of an int, which is what fread() actually returns.
+    */
+   check = (png_size_t)fread(data, (png_size_t)1, length,
+      (FILE *)png_ptr->io_ptr);
+
+   if (check != length)
+   {
+      png_error(png_ptr, "Read Error");
+   }
+}
 #else
-char *inname = "pngtest.png";
-char *outname = "pngout.png";
+/* this is the model-independent version. Since the standard I/O library
+   can't handle far buffers in the medium and small models, we have to copy
+   the data.
+*/
+ 
+#define NEAR_BUF_SIZE 1024
+#define MIN(a,b) (a <= b ? a : b)
+ 
+static void
+png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length);
+static void
+png_default_read_data(png_structp png_ptr, png_bytep data, png_size_t length)
+{
+   int check;
+   png_byte *n_data;
+   FILE *io_ptr;
+
+   /* Check if data really is near. If so, use usual code. */
+   n_data = (png_byte *)CVT_PTR_NOCHECK(data);
+   io_ptr = (FILE *)CVT_PTR(png_ptr->io_ptr);
+   if ((png_bytep)n_data == data)
+   {
+      check = fread(n_data, 1, length, io_ptr);
+   }
+   else
+   {
+      png_byte buf[NEAR_BUF_SIZE];
+      png_size_t read, remaining, err;
+      check = 0;
+      remaining = length;
+      do
+      {
+         read = MIN(NEAR_BUF_SIZE, remaining);
+         err = fread(buf, (png_size_t)1, read, io_ptr);
+         png_memcpy(data, buf, read); /* copy far buffer to near buffer */
+         if(err != read)
+            break;
+         else
+            check += err;
+         data += read;
+         remaining -= read;
+      }
+      while (remaining != 0);
+   }
+   if (check != length)
+   {
+      png_error(png_ptr, "read Error");
+   }
+}
+#endif /* USE_FAR_KEYWORD */
+
+#if defined(PNG_WRITE_FLUSH_SUPPORTED)
+static void
+png_default_flush(png_structp png_ptr);
+static void
+png_default_flush(png_structp png_ptr)
+{
+   FILE *io_ptr;
+   io_ptr = (FILE *)CVT_PTR((png_ptr->io_ptr));
+   if (io_ptr != NULL)
+      fflush(io_ptr);
+}
 #endif
 
-char inbuf[256], outbuf[256];
-
-int
-main(int argc, char *argv[])
+/* This is the function which does the actual writing of data.  If you are
+   not writing to a standard C stream, you should create a replacement
+   write_data function and use it at run time with png_set_write_fn(), rather
+   than changing the library. */
+#ifndef USE_FAR_KEYWORD
+static void
+png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length);
+static void
+png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
 {
-   FILE *fpin, *fpout;
+   png_uint_32 check;
+
+   check = fwrite(data, 1, length, (FILE *)(png_ptr->io_ptr));
+   if (check != length)
+   {
+      png_error(png_ptr, "Write Error");
+   }
+}
+#else
+/* this is the model-independent version. Since the standard I/O library
+   can't handle far buffers in the medium and small models, we have to copy
+   the data.
+*/
+
+#define NEAR_BUF_SIZE 1024
+#define MIN(a,b) (a <= b ? a : b)
+
+static void
+png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length);
+static void
+png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
+{
+   png_uint_32 check;
+   png_byte *near_data;  /* Needs to be "png_byte *" instead of "png_bytep" */
+   FILE *io_ptr;
+
+   /* Check if data really is near. If so, use usual code. */
+   near_data = (png_byte *)CVT_PTR_NOCHECK(data);
+   io_ptr = (FILE *)CVT_PTR(png_ptr->io_ptr);
+   if ((png_bytep)near_data == data)
+   {
+      check = fwrite(near_data, 1, length, io_ptr);
+   }
+   else
+   {
+      png_byte buf[NEAR_BUF_SIZE];
+      png_size_t written, remaining, err;
+      check = 0;
+      remaining = length;
+      do
+      {
+         written = MIN(NEAR_BUF_SIZE, remaining);
+         png_memcpy(buf, data, written); /* copy far buffer to near buffer */
+         err = fwrite(buf, 1, written, io_ptr);
+         if (err != written)
+            break;
+         else
+            check += err;
+         data += written;
+         remaining -= written;
+      }
+      while (remaining != 0);
+   }
+   if (check != length)
+   {
+      png_error(png_ptr, "Write Error");
+   }
+}
+
+#endif /* USE_FAR_KEYWORD */
+
+/* This function is called when there is a warning, but the library thinks
+ * it can continue anyway.  Replacement functions don't have to do anything
+ * here if you don't want to.  In the default configuration, png_ptr is
+ * not used, but it is passed in case it may be useful.
+ */
+static void
+png_default_warning(png_structp png_ptr, png_const_charp message)
+{
+   PNG_CONST char *name = "UNKNOWN (ERROR!)";
+   if (png_ptr != NULL && png_ptr->error_ptr != NULL)
+      name = png_ptr->error_ptr;
+   fprintf(STDERR, "%s: libpng warning: %s\n", name, message);
+}
+
+/* This is the default error handling function.  Note that replacements for
+ * this function MUST NOT RETURN, or the program will likely crash.  This
+ * function is used by default, or if the program supplies NULL for the
+ * error function pointer in png_set_error_fn().
+ */
+static void
+png_default_error(png_structp png_ptr, png_const_charp message)
+{
+   png_default_warning(png_ptr, message);
+   /* We can return because png_error calls the default handler which is
+    * actually ok in this case. */
+}
+#endif /* PNG_NO_STDIO */
+/* END of code to validate stdio-free compilation */
+
+/* START of code to validate memory allocation and deallocation */
+#ifdef PNGTEST_MEMORY_DEBUG
+/* Borland DOS special memory handler */
+#if defined(__TURBOC__) && !defined(_Windows) && !defined(__FLAT__)
+ERROR - memory debugging is not supported on this platform
+#else
+
+/* Allocate memory.  For reasonable files, size should never exceed
+   64K.  However, zlib may allocate more then 64K if you don't tell
+   it not to.  See zconf.h and png.h for more information.  zlib does
+   need to allocate exactly 64K, so whatever you call here must
+   have the ability to do that.
+
+   This piece of code can be compiled to validate max 64K allocations
+   by setting MAXSEG_64K in zlib zconf.h *or* PNG_MAX_MALLOC_64K. */
+typedef struct memory_information {
+   png_uint_32                    size;
+   png_voidp                      pointer;
+   struct memory_information FAR *next;
+} memory_information;
+typedef memory_information FAR *memory_infop;
+
+static memory_infop pinformation = NULL;
+static int current_allocation = 0;
+static int maximum_allocation = 0;
+
+extern PNG_EXPORT(png_voidp,png_debug_malloc) PNGARG((png_structp png_ptr,
+   png_uint_32 size));
+extern PNG_EXPORT(void,png_debug_free) PNGARG((png_structp png_ptr,
+   png_voidp ptr));
+
+png_voidp
+png_malloc(png_structp png_ptr, png_uint_32 size) {
+   if (png_ptr == NULL) {
+      fprintf(STDERR, "NULL pointer to memory allocator\n");
+      return (NULL);
+   }
+   if (size == 0)
+      return (NULL);
+
+   /* This calls the library allocator twice, once to get the requested
+      buffer and once to get a new free list entry. */
+   {
+      memory_infop pinfo = png_debug_malloc(png_ptr, sizeof *pinfo);
+      pinfo->size = size;
+      current_allocation += size;
+      if (current_allocation > maximum_allocation)
+         maximum_allocation = current_allocation;
+      pinfo->pointer = png_debug_malloc(png_ptr, size);
+      pinfo->next = pinformation;
+      pinformation = pinfo;
+      /* Make sure the caller isn't assuming zeroed memory. */
+      png_memset(pinfo->pointer, 0xdd, pinfo->size);
+      return ((png_voidp)pinfo->pointer);
+   }
+}
+
+/* Free a pointer.  It is removed from the list at the same time. */
+void
+png_free(png_structp png_ptr, png_voidp ptr)
+{
+   if (png_ptr == NULL)
+      fprintf(STDERR, "NULL pointer to memory allocator\n");
+   if (ptr == 0) {
+#if 0 /* This happens all the time. */
+      fprintf(STDERR, "WARNING: freeing NULL pointer\n");
+#endif
+      return;
+   }
+
+   /* Unlink the element from the list. */
+   {
+      memory_infop FAR *ppinfo = &pinformation;
+      for (;;) {
+         memory_infop pinfo = *ppinfo;
+         if (pinfo->pointer == ptr) {
+            *ppinfo = pinfo->next;
+            current_allocation -= pinfo->size;
+            if (current_allocation < 0)
+               fprintf(STDERR, "Duplicate free of memory\n");
+            /* We must free the list element too, but first kill
+               the memory which is to be freed. */
+            memset(ptr, 0x55, pinfo->size);
+            png_debug_free(png_ptr, pinfo);
+            break;
+         }
+         if (pinfo->next == NULL) {
+            fprintf(STDERR, "Pointer %x not found\n", ptr);
+            break;
+         }
+         ppinfo = &pinfo->next;
+      }
+   }
+
+   /* Finally free the data. */
+   png_debug_free(png_ptr, ptr);
+}
+#endif /* Not Borland DOS special memory handler */
+#endif
+/* END of code to test memory allocation/deallocation */
+
+/* Test one file */
+int test_one_file(PNG_CONST char *inname, PNG_CONST char *outname)
+{
+   static FILE *fpin, *fpout;  /* "static" prevents setjmp corruption */
    png_structp read_ptr, write_ptr;
    png_infop read_info_ptr, write_info_ptr, end_info_ptr;
    png_bytep row_buf;
@@ -51,51 +361,40 @@ main(int argc, char *argv[])
 #ifdef USE_FAR_KEYWORD
    jmp_buf jmpbuf;
 #endif   
+   
+   char inbuf[256], outbuf[256];
+
    row_buf = (png_bytep)NULL;
 
-   fprintf(STDERR, "Testing libpng version %s\n", PNG_LIBPNG_VER_STRING);
-
-   if (strcmp(png_libpng_ver, PNG_LIBPNG_VER_STRING))
-   {
-      fprintf(STDERR,
-         "Warning: versions are different between png.h and png.c\n");
-      fprintf(STDERR, "  png.h version: %s\n", PNG_LIBPNG_VER_STRING);
-      fprintf(STDERR, "  png.c version: %s\n\n", png_libpng_ver);
-   }
-
-   if (argc > 1)
-     inname = argv[1];
-
-   if (argc > 2)
-     outname = argv[2];
-
-   if (argc > 3)
-   {
-     fprintf(stderr, "usage: %s [infile.png] [outfile.png]\n", argv[0]);
-     exit(1);
-   }
-
    if ((fpin = fopen(inname, "rb")) == NULL)
    {
       fprintf(STDERR, "Could not find input file %s\n", inname);
-      return 1;
+      return (1);
    }
 
    if ((fpout = fopen(outname, "wb")) == NULL)
    {
       fprintf(STDERR, "Could not open output file %s\n", outname);
       fclose(fpin);
-      return 1;
+      return (1);
    }
 
    png_debug(0, "Allocating read and write structures\n");
    read_ptr = png_create_read_struct(PNG_LIBPNG_VER_STRING, (png_voidp)NULL,
       (png_error_ptr)NULL, (png_error_ptr)NULL);
+#if defined(PNG_NO_STDIO)
+   png_set_error_fn(read_ptr, (png_voidp)inname, png_default_error,
+       png_default_warning);
+#endif
    write_ptr = png_create_write_struct(PNG_LIBPNG_VER_STRING, (png_voidp)NULL,
       (png_error_ptr)NULL, (png_error_ptr)NULL);
+#if defined(PNG_NO_STDIO)
+   png_set_error_fn(write_ptr, (png_voidp)inname, png_default_error,
+       png_default_warning);
+#endif
    png_debug(0, "Allocating read_info, write_info and end_info structures\n");
    read_info_ptr = png_create_info_struct(read_ptr);
-   write_info_ptr = png_create_info_struct(read_ptr);
+   write_info_ptr = png_create_info_struct(write_ptr);
    end_info_ptr = png_create_info_struct(read_ptr);
 
    png_debug(0, "Setting jmpbuf for read struct\n");
@@ -105,12 +404,12 @@ main(int argc, char *argv[])
    if (setjmp(read_ptr->jmpbuf))
 #endif
    {
-      fprintf(STDERR, "libpng read error\n");
+      fprintf(STDERR, "%s -> %s: libpng read error\n", inname, outname);
       png_destroy_read_struct(&read_ptr, &read_info_ptr, &end_info_ptr);
       png_destroy_write_struct(&write_ptr, &write_info_ptr);
       fclose(fpin);
       fclose(fpout);
-      return 1;
+      return (1);
    }
 
    png_debug(0, "Setting jmpbuf for write struct\n");
@@ -121,20 +420,30 @@ main(int argc, char *argv[])
    if (setjmp(write_ptr->jmpbuf))
 #endif
    {
-      fprintf(STDERR, "libpng write error\n");
+      fprintf(STDERR, "%s -> %s: libpng write error\n", inname, outname);
       png_destroy_read_struct(&read_ptr, &read_info_ptr, &end_info_ptr);
       png_destroy_write_struct(&write_ptr, &write_info_ptr);
       fclose(fpin);
       fclose(fpout);
-      return 1;
+      return (1);
    }
 
 #ifdef USE_FAR_KEYWORD
    png_memcpy(write_ptr->jmpbuf,jmpbuf,sizeof(jmp_buf));
 #endif
    png_debug(0, "Initializing input and output streams\n");
+#if !defined(PNG_NO_STDIO)
    png_init_io(read_ptr, fpin);
    png_init_io(write_ptr, fpout);
+#else
+   png_set_read_fn(read_ptr, (png_voidp)fpin, png_default_read_data);
+   png_set_write_fn(write_ptr, (png_voidp)fpout,  png_default_write_data,
+#if defined(PNG_WRITE_FLUSH_SUPPORTED)
+      png_default_flush);
+#else
+      NULL);
+#endif
+#endif
 
    png_debug(0, "Reading info struct\n");
    png_read_info(read_ptr, read_info_ptr);
@@ -147,7 +456,11 @@ main(int argc, char *argv[])
           &color_type, &interlace_type, &compression_type, &filter_type))
       {
          png_set_IHDR(write_ptr, write_info_ptr, width, height, bit_depth,
+#if defined(PNG_WRITE_INTERLACING_SUPPORTED)
             color_type, interlace_type, compression_type, filter_type);
+#else
+            color_type, PNG_INTERLACE_NONE, compression_type, filter_type);
+#endif
       }
    }
 #if defined(PNG_READ_bKGD_SUPPORTED) && defined(PNG_WRITE_bKGD_SUPPORTED)
@@ -182,6 +495,16 @@ main(int argc, char *argv[])
       }
    }
 #endif
+#if defined(PNG_READ_sRGB_SUPPORTED) && defined(PNG_WRITE_sRGB_SUPPORTED)
+   {
+      int intent;
+
+      if (png_get_sRGB(read_ptr, read_info_ptr, &intent))
+      {
+         png_set_sRGB(write_ptr, write_info_ptr, intent);
+      }
+   }
+#endif
 #if defined(PNG_READ_hIST_SUPPORTED) && defined(PNG_WRITE_hIST_SUPPORTED)
    {
       png_uint_16p hist;
@@ -298,7 +621,7 @@ main(int argc, char *argv[])
       png_destroy_write_struct(&write_ptr, &write_info_ptr);
       fclose(fpin);
       fclose(fpout);
-      return 1;
+      return (1);
    }
 
    num_pass = png_set_interlace_handling(read_ptr);
@@ -316,28 +639,38 @@ main(int argc, char *argv[])
    png_debug(0, "Reading and writing end_info data\n");
    png_read_end(read_ptr, end_info_ptr);
    png_write_end(write_ptr, end_info_ptr);
+ 
+#ifdef PNG_EASY_ACCESS_SUPPORTED
+   if(verbose)
+   {
+      png_uint_32 iwidth, iheight;
+      iwidth = png_get_image_width(write_ptr, write_info_ptr);
+      iheight = png_get_image_height(write_ptr, write_info_ptr);
+      fprintf(STDERR, "Image width = %lu, height = %lu\n",
+         iwidth, iheight);
+   }
+#endif
 
    png_debug(0, "Destroying data structs\n");
+   png_free(read_ptr, row_buf);
    png_destroy_read_struct(&read_ptr, &read_info_ptr, &end_info_ptr);
    png_destroy_write_struct(&write_ptr, &write_info_ptr);
 
    fclose(fpin);
    fclose(fpout);
 
-   png_free(read_ptr, row_buf);
-
    png_debug(0, "Opening files for comparison\n");
    if ((fpin = fopen(inname, "rb")) == NULL)
    {
       fprintf(STDERR, "Could not find file %s\n", inname);
-      return 1;
+      return (1);
    }
 
    if ((fpout = fopen(outname, "rb")) == NULL)
    {
       fprintf(STDERR, "Could not find file %s\n", outname);
       fclose(fpin);
-      return 1;
+      return (1);
    }
 
    while (1)
@@ -353,7 +686,7 @@ main(int argc, char *argv[])
                  inname, outname);
          fclose(fpin);
          fclose(fpout);
-         return 1;
+         return (1);
       }
 
       if (!num_in)
@@ -364,14 +697,175 @@ main(int argc, char *argv[])
          fprintf(STDERR, "Files %s and %s are different\n", inname, outname);
          fclose(fpin);
          fclose(fpout);
-         return 1;
+         return (1);
       }
    }
 
    fclose(fpin);
    fclose(fpout);
-   fprintf(STDERR, "libpng passes test\n");
 
-   return 0;
+   return (0);
 }
 
+/* input and output filenames */
+#ifdef RISCOS
+PNG_CONST char *inname = "pngtest_png";
+PNG_CONST char *outname = "pngout_png";
+#else
+static char *inname = "pngtest.png";
+static char *outname = "pngout.png";
+#endif
+
+int
+main(int argc, char *argv[])
+{
+   int multiple = 0;
+   int ierror = 0;
+
+   fprintf(STDERR, "Testing libpng version %s\n", PNG_LIBPNG_VER_STRING);
+   fprintf(STDERR, "   with zlib   version %s\n", ZLIB_VERSION);
+
+   /* Do some consistency checking on the memory allocation settings, I'm
+      not sure this matters, but it is nice to know, the first of these
+      tests should be impossible because of the way the macros are set
+      in pngconf.h */
+   #if defined(MAXSEG_64K) && !defined(PNG_MAX_MALLOC_64K)
+      fprintf(STDERR, " NOTE: Zlib compiled for max 64k, libpng not\n");
+   #endif
+   /* I think the following can happen. */
+   #if !defined(MAXSEG_64K) && defined(PNG_MAX_MALLOC_64K)
+      fprintf(STDERR, " NOTE: libpng compiled for max 64k, zlib not\n");
+   #endif
+
+   if (strcmp(png_libpng_ver, PNG_LIBPNG_VER_STRING))
+   {
+      fprintf(STDERR,
+         "Warning: versions are different between png.h and png.c\n");
+      fprintf(STDERR, "  png.h version: %s\n", PNG_LIBPNG_VER_STRING);
+      fprintf(STDERR, "  png.c version: %s\n\n", png_libpng_ver);
+      ++ierror;
+   }
+
+   if (argc > 1)
+   {
+      if (strcmp(argv[1], "-m") == 0)
+         multiple = 1;
+      else if (strcmp(argv[1], "-mv") == 0 ||
+               strcmp(argv[1], "-vm") == 0 )
+      {
+         multiple = 1;
+         verbose = 1;
+      }
+      else if (strcmp(argv[1], "-v") == 0)
+      {
+         verbose = 1;
+         inname = argv[2];
+      }
+      else
+         inname = argv[1];
+   }
+
+   if (!multiple && argc == 3+verbose)
+     outname = argv[2+verbose];
+
+   if ((!multiple && argc > 3+verbose) || (multiple && argc < 2))
+   {
+     fprintf(STDERR,
+       "usage: %s [infile.png] [outfile.png]\n\t%s -m {infile.png}\n",
+        argv[0], argv[0]);
+     fprintf(STDERR,
+       "  reads/writes one PNG file (without -m) or multiple files (-m)\n");
+     fprintf(STDERR,
+       "  with -m %s is used as a temporary file\n", outname);
+     exit(1);
+   }
+
+   if (multiple)
+   {
+      int i;
+#ifdef PNGTEST_MEMORY_DEBUG
+      int allocation_now = current_allocation;
+#endif
+      for (i=2; i<argc; ++i)
+      {
+         int kerror;
+         fprintf(STDERR, "Testing %s:",argv[i]);
+         kerror = test_one_file(argv[i], outname);
+         if (kerror == 0) 
+            fprintf(STDERR, " PASS\n");
+         else {
+            fprintf(STDERR, " FAIL\n");
+            ierror += kerror;
+            }
+#ifdef PNGTEST_MEMORY_DEBUG
+         if (allocation_now != current_allocation)
+            fprintf(STDERR, "MEMORY ERROR: %d bytes lost\n",
+               current_allocation-allocation_now);
+         if (current_allocation != 0) {
+            memory_infop pinfo = pinformation;
+
+            fprintf(STDERR, "MEMORY ERROR: %d bytes still allocated\n",
+               current_allocation);
+            while (pinfo != NULL) {
+               fprintf(STDERR, " %d bytes at %x\n", pinfo->size, pinfo->pointer);
+               pinfo = pinfo->next;
+               }
+         }
+#endif
+      }
+#ifdef PNGTEST_MEMORY_DEBUG
+         fprintf(STDERR, "Maximum memory allocation: %d bytes\n",
+            maximum_allocation);
+#endif
+   }
+   else
+   {
+      int i;
+      for (i=0; i<3; ++i) {
+         int kerror;
+#ifdef PNGTEST_MEMORY_DEBUG
+         int allocation_now = current_allocation;
+#endif
+         if (i == 0 || verbose == 1 || ierror != 0)
+            fprintf(STDERR, "Testing %s:",inname);
+         kerror = test_one_file(inname, outname);
+         if(kerror == 0)
+         {
+            if(verbose == 1 || i == 2) fprintf(STDERR, " PASS\n");
+         }
+         else
+         {
+            if(verbose == 0 && i != 2)
+               fprintf(STDERR, "Testing %s:",inname);
+            fprintf(STDERR, " FAIL\n");
+            ierror += kerror;
+         }
+#ifdef PNGTEST_MEMORY_DEBUG
+         if (allocation_now != current_allocation)
+             fprintf(STDERR, "MEMORY ERROR: %d bytes lost\n",
+               current_allocation-allocation_now);
+         if (current_allocation != 0) {
+             memory_infop pinfo = pinformation;
+   
+             fprintf(STDERR, "MEMORY ERROR: %d bytes still allocated\n",
+                current_allocation);
+             while (pinfo != NULL) {
+                fprintf(STDERR, " %d bytes at %x\n", pinfo->size, pinfo->pointer);
+                pinfo = pinfo->next;
+             }
+          }
+         fprintf(STDERR, "sbrk(0)=%d\n",sbrk(0));
+#endif
+       }
+#ifdef PNGTEST_MEMORY_DEBUG
+       fprintf(STDERR, "Maximum memory allocation: %d bytes\n",
+          maximum_allocation);
+#endif
+   }
+
+   if (ierror == 0)
+      fprintf(STDERR, "libpng passes test\n");
+   else
+      fprintf(STDERR, "libpng FAILS test\n");
+   return ((int)(ierror != 0));
+}

pngtrans.c

@@ -1,12 +1,13 @@
 
 /* pngtrans.c - transforms the data in a row (used by both readers and writers)
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-   */
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ */
 
 #define PNG_INTERNAL
 #include "png.h"
@@ -67,7 +68,8 @@ png_set_shift(png_structp png_ptr, png_color_8p true_bits)
 }
 #endif
 
-#if defined(PNG_READ_INTERLACING_SUPPORTED) || defined(PNG_WRITE_INTERLACING_SUPPORTED)
+#if defined(PNG_READ_INTERLACING_SUPPORTED) || \
+    defined(PNG_WRITE_INTERLACING_SUPPORTED)
 int
 png_set_interlace_handling(png_structp png_ptr)
 {
@@ -75,10 +77,10 @@ png_set_interlace_handling(png_structp png_ptr)
    if (png_ptr->interlaced)
    {
       png_ptr->transformations |= PNG_INTERLACE;
-      return 7;
+      return (7);
    }
 
-   return 1;
+   return (1);
 }
 #endif
 
@@ -117,6 +119,16 @@ png_set_swap_alpha(png_structp png_ptr)
 }
 #endif
 
+#if defined(PNG_READ_INVERT_ALPHA_SUPPORTED) || \
+    defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
+void
+png_set_invert_alpha(png_structp png_ptr)
+{
+   png_debug(1, "in png_set_invert_alpha\n");
+   png_ptr->transformations |= PNG_INVERT_ALPHA;
+}
+#endif
+
 #if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
 void
 png_set_invert_mono(png_structp png_ptr)
@@ -288,7 +300,7 @@ png_do_packswap(png_row_infop row_info, png_bytep row)
    png_debug(1, "in png_do_packswap\n");
    if (
 #if defined(PNG_USELESS_TESTS_SUPPORTED)
-       row != NULL && row_info != NULL
+       row != NULL && row_info != NULL &&
 #endif
        row_info->bit_depth < 8)
    {

pngwio.c

@@ -1,18 +1,20 @@
 
 /* pngwio.c - functions for data output
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-
-   This file provides a location for all output.  Users which need
-   special handling are expected to write functions which have the same
-   arguments as these, and perform similar functions, but possibly use
-   different output methods.  Note that you shouldn't change these
-   functions, but rather write replacement functions and then change
-   them at run time with png_set_write_fn(...) */
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ *
+ * This file provides a location for all output.  Users which need
+ * special handling are expected to write functions which have the same
+ * arguments as these, and perform similar functions, but possibly use
+ * different output methods.  Note that you shouldn't change these
+ * functions, but rather write replacement functions and then change
+ * them at run time with png_set_write_fn(...).
+ */
 
 #define PNG_INTERNAL
 #include "png.h"
@@ -32,6 +34,7 @@ png_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
       png_error(png_ptr, "Call to NULL write function");
 }
 
+#if !defined(PNG_NO_STDIO)
 /* This is the function which does the actual writing of data.  If you are
    not writing to a standard C stream, you should create a replacement
    write_data function and use it at run time with png_set_write_fn(), rather
@@ -97,6 +100,7 @@ png_default_write_data(png_structp png_ptr, png_bytep data, png_size_t length)
    }
 }
 
+#endif
 #endif
 
 /* This function is called to output any data pending writing (normally
@@ -110,6 +114,7 @@ png_flush(png_structp png_ptr)
       (*(png_ptr->output_flush_fn))(png_ptr);
 }
 
+#if !defined(PNG_NO_STDIO)
 static void
 png_default_flush(png_structp png_ptr)
 {
@@ -119,6 +124,7 @@ png_default_flush(png_structp png_ptr)
       fflush(io_ptr);
 }
 #endif
+#endif
 
 /* This function allows the application to supply new output functions for
    libpng if standard C streams aren't being used.
@@ -148,16 +154,24 @@ png_set_write_fn(png_structp png_ptr, png_voidp io_ptr,
 {
    png_ptr->io_ptr = io_ptr;
 
+#if !defined(PNG_NO_STDIO)
    if (write_data_fn != NULL)
       png_ptr->write_data_fn = write_data_fn;
    else
       png_ptr->write_data_fn = png_default_write_data;
+#else
+   png_ptr->write_data_fn = write_data_fn;
+#endif
 
 #if defined(PNG_WRITE_FLUSH_SUPPORTED)
+#if !defined(PNG_NO_STDIO)
    if (output_flush_fn != NULL)
       png_ptr->output_flush_fn = output_flush_fn;
    else
       png_ptr->output_flush_fn = png_default_flush;
+#else
+   png_ptr->output_flush_fn = output_flush_fn;
+#endif
 #endif /* PNG_WRITE_FLUSH_SUPPORTED */
 
    /* It is an error to read while writing a png file */

pngwrite.c

@@ -1,12 +1,13 @@
    
 /* pngwrite.c - general routines to write a PNG file
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-   */
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ */
 
 /* get internal access to png.h */
 #define PNG_INTERNAL
@@ -24,20 +25,31 @@
 void
 png_write_info(png_structp png_ptr, png_infop info_ptr)
 {
+#if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
    int i;
+#endif
 
    png_debug(1, "in png_write_info\n");
    png_write_sig(png_ptr); /* write PNG signature */
    /* write IHDR information. */
    png_write_IHDR(png_ptr, info_ptr->width, info_ptr->height,
       info_ptr->bit_depth, info_ptr->color_type, info_ptr->compression_type,
-      info_ptr->filter_type, info_ptr->interlace_type);
+      info_ptr->filter_type,
+#if defined(PNG_WRITE_INTERLACING_SUPPORTED)
+      info_ptr->interlace_type);
+#else
+      0);
+#endif
    /* the rest of these check to see if the valid field has the appropriate
       flag set, and if it does, writes the chunk. */
 #if defined(PNG_WRITE_gAMA_SUPPORTED)
    if (info_ptr->valid & PNG_INFO_gAMA)
       png_write_gAMA(png_ptr, info_ptr->gamma);
 #endif
+#if defined(PNG_WRITE_sRGB_SUPPORTED)
+   if (info_ptr->valid & PNG_INFO_sRGB)
+      png_write_sRGB(png_ptr, (int)info_ptr->srgb_intent);
+#endif
 #if defined(PNG_WRITE_sBIT_SUPPORTED)
    if (info_ptr->valid & PNG_INFO_sBIT)
       png_write_sBIT(png_ptr, &(info_ptr->sig_bit), info_ptr->color_type);
@@ -55,10 +67,23 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
          (png_uint_32)info_ptr->num_palette);
    else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
       png_error(png_ptr, "Valid palette required for paletted images\n");
+
 #if defined(PNG_WRITE_tRNS_SUPPORTED)
    if (info_ptr->valid & PNG_INFO_tRNS)
+      {
+#if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
+         /* invert the alpha channel (in tRNS) */
+         if (png_ptr->transformations & PNG_INVERT_ALPHA &&
+            info_ptr->color_type == PNG_COLOR_TYPE_PALETTE)
+         {
+            int j;
+            for (j=0; j<info_ptr->num_trans; j++)
+               info_ptr->trans[j] = 255 - info_ptr->trans[j];
+         }
+#endif
       png_write_tRNS(png_ptr, info_ptr->trans, &(info_ptr->trans_values),
          info_ptr->num_trans, info_ptr->color_type);
+      }
 #endif
 #if defined(PNG_WRITE_bKGD_SUPPORTED)
    if (info_ptr->valid & PNG_INFO_bKGD)
@@ -128,9 +153,10 @@ png_write_info(png_structp png_ptr, png_infop info_ptr)
 }
 
 /* Writes the end of the PNG file.  If you don't want to write comments or
-   time information, you can pass NULL for info.  If you already wrote these
-   in png_write_info(), do not write them again here.  If you have long
-   comments, I suggest writing them here, and compressing them. */
+ * time information, you can pass NULL for info.  If you already wrote these
+ * in png_write_info(), do not write them again here.  If you have long
+ * comments, I suggest writing them here, and compressing them.
+ */
 void
 png_write_end(png_structp png_ptr, png_infop info_ptr)
 {
@@ -141,7 +167,9 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
    /* see if user wants us to write information chunks */
    if (info_ptr != NULL)
    {
+#if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
       int i; /* local index variable */
+#endif
 #if defined(PNG_WRITE_tIME_SUPPORTED)
       /* check to see if user has supplied a time chunk */
       if (info_ptr->valid & PNG_INFO_tIME &&
@@ -190,6 +218,41 @@ png_write_end(png_structp png_ptr, png_infop info_ptr)
    png_write_IEND(png_ptr);
 }
 
+#if defined(PNG_TIME_RFC1123_SUPPORTED)
+/* Convert the supplied time into an RFC 1123 string suitable for use in
+ * a "Creation Time" or other text-based time string.
+ */
+png_charp
+png_convert_to_rfc1123(png_structp png_ptr, png_timep ptime)
+{
+   const char *short_months[12] = {"Jan", "Feb", "Mar", "Apr", "May", "Jun",
+                                   "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"};
+
+   if (png_ptr->time_buffer == NULL)
+   {
+      png_ptr->time_buffer = (png_charp)png_malloc(png_ptr, 29*sizeof(char));
+   }
+
+#ifdef USE_FAR_KEYWORD
+   {
+      char near_time_buf[29];
+      sprintf(near_time_buf, "%d %s %d %02d:%02d:%02d +0000",
+               ptime->day % 31, short_months[ptime->month],
+               ptime->year, ptime->hour % 24, ptime->minute % 60,
+               ptime->second % 61);
+      png_memcpy(png_ptr->time_buffer, near_time_buf,
+      29*sizeof(char));
+   }
+#else
+   sprintf(png_ptr->time_buffer, "%d %s %d %02d:%02d:%02d +0000",
+               ptime->day % 31, short_months[ptime->month],
+               ptime->year, ptime->hour % 24, ptime->minute % 60,
+               ptime->second % 61);
+#endif
+   return ((png_charp)png_ptr->time_buffer);
+}
+#endif /* PNG_TIME_RFC1123_SUPPORTED */
+
 #if defined(PNG_WRITE_tIME_SUPPORTED)
 void
 png_convert_from_struct_tm(png_timep ptime, struct tm FAR * ttime)
@@ -226,7 +289,7 @@ png_create_write_struct(png_const_charp user_png_ver, voidp error_ptr,
    png_debug(1, "in png_create_write_struct\n");
    if ((png_ptr = (png_structp)png_create_struct(PNG_STRUCT_PNG)) == NULL)
    {
-      return (png_structp)NULL;
+      return ((png_structp)NULL);
    }
 #ifdef USE_FAR_KEYWORD
    if (setjmp(jmpbuf))
@@ -236,7 +299,7 @@ png_create_write_struct(png_const_charp user_png_ver, voidp error_ptr,
    {
       png_free(png_ptr, png_ptr->zbuf);
       png_destroy_struct(png_ptr);
-      return (png_structp)NULL;
+      return ((png_structp)NULL);
    }
 #ifdef USE_FAR_KEYWORD
    png_memcpy(png_ptr->jmpbuf,jmpbuf,sizeof(jmp_buf));
@@ -257,11 +320,16 @@ png_create_write_struct(png_const_charp user_png_ver, voidp error_ptr,
 
    /* initialize zbuf - compression buffer */
    png_ptr->zbuf_size = PNG_ZBUF_SIZE;
-   png_ptr->zbuf = png_malloc(png_ptr, png_ptr->zbuf_size);
+   png_ptr->zbuf = (png_bytep)png_malloc(png_ptr, png_ptr->zbuf_size);
 
    png_set_write_fn(png_ptr, NULL, NULL, NULL);
 
-   return (png_ptr);
+#if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
+   png_set_filter_heuristics(png_ptr, PNG_FILTER_HEURISTIC_DEFAULT,
+      1, NULL, NULL);
+#endif
+
+   return ((png_structp)png_ptr);
 }
 
 
@@ -283,7 +351,7 @@ png_write_init(png_structp png_ptr)
 
    /* initialize zbuf - compression buffer */
    png_ptr->zbuf_size = PNG_ZBUF_SIZE;
-   png_ptr->zbuf = png_malloc(png_ptr, png_ptr->zbuf_size);
+   png_ptr->zbuf = (png_bytep)png_malloc(png_ptr, png_ptr->zbuf_size);
    png_set_write_fn(png_ptr, NULL, NULL, NULL);
 
 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
@@ -292,10 +360,11 @@ png_write_init(png_structp png_ptr)
 #endif
 }
 
-/* write a few rows of image data.  If the image is interlaced,
-   either you will have to write the 7 sub images, or, if you
-   have called png_set_interlace_handling(), you will have to
-   "write" the image seven times */
+/* Write a few rows of image data.  If the image is interlaced,
+ * either you will have to write the 7 sub images, or, if you
+ * have called png_set_interlace_handling(), you will have to
+ * "write" the image seven times.
+ */
 void
 png_write_rows(png_structp png_ptr, png_bytepp row,
    png_uint_32 num_rows)
@@ -311,8 +380,9 @@ png_write_rows(png_structp png_ptr, png_bytepp row,
    }
 }
 
-/* write the image.  You only need to call this function once, even
-   if you are writing an interlaced image. */
+/* Write the image.  You only need to call this function once, even
+ * if you are writing an interlaced image.
+ */
 void
 png_write_image(png_structp png_ptr, png_bytepp image)
 {
@@ -321,9 +391,13 @@ png_write_image(png_structp png_ptr, png_bytepp image)
    png_bytepp rp; /* points to current row */
 
    png_debug(1, "in png_write_image\n");
+#if defined(PNG_WRITE_INTERLACING_SUPPORTED)
    /* intialize interlace handling.  If image is not interlaced,
       this will set pass to 1 */
    num_pass = png_set_interlace_handling(png_ptr);
+#else
+   num_pass = 1;
+#endif
    /* loop through passes */
    for (pass = 0; pass < num_pass; pass++)
    {
@@ -339,7 +413,8 @@ png_write_image(png_structp png_ptr, png_bytepp image)
 void
 png_write_row(png_structp png_ptr, png_bytep row)
 {
-   png_debug(1, "in png_write_row\n");
+   png_debug2(1, "in png_write_row (row %ld, pass %d)\n",
+      png_ptr->row_number, png_ptr->pass);
    /* initialize transformations and other stuff if first time */
    if (png_ptr->row_number == 0 && png_ptr->pass == 0)
    {
@@ -415,12 +490,12 @@ png_write_row(png_structp png_ptr, png_bytep row)
    png_ptr->row_info.rowbytes = ((png_ptr->row_info.width *
       (png_uint_32)png_ptr->row_info.pixel_depth + 7) >> 3);
 
-   png_debug1(4, "row_info->color_type = %d\n", png_ptr->row_info.color_type);
-   png_debug1(4, "row_info->width = %d\n", png_ptr->row_info.width);
-   png_debug1(4, "row_info->channels = %d\n", png_ptr->row_info.channels);
-   png_debug1(4, "row_info->bit_depth = %d\n", png_ptr->row_info.bit_depth);
-   png_debug1(4, "row_info->pixel_depth = %d\n", png_ptr->row_info.pixel_depth);
-   png_debug1(4, "row_info->rowbytes = %d\n", png_ptr->row_info.rowbytes);
+   png_debug1(3, "row_info->color_type = %d\n", png_ptr->row_info.color_type);
+   png_debug1(3, "row_info->width = %d\n", png_ptr->row_info.width);
+   png_debug1(3, "row_info->channels = %d\n", png_ptr->row_info.channels);
+   png_debug1(3, "row_info->bit_depth = %d\n", png_ptr->row_info.bit_depth);
+   png_debug1(3, "row_info->pixel_depth = %d\n", png_ptr->row_info.pixel_depth);
+   png_debug1(3, "row_info->rowbytes = %d\n", png_ptr->row_info.rowbytes);
 
    /* Copy user's row into buffer, leaving room for filter byte. */
    png_memcpy(png_ptr->row_buf + 1, row, png_ptr->row_info.rowbytes);
@@ -527,6 +602,22 @@ png_destroy_write_struct(png_structpp png_ptr_ptr, png_infopp info_ptr_ptr)
 
    if (info_ptr != NULL)
    {
+#ifdef PNG_WRITE_tEXt_SUPPORTED
+      png_free(png_ptr, info_ptr->text);
+#endif
+#if defined(PNG_READ_pCAL_SUPPORTED)
+      png_free(png_ptr, info_ptr->pcal_purpose);
+      png_free(png_ptr, info_ptr->pcal_units);
+      if (info_ptr->pcal_params != NULL)
+      {
+         int i;
+         for (i = 0; i < info_ptr->pcal_nparams; i++)
+         {
+            png_free(png_ptr, info_ptr->pcal_params[i]);
+         }
+         png_free(png_ptr, info_ptr->pcal_params);
+      }
+#endif
       png_destroy_struct((png_voidp)info_ptr);
       *info_ptr_ptr = (png_infop)NULL;
    }
@@ -561,6 +652,9 @@ png_write_destroy(png_structp png_ptr)
    png_free(png_ptr, png_ptr->up_row);
    png_free(png_ptr, png_ptr->avg_row);
    png_free(png_ptr, png_ptr->paeth_row);
+#if defined(PNG_TIME_RFC1123_SUPPORTED)
+   png_free(png_ptr, png_ptr->time_buffer);
+#endif /* PNG_TIME_RFC1123_SUPPORTED */
 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)
    png_free(png_ptr, png_ptr->prev_filters);
    png_free(png_ptr, png_ptr->filter_weights);
@@ -664,7 +758,7 @@ png_set_filter(png_structp png_ptr, int method, int filters)
             }
             else
             {
-               png_ptr->paeth_row = (png_bytep )png_malloc(png_ptr,
+               png_ptr->paeth_row = (png_bytep)png_malloc(png_ptr,
                   png_ptr->rowbytes + 1);
                png_ptr->paeth_row[0] = PNG_FILTER_VALUE_PAETH;
             }
@@ -683,14 +777,17 @@ png_set_filter(png_structp png_ptr, int method, int filters)
  * differences metric is relatively fast and effective, there is some
  * question as to whether it can be improved upon by trying to keep the
  * filtered data going to zlib more consistent, hopefully resulting in
- * better compression. */
+ * better compression.
+ */
 #if defined(PNG_WRITE_WEIGHTED_FILTER_SUPPORTED)      /* GRR 970116 */
 void
 png_set_filter_heuristics(png_structp png_ptr, int heuristic_method,
    int num_weights, png_doublep filter_weights,
    png_doublep filter_costs)
 {
+#if defined(PNG_WRITE_tEXt_SUPPORTED) || defined(PNG_WRITE_zTXt_SUPPORTED)
    int i;
+#endif
 
    png_debug(1, "in png_set_filter_heuristics\n");
    if (heuristic_method >= PNG_FILTER_HEURISTIC_LAST)

pngwtran.c

@@ -1,18 +1,20 @@
 
 /* pngwtran.c - transforms the data in a row for PNG writers
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-   */
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ */
 
 #define PNG_INTERNAL
 #include "png.h"
 
-/* transform the data according to the users wishes.  The order of
-   transformations is significant. */
+/* Transform the data according to the users wishes.  The order of
+ * transformations is significant.
+ */
 void
 png_do_write_transformations(png_structp png_ptr)
 {
@@ -22,6 +24,10 @@ png_do_write_transformations(png_structp png_ptr)
       png_do_strip_filler(&(png_ptr->row_info), png_ptr->row_buf + 1,
          png_ptr->flags);
 #endif
+#if defined(PNG_WRITE_PACKSWAP_SUPPORTED)
+   if (png_ptr->transformations & PNG_PACKSWAP)
+      png_do_packswap(&(png_ptr->row_info), png_ptr->row_buf + 1);
+#endif
 #if defined(PNG_WRITE_PACK_SUPPORTED)
    if (png_ptr->transformations & PNG_PACK)
       png_do_pack(&(png_ptr->row_info), png_ptr->row_buf + 1,
@@ -40,6 +46,10 @@ png_do_write_transformations(png_structp png_ptr)
    if (png_ptr->transformations & PNG_SWAP_ALPHA)
       png_do_write_swap_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
 #endif
+#if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
+   if (png_ptr->transformations & PNG_INVERT_ALPHA)
+      png_do_write_invert_alpha(&(png_ptr->row_info), png_ptr->row_buf + 1);
+#endif
 #if defined(PNG_WRITE_BGR_SUPPORTED)
    if (png_ptr->transformations & PNG_BGR)
       png_do_bgr(&(png_ptr->row_info), png_ptr->row_buf + 1);
@@ -51,9 +61,10 @@ png_do_write_transformations(png_structp png_ptr)
 }
 
 #if defined(PNG_WRITE_PACK_SUPPORTED)
-/* pack pixels into bytes.  Pass the true bit depth in bit_depth.  The
-   row_info bit depth should be 8 (one pixel per byte).  The channels
-   should be 1 (this only happens on grayscale and paletted images) */
+/* Pack pixels into bytes.  Pass the true bit depth in bit_depth.  The
+ * row_info bit depth should be 8 (one pixel per byte).  The channels
+ * should be 1 (this only happens on grayscale and paletted images).
+ */
 void
 png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
 {
@@ -169,12 +180,13 @@ png_do_pack(png_row_infop row_info, png_bytep row, png_uint_32 bit_depth)
 #endif
 
 #if defined(PNG_WRITE_SHIFT_SUPPORTED)
-/* shift pixel values to take advantage of whole range.  Pass the
-   true number of bits in bit_depth.  The row should be packed
-   according to row_info->bit_depth.  Thus, if you had a row of
-   bit depth 4, but the pixels only had values from 0 to 7, you
-   would pass 3 as bit_depth, and this routine would translate the
-   data to 0 to 15. */
+/* Shift pixel values to take advantage of whole range.  Pass the
+ * true number of bits in bit_depth.  The row should be packed
+ * according to row_info->bit_depth.  Thus, if you had a row of
+ * bit depth 4, but the pixels only had values from 0 to 7, you
+ * would pass 3 as bit_depth, and this routine would translate the
+ * data to 0 to 15.
+ */
 void
 png_do_shift(png_row_infop row_info, png_bytep row, png_color_8p bit_depth)
 {
@@ -252,7 +264,7 @@ png_do_shift(png_row_infop row_info, png_bytep row, png_color_8p bit_depth)
 
          for (bp = row, i = 0; i < row_info->width; i++)
          {
-            int c;
+            png_uint_32 c;
 
             for (c = 0; c < channels; c++, bp++)
             {
@@ -278,7 +290,7 @@ png_do_shift(png_row_infop row_info, png_bytep row, png_color_8p bit_depth)
 
          for (bp = row, i = 0; i < row_info->width * row_info->channels; i++)
          {
-            int c;
+            png_uint_32 c;
 
             for (c = 0; c < channels; c++, bp += 2)
             {
@@ -390,3 +402,79 @@ png_do_write_swap_alpha(png_row_infop row_info, png_bytep row)
 }
 #endif
 
+#if defined(PNG_WRITE_INVERT_ALPHA_SUPPORTED)
+void
+png_do_write_invert_alpha(png_row_infop row_info, png_bytep row)
+{
+   png_debug(1, "in png_do_write_invert_alpha\n");
+#if defined(PNG_USELESS_TESTS_SUPPORTED)
+   if (row != NULL && row_info != NULL)
+#endif
+   {
+      if (row_info->color_type == PNG_COLOR_TYPE_RGB_ALPHA)
+      {
+         /* This inverts the alpha channel in RGBA */
+         if (row_info->bit_depth == 8)
+         {
+            png_bytep sp, dp;
+            png_uint_32 i;
+
+            for (i = 0, sp = dp = row; i < row_info->width; i++)
+            {
+               *(dp++) = *(sp++);
+               *(dp++) = *(sp++);
+               *(dp++) = *(sp++);
+               *(dp++) = 255 - *(sp++);
+            }
+         }
+         /* This inverts the alpha channel in RRGGBBAA */
+         else
+         {
+            png_bytep sp, dp;
+            png_uint_32 i;
+
+            for (i = 0, sp = dp = row; i < row_info->width; i++)
+            {
+               *(dp++) = *(sp++);
+               *(dp++) = *(sp++);
+               *(dp++) = *(sp++);
+               *(dp++) = *(sp++);
+               *(dp++) = *(sp++);
+               *(dp++) = *(sp++);
+               *(dp++) = 255 - *(sp++);
+               *(dp++) = 255 - *(sp++);
+            }
+         }
+      }
+      else if (row_info->color_type == PNG_COLOR_TYPE_GRAY_ALPHA)
+      {
+         /* This inverts the alpha channel in GA */
+         if (row_info->bit_depth == 8)
+         {
+            png_bytep sp, dp;
+            png_uint_32 i;
+
+            for (i = 0, sp = dp = row; i < row_info->width; i++)
+            {
+               *(dp++) = *(sp++);
+               *(dp++) = 255 - *(sp++);
+            }
+         }
+         /* This inverts the alpha channel in GGAA */
+         else
+         {
+            png_bytep sp, dp;
+            png_uint_32 i;
+
+            for (i = 0, sp = dp = row; i < row_info->width; i++)
+            {
+               *(dp++) = *(sp++);
+               *(dp++) = *(sp++);
+               *(dp++) = 255 - *(sp++);
+               *(dp++) = 255 - *(sp++);
+            }
+         }
+      }
+   }
+}
+#endif

pngwutil.c

@@ -1,12 +1,13 @@
 
 /* pngwutil.c - utilities to write a PNG file
-
-   libpng 1.0 beta 6 - version 0.96
-   For conditions of distribution and use, see copyright notice in png.h
-   Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
-   Copyright (c) 1996, 1997 Andreas Dilger
-   May 12, 1997
-   */
+ *
+ * libpng 0.99a
+ * For conditions of distribution and use, see copyright notice in png.h
+ * Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.
+ * Copyright (c) 1996, 1997 Andreas Dilger
+ * Copyright (c) 1998, Glenn Randers-Pehrson
+ * January 31, 1998
+ */
 
 #define PNG_INTERNAL
 #include "png.h"
@@ -26,8 +27,9 @@ png_save_uint_32(png_bytep buf, png_uint_32 i)
 
 #if defined(PNG_WRITE_pCAL_SUPPORTED)
 /* The png_save_int_32 function assumes integers are stored in two's
-   complement format.  If this isn't the case, then this routine needs to
-   be modified to write data in two's complement format. */
+ * complement format.  If this isn't the case, then this routine needs to
+ * be modified to write data in two's complement format.
+ */
 void
 png_save_int_32(png_bytep buf, png_int_32 i)
 {
@@ -38,22 +40,26 @@ png_save_int_32(png_bytep buf, png_int_32 i)
 }
 #endif
 
-/* Place a 16-bit number into a buffer in PNG byte order. */
+/* Place a 16-bit number into a buffer in PNG byte order.
+ * The parameter is declared unsigned int, not png_uint_16,
+ * just to avoid potential problems on pre-ANSI C compilers.
+ */
 void
-png_save_uint_16(png_bytep buf, png_uint_16 i)
+png_save_uint_16(png_bytep buf, unsigned int i)
 {
    buf[0] = (png_byte)((i >> 8) & 0xff);
    buf[1] = (png_byte)(i & 0xff);
 }
 
 /* Write a PNG chunk all at once.  The type is an array of ASCII characters
-   representing the chunk name.  The array must be at least 4 bytes in
-   length, and does not need to be null terminated.  To be safe, pass the
-   pre-defined chunk names here, and if you need a new one, define it
-   where the others are defined.  The length is the length of the data.
-   All the data must be present.  If that is not possible, use the
-   png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
-   functions instead.  */
+ * representing the chunk name.  The array must be at least 4 bytes in
+ * length, and does not need to be null terminated.  To be safe, pass the
+ * pre-defined chunk names here, and if you need a new one, define it
+ * where the others are defined.  The length is the length of the data.
+ * All the data must be present.  If that is not possible, use the
+ * png_write_chunk_start(), png_write_chunk_data(), and png_write_chunk_end()
+ * functions instead.
+ */
 void
 png_write_chunk(png_structp png_ptr, png_bytep chunk_name,
    png_bytep data, png_size_t length)
@@ -64,8 +70,9 @@ png_write_chunk(png_structp png_ptr, png_bytep chunk_name,
 }
 
 /* Write the start of a PNG chunk.  The type is the chunk type.
-   The total_length is the sum of the lengths of all the data you will be
-   passing in png_write_chunk_data() */
+ * The total_length is the sum of the lengths of all the data you will be
+ * passing in png_write_chunk_data().
+ */
 void
 png_write_chunk_start(png_structp png_ptr, png_bytep chunk_name,
    png_uint_32 length)
@@ -85,9 +92,10 @@ png_write_chunk_start(png_structp png_ptr, png_bytep chunk_name,
 }
 
 /* Write the data of a PNG chunk started with png_write_chunk_start().
-   Note that multiple calls to this function are allowed, and that the
-   sum of the lengths from these calls *must* add up to the total_length
-   given to png_write_chunk_start(). */
+ * Note that multiple calls to this function are allowed, and that the
+ * sum of the lengths from these calls *must* add up to the total_length
+ * given to png_write_chunk_start().
+ */
 void
 png_write_chunk_data(png_structp png_ptr, png_bytep data, png_size_t length)
 {
@@ -106,11 +114,7 @@ png_write_chunk_end(png_structp png_ptr)
    png_byte buf[4];
 
    /* write the crc */
-#ifdef PNG_USE_OWN_CRC
-   png_save_uint_32(buf, ~png_ptr->crc);
-#else
    png_save_uint_32(buf, png_ptr->crc);
-#endif
 
    png_write_data(png_ptr, buf, (png_size_t)4);
 }
@@ -119,7 +123,8 @@ png_write_chunk_end(png_structp png_ptr)
  * the magic bytes of the signature, or more likely, the PNG stream is
  * being embedded into another stream and doesn't need its own signature,
  * we should call png_set_sig_bytes() to tell libpng how many of the
- * bytes have already been written. */
+ * bytes have already been written.
+ */
 void
 png_write_sig(png_structp png_ptr)
 {
@@ -129,8 +134,9 @@ png_write_sig(png_structp png_ptr)
 }
 
 /* Write the IHDR chunk, and update the png_struct with the necessary
-   information.  Note that the rest of this code depends upon this
-   information being correct.  */
+ * information.  Note that the rest of this code depends upon this
+ * information being correct.
+ */
 void
 png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
    int bit_depth, int color_type, int compression_type, int filter_type,
@@ -194,12 +200,16 @@ png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
       filter_type = PNG_FILTER_TYPE_BASE;
    }
 
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
    if (interlace_type != PNG_INTERLACE_NONE &&
       interlace_type != PNG_INTERLACE_ADAM7)
    {
       png_warning(png_ptr, "Invalid interlace type specified");
       interlace_type = PNG_INTERLACE_ADAM7;
    }
+#else
+   interlace_type=PNG_INTERLACE_NONE;
+#endif
 
    /* save off the relevent information */
    png_ptr->bit_depth = (png_byte)bit_depth;
@@ -264,8 +274,9 @@ png_write_IHDR(png_structp png_ptr, png_uint_32 width, png_uint_32 height,
 }
 
 /* write the palette.  We are careful not to trust png_color to be in the
-   correct order for PNG, so people can redefine it to any convient
-   structure. */
+ * correct order for PNG, so people can redefine it to any convient
+ * structure.
+ */
 void
 png_write_PLTE(png_structp png_ptr, png_colorp palette, png_uint_32 num_pal)
 {
@@ -336,6 +347,22 @@ png_write_gAMA(png_structp png_ptr, double file_gamma)
 }
 #endif
 
+#if defined(PNG_WRITE_sRGB_SUPPORTED)
+/* write a sRGB chunk */
+void
+png_write_sRGB(png_structp png_ptr, int srgb_intent)
+{
+   png_byte buf[1];
+
+   png_debug(1, "in png_write_sRGB\n");
+   if(srgb_intent >= PNG_sRGB_INTENT_LAST)
+         png_warning(png_ptr,
+            "Invalid sRGB rendering intent specified");
+   buf[0]=(png_byte)srgb_intent;
+   png_write_chunk(png_ptr, png_sRGB, buf, (png_size_t)1);
+}
+#endif
+
 #if defined(PNG_WRITE_sBIT_SUPPORTED)
 /* write the sBIT chunk */
 void
@@ -483,7 +510,7 @@ png_write_tRNS(png_structp png_ptr, png_bytep trans, png_color_16p tran,
    }
    else
    {
-      png_warning(png_ptr, "Can't write tRNS with and alpha channel");
+      png_warning(png_ptr, "Can't write tRNS with an alpha channel");
    }
 }
 #endif
@@ -560,11 +587,10 @@ png_write_hIST(png_structp png_ptr, png_uint_16p hist, png_uint_32 num_hist)
  * static keywords without having to have duplicate copies of the strings.
  */
 png_size_t
-png_check_keyword(png_structp png_ptr, png_charp key, png_bytepp new_key)
+png_check_keyword(png_structp png_ptr, png_charp key, png_charpp new_key)
 {
    png_size_t key_len;
-   png_charp kp;
-   png_bytep dp;
+   png_charp kp, dp;
    int kflag;
 
    png_debug(1, "in png_check_keyword\n");
@@ -572,27 +598,27 @@ png_check_keyword(png_structp png_ptr, png_charp key, png_bytepp new_key)
 
    if (key == NULL || (key_len = png_strlen(key)) == 0)
    {
-      char msg[40];
-
-      sprintf(msg, "Zero length %s keyword", png_ptr->chunk_name);
-      png_warning(png_ptr, msg);
-      return 0;
+      png_chunk_warning(png_ptr, "zero length keyword");
+      return ((png_size_t)0);
    }
 
    png_debug1(2, "Keyword to be checked is '%s'\n", key);
 
-   *new_key = (png_bytep)png_malloc(png_ptr, key_len + 1);
+   *new_key = (png_charp)png_malloc(png_ptr, key_len + 1);
 
    /* Replace non-printing characters with a blank and print a warning */
    for (kp = key, dp = *new_key; *kp != '\0'; kp++, dp++)
    {
-      if (*kp < 0x20 || ((png_byte)*kp > 0x7E && (png_byte)*kp < 0xA1))
+      if (*kp < 0x20 || (*kp > 0x7E && (png_byte)*kp < 0xA1))
       {
+#if !defined(PNG_NO_STDIO)
          char msg[40];
 
-         sprintf(msg, "Invalid %s keyword character 0x%02X",
-            png_ptr->chunk_name, *kp);
-         png_warning(png_ptr, msg);
+         sprintf(msg, "invalid keyword character 0x%02X", *kp);
+         png_chunk_warning(png_ptr, msg);
+#else
+         png_chunk_warning(png_ptr, "invalid character in keyword");
+#endif
          *dp = ' ';
       }
       else
@@ -606,11 +632,7 @@ png_check_keyword(png_structp png_ptr, png_charp key, png_bytepp new_key)
    kp = *new_key + key_len - 1;
    if (*kp == ' ')
    {
-      char msg[50];
-      sprintf(msg, "Trailing spaces removed from %s keyword",
-         png_ptr->chunk_name);
-
-      png_warning(png_ptr, msg);
+      png_chunk_warning(png_ptr, "trailing spaces removed from keyword");
 
       while (*kp == ' ')
       {
@@ -623,11 +645,7 @@ png_check_keyword(png_structp png_ptr, png_charp key, png_bytepp new_key)
    kp = *new_key;
    if (*kp == ' ')
    {
-      char msg[50];
-      sprintf(msg, "Leading spaces removed from %s keyword",
-         png_ptr->chunk_name);
-
-      png_warning(png_ptr, msg);
+      png_chunk_warning(png_ptr, "leading spaces removed from keyword");
 
       while (*kp == ' ')
       {
@@ -660,24 +678,17 @@ png_check_keyword(png_structp png_ptr, png_charp key, png_bytepp new_key)
 
    if (key_len == 0)
    {
-      char msg[40];
-
-      sprintf(msg, "Zero length %s keyword", png_ptr->chunk_name);
-      png_warning(png_ptr, msg);
+      png_chunk_warning(png_ptr, "zero length keyword");
    }
 
    if (key_len > 79)
    {
-      char msg[50];
-
-      sprintf(msg, "%s keyword length must be 1 - 79 characters",
-         png_ptr->chunk_name);
-      png_warning(png_ptr, msg);
+      png_chunk_warning(png_ptr, "keyword length must be 1 - 79 characters");
       new_key[79] = '\0';
       key_len = 79;
    }
 
-   return key_len;
+   return (key_len);
 }
 #endif
 
@@ -688,15 +699,12 @@ png_write_tEXt(png_structp png_ptr, png_charp key, png_charp text,
    png_size_t text_len)
 {
    png_size_t key_len;
-   png_bytep new_key;
+   png_charp new_key;
 
    png_debug(1, "in png_write_tEXt\n");
    if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
    {
-      char msg[40];
-
-      sprintf(msg, "Empty keyword in %s chunk", "tEXt");
-      png_warning(png_ptr, msg);
+      png_warning(png_ptr, "Empty keyword in tEXt chunk");
       return;
    }
 
@@ -705,7 +713,7 @@ png_write_tEXt(png_structp png_ptr, png_charp key, png_charp text,
 
    /* make sure we include the 0 after the key */
    png_write_chunk_start(png_ptr, png_tEXt, (png_uint_32)key_len+text_len+1);
-   png_write_chunk_data(png_ptr, new_key, key_len + 1);
+   png_write_chunk_data(png_ptr, (png_bytep)new_key, key_len + 1);
    if (text_len)
       png_write_chunk_data(png_ptr, (png_bytep)text, text_len);
 
@@ -722,7 +730,7 @@ png_write_zTXt(png_structp png_ptr, png_charp key, png_charp text,
 {
    png_size_t key_len;
    char buf[1];
-   png_bytep new_key;
+   png_charp new_key;
    int i, ret;
    png_charpp output_ptr = NULL; /* array of pointers to output */
    int num_output_ptr = 0; /* number of output pointers used */
@@ -732,10 +740,7 @@ png_write_zTXt(png_structp png_ptr, png_charp key, png_charp text,
 
    if (key == NULL || (key_len = png_check_keyword(png_ptr, key, &new_key))==0)
    {
-      char msg[40];
-
-      sprintf(msg, "Empty keyword in %s chunk", "zTXt");
-      png_warning(png_ptr, msg);
+      png_warning(png_ptr, "Empty keyword in zTXt chunk");
       return;
    }
 
@@ -750,9 +755,13 @@ png_write_zTXt(png_structp png_ptr, png_charp key, png_charp text,
 
    if (compression >= PNG_TEXT_COMPRESSION_LAST)
    {
+#if !defined(PNG_NO_STDIO)
       char msg[50];
       sprintf(msg, "Unknown zTXt compression type %d", compression);
       png_warning(png_ptr, msg);
+#else
+      png_warning(png_ptr, "Unknown zTXt compression type");
+#endif
       compression = PNG_TEXT_COMPRESSION_zTXt;
    }
 
@@ -816,7 +825,8 @@ png_write_zTXt(png_structp png_ptr, png_charp key, png_charp text,
          }
 
          /* save the data */
-         output_ptr[num_output_ptr] = png_malloc(png_ptr, png_ptr->zbuf_size);
+         output_ptr[num_output_ptr] = (png_charp)png_malloc(png_ptr,
+            png_ptr->zbuf_size);
          png_memcpy(output_ptr[num_output_ptr], png_ptr->zbuf,
             png_ptr->zbuf_size);
          num_output_ptr++;
@@ -869,7 +879,7 @@ png_write_zTXt(png_structp png_ptr, png_charp key, png_charp text,
          }
 
          /* save off the data */
-         output_ptr[num_output_ptr] = png_malloc(png_ptr,
+         output_ptr[num_output_ptr] = (png_charp)png_malloc(png_ptr,
             png_ptr->zbuf_size);
          png_memcpy(output_ptr[num_output_ptr], png_ptr->zbuf,
             png_ptr->zbuf_size);
@@ -945,7 +955,7 @@ png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
    png_size_t purpose_len, units_len, total_len; 
    png_uint_32p params_len;
    png_byte buf[10];
-   png_bytep new_purpose;
+   png_charp new_purpose;
    int i;
 
    png_debug1(1, "in png_write_pCAL (%d parameters)\n", nparams);
@@ -971,7 +981,7 @@ png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
 
    png_debug1(3, "pCAL total length = %d\n", total_len);
    png_write_chunk_start(png_ptr, png_pCAL, total_len);
-   png_write_chunk_data(png_ptr, new_purpose, purpose_len);
+   png_write_chunk_data(png_ptr, (png_bytep)new_purpose, purpose_len);
    png_save_int_32(buf, X0);
    png_save_int_32(buf + 4, X1);
    buf[8] = (png_byte)type;
@@ -987,6 +997,7 @@ png_write_pCAL(png_structp png_ptr, png_charp purpose, png_int_32 X0,
          (png_size_t)params_len[i]);
    }
 
+   png_free(png_ptr, params_len);
    png_write_chunk_end(png_ptr);
 }
 #endif
@@ -1013,8 +1024,9 @@ png_write_pHYs(png_structp png_ptr, png_uint_32 x_pixels_per_unit,
 #endif
 
 #if defined(PNG_WRITE_tIME_SUPPORTED)
-/* write the tIME chunk.  Use either png_convert_from_struct_tm()
-   or png_convert_from_time_t(), or fill in the structure yourself */
+/* Write the tIME chunk.  Use either png_convert_from_struct_tm()
+ * or png_convert_from_time_t(), or fill in the structure yourself.
+ */
 void
 png_write_tIME(png_structp png_ptr, png_timep mod_time)
 {
@@ -1091,6 +1103,7 @@ png_write_start_row(png_structp png_ptr)
       }
    }
 
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
    /* if interlaced, we need to set up width and height of pass */
    if (png_ptr->interlaced)
    {
@@ -1108,6 +1121,7 @@ png_write_start_row(png_structp png_ptr)
       }
    }
    else
+#endif
    {
       png_ptr->num_rows = png_ptr->height;
       png_ptr->usr_width = png_ptr->width;
@@ -1130,6 +1144,7 @@ png_write_finish_row(png_structp png_ptr)
    if (png_ptr->row_number < png_ptr->num_rows)
       return;
 
+#ifdef PNG_WRITE_INTERLACING_SUPPORTED
    /* if interlaced, go to next pass */
    if (png_ptr->interlaced)
    {
@@ -1171,6 +1186,7 @@ png_write_finish_row(png_structp png_ptr)
          return;
       }
    }
+#endif
 
    /* if we get here, we've just written the last row, so we need
       to flush the compressor */
@@ -1206,14 +1222,13 @@ png_write_finish_row(png_structp png_ptr)
 }
 
 #if defined(PNG_WRITE_INTERLACING_SUPPORTED)
-/* pick out the correct pixels for the interlace pass.
-
-   The basic idea here is to go through the row with a source
-   pointer and a destination pointer (sp and dp), and copy the
-   correct pixels for the pass.  As the row gets compacted,
-   sp will always be >= dp, so we should never overwrite anything.
-   See the default: case for the easiest code to understand.
-   */
+/* Pick out the correct pixels for the interlace pass.
+ * The basic idea here is to go through the row with a source
+ * pointer and a destination pointer (sp and dp), and copy the
+ * correct pixels for the pass.  As the row gets compacted,
+ * sp will always be >= dp, so we should never overwrite anything.
+ * See the default: case for the easiest code to understand.
+ */
 void
 png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
 {
@@ -1366,11 +1381,12 @@ png_do_write_interlace(png_row_infop row_info, png_bytep row, int pass)
 
 /* This filters the row, chooses which filter to use, if it has not already
  * been specified by the application, and then writes the row out with the
- * chosen filter. */
-#define PNG_MAXSUM (~0x0UL >> 1)
+ * chosen filter.
+ */
+#define PNG_MAXSUM (png_uint_32)(~0x0UL >> 1)
 #define PNG_HISHIFT 10
-#define PNG_LOMASK 0xffffL
-#define PNG_HIMASK (~PNG_LOMASK >> PNG_HISHIFT)
+#define PNG_LOMASK (png_uint_32)0xffffL
+#define PNG_HIMASK (png_uint_32)(~PNG_LOMASK >> PNG_HISHIFT)
 void
 png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
 {
@@ -1389,7 +1405,7 @@ png_write_find_filter(png_structp png_ptr, png_row_infop row_info)
     * smallest value when summing the absolute values of the distances
     * from zero using anything >= 128 as negative numbers.  This is known
     * as the "minimum sum of absolute differences" heuristic.  Other
-    * heruistics are the "weighted minumum sum of absolute differences"
+    * heuristics are the "weighted minumum sum of absolute differences"
     * (experimental and can in theory improve compression), and the "zlib
     * predictive" method (not implemented in libpng 0.95), which does test
     * compressions of lines using different filter methods, and then chooses