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[devel] Update documentation
This commit is contained in:
Glenn Randers-Pehrson
parent
a7a76a674f
commit
2be8b64af2
@ -105,6 +105,11 @@ scripts/pnglibconf.h:
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@echo "a new one simply make 'scripts/pnglibconf.out' and copy that" >&2
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@exit 1
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# The following is necessary to ensure that the local pnglibconf.h is used, not
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# an installed one (this can happen immediately after on a clean system if
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# 'make test' is the first thing the user does.)
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pngvalid.o pngtest.o: pnglibconf.h
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SYMBOL_CFLAGS = -DPNGLIB_LIBNAME='PNG@PNGLIB_MAJOR@@PNGLIB_MINOR@_0'\
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-DPNGLIB_VERSION='@PNGLIB_VERSION@'\
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-DSYMBOL_PREFIX='$(SYMBOL_PREFIX)'
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@ -1289,6 +1289,11 @@ scripts/pnglibconf.h:
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@echo "a new one simply make 'scripts/pnglibconf.out' and copy that" >&2
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@exit 1
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# The following is necessary to ensure that the local pnglibconf.h is used, not
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# an installed one (this can happen immediately after on a clean system if
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# 'make test' is the first thing the user does.)
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pngvalid.o pngtest.o: pnglibconf.h
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.dfn.out:
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rm -f $@ dfn.c dfn?.out
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test -d scripts || mkdir scripts
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@ -1,6 +1,6 @@
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libpng.txt - A description on how to use and modify libpng
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libpng version 1.5.0beta36 - July 29, 2010
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libpng version 1.5.0beta36 - July 30, 2010
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Updated and distributed by Glenn Randers-Pehrson
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<glennrp at users.sourceforge.net>
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Copyright (c) 1998-2010 Glenn Randers-Pehrson
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@ -11,7 +11,7 @@ libpng.txt - A description on how to use and modify libpng
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Based on:
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libpng versions 0.97, January 1998, through 1.5.0beta36 - July 29, 2010
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libpng versions 0.97, January 1998, through 1.5.0beta36 - July 30, 2010
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Updated and distributed by Glenn Randers-Pehrson
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Copyright (c) 1998-2010 Glenn Randers-Pehrson
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@ -99,34 +99,68 @@ same instance of a structure.
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II. Structures
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There are two main structures that are important to libpng, png_struct
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and png_info. The first, png_struct, is an internal structure that
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will not, for the most part, be used by a user except as the first
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variable passed to every libpng function call.
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and png_info. Both are internal structures that are no longer exposed
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in the libpng interface (as of libpng 1.5.0).
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The png_info structure is designed to provide information about the
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PNG file. At one time, the fields of png_info were intended to be
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directly accessible to the user. However, this tended to cause problems
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with applications using dynamically loaded libraries, and as a result
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a set of interface functions for png_info (the png_get_*() and png_set_*()
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functions) was developed. The fields of png_info are still available for
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older applications, but it is suggested that applications use the new
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interfaces if at all possible.
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functions) was developed.
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Applications that do make direct access to the members of png_struct (except
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for png_ptr->jmpbuf) must be recompiled whenever the library is updated,
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and applications that make direct access to the members of png_info must
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be recompiled if they were compiled or loaded with libpng version 1.0.6,
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in which the members were in a different order. In version 1.0.7, the
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members of the png_info structure reverted to the old order, as they were
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in versions 0.97c through 1.0.5. Starting with version 2.0.0, both
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structures are going to be hidden, and the contents of the structures will
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only be accessible through the png_get/png_set functions.
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The png_struct structure is the object used by the library to decode a
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single image. As of 1.5.0 this structure is also not exposed.
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Almost all libpng APIs require a pointer to a png_struct as the first argument.
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Many (in particular the png_set and png_get APIs) also require a pointer
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to png_info as the second argument. Some application visible macros
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defined in png.h designed for basic data access (reading and writing
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integers in the PNG format) break this rule, but it's almost always safe
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to assume that a (png_struct*) has to be passed to call an API function.
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The png.h header file is an invaluable reference for programming with libpng.
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And while I'm on the topic, make sure you include the libpng header file:
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#include <png.h>
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Types
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The png.h header file defines a number of integral types used by the
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APIs. Most of these are fairly obvious; for example types corresponding
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to integers of particular sizes and types for passing color values.
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One exception is how non-integral numbers are handled. For application
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convenience most APIs that take such numbers have C (double) arguments,
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however internally PNG, and libpng, use 32 bit signed integers and encode
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the value by multiplying by 100,000. As of libpng 1.5.0 a convenience
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macro PNG_FP_1 is defined in png.h along with a type (png_fixed_point)
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which is simply (png_int_32).
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All APIs that take (double) arguments also have an matching API that
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takes the corresponding fixed point integer arguments. The fixed point
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API has the same name as the floating point one with _fixed appended.
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The actual range of values permitted in the APIs is frequently less than
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the full range of (png_fixed_point) (-21474 to +21474). When APIs require
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a non-negative argument the type is recorded as png_uint_32 above. Consult
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the header file and the text below for more information.
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Configuration
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The main header file function declarations are frequently protected by C
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preprocessing directives of the form:
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#ifdef PNG_feature_SUPPORTED
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declare-function
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#endif
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The library can be built without support for these APIs, although a
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standard build will have all implemented APIs. Application programs
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should check the feature macros before using an API for maximum
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portability. From libpng 1.5.0 the feature macros set during the build
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of libpng are recorded in the header file "pnglibconf.h" and this file
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is always included by png.h.
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III. Reading
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We'll now walk you through the possible functions to call when reading
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@ -1152,7 +1186,8 @@ a slightly smaller exponent is better.
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guess for Mac systems */
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}
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The png_set_gamma() function handles gamma transformations of the data.
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The functions png_set_gamma() and its fixed point equivalent
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png_set_gamma_fixed() handle gamma transformations of the data.
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Pass both the file gamma and the current screen_gamma. If the file does
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not have a gamma value, you can pass one anyway if you have an idea what
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it is (usually 0.45455 is a good guess for GIF images on PCs). Note
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@ -1356,6 +1391,26 @@ while the sixth pass will be 1/2 as wide and 1/2 as high as the original
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wide as the original, and 1/2 as high, containing all of the odd
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numbered scanlines. Phew!
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If you want to retrieve the separate images you must pass the correct
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number of rows to each successive call of png_read_rows().
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Calculating the number isn't quite as straightforward as the previous
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paragraph might suggest; think about what happens with an image with a odd
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number of rows, which passes get the extra row? To help you libpng 1.5.0
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implements a function to return the number of rows and columns in the current
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pass:
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int number_of_rows = png_get_num_rows(png_ptr);
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int number_of_cols = png_get_num_cols(png_ptr);
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Simply call that before each call to png_read_rows(). You must call
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png_start_read_image() (or png_read_update_info) before the first call to
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ensure that the number libpng holds internally has been updated.
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For very small interlaced images the number of rows or columns in a pass
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can be zero.
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You don't need to call png_read_rows() in this case, libpng will simply
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skip to the next pass.
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If you want libpng to expand the images, call this before calling
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png_start_read_image() or png_read_update_info():
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@ -1368,6 +1423,14 @@ is seven, but may change if another interlace type is added.
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This function can be called even if the file is not interlaced,
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where it will return one pass.
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If you need to get the number of passes later (for example after the call
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to png_start_read_image()) just call:
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number_of_passes = png_get_num_passes(png_ptr);
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This function just returns the number - it doesn't make any changes to the
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libpng state.
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If you are not going to display the image after each pass, but are
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going to wait until the entire image is read in, use the sparkle
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effect. This effect is faster and the end result of either method
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@ -2529,9 +2592,11 @@ these functions, call the appropriate png_set_*_fn() function.
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Memory allocation is done through the functions png_malloc(), png_calloc(),
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and png_free(). These currently just call the standard C functions.
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png_calloc() calls png_malloc() and then png_memset() to clear the newly
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allocated memory to zero. If your pointers can't access more then 64K
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at a time, you will want to set MAXSEG_64K in zlib.h. Since it is
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png_calloc() calls png_malloc() and then clears the newly
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allocated memory to zero. There is limited support for certain systems
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with segmented memory architectures and the types of pointers declared by
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png.h match this; you will have to use appropriate pointers in your
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application. Since it is
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unlikely that the method of handling memory allocation on a platform
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will change between applications, these functions must be modified in
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the library at compile time. If you prefer to use a different method
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@ -3118,8 +3183,8 @@ png_get_mmx_bitdepth_threshold(), png_get_mmx_rowbytes_threshold(),
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png_set_asm_flags(), and png_mmx_supported()
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We removed the obsolete png_check_sig(), png_memcpy_check(), and
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png_memset_check() functions. Instead use !png_sig_cmp(), png_memcpy(),
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and png_memset(), respectively.
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png_memset_check() functions. Instead use !png_sig_cmp(), memcpy(),
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and memset(), respectively.
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The function png_set_gray_1_2_4_to_8() was removed. It has been
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deprecated since libpng-1.0.18 and 1.2.9, when it was replaced with
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@ -3134,7 +3199,7 @@ to
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This also applies to the prototype for the user replacement malloc_fn().
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The png_calloc() function was added and is used in place of
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of "png_malloc(); png_memset();" except in the case in png_read_png()
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of "png_malloc(); memset();" except in the case in png_read_png()
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where the array consists of pointers; in this case a "for" loop is used
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after the png_malloc() to set the pointers to NULL, to give robust.
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behavior in case the application runs out of memory part-way through
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@ -3301,7 +3366,7 @@ Other rules can be inferred by inspecting the libpng source.
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XIII. Y2K Compliance in libpng
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July 29, 2010
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July 30, 2010
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Since the PNG Development group is an ad-hoc body, we can't make
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an official declaration.
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205
libpng.3
205
libpng.3
@ -1,4 +1,4 @@
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.TH LIBPNG 3 "July 29, 2010"
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.TH LIBPNG 3 "July 30, 2010"
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.SH NAME
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libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
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.SH SYNOPSIS
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@ -200,6 +200,18 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
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\fI\fB
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\fBint png_get_num_cols (png_structp \fIpng_ptr\fP\fB);\fP
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\fI\fB
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\fBint png_get_num_passes (png_structp \fIpng_ptr\fP\fB);\fP
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\fI\fB
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\fBint png_get_num_rows (png_structp \fIpng_ptr\fP\fB);\fP
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\fI\fB
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\fBpng_uint_32 png_get_oFFs (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fP\fI*offset_x\fP\fB, png_uint_32 \fP\fI*offset_y\fP\fB, int \fI*unit_type\fP\fB);\fP
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\fI\fB
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@ -216,6 +228,10 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
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\fI\fB
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\fBpng_fixed_point png_get_pixel_aspect_ratio_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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\fI\fB
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\fBpng_uint_32 png_get_pixels_per_meter (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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\fI\fB
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@ -242,6 +258,18 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
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\fI\fB
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\fBvoid png_get_sCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, double* \fP\fIwidth\fP\fB, double* \fIheight\fP\fB);\fP
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\fI\fB
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\fBvoid png_get_sCAL_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, png_fixed_pointp \fP\fIwidth\fP\fB, png_fixed_pointp \fIheight\fP\fB);\fP
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\fI\fB
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\fBvoid png_get_sCAL_s (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int* \fP\fIunit\fP\fB, png_charpp \fP\fIwidth\fP\fB, \fIpng_charppheight\fP\fB);\fP
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\fI\fB
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\fBpng_bytep png_get_signature (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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\fI\fB
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@ -306,6 +334,14 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
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\fI\fB
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\fBfloat png_get_x_offset_inches (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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\fI\fB
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\fBpng_fixed_point png_get_x_offset_inches_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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\fI\fB
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\fBpng_int_32 png_get_x_offset_microns (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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\fI\fB
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@ -318,6 +354,14 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
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\fI\fB
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\fBfloat png_get_y_offset_inches (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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\fI\fB
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\fBpng_fixed_point png_get_y_offset_inches_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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\fI\fB
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\fBpng_int_32 png_get_y_offset_microns (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fIinfo_ptr\fP\fB);\fP
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\fI\fB
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@ -350,14 +394,6 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
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\fI\fB
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\fBvoidp png_memcpy (png_voidp \fP\fIs1\fP\fB, png_voidp \fP\fIs2\fP\fB, png_size_t \fIsize\fP\fB);\fP
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\fI\fB
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\fBvoidp png_memset (png_voidp \fP\fIs1\fP\fB, int \fP\fIvalue\fP\fB, png_size_t \fIsize\fP\fB);\fP
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\fI\fB
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\fBvoid png_process_data (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_bytep \fP\fIbuffer\fP\fB, png_size_t \fIbuffer_size\fP\fB);\fP
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\fI\fB
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@ -414,6 +450,10 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
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\fI\fB
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\fBvoid png_set_background_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_color_16p \fP\fIbackground_color\fP\fB, int \fP\fIbackground_gamma_code\fP\fB, int \fP\fIneed_expand\fP\fB, png_uint_32 \fIbackground_gamma\fP\fB);\fP
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\fI\fB
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\fBvoid png_set_bgr (png_structp \fIpng_ptr\fP\fB);\fP
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\fI\fB
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@ -482,6 +522,10 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
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\fI\fB
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\fBvoid png_set_filter_heuristics_fixed (png_structp \fP\fIpng_ptr\fP\fB, int \fP\fIheuristic_method\fP\fB, int \fP\fInum_weights\fP\fB, png_fixed_point_p \fP\fIfilter_weights\fP\fB, png_fixed_point_p \fIfilter_costs\fP\fB);\fP
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\fI\fB
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\fBvoid png_set_flush (png_structp \fP\fIpng_ptr\fP\fB, int \fInrows\fP\fB);\fP
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\fI\fB
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@ -490,6 +534,10 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
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\fI\fB
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\fBvoid png_set_gamma_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_uint_32 \fP\fIscreen_gamma\fP\fB, png_uint_32 \fIdefault_file_gamma\fP\fB);\fP
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\fI\fB
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\fBvoid png_set_gAMA (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, double \fIfile_gamma\fP\fB);\fP
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\fI\fB
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@ -602,7 +650,7 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
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\fI\fB
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\fBvoid png_set_rgb_to_gray_fixed (png_structp \fP\fIpng_ptr\fP\fB, int error_action png_fixed_point \fP\fIred\fP\fB, png_fixed_point \fIgreen\fP\fB);\fP
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\fBvoid png_set_rgb_to_gray_fixed (png_structp \fP\fIpng_ptr\fP\fB, int error_action png_uint_32 \fP\fIred\fP\fB, png_uint_32 \fIgreen\fP\fB);\fP
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|
||||
\fI\fB
|
||||
|
||||
@ -614,7 +662,21 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBvoid png_set_sCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_charp \fP\fIunit\fP\fB, double \fP\fIwidth\fP\fB, double \fIheight\fP\fB);\fP
|
||||
\fBvoid png_set_sCAL (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, double \fP\fIwidth\fP\fB, double \fIheight\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBvoid png_set_sCAL_fixed (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, png_fixed_point \fP\fIwidth\fP\fB, png_fixed_point \fIheight\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBvoid png_set_sCAL_s (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, int \fP\fIunit\fP\fB, png_charp \fP\fIwidth\fP\fB, png_charp \fIheight\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
@ -789,7 +851,7 @@ Following is a copy of the libpng.txt file that accompanies libpng.
|
||||
.SH LIBPNG.TXT
|
||||
libpng.txt - A description on how to use and modify libpng
|
||||
|
||||
libpng version 1.5.0beta36 - July 29, 2010
|
||||
libpng version 1.5.0beta36 - July 30, 2010
|
||||
Updated and distributed by Glenn Randers-Pehrson
|
||||
<glennrp at users.sourceforge.net>
|
||||
Copyright (c) 1998-2010 Glenn Randers-Pehrson
|
||||
@ -800,7 +862,7 @@ libpng.txt - A description on how to use and modify libpng
|
||||
|
||||
Based on:
|
||||
|
||||
libpng versions 0.97, January 1998, through 1.5.0beta36 - July 29, 2010
|
||||
libpng versions 0.97, January 1998, through 1.5.0beta36 - July 30, 2010
|
||||
Updated and distributed by Glenn Randers-Pehrson
|
||||
Copyright (c) 1998-2010 Glenn Randers-Pehrson
|
||||
|
||||
@ -888,34 +950,68 @@ same instance of a structure.
|
||||
.SH 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.
|
||||
and png_info. Both are internal structures that are no longer exposed
|
||||
in the libpng interface (as of libpng 1.5.0).
|
||||
|
||||
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 (the png_get_*() and png_set_*()
|
||||
functions) 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.
|
||||
functions) was developed.
|
||||
|
||||
Applications that do make direct access to the members of png_struct (except
|
||||
for png_ptr->jmpbuf) must be recompiled whenever the library is updated,
|
||||
and applications that make direct access to the members of png_info must
|
||||
be recompiled if they were compiled or loaded with libpng version 1.0.6,
|
||||
in which the members were in a different order. In version 1.0.7, the
|
||||
members of the png_info structure reverted to the old order, as they were
|
||||
in versions 0.97c through 1.0.5. Starting with version 2.0.0, both
|
||||
structures are going to be hidden, and the contents of the structures will
|
||||
only be accessible through the png_get/png_set functions.
|
||||
The png_struct structure is the object used by the library to decode a
|
||||
single image. As of 1.5.0 this structure is also not exposed.
|
||||
|
||||
Almost all libpng APIs require a pointer to a png_struct as the first argument.
|
||||
Many (in particular the png_set and png_get APIs) also require a pointer
|
||||
to png_info as the second argument. Some application visible macros
|
||||
defined in png.h designed for basic data access (reading and writing
|
||||
integers in the PNG format) break this rule, but it's almost always safe
|
||||
to assume that a (png_struct*) has to be passed to call an API function.
|
||||
|
||||
The png.h header file is an invaluable reference for programming with libpng.
|
||||
And while I'm on the topic, make sure you include the libpng header file:
|
||||
|
||||
#include <png.h>
|
||||
|
||||
.SS Types
|
||||
|
||||
The png.h header file defines a number of integral types used by the
|
||||
APIs. Most of these are fairly obvious; for example types corresponding
|
||||
to integers of particular sizes and types for passing color values.
|
||||
|
||||
One exception is how non-integral numbers are handled. For application
|
||||
convenience most APIs that take such numbers have C (double) arguments,
|
||||
however internally PNG, and libpng, use 32 bit signed integers and encode
|
||||
the value by multiplying by 100,000. As of libpng 1.5.0 a convenience
|
||||
macro PNG_FP_1 is defined in png.h along with a type (png_fixed_point)
|
||||
which is simply (png_int_32).
|
||||
|
||||
All APIs that take (double) arguments also have an matching API that
|
||||
takes the corresponding fixed point integer arguments. The fixed point
|
||||
API has the same name as the floating point one with _fixed appended.
|
||||
The actual range of values permitted in the APIs is frequently less than
|
||||
the full range of (png_fixed_point) (-21474 to +21474). When APIs require
|
||||
a non-negative argument the type is recorded as png_uint_32 above. Consult
|
||||
the header file and the text below for more information.
|
||||
|
||||
.SS Configuration
|
||||
|
||||
The main header file function declarations are frequently protected by C
|
||||
preprocessing directives of the form:
|
||||
|
||||
#ifdef PNG_feature_SUPPORTED
|
||||
declare-function
|
||||
#endif
|
||||
|
||||
The library can be built without support for these APIs, although a
|
||||
standard build will have all implemented APIs. Application programs
|
||||
should check the feature macros before using an API for maximum
|
||||
portability. From libpng 1.5.0 the feature macros set during the build
|
||||
of libpng are recorded in the header file "pnglibconf.h" and this file
|
||||
is always included by png.h.
|
||||
|
||||
.SH III. Reading
|
||||
|
||||
We'll now walk you through the possible functions to call when reading
|
||||
@ -1941,7 +2037,8 @@ a slightly smaller exponent is better.
|
||||
guess for Mac systems */
|
||||
}
|
||||
|
||||
The png_set_gamma() function handles gamma transformations of the data.
|
||||
The functions png_set_gamma() and its fixed point equivalent
|
||||
png_set_gamma_fixed() handle 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 0.45455 is a good guess for GIF images on PCs). Note
|
||||
@ -2145,6 +2242,26 @@ while the sixth pass will be 1/2 as wide and 1/2 as high as the original
|
||||
wide as the original, and 1/2 as high, containing all of the odd
|
||||
numbered scanlines. Phew!
|
||||
|
||||
If you want to retrieve the separate images you must pass the correct
|
||||
number of rows to each successive call of png_read_rows().
|
||||
Calculating the number isn't quite as straightforward as the previous
|
||||
paragraph might suggest; think about what happens with an image with a odd
|
||||
number of rows, which passes get the extra row? To help you libpng 1.5.0
|
||||
implements a function to return the number of rows and columns in the current
|
||||
pass:
|
||||
|
||||
int number_of_rows = png_get_num_rows(png_ptr);
|
||||
int number_of_cols = png_get_num_cols(png_ptr);
|
||||
|
||||
Simply call that before each call to png_read_rows(). You must call
|
||||
png_start_read_image() (or png_read_update_info) before the first call to
|
||||
ensure that the number libpng holds internally has been updated.
|
||||
|
||||
For very small interlaced images the number of rows or columns in a pass
|
||||
can be zero.
|
||||
You don't need to call png_read_rows() in this case, libpng will simply
|
||||
skip to the next pass.
|
||||
|
||||
If you want libpng to expand the images, call this before calling
|
||||
png_start_read_image() or png_read_update_info():
|
||||
|
||||
@ -2157,6 +2274,14 @@ is seven, but may change if another interlace type is added.
|
||||
This function can be called even if the file is not interlaced,
|
||||
where it will return one pass.
|
||||
|
||||
If you need to get the number of passes later (for example after the call
|
||||
to png_start_read_image()) just call:
|
||||
|
||||
number_of_passes = png_get_num_passes(png_ptr);
|
||||
|
||||
This function just returns the number - it doesn't make any changes to the
|
||||
libpng state.
|
||||
|
||||
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
|
||||
@ -3318,9 +3443,11 @@ these functions, call the appropriate png_set_*_fn() function.
|
||||
|
||||
Memory allocation is done through the functions png_malloc(), png_calloc(),
|
||||
and png_free(). These currently just call the standard C functions.
|
||||
png_calloc() calls png_malloc() and then png_memset() to clear the newly
|
||||
allocated memory to zero. If your pointers can't access more then 64K
|
||||
at a time, you will want to set MAXSEG_64K in zlib.h. Since it is
|
||||
png_calloc() calls png_malloc() and then clears the newly
|
||||
allocated memory to zero. There is limited support for certain systems
|
||||
with segmented memory architectures and the types of pointers declared by
|
||||
png.h match this; you will have to use appropriate pointers in your
|
||||
application. 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. If you prefer to use a different method
|
||||
@ -3907,8 +4034,8 @@ png_get_mmx_bitdepth_threshold(), png_get_mmx_rowbytes_threshold(),
|
||||
png_set_asm_flags(), and png_mmx_supported()
|
||||
|
||||
We removed the obsolete png_check_sig(), png_memcpy_check(), and
|
||||
png_memset_check() functions. Instead use !png_sig_cmp(), png_memcpy(),
|
||||
and png_memset(), respectively.
|
||||
png_memset_check() functions. Instead use !png_sig_cmp(), memcpy(),
|
||||
and memset(), respectively.
|
||||
|
||||
The function png_set_gray_1_2_4_to_8() was removed. It has been
|
||||
deprecated since libpng-1.0.18 and 1.2.9, when it was replaced with
|
||||
@ -3923,7 +4050,7 @@ to
|
||||
This also applies to the prototype for the user replacement malloc_fn().
|
||||
|
||||
The png_calloc() function was added and is used in place of
|
||||
of "png_malloc(); png_memset();" except in the case in png_read_png()
|
||||
of "png_malloc(); memset();" except in the case in png_read_png()
|
||||
where the array consists of pointers; in this case a "for" loop is used
|
||||
after the png_malloc() to set the pointers to NULL, to give robust.
|
||||
behavior in case the application runs out of memory part-way through
|
||||
@ -4090,7 +4217,7 @@ Other rules can be inferred by inspecting the libpng source.
|
||||
|
||||
.SH XIII. Y2K Compliance in libpng
|
||||
|
||||
July 29, 2010
|
||||
July 30, 2010
|
||||
|
||||
Since the PNG Development group is an ad-hoc body, we can't make
|
||||
an official declaration.
|
||||
@ -4332,7 +4459,7 @@ possible without all of you.
|
||||
|
||||
Thanks to Frank J. T. Wojcik for helping with the documentation.
|
||||
|
||||
Libpng version 1.5.0beta36 - July 29, 2010:
|
||||
Libpng version 1.5.0beta36 - July 30, 2010:
|
||||
Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
|
||||
Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
|
||||
|
||||
@ -4355,7 +4482,7 @@ this sentence.
|
||||
|
||||
This code is released under the libpng license.
|
||||
|
||||
libpng versions 1.2.6, August 15, 2004, through 1.5.0beta36, July 29, 2010, are
|
||||
libpng versions 1.2.6, August 15, 2004, through 1.5.0beta36, July 30, 2010, are
|
||||
Copyright (c) 2004,2006-2007 Glenn Randers-Pehrson, and are
|
||||
distributed according to the same disclaimer and license as libpng-1.2.5
|
||||
with the following individual added to the list of Contributing Authors
|
||||
@ -4454,7 +4581,7 @@ certification mark of the Open Source Initiative.
|
||||
|
||||
Glenn Randers-Pehrson
|
||||
glennrp at users.sourceforge.net
|
||||
July 29, 2010
|
||||
July 30, 2010
|
||||
|
||||
.\" end of man page
|
||||
|
||||
|
||||
138
libpngpf.3
138
libpngpf.3
@ -1,4 +1,4 @@
|
||||
.TH LIBPNGPF 3 "July 29, 2010"
|
||||
.TH LIBPNGPF 3 "July 30, 2010"
|
||||
.SH NAME
|
||||
libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
|
||||
(private functions)
|
||||
@ -7,9 +7,15 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBvoid png_64bit_product (long \fP\fIv1\fP\fB, long \fP\fIv2\fP\fB, unsigned long \fI*hi_product,
|
||||
\fBvoid png_64bit_product (long \fP\fIv1\fP\fB, long \fP\fIv2\fP\fB, unsigned long \fP\fI*hi_product\fP\fB, unsigned long \fI*lo_product\fP\fB);\fP
|
||||
|
||||
\fBunsigned long \fI*lo_product\fP\fB);\fP
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBvoid png_ascii_from_fp (png_structp \fP\fIpng_ptr\fP\fB, png_charp \fP\fIascii\fP\fB, png_size_t \fP\fIsize\fP\fB, double \fP\fIfp\fP\fB, unsigned \fIprecision\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
@ -43,6 +49,30 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBint png_check_fp_number (png_charp \fP\fIstring\fP\fB, png_size_t \fP\fIsize\fP\fB, int* \fP\fIstatep\fP\fB, png_size_tp \fIwhereami\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBint png_check_fp_string (png_charp \fP\fIstring\fP\fB, png_size_t \fIsize\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBpng_size_t png_check_keyword (png_structp \fP\fIpng_ptr\fP\fB, png_charp \fP\fIkey\fP\fB, png_charpp \fInew_key\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
@ -281,7 +311,21 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBvoid *png_far_to_near (png_structp png_ptr,png_voidp \fP\fIptr\fP\fB, int \fIcheck\fP\fB);\fP
|
||||
\fBvoid *png_far_to_near (png_structp \fP\fIpng_ptr\fP\fB, png_voidp \fP\fIptr\fP\fB, int \fIcheck\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBvoid png_fixed_error (png_structp \fP\fIpng_ptr\fP\fB, \fIpng_const_charp
|
||||
|
||||
\fBname, double \fIvalue\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
|
||||
@ -293,6 +337,42 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBint png_gamma_significant (png_fixed_point \fIgamma\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBpng_uint_16 png_gamma_16bit_correct (png_structp \fP\fIpng_ptr\fP\fB, unsigned \fP\fIvalue\fP\fB, png_fixed_point \fIgamma\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBpng_byte png_gamma_8bit_correct (png_structp \fP\fIpng_ptr\fP\fB, unsigned \fP\fIvalue\fP\fB, png_fixed_point \fIgamma\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBvoid png_handle_bKGD (png_structp \fP\fIpng_ptr\fP\fB, png_infop \fP\fIinfo_ptr\fP\fB, png_uint_32 \fIlength\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
@ -437,6 +517,30 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBint png_muldiv (png_fixed_point_p \fP\fIres\fP\fB, png_fixed_point \fP\fIa\fP\fB, png_int_32 \fP\fItimes\fP\fB, png_int_32 \fIdiv\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBpng_fixed_point png_muldiv_warn (png_structp \fP\fIpng_ptr\fP\fB, png_fixed_point \fP\fIa\fP\fB, png_int_32 \fP\fItimes\fP\fB, png_int_32 \fIdiv\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBvoid png_process_IDAT_data (png_structp \fP\fIpng_ptr\fP\fB, png_bytep \fP\fIbuffer\fP\fB, png_size_t \fIbuffer_length\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
@ -601,6 +705,30 @@ libpng \- Portable Network Graphics (PNG) Reference Library 1.5.0beta36
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBpng_fixed_point png_reciprocal (png_fixed_point \fIa\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBpng_fixed_point png_reciprocal2 (png_fixed_point \fP\fIa\fP\fB, png_fixed_point \fIb\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fI\fB
|
||||
|
||||
\fBvoid png_reset_crc (png_structp \fIpng_ptr\fP\fB);\fP
|
||||
|
||||
\fI\fB
|
||||
@ -812,7 +940,7 @@ The functions listed above are used privately by libpng
|
||||
and are not recommended for use by applications. They are
|
||||
not "exported" to applications using shared libraries. They
|
||||
are listed alphabetically here as an aid to libpng maintainers.
|
||||
See png.h for more information on these functions.
|
||||
See pngpriv.h for more information on these functions.
|
||||
|
||||
.SH SEE ALSO
|
||||
.BR "png"(5), " libpng"(3), " zlib"(3), " deflate"(5), " " and " zlib"(5)
|
||||
|
||||
13
png.h
13
png.h
@ -1,7 +1,7 @@
|
||||
|
||||
/* png.h - header file for PNG reference library
|
||||
*
|
||||
* libpng version 1.5.0beta36 - July 29, 2010
|
||||
* libpng version 1.5.0beta36 - July 30, 2010
|
||||
* Copyright (c) 1998-2010 Glenn Randers-Pehrson
|
||||
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
|
||||
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
|
||||
@ -11,7 +11,7 @@
|
||||
* Authors and maintainers:
|
||||
* libpng versions 0.71, May 1995, through 0.88, January 1996: Guy Schalnat
|
||||
* libpng versions 0.89c, June 1996, through 0.96, May 1997: Andreas Dilger
|
||||
* libpng versions 0.97, January 1998, through 1.5.0beta36 - July 29, 2010: Glenn
|
||||
* libpng versions 0.97, January 1998, through 1.5.0beta36 - July 30, 2010: Glenn
|
||||
* See also "Contributing Authors", below.
|
||||
*
|
||||
* Note about libpng version numbers:
|
||||
@ -172,7 +172,7 @@
|
||||
*
|
||||
* This code is released under the libpng license.
|
||||
*
|
||||
* libpng versions 1.2.6, August 15, 2004, through 1.5.0beta36, July 29, 2010, are
|
||||
* libpng versions 1.2.6, August 15, 2004, through 1.5.0beta36, July 30, 2010, are
|
||||
* Copyright (c) 2004, 2006-2010 Glenn Randers-Pehrson, and are
|
||||
* distributed according to the same disclaimer and license as libpng-1.2.5
|
||||
* with the following individual added to the list of Contributing Authors:
|
||||
@ -284,7 +284,7 @@
|
||||
* Y2K compliance in libpng:
|
||||
* =========================
|
||||
*
|
||||
* July 29, 2010
|
||||
* July 30, 2010
|
||||
*
|
||||
* Since the PNG Development group is an ad-hoc body, we can't make
|
||||
* an official declaration.
|
||||
@ -348,7 +348,7 @@
|
||||
/* Version information for png.h - this should match the version in png.c */
|
||||
#define PNG_LIBPNG_VER_STRING "1.5.0beta36"
|
||||
#define PNG_HEADER_VERSION_STRING \
|
||||
" libpng version 1.5.0beta36 - July 29, 2010\n"
|
||||
" libpng version 1.5.0beta36 - July 30, 2010\n"
|
||||
|
||||
#define PNG_LIBPNG_VER_SONUM 15
|
||||
#define PNG_LIBPNG_VER_DLLNUM 15
|
||||
@ -1092,6 +1092,7 @@ PNG_EXPORT(int,png_set_interlace_handling,(png_structp png_ptr),,45);
|
||||
*/
|
||||
PNG_EXPORT(int,png_get_num_passes,(png_structp png_ptr),,215);
|
||||
PNG_EXPORT(png_uint_32,png_get_num_rows,(png_structp png_ptr),,216);
|
||||
PNG_EXPORT(png_uint_32,png_get_num_cols,(png_structp png_ptr),,218);
|
||||
#endif
|
||||
|
||||
#if defined(PNG_READ_INVERT_SUPPORTED) || defined(PNG_WRITE_INVERT_SUPPORTED)
|
||||
@ -2055,7 +2056,7 @@ PNG_EXPORT(void,png_save_uint_16,(png_bytep buf, unsigned int i),,207);
|
||||
* use is one more than this.)
|
||||
*/
|
||||
#ifdef PNG_EXPORT_LAST_ORDINAL
|
||||
PNG_EXPORT_LAST_ORDINAL(217);
|
||||
PNG_EXPORT_LAST_ORDINAL(218);
|
||||
#endif
|
||||
|
||||
#ifdef __cplusplus
|
||||
|
||||
@ -1,7 +1,7 @@
|
||||
|
||||
/* pngerror.c - stub functions for i/o and memory allocation
|
||||
*
|
||||
* Last changed in libpng 1.5.0 [July 29, 2010]
|
||||
* Last changed in libpng 1.5.0 [July 30, 2010]
|
||||
* Copyright (c) 1998-2010 Glenn Randers-Pehrson
|
||||
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
|
||||
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
|
||||
@ -256,7 +256,7 @@ png_fixed_error(png_structp png_ptr, png_const_charp name, double value)
|
||||
msg[fixed_message_ln + iin] = 0;
|
||||
/* To discover 'value' put a breakpoint here: */
|
||||
png_error(png_ptr, msg);
|
||||
value = value; png_ptr = png_ptr; /* Quiet the compiler */
|
||||
value = value; /* Quiet the compiler */
|
||||
}
|
||||
#endif
|
||||
#endif
|
||||
|
||||
12
pngpriv.h
12
pngpriv.h
@ -1,7 +1,7 @@
|
||||
|
||||
/* pngpriv.h - private declarations for use inside libpng
|
||||
*
|
||||
* libpng version 1.5.0beta36 - July 29, 2010
|
||||
* libpng version 1.5.0beta36 - July 30, 2010
|
||||
* For conditions of distribution and use, see copyright notice in png.h
|
||||
* Copyright (c) 1998-2010 Glenn Randers-Pehrson
|
||||
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
|
||||
@ -1042,8 +1042,8 @@ PNG_EXTERN void png_fixed_error PNGARG((png_structp png_ptr,
|
||||
* maximum ridiculous exponent.
|
||||
*/
|
||||
#define PNG_sCAL_MAX_DIGITS (PNG_sCAL_PRECISION+1/*.*/+1/*E*/+10/*exponent*/)
|
||||
PNG_EXTERN void png_ascii_from_fp(png_structp png_ptr, png_charp ascii,
|
||||
png_size_t size, double fp, unsigned precision);
|
||||
PNG_EXTERN void png_ascii_from_fp PNGARG((png_structp png_ptr, png_charp ascii,
|
||||
png_size_t size, double fp, unsigned precision));
|
||||
#endif /* READ_sCAL && FLOATING_POINT */
|
||||
|
||||
#if defined(PNG_sCAL_SUPPORTED) || defined(PNG_pCAL_SUPPORTED)
|
||||
@ -1110,13 +1110,13 @@ PNG_EXTERN void png_ascii_from_fp(png_structp png_ptr, png_charp ascii,
|
||||
* that omits the last character (i.e. set the size to the index of
|
||||
* the problem character.) This has not been tested within libpng.
|
||||
*/
|
||||
PNG_EXTERN int png_check_fp_number(png_charp string, png_size_t size,
|
||||
int *statep, png_size_tp whereami);
|
||||
PNG_EXTERN int png_check_fp_number PNGARG((png_charp string, png_size_t size,
|
||||
int *statep, png_size_tp whereami));
|
||||
|
||||
/* This is the same but it checks a complete string and returns true
|
||||
* only if it just contains a floating point number.
|
||||
*/
|
||||
PNG_EXTERN int png_check_fp_string(png_charp string, png_size_t size);
|
||||
PNG_EXTERN int png_check_fp_string PNGARG((png_charp string, png_size_t size));
|
||||
#endif /* pCAL || sCAL */
|
||||
|
||||
#if defined(PNG_READ_GAMMA_SUPPORTED) || defined(PNG_INCH_CONVERSIONS_SUPPORTED)
|
||||
|
||||
18
pngrutil.c
18
pngrutil.c
@ -1,7 +1,7 @@
|
||||
|
||||
/* pngrutil.c - utilities to read a PNG file
|
||||
*
|
||||
* Last changed in libpng 1.4.1 [July 29, 2010]
|
||||
* Last changed in libpng 1.4.1 [July 30, 2010]
|
||||
* Copyright (c) 1998-2010 Glenn Randers-Pehrson
|
||||
* (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
|
||||
* (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
|
||||
@ -3485,5 +3485,21 @@ png_get_num_rows(png_structp png_ptr)
|
||||
/* Here on error */
|
||||
return 0;
|
||||
}
|
||||
|
||||
png_uint_32 PNGAPI
|
||||
png_get_num_cols(png_structp png_ptr)
|
||||
{
|
||||
if (png_ptr != NULL)
|
||||
{
|
||||
if (png_ptr->flags & PNG_FLAG_ROW_INIT)
|
||||
return png_ptr->iwidth;
|
||||
else
|
||||
png_error(png_ptr, "Call png_start_read_image or png_read_update_info "
|
||||
"before png_get_num_cols");
|
||||
}
|
||||
|
||||
/* Here on error */
|
||||
return 0;
|
||||
}
|
||||
#endif /* SEQUENTIAL READ */
|
||||
#endif /* PNG_READ_SUPPORTED */
|
||||
|
||||
@ -227,3 +227,4 @@ EXPORTS
|
||||
png_get_num_passes @215
|
||||
png_get_num_rows @216
|
||||
png_set_background_fixed @217
|
||||
png_get_num_cols @218
|
||||
|
||||
@ -223,3 +223,4 @@ EXPORTS
|
||||
png_get_num_passes @215
|
||||
png_get_num_rows @216
|
||||
png_set_background_fixed @217
|
||||
png_get_num_cols @218
|
||||
|
||||
Loading…
x
Reference in New Issue
Block a user