[devel] Minor editing of the manual.

ANNOUNCE

@@ -27,7 +27,7 @@ Other information:
 Changes since the last public release (1.5.4):
 
 Version 1.5.5beta01 [July 12, 2011]
-  Fixed some typos in the manual.
+  Fixed some typos and made other minor changes in the manual.
   Updated contrib/pngminus/makefile.std (Samuli Souminen)
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net:

CHANGES

@@ -3510,7 +3510,7 @@ Version 1.5.4 [July 7, 2011]
   No changes.
 
 Version 1.5.5beta01 [July 12, 2011]
-  Fixed some typos in the manual.
+  Fixed some typos and made other minor changes in the manual.
   Updated contrib/pngminus/makefile.std (Samuli Souminen)
 
 Send comments/corrections/commendations to png-mng-implement at lists.sf.net

libpng-manual.txt

@@ -1,6 +1,6 @@
 libpng-manual.txt - A description on how to use and modify libpng
 
- libpng version 1.5.5beta01 - July 10, 2011
+ libpng version 1.5.5beta01 - July 12, 2011
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
  Copyright (c) 1998-2011 Glenn Randers-Pehrson
@@ -11,7 +11,7 @@ libpng-manual.txt - A description on how to use and modify libpng
 
  Based on:
 
- libpng versions 0.97, January 1998, through 1.5.5beta01 - July 10, 2011
+ libpng versions 0.97, January 1998, through 1.5.5beta01 - July 12, 2011
  Updated and distributed by Glenn Randers-Pehrson
  Copyright (c) 1998-2011 Glenn Randers-Pehrson
 
@@ -116,14 +116,23 @@ 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
+integers in the PNG format) don't take a png_info pointer, but it's almost
-to assume that a (png_struct*) has to be passed to call an API function.
+always safe to assume that a (png_struct*) has to be passed to call an API
+function.
+
+You can have more than one png_info structure associated with an image,
+as illustrated in pngtest.c, one for information valid prior to the
+IDAT chunks and another (called "end_info" below) for things after them.
 
 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>
 
+and also (as of libpng-1.5.0) the zlib header file, if you need it:
+
+#include <zlib.h>
+
 Types
 
 The png.h header file defines a number of integral types used by the
@@ -165,7 +174,7 @@ 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.
 
-If you don't need to change the library configuration from the default skip to
+If you don't need to change the library configuration from the default, skip to
 the next section ("Reading").
 
 Notice that some of the makefiles in the 'scripts' directory and (in 1.5.0) all
@@ -238,6 +247,10 @@ source code.  Most of these values have performance implications for the library
 but most of them have no visible effect on the API.  Some can also be overridden
 from the API.
 
+This method of building a customized pnglibconf.h is illustrated in
+contrib/pngminim/*.  See the "$(PNGCONF):" target in the makefile and
+pngusr.dfa in these directories.
+
 C. Configuration using PNG_USR_CONFIG
 
 If -DPNG_USR_CONFIG is added to the CFLAGS when pnglibconf.h is built the file
@@ -274,6 +287,9 @@ examine the intermediate file pnglibconf.dfn to find the full set of
 dependency information for each setting and option.  Simply locate the
 feature in the file and read the C comments that precede it.
 
+This method is also illustrated in the contrib/pngminim/* makefiles and
+pngusr.h.
+
 III. Reading
 
 We'll now walk you through the possible functions to call when reading
@@ -3448,7 +3464,8 @@ However, there are some uncertainties about the status of local variables
 after a longjmp, so the user may want to be careful about doing anything
 after setjmp returns non-zero besides returning itself.  Consult your
 compiler documentation for more details.  For an alternative approach, you
-may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net).
+may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net),
+which is illustrated in pngvalid.c and in contrib/visupng.
 
 Custom chunks
 
@@ -3466,8 +3483,11 @@ and look at how other chunks were designed, so you can do things
 similarly.  Second, check out the sections of libpng that read and
 write chunks.  Try to find a chunk that is similar to yours and use
 it as a template.  More details can be found in the comments inside
-the code.  It is best to handle unknown chunks in a generic method,
+the code.  It is best to handle private or unknown chunks in a generic method,
-via callback functions, instead of by modifying libpng functions.
+via callback functions, instead of by modifying libpng functions. This
+is illustrated in pngtest.c, which uses a callback function to handle a
+private "vpAg" chunk and the new "sTER" chunk, which are both unknown to
+libpng.
 
 If you wish to write your own transformation for the data, look through
 the part of the code that does the transformations, and check out some of
@@ -3663,8 +3683,8 @@ capability, which you'll still have).
 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
+reading files start with "pngr" and all the writing files start with "pngw".
-pngw.  The files that don't match either (like png.c, pngtrans.c, etc.)
+The files that don't match either (like png.c, pngtrans.c, etc.)
 are used for both reading and writing, and always need to be included.
 The progressive reader is in pngpread.c
 
@@ -4042,7 +4062,6 @@ absolutely necessary) interlace an image.
 
 libpng 1.5.0 adds an API png_longjmp(png_ptr, value).  This API calls
 the application-provided png_longjmp_ptr on the internal, but application
-initialized, jmpbuf.  It is provided as a convenience to avoid the need
 initialized, longjmp buffer.  It is provided as a convenience to avoid
 the need to use the png_jmpbuf macro, which had the unnecessary side
 effect of resetting the internal png_longjmp_ptr value.
@@ -4121,9 +4140,9 @@ increase the limits.
 B. Changes to the build and configuration of libpng
 
 Details of internal changes to the library code can be found in the CHANGES
-file.  These will be of no concern to the vast majority of library users or
+file and in the GIT repository logs.  These will be of no concern to the vast
-builders, however the few who configure libpng to a non-default feature
+majority of library users or builders, however the few who configure libpng
-set may need to change how this is done.
+to a non-default feature set may need to change how this is done.
 
 There should be no need for library builders to alter build scripts if
 these use the distributed build support - configure or the makefiles -
@@ -4132,14 +4151,14 @@ to build pnglibconf.h where the corresponding makefile does not do so.
 
 Building libpng with a non-default configuration has changed completely.
 The old method using pngusr.h should still work correctly even though the
-way pngusr.h is used in the build has been changed, however library
+way pngusr.h is used in the build has been changed; however, library
 builders will probably want to examine the changes to take advantage of
 new capabilities and to simplify their build system.
 
 B.1 Specific changes to library configuration capabilities
 
 The library now supports a complete fixed point implementation and can
-thus be used on systems which have no floating point support or very
+thus be used on systems that have no floating point support or very
 limited or slow support.  Previously gamma correction, an essential part
 of complete PNG support, required reasonably fast floating point.
 
@@ -4155,14 +4174,14 @@ pnglibconf.h
 As part of this the mechanism used to choose procedure call standards on
 those systems that allow a choice has been changed.  At present this only
 affects certain Microsoft (DOS, Windows) and IBM (OS/2) operating systems
-running on Intel processors.  As before PNGAPI is defined where required
+running on Intel processors.  As before, PNGAPI is defined where required
 to control the exported API functions; however, two new macros, PNGCBAPI
 and PNGCAPI, are used instead for callback functions (PNGCBAPI) and
 (PNGCAPI) for functions that must match a C library prototype (currently
 only png_longjmp_ptr, which must match the C longjmp function.)  The new
 approach is documented in pngconf.h
 
-Despite these changes libpng 1.5.0 only supports the native C function
+Despite these changes, libpng 1.5.0 only supports the native C function
 calling standard on those platforms tested so far (__cdecl on Microsoft
 Windows).  This is because the support requirements for alternative
 calling conventions seem to no longer exist.  Developers who find it
@@ -4196,7 +4215,9 @@ if the feature is supported or:
 
 if it is not.  Library code consistently checks for the 'SUPPORTED' macro.
 It does not, and should not, check for the 'NO' macro which will not
-normally be defined even if the feature is not supported.
+normally be defined even if the feature is not supported.  The 'NO' macros
+are only used internally for setting the corresponding 'SUPPORTED' macros
+or not.
 
 Compatibility with the old names is provided as follows:
 
@@ -4253,10 +4274,10 @@ application built without PNG_USER_CONFIG defined would see the
 unmodified, default, libpng API and thus would probably fail to link.
 
 These mechanisms still work in the configure build and in any makefile
-build that builds pnglibconf.h although the feature selection macros
+build that builds pnglibconf.h, although the feature selection macros
 have changed somewhat as described above.  In 1.5.0, however, pngusr.h is
 processed only once, when the exported header file pnglibconf.h is built.
-pngconf.h no longer includes pngusr.h, therefore it is ignored after the
+pngconf.h no longer includes pngusr.h, therefore pngusr.h is ignored after the
 build of pnglibconf.h and it is never included in an application build.
 
 The rarely used alternative of adding a list of feature macros to the
@@ -4270,7 +4291,7 @@ scripts/pnglibconf.dfa.  This requires the program awk.  Brian Kernighan
 and all known later implementations (often called by subtly different
 names - nawk and gawk for example) are adequate to build pnglibconf.h.
 The Sun Microsystems (now Oracle) program 'awk' is an earlier version
-and does not work, this may also apply to other systems that have a
+and does not work; this may also apply to other systems that have a
 functioning awk called 'nawk'.
 
 Configuration options are now documented in scripts/pnglibconf.dfa.  This
@@ -4312,8 +4333,8 @@ the libpng bug tracker at
 
 We also accept patches built from the tar or zip distributions, and
 simple verbal discriptions of bug fixes, reported either to the
-SourceForge bug tracker or to the png-mng-implement at lists.sf.net
+SourceForge bug tracker, to the png-mng-implement at lists.sf.net
-mailing list.
+mailing list, or directly to glennrp.
 
 XIII. Coding style
 
@@ -4426,7 +4447,7 @@ Other rules can be inferred by inspecting the libpng source.
 
 XIV. Y2K Compliance in libpng
 
-July 10, 2011
+July 12, 2011
 
 Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.

libpng.3

@@ -1,4 +1,4 @@
-.TH LIBPNG 3 "July 10, 2011"
+.TH LIBPNG 3 "July 12, 2011"
 .SH NAME
 libpng \- Portable Network Graphics (PNG) Reference Library 1.5.5beta01
 .SH SYNOPSIS
@@ -955,7 +955,7 @@ Following is a copy of the libpng-manual.txt file that accompanies libpng.
 .SH LIBPNG.TXT
 libpng-manual.txt - A description on how to use and modify libpng
 
- libpng version 1.5.5beta01 - July 10, 2011
+ libpng version 1.5.5beta01 - July 12, 2011
  Updated and distributed by Glenn Randers-Pehrson
  <glennrp at users.sourceforge.net>
  Copyright (c) 1998-2011 Glenn Randers-Pehrson
@@ -966,7 +966,7 @@ libpng-manual.txt - A description on how to use and modify libpng
 
  Based on:
 
- libpng versions 0.97, January 1998, through 1.5.5beta01 - July 10, 2011
+ libpng versions 0.97, January 1998, through 1.5.5beta01 - July 12, 2011
  Updated and distributed by Glenn Randers-Pehrson
  Copyright (c) 1998-2011 Glenn Randers-Pehrson
 
@@ -1071,14 +1071,23 @@ 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
+integers in the PNG format) don't take a png_info pointer, but it's almost
-to assume that a (png_struct*) has to be passed to call an API function.
+always safe to assume that a (png_struct*) has to be passed to call an API
+function.
+
+You can have more than one png_info structure associated with an image,
+as illustrated in pngtest.c, one for information valid prior to the
+IDAT chunks and another (called "end_info" below) for things after them.
 
 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>
 
+and also (as of libpng-1.5.0) the zlib header file, if you need it:
+
+#include <zlib.h>
+
 .SS Types
 
 The png.h header file defines a number of integral types used by the
@@ -1120,7 +1129,7 @@ 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.
 
-If you don't need to change the library configuration from the default skip to
+If you don't need to change the library configuration from the default, skip to
 the next section ("Reading").
 
 Notice that some of the makefiles in the 'scripts' directory and (in 1.5.0) all
@@ -1193,6 +1202,10 @@ source code.  Most of these values have performance implications for the library
 but most of them have no visible effect on the API.  Some can also be overridden
 from the API.
 
+This method of building a customized pnglibconf.h is illustrated in
+contrib/pngminim/*.  See the "$(PNGCONF):" target in the makefile and
+pngusr.dfa in these directories.
+
 C. Configuration using PNG_USR_CONFIG
 
 If -DPNG_USR_CONFIG is added to the CFLAGS when pnglibconf.h is built the file
@@ -1229,6 +1242,9 @@ examine the intermediate file pnglibconf.dfn to find the full set of
 dependency information for each setting and option.  Simply locate the
 feature in the file and read the C comments that precede it.
 
+This method is also illustrated in the contrib/pngminim/* makefiles and
+pngusr.h.
+
 .SH III. Reading
 
 We'll now walk you through the possible functions to call when reading
@@ -4403,7 +4419,8 @@ However, there are some uncertainties about the status of local variables
 after a longjmp, so the user may want to be careful about doing anything
 after setjmp returns non-zero besides returning itself.  Consult your
 compiler documentation for more details.  For an alternative approach, you
-may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net).
+may wish to use the "cexcept" facility (see http://cexcept.sourceforge.net),
+which is illustrated in pngvalid.c and in contrib/visupng.
 
 .SS Custom chunks
 
@@ -4421,8 +4438,11 @@ and look at how other chunks were designed, so you can do things
 similarly.  Second, check out the sections of libpng that read and
 write chunks.  Try to find a chunk that is similar to yours and use
 it as a template.  More details can be found in the comments inside
-the code.  It is best to handle unknown chunks in a generic method,
+the code.  It is best to handle private or unknown chunks in a generic method,
-via callback functions, instead of by modifying libpng functions.
+via callback functions, instead of by modifying libpng functions. This
+is illustrated in pngtest.c, which uses a callback function to handle a
+private "vpAg" chunk and the new "sTER" chunk, which are both unknown to
+libpng.
 
 If you wish to write your own transformation for the data, look through
 the part of the code that does the transformations, and check out some of
@@ -4618,8 +4638,8 @@ capability, which you'll still have).
 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
+reading files start with "pngr" and all the writing files start with "pngw".
-pngw.  The files that don't match either (like png.c, pngtrans.c, etc.)
+The files that don't match either (like png.c, pngtrans.c, etc.)
 are used for both reading and writing, and always need to be included.
 The progressive reader is in pngpread.c
 
@@ -4997,7 +5017,6 @@ absolutely necessary) interlace an image.
 
 libpng 1.5.0 adds an API png_longjmp(png_ptr, value).  This API calls
 the application-provided png_longjmp_ptr on the internal, but application
-initialized, jmpbuf.  It is provided as a convenience to avoid the need
 initialized, longjmp buffer.  It is provided as a convenience to avoid
 the need to use the png_jmpbuf macro, which had the unnecessary side
 effect of resetting the internal png_longjmp_ptr value.
@@ -5076,9 +5095,9 @@ increase the limits.
 B. Changes to the build and configuration of libpng
 
 Details of internal changes to the library code can be found in the CHANGES
-file.  These will be of no concern to the vast majority of library users or
+file and in the GIT repository logs.  These will be of no concern to the vast
-builders, however the few who configure libpng to a non-default feature
+majority of library users or builders, however the few who configure libpng
-set may need to change how this is done.
+to a non-default feature set may need to change how this is done.
 
 There should be no need for library builders to alter build scripts if
 these use the distributed build support - configure or the makefiles -
@@ -5087,14 +5106,14 @@ to build pnglibconf.h where the corresponding makefile does not do so.
 
 Building libpng with a non-default configuration has changed completely.
 The old method using pngusr.h should still work correctly even though the
-way pngusr.h is used in the build has been changed, however library
+way pngusr.h is used in the build has been changed; however, library
 builders will probably want to examine the changes to take advantage of
 new capabilities and to simplify their build system.
 
 B.1 Specific changes to library configuration capabilities
 
 The library now supports a complete fixed point implementation and can
-thus be used on systems which have no floating point support or very
+thus be used on systems that have no floating point support or very
 limited or slow support.  Previously gamma correction, an essential part
 of complete PNG support, required reasonably fast floating point.
 
@@ -5110,14 +5129,14 @@ pnglibconf.h
 As part of this the mechanism used to choose procedure call standards on
 those systems that allow a choice has been changed.  At present this only
 affects certain Microsoft (DOS, Windows) and IBM (OS/2) operating systems
-running on Intel processors.  As before PNGAPI is defined where required
+running on Intel processors.  As before, PNGAPI is defined where required
 to control the exported API functions; however, two new macros, PNGCBAPI
 and PNGCAPI, are used instead for callback functions (PNGCBAPI) and
 (PNGCAPI) for functions that must match a C library prototype (currently
 only png_longjmp_ptr, which must match the C longjmp function.)  The new
 approach is documented in pngconf.h
 
-Despite these changes libpng 1.5.0 only supports the native C function
+Despite these changes, libpng 1.5.0 only supports the native C function
 calling standard on those platforms tested so far (__cdecl on Microsoft
 Windows).  This is because the support requirements for alternative
 calling conventions seem to no longer exist.  Developers who find it
@@ -5151,7 +5170,9 @@ if the feature is supported or:
 
 if it is not.  Library code consistently checks for the 'SUPPORTED' macro.
 It does not, and should not, check for the 'NO' macro which will not
-normally be defined even if the feature is not supported.
+normally be defined even if the feature is not supported.  The 'NO' macros
+are only used internally for setting the corresponding 'SUPPORTED' macros
+or not.
 
 Compatibility with the old names is provided as follows:
 
@@ -5208,10 +5229,10 @@ application built without PNG_USER_CONFIG defined would see the
 unmodified, default, libpng API and thus would probably fail to link.
 
 These mechanisms still work in the configure build and in any makefile
-build that builds pnglibconf.h although the feature selection macros
+build that builds pnglibconf.h, although the feature selection macros
 have changed somewhat as described above.  In 1.5.0, however, pngusr.h is
 processed only once, when the exported header file pnglibconf.h is built.
-pngconf.h no longer includes pngusr.h, therefore it is ignored after the
+pngconf.h no longer includes pngusr.h, therefore pngusr.h is ignored after the
 build of pnglibconf.h and it is never included in an application build.
 
 The rarely used alternative of adding a list of feature macros to the
@@ -5225,7 +5246,7 @@ scripts/pnglibconf.dfa.  This requires the program awk.  Brian Kernighan
 and all known later implementations (often called by subtly different
 names - nawk and gawk for example) are adequate to build pnglibconf.h.
 The Sun Microsystems (now Oracle) program 'awk' is an earlier version
-and does not work, this may also apply to other systems that have a
+and does not work; this may also apply to other systems that have a
 functioning awk called 'nawk'.
 
 Configuration options are now documented in scripts/pnglibconf.dfa.  This
@@ -5267,8 +5288,8 @@ the libpng bug tracker at
 
 We also accept patches built from the tar or zip distributions, and
 simple verbal discriptions of bug fixes, reported either to the
-SourceForge bug tracker or to the png-mng-implement at lists.sf.net
+SourceForge bug tracker, to the png-mng-implement at lists.sf.net
-mailing list.
+mailing list, or directly to glennrp.
 
 .SH XIII. Coding style
 
@@ -5381,7 +5402,7 @@ Other rules can be inferred by inspecting the libpng source.
 
 .SH XIV. Y2K Compliance in libpng
 
-July 10, 2011
+July 12, 2011
 
 Since the PNG Development group is an ad-hoc body, we can't make
 an official declaration.
@@ -5639,7 +5660,7 @@ possible without all of you.
 
 Thanks to Frank J. T. Wojcik for helping with the documentation.
 
-Libpng version 1.5.5beta01 - July 10, 2011:
+Libpng version 1.5.5beta01 - July 12, 2011:
 Initially created in 1995 by Guy Eric Schalnat, then of Group 42, Inc.
 Currently maintained by Glenn Randers-Pehrson (glennrp at users.sourceforge.net).
 
@@ -5662,7 +5683,7 @@ this sentence.
 
 This code is released under the libpng license.
 
-libpng versions 1.2.6, August 15, 2004, through 1.5.5beta01, July 10, 2011, are
+libpng versions 1.2.6, August 15, 2004, through 1.5.5beta01, July 12, 2011, 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
@@ -5761,7 +5782,7 @@ certification mark of the Open Source Initiative.
 
 Glenn Randers-Pehrson
 glennrp at users.sourceforge.net
-July 10, 2011
+July 12, 2011
 
 .\" end of man page