diff --git a/ANNOUNCE b/ANNOUNCE index e6fd6d2c5..12bf16acb 100644 --- a/ANNOUNCE +++ b/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: diff --git a/CHANGES b/CHANGES index 5725fc251..8256c4a23 100644 --- a/CHANGES +++ b/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 diff --git a/libpng-manual.txt b/libpng-manual.txt index 15a3c1a51..a1a6db72e 100644 --- a/libpng-manual.txt +++ b/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 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 -to assume that a (png_struct*) has to be passed to call an API function. +integers in the PNG format) don't take a png_info pointer, but it's almost +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 +and also (as of libpng-1.5.0) the zlib header file, if you need it: + +#include + 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, -via callback functions, instead of by modifying libpng functions. +the code. It is best to handle private or unknown chunks in a generic method, +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 -pngw. The files that don't match either (like png.c, pngtrans.c, etc.) +reading files start with "pngr" and all the writing files start with "pngw". +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 -builders, however the few who configure libpng to a non-default feature -set may need to change how this is done. +file and in the GIT repository logs. These will be of no concern to the vast +majority of library users or builders, however the few who configure libpng +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 -mailing list. +SourceForge bug tracker, to the png-mng-implement at lists.sf.net +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. diff --git a/libpng.3 b/libpng.3 index 4b3da9ae8..eb2b5145f 100644 --- a/libpng.3 +++ b/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 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 -to assume that a (png_struct*) has to be passed to call an API function. +integers in the PNG format) don't take a png_info pointer, but it's almost +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 +and also (as of libpng-1.5.0) the zlib header file, if you need it: + +#include + .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, -via callback functions, instead of by modifying libpng functions. +the code. It is best to handle private or unknown chunks in a generic method, +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 -pngw. The files that don't match either (like png.c, pngtrans.c, etc.) +reading files start with "pngr" and all the writing files start with "pngw". +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 -builders, however the few who configure libpng to a non-default feature -set may need to change how this is done. +file and in the GIT repository logs. These will be of no concern to the vast +majority of library users or builders, however the few who configure libpng +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 -mailing list. +SourceForge bug tracker, to the png-mng-implement at lists.sf.net +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