-README for libpng version 1.2.50 - July 10, 2012 (shared library 12.0)
-See the note about version numbers near the top of png.h
+README for libpng version 1.6.37 - April 14, 2019
+=================================================
+See the note about version numbers near the top of png.h.
See INSTALL for instructions on how to install libpng.
-Libpng comes in several distribution formats. Get libpng-*.tar.gz,
-libpng-*.tar.xz, or libpng-*.tar.bz2 if you want UNIX-style line
-endings in the text files, or lpng*.7z or lpng*.zip if you want DOS-style
-line endings. You can get UNIX-style line endings from the *.zip file
-by using "unzip -a" but there seems to be no simple way to recover
-UNIX-style line endings from the *.7z file. The *.tar.xz file is
-recommended for *NIX users instead.
+Libpng comes in several distribution formats. Get libpng-*.tar.gz or
+libpng-*.tar.xz or if you want UNIX-style line endings in the text
+files, or lpng*.7z or lpng*.zip if you want DOS-style line endings.
Version 0.89 was the first official release of libpng. Don't let the
-fact that it's the first release fool you. The libpng library has been in
-extensive use and testing since mid-1995. By late 1997 it had
+fact that it's the first release fool you. The libpng library has been
+in extensive use and testing since mid-1995. By late 1997 it had
finally gotten to the stage where there hadn't been significant
changes to the API in some time, and people have a bad feeling about
libraries with versions < 1.0. Version 1.0.0 was released in
png_uint_32, which will affect shared-library applications that use
this function.
-To avoid problems with changes to the internals of png_info_struct,
+To avoid problems with changes to the internals of the png info_struct,
new APIs have been made available in 0.95 to avoid direct application
access to info_ptr. These functions are the png_set_<chunk> and
png_get_<chunk> functions. These functions should be used when
accessing/storing the info_struct data, rather than manipulating it
directly, to avoid such problems in the future.
-It is important to note that the APIs do not make current programs
+It is important to note that the APIs did not make current programs
that access the info struct directly incompatible with the new
-library. However, it is strongly suggested that new programs use
-the new APIs (as shown in example.c and pngtest.c), and older programs
-be converted to the new format, to facilitate upgrades in the future.
+library, through libpng-1.2.x. In libpng-1.4.x, which was meant to
+be a transitional release, members of the png_struct and the
+info_struct can still be accessed, but the compiler will issue a
+warning about deprecated usage. Since libpng-1.5.0, direct access
+to these structs is not allowed, and the definitions of the structs
+reside in private pngstruct.h and pnginfo.h header files that are not
+accessible to applications. It is strongly suggested that new
+programs use the new APIs (as shown in example.c and pngtest.c), and
+older programs be converted to the new format, to facilitate upgrades
+in the future.
****
Additions since 0.90 include the ability to compile libpng as a
to set different actions based on whether the CRC error occurred in a
critical or an ancillary chunk.
-The changes made to the library, and bugs fixed are based on discussions
-on the png-mng-implement mailing list and not on material submitted
-privately to Guy, Andreas, or Glenn. They will forward any good
-suggestions to the list.
-
-For a detailed description on using libpng, read libpng.txt. For
-examples of libpng in a program, see example.c and pngtest.c. For usage
-information and restrictions (what little they are) on libpng, see
-png.h. For a description on using zlib (the compression library used by
-libpng) and zlib's restrictions, see zlib.h
+For a detailed description on using libpng, read libpng-manual.txt.
+For examples of libpng in a program, see example.c and pngtest.c. For
+usage information and restrictions (what little they are) on libpng,
+see png.h. For a description on using zlib (the compression library
+used by libpng) and zlib's restrictions, see zlib.h
I have included a general makefile, as well as several machine and
-compiler specific ones, but you may have to modify one for your own needs.
+compiler specific ones, but you may have to modify one for your own
+needs.
You should use zlib 1.0.4 or later to run this, but it MAY work with
versions as old as zlib 0.95. Even so, there are bugs in older zlib
versions which can cause the output of invalid compression streams for
-some images. You will definitely need zlib 1.0.4 or later if you are
-taking advantage of the MS-DOS "far" structure allocation for the small
-and medium memory models. You should also note that zlib is a
-compression library that is useful for more things than just PNG files.
-You can use zlib as a drop-in replacement for fread() and fwrite() if
-you are so inclined.
+some images.
+
+You should also note that zlib is a compression library that is useful
+for more things than just PNG files. You can use zlib as a drop-in
+replacement for fread() and fwrite(), if you are so inclined.
zlib should be available at the same place that libpng is, or at
-ftp://ftp.simplesystems.org/pub/png/src/
+https://zlib.net.
You may also want a copy of the PNG specification. It is available
as an RFC, a W3C Recommendation, and an ISO/IEC Standard. You can find
-these at http://www.libpng.org/pub/png/pngdocs.html
+these at http://www.libpng.org/pub/png/pngdocs.html .
-This code is currently being archived at libpng.sf.net in the
-[DOWNLOAD] area, and on CompuServe, Lib 20 (PNG SUPPORT)
-at GO GRAPHSUP. If you can't find it in any of those places,
-e-mail me, and I'll help you find it.
+This code is currently being archived at libpng.sourceforge.io in the
+[DOWNLOAD] area, and at http://libpng.download/src .
-If you have any code changes, requests, problems, etc., please e-mail
-them to me. Also, I'd appreciate any make files or project files,
-and any modifications you needed to make to get libpng to compile,
-along with a #define variable to tell what compiler/system you are on.
-If you needed to add transformations to libpng, or wish libpng would
-provide the image in a different way, drop me a note (and code, if
-possible), so I can consider supporting the transformation.
-Finally, if you get any warning messages when compiling libpng
-(note: not zlib), and they are easy to fix, I'd appreciate the
-fix. Please mention "libpng" somewhere in the subject line. Thanks.
-
-This release was created and will be supported by myself (of course
-based in a large way on Guy's and Andreas' earlier work), and the PNG
+This release, based in a large way on Glenn's, Guy's and Andreas'
+earlier work, was created and will be supported by myself and the PNG
development group.
-Send comments/corrections/commendations to png-mng-implement at lists.sf.net
-(subscription required; visit
+Send comments/corrections/commendations to png-mng-implement at
+lists.sourceforge.net (subscription required; visit
https://lists.sourceforge.net/lists/listinfo/png-mng-implement
-to subscribe) or to glennrp at users.sourceforge.net
-
-You can't reach Guy, the original libpng author, at the addresses
-given in previous versions of this document. He and Andreas will
-read mail addressed to the png-mng-implement list, however.
+to subscribe).
-Please do not send general questions about PNG. Send them to
-the (png-mng-misc at lists.sourceforge.net, subscription required, visit
+Send general questions about the PNG specification to png-mng-misc
+at lists.sourceforge.net (subscription required; visit
https://lists.sourceforge.net/lists/listinfo/png-mng-misc to
-subscribe). On the other hand, please do not send libpng questions to
-that address, send them to me or to the png-mng-implement list. I'll
-get them in the end anyway. If you have a question about something
-in the PNG specification that is related to using libpng, send it
-to me. Send me any questions that start with "I was using libpng,
-and ...". If in doubt, send questions to me. I'll bounce them
-to others, if necessary.
-
-Please do not send suggestions on how to change PNG. We have
-been discussing PNG for twelve years now, and it is official and
-finished. If you have suggestions for libpng, however, I'll
-gladly listen. Even if your suggestion is not used immediately,
-it may be used later.
+subscribe).
Files in this distribution:
ANNOUNCE => Announcement of this version, with recent changes
+ AUTHORS => List of contributing authors
CHANGES => Description of changes between libpng versions
KNOWNBUG => List of known bugs and deficiencies
LICENSE => License to use and redistribute libpng
README => This file
TODO => Things not implemented in the current library
- Y2KINFO => Statement of Y2K compliance
+ TRADEMARK => Trademark information
example.c => Example code for using libpng functions
- libpng-*-*-diff.txt => Diff from previous release
- libpng.3 => manual page for libpng (includes libpng.txt)
- libpng.txt => Description of libpng and its functions
+ libpng.3 => manual page for libpng (includes libpng-manual.txt)
+ libpng-manual.txt => Description of libpng and its functions
libpngpf.3 => manual page for libpng's private functions
png.5 => manual page for the PNG format
png.c => Basic interface functions common to library
- png.h => Library function and interface declarations
- pngconf.h => System specific library configuration
+ png.h => Library function and interface declarations (public)
+ pngpriv.h => Library function and interface declarations (private)
+ pngconf.h => System specific library configuration (public)
+ pngstruct.h => png_struct declaration (private)
+ pnginfo.h => png_info struct declaration (private)
+ pngdebug.h => debugging macros (private)
pngerror.c => Error/warning message I/O functions
pngget.c => Functions for retrieving info from struct
pngmem.c => Memory handling functions
pngwrite.c => High-level write functions
pngwtran.c => Write data transformations
pngwutil.c => Write utility functions
+ arm => Contains optimized code for the ARM platform
+ powerpc => Contains optimized code for the PowerPC platform
contrib => Contributions
+ arm-neon => Optimized code for ARM-NEON platform
+ powerpc-vsx => Optimized code for POWERPC-VSX platform
+ examples => Example programs
gregbook => source code for PNG reading and writing, from
Greg Roelofs' "PNG: The Definitive Guide",
O'Reilly, 1999
- msvctest => Builds and runs pngtest using a MSVC workspace
- pngminim => Simple pnm2pngm and png2pnmm programs
- pngminus => Simple pnm2png and png2pnm programs
- pngsuite => Test images
- visupng => Contains a MSVC workspace for VisualPng
+ libtests => Test programs
+ mips-msa => Optimized code for MIPS-MSA platform
+ pngminim => Minimal decoder, encoder, and progressive decoder
+ programs demonstrating use of pngusr.dfa
+ pngminus => Simple pnm2png and png2pnm programs
+ pngsuite => Test images
+ testpngs
+ tools => Various tools
+ visupng => Contains a MSVC workspace for VisualPng
+ intel => Optimized code for INTEL-SSE2 platform
+ mips => Optimized code for MIPS platform
projects => Contains project files and workspaces for
building a DLL
- beos => Contains a Beos workspace for building libpng
- c5builder => Contains a Borland workspace for building
- libpng and zlib
- netware.txt => Contains instructions for downloading a set
- of project files for building libpng and
- zlib on Netware.
- visualc6 => Contains a Microsoft Visual C++ (MSVC)
+ owatcom => Contains a WATCOM project for building libpng
+ visualc71 => Contains a Microsoft Visual C++ (MSVC)
+ workspace for building libpng and zlib
+ vstudio => Contains a Microsoft Visual C++ (MSVC)
workspace for building libpng and zlib
- wince.txt => Contains instructions for downloading a
- Microsoft Visual C++ (Windows CD Toolkit)
- workspace for building libpng and zlib on
- WindowsCE
- xcode => Contains xcode project files
scripts => Directory containing scripts for building libpng:
- descrip.mms => VMS makefile for MMS or MMK
- makefile.std => Generic UNIX makefile (cc, creates static
- libpng.a)
- makefile.elf => Linux/ELF gcc makefile symbol versioning,
- creates libpng12.so.0.1.2.50)
- makefile.linux => Linux/ELF makefile (gcc, creates
- libpng12.so.0.1.2.50)
- makefile.gcmmx => Linux/ELF makefile (gcc, creates
- libpng12.so.0.1.2.50, previously
- used assembler code tuned for Intel MMX
- platform)
- makefile.gcc => Generic makefile (gcc, creates static
- libpng.a)
- makefile.knr => Archaic UNIX Makefile that converts files
- with ansi2knr (Requires ansi2knr.c from
- ftp://ftp.cs.wisc.edu/ghost)
- makefile.aix => AIX makefile
- makefile.cygwin => Cygwin/gcc makefile
- makefile.darwin => Darwin makefile
- makefile.dec => DEC Alpha UNIX makefile
- makefile.freebsd => FreeBSD makefile
- makefile.hpgcc => HPUX makefile using gcc
- makefile.hpux => HPUX (10.20 and 11.00) makefile
- makefile.hp64 => HPUX (10.20 and 11.00) makefile, 64 bit
- makefile.ibmc => IBM C/C++ version 3.x for Win32 and OS/2
- (static)
- makefile.intel => Intel C/C++ version 4.0 and later
- libpng.icc => Project file, IBM VisualAge/C++ 4.0 or later
- makefile.netbsd => NetBSD/cc makefile, makes libpng.so.
- makefile.ne12bsd => NetBSD/cc makefile, makes libpng12.so
- makefile.openbsd => OpenBSD makefile
- makefile.sgi => Silicon Graphics IRIX (cc, creates static lib)
- makefile.sggcc => Silicon Graphics
- (gcc, creates libpng12.so.0.1.2.50)
- makefile.sunos => Sun makefile
- makefile.solaris => Solaris 2.X makefile
- (gcc, creates libpng12.so.0.1.2.50)
- makefile.so9 => Solaris 9 makefile
- (gcc, creates libpng12.so.0.1.2.50)
- makefile.32sunu => Sun Ultra 32-bit makefile
- makefile.64sunu => Sun Ultra 64-bit makefile
- makefile.sco => For SCO OSr5 ELF and Unixware 7 with Native cc
- makefile.mips => MIPS makefile
- makefile.acorn => Acorn makefile
- makefile.amiga => Amiga makefile
- smakefile.ppc => AMIGA smakefile for SAS C V6.58/7.00 PPC
- compiler (Requires SCOPTIONS, copied from
- scripts/SCOPTIONS.ppc)
- makefile.atari => Atari makefile
- makefile.beos => BEOS makefile for X86
- makefile.bor => Borland makefile (uses bcc)
- makefile.bc32 => 32-bit Borland C++ (all modules compiled in C mode)
- makefile.tc3 => Turbo C 3.0 makefile
- makefile.dj2 => DJGPP 2 makefile
- makefile.msc => Microsoft C makefile
- makefile.vcawin32=> makefile for Microsoft Visual C++ 5.0 and
- later (previously used assembler code tuned
- for Intel MMX platform)
- makefile.vcwin32 => makefile for Microsoft Visual C++ 4.0 and
- later (does not use assembler code)
- makefile.os2 => OS/2 Makefile (gcc and emx, requires pngos2.def)
- pngos2.def => OS/2 module definition file used by makefile.os2
- makefile.watcom => Watcom 10a+ Makefile, 32-bit flat memory model
- makevms.com => VMS build script
- SCOPTIONS.ppc => Used with smakefile.ppc
-
-Good luck, and happy coding.
-
--Glenn Randers-Pehrson (current maintainer, since 1998)
- Internet: glennrp at users.sourceforge.net
+ (see scripts/README.txt for the list of scripts)
--Andreas Eric Dilger (former maintainer, 1996-1997)
- Internet: adilger at enel.ucalgary.ca
- Web: http://members.shaw.ca/adilger/
+Good luck, and happy coding!
--Guy Eric Schalnat (original author and former maintainer, 1995-1996)
- (formerly of Group 42, Inc)
- Internet: gschal at infinet.com
+ * Cosmin Truta (current maintainer, since 2018)
+ * Glenn Randers-Pehrson (former maintainer, 1998-2018)
+ * Andreas Eric Dilger (former maintainer, 1996-1997)
+ * Guy Eric Schalnat (original author and former maintainer, 1995-1996)
+ (formerly of Group 42, Inc.)
projects / platform / upstream / libpng.git / blobdiff