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@@ -0,0 +1,264 @@ +README for libpng version 1.2.29 - May 8, 2008 (shared library 12.0) +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.lzma, 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. + +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 +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 +March 1998. + +**** +Note that some of the changes to the png_info structure render this +version of the library binary incompatible with libpng-0.89 or +earlier versions if you are using a shared library. The type of the +"filler" parameter for png_set_filler() has changed from png_byte to +png_uint_32, which will affect shared-library applications that use +this function. + +To avoid problems with changes to the internals of 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 +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. +**** + +Additions since 0.90 include the ability to compile libpng as a +Windows DLL, and new APIs for accessing data in the info struct. +Experimental functions include the ability to set weighting and cost +factors for row filter selection, direct reads of integers from buffers +on big-endian processors that support misaligned data access, faster +methods of doing alpha composition, and more accurate 16->8 bit color +conversion. + +The additions since 0.89 include the ability to read from a PNG stream +which has had some (or all) of the signature bytes read by the calling +application. This also allows the reading of embedded PNG streams that +do not have the PNG file signature. As well, it is now possible to set +the library action on the detection of chunk CRC errors. It is possible +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-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 + +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. + +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. + +zlib should be available at the same place that libpng is, or at +ftp://ftp.simplesystems.org/pub/png/src/ + +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 + +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. + +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 group. + +Send comments/corrections/commendations to png-mng-implement at lists.sf.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-implement list, however. + +Please do not send general questions about PNG. Send them to +the (png-mng-misc at lists.sourceforge.net, subscription required, visit +https://lists.sourceforge.net/lists/listinfo/png-mng-implement to subscribe) +On the other hand, +please do not send libpng questions to that address, send them to me +or to the png-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. + +Files in this distribution: + + ANNOUNCE => Announcement of this version, with recent changes + 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 + 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 + 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 + pngerror.c => Error/warning message I/O functions + pngget.c => Functions for retrieving info from struct + pngmem.c => Memory handling functions + pngbar.png => PNG logo, 88x31 + pngnow.png => PNG logo, 98x31 + pngpread.c => Progressive reading functions + pngread.c => Read data/helper high-level functions + pngrio.c => Lowest-level data read I/O functions + pngrtran.c => Read data transformation functions + pngrutil.c => Read data utility functions + pngset.c => Functions for storing data into the info_struct + pngtest.c => Library test program + pngtest.png => Library test sample image + pngtrans.c => Common data transformation functions + pngwio.c => Lowest-level write I/O functions + pngwrite.c => High-level write functions + pngwtran.c => Write data transformations + pngwutil.c => Write utility functions + contrib => Contributions + 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 + pngminus => Simple pnm2png and png2pnm programs + pngsuite => Test images + visupng => Contains a MSVC workspace for VisualPng + projects => Contains project files and workspaces for building DLL + beos => Contains a Beos workspace for building libpng + c5builder => Contains a Borland workspace for building libpng + and zlib + visualc6 => Contains a Microsoft Visual C++ (MSVC) workspace + for building libpng and zlib + netware.txt => Contains instructions for downloading a set of + project files for building libpng and zlib on + Netware. + wince.txt => Contains instructions for downloading a Microsoft + Visual C++ (Windows CD Toolkit) workspace for + building libpng and zlib on WindowsCE + 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 makefile symbol versioning, + gcc, creates libpng12.so.0.1.2.29) + makefile.linux => Linux/ELF makefile + (gcc, creates libpng12.so.0.1.2.29) + makefile.gcmmx => Linux/ELF makefile + (gcc, creates libpng12.so.0.1.2.29, + uses 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, PNGGCCRD, makes libpng.so. + makefile.ne12bsd => NetBSD/cc makefile, PNGGCCRD, makes libpng12.so + makefile.openbsd => OpenBSD makefile + makefile.sgi => Silicon Graphics IRIX (cc, creates static lib) + makefile.sggcc => Silicon Graphics + (gcc, creates libpng12.so.0.1.2.29) + makefile.sunos => Sun makefile + makefile.solaris => Solaris 2.X makefile + (gcc, creates libpng12.so.0.1.2.29) + makefile.so9 => Solaris 9 makefile + (gcc, creates libpng12.so.0.1.2.29) + 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 (uses 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) + Internet: glennrp at users.sourceforge.net + +-Andreas Eric Dilger (former maintainer, 1996-1997) + Internet: adilger at enel.ucalgary.ca + Web: http://members.shaw.ca/adilger/ + +-Guy Eric Schalnat (original author and former maintainer, 1995-1996) + (formerly of Group 42, Inc) + Internet: gschal at infinet.com |