1README for libpng version 1.2.8 - December 3, 2004 (shared library 12.0) 2See the note about version numbers near the top of png.h 3 4See INSTALL for instructions on how to install libpng. 5 6Libpng comes in several distribution formats. Get libpng-*.tar.gz 7or libpng-*.tar.bz2 if you want UNIX-style line endings in the text 8files, or lpng*.zip if you want DOS-style line endings. 9 10Version 0.89 was the first official release of libpng. Don't let the 11fact that it's the first release fool you. The libpng library has been in 12extensive use and testing since mid-1995. By late 1997 it had 13finally gotten to the stage where there hadn't been significant 14changes to the API in some time, and people have a bad feeling about 15libraries with versions < 1.0. Version 1.0.0 was released in 16March 1998. 17 18**** 19Note that some of the changes to the png_info structure render this 20version of the library binary incompatible with libpng-0.89 or 21earlier versions if you are using a shared library. The type of the 22"filler" parameter for png_set_filler() has changed from png_byte to 23png_uint_32, which will affect shared-library applications that use 24this function. 25 26To avoid problems with changes to the internals of png_info_struct, 27new APIs have been made available in 0.95 to avoid direct application 28access to info_ptr. These functions are the png_set_<chunk> and 29png_get_<chunk> functions. These functions should be used when 30accessing/storing the info_struct data, rather than manipulating it 31directly, to avoid such problems in the future. 32 33It is important to note that the APIs do not make current programs 34that access the info struct directly incompatible with the new 35library. However, it is strongly suggested that new programs use 36the new APIs (as shown in example.c and pngtest.c), and older programs 37be converted to the new format, to facilitate upgrades in the future. 38**** 39 40Additions since 0.90 include the ability to compile libpng as a 41Windows DLL, and new APIs for accessing data in the info struct. 42Experimental functions include the ability to set weighting and cost 43factors for row filter selection, direct reads of integers from buffers 44on big-endian processors that support misaligned data access, faster 45methods of doing alpha composition, and more accurate 16->8 bit color 46conversion. 47 48The additions since 0.89 include the ability to read from a PNG stream 49which has had some (or all) of the signature bytes read by the calling 50application. This also allows the reading of embedded PNG streams that 51do not have the PNG file signature. As well, it is now possible to set 52the library action on the detection of chunk CRC errors. It is possible 53to set different actions based on whether the CRC error occurred in a 54critical or an ancillary chunk. 55 56The changes made to the library, and bugs fixed are based on discussions 57on the PNG-implement mailing list 58and not on material submitted privately to Guy, Andreas, or Glenn. They will 59forward any good suggestions to the list. 60 61For a detailed description on using libpng, read libpng.txt. For 62examples of libpng in a program, see example.c and pngtest.c. For usage 63information and restrictions (what little they are) on libpng, see 64png.h. For a description on using zlib (the compression library used by 65libpng) and zlib's restrictions, see zlib.h 66 67I have included a general makefile, as well as several machine and 68compiler specific ones, but you may have to modify one for your own needs. 69 70You should use zlib 1.0.4 or later to run this, but it MAY work with 71versions as old as zlib 0.95. Even so, there are bugs in older zlib 72versions which can cause the output of invalid compression streams for 73some images. You will definitely need zlib 1.0.4 or later if you are 74taking advantage of the MS-DOS "far" structure allocation for the small 75and medium memory models. You should also note that zlib is a 76compression library that is useful for more things than just PNG files. 77You can use zlib as a drop-in replacement for fread() and fwrite() if 78you are so inclined. 79 80zlib should be available at the same place that libpng is, or at. 81ftp://ftp.info-zip.org/pub/infozip/zlib 82 83You may also want a copy of the PNG specification. It is available 84as an RFC, a W3C Recommendation, and an ISO/IEC Standard. You can find 85these at http://www.libpng.org/pub/png/documents/ 86 87This code is currently being archived at libpng.sf.net in the 88[DOWNLOAD] area, and on CompuServe, Lib 20 (PNG SUPPORT) 89at GO GRAPHSUP. If you can't find it in any of those places, 90e-mail me, and I'll help you find it. 91 92If you have any code changes, requests, problems, etc., please e-mail 93them to me. Also, I'd appreciate any make files or project files, 94and any modifications you needed to make to get libpng to compile, 95along with a #define variable to tell what compiler/system you are on. 96If you needed to add transformations to libpng, or wish libpng would 97provide the image in a different way, drop me a note (and code, if 98possible), so I can consider supporting the transformation. 99Finally, if you get any warning messages when compiling libpng 100(note: not zlib), and they are easy to fix, I'd appreciate the 101fix. Please mention "libpng" somewhere in the subject line. Thanks. 102 103This release was created and will be supported by myself (of course 104based in a large way on Guy's and Andreas' earlier work), and the PNG group. 105 106glennrp at users.sourceforge.net 107png-implement at ccrc.wustl.edu (subscription required; write to 108majordomo at ccrc.wustl.edu with "subscribe png-implement" in the message). 109 110You can't reach Guy, the original libpng author, at the addresses 111given in previous versions of this document. He and Andreas will read mail 112addressed to the png-implement list, however. 113 114Please do not send general questions about PNG. Send them to 115the (png-list at ccrc.wustl.edu, subscription required, write to 116majordomo at ccrc.wustl.edu with "subscribe png-list" in your message). 117On the other hand, 118please do not send libpng questions to that address, send them to me 119or to the png-implement list. I'll 120get them in the end anyway. If you have a question about something 121in the PNG specification that is related to using libpng, send it 122to me. Send me any questions that start with "I was using libpng, 123and ...". If in doubt, send questions to me. I'll bounce them 124to others, if necessary. 125 126Please do not send suggestions on how to change PNG. We have 127been discussing PNG for nine years now, and it is official and 128finished. If you have suggestions for libpng, however, I'll 129gladly listen. Even if your suggestion is not used immediately, 130it may be used later. 131 132Files in this distribution: 133 134 ANNOUNCE => Announcement of this version, with recent changes 135 CHANGES => Description of changes between libpng versions 136 KNOWNBUG => List of known bugs and deficiencies 137 LICENSE => License to use and redistribute libpng 138 README => This file 139 TODO => Things not implemented in the current library 140 Y2KINFO => Statement of Y2K compliance 141 example.c => Example code for using libpng functions 142 libpng.3 => manual page for libpng (includes libpng.txt) 143 libpng.txt => Description of libpng and its functions 144 libpngpf.3 => manual page for libpng's private functions 145 png.5 => manual page for the PNG format 146 png.c => Basic interface functions common to library 147 png.h => Library function and interface declarations 148 pngconf.h => System specific library configuration 149 pngasmrd.h => Header file for assembler-coded functions 150 pngerror.c => Error/warning message I/O functions 151 pngget.c => Functions for retrieving info from struct 152 pngmem.c => Memory handling functions 153 pngbar.png => PNG logo, 88x31 154 pngnow.png => PNG logo, 98x31 155 pngpread.c => Progressive reading functions 156 pngread.c => Read data/helper high-level functions 157 pngrio.c => Lowest-level data read I/O functions 158 pngrtran.c => Read data transformation functions 159 pngrutil.c => Read data utility functions 160 pngset.c => Functions for storing data into the info_struct 161 pngtest.c => Library test program 162 pngtest.png => Library test sample image 163 pngtrans.c => Common data transformation functions 164 pngwio.c => Lowest-level write I/O functions 165 pngwrite.c => High-level write functions 166 pngwtran.c => Write data transformations 167 pngwutil.c => Write utility functions 168 contrib => Contributions 169 gregbook => source code for PNG reading and writing, from 170 Greg Roelofs' "PNG: The Definitive Guide", 171 O'Reilly, 1999 172 msvctest => Builds and runs pngtest using a MSVC workspace 173 pngminus => Simple pnm2png and png2pnm programs 174 pngsuite => Test images 175 visupng => Contains a MSVC workspace for VisualPng 176 projects => Contains project files and workspaces for building DLL 177 beos => Contains a Beos workspace for building libpng 178 c5builder => Contains a Borland workspace for building libpng 179 and zlib 180 visualc6 => Contains a Microsoft Visual C++ (MSVC) workspace 181 for building libpng and zlib 182 netware.txt => Contains instructions for downloading a set of 183 project files for building libpng and zlib on 184 Netware. 185 wince.txt => Contains instructions for downloading a Microsoft 186 Visual C++ (Windows CD Toolkit) workspace for 187 building libpng and zlib on WindowsCE 188 scripts => Directory containing scripts for building libpng: 189 descrip.mms => VMS makefile for MMS or MMK 190 makefile.std => Generic UNIX makefile (cc, creates static libpng.a) 191 makefile.elf => Linux/ELF makefile symbol versioning, 192 gcc, creates libpng12.so.0.1.2.8) 193 makefile.linux => Linux/ELF makefile 194 (gcc, creates libpng12.so.0.1.2.8) 195 makefile.gcmmx => Linux/ELF makefile 196 (gcc, creates libpng12.so.0.1.2.8, 197 uses assembler code tuned for Intel MMX platform) 198 makefile.gcc => Generic makefile (gcc, creates static libpng.a) 199 makefile.knr => Archaic UNIX Makefile that converts files with 200 ansi2knr (Requires ansi2knr.c from 201 ftp://ftp.cs.wisc.edu/ghost) 202 makefile.aix => AIX makefile 203 makefile.cygwin => Cygwin/gcc makefile 204 makefile.darwin => Darwin makefile 205 makefile.dec => DEC Alpha UNIX makefile 206 makefile.freebsd => FreeBSD makefile 207 makefile.hpgcc => HPUX makefile using gcc 208 makefile.hpux => HPUX (10.20 and 11.00) makefile 209 makefile.hp64 => HPUX (10.20 and 11.00) makefile, 64 bit 210 makefile.ibmc => IBM C/C++ version 3.x for Win32 and OS/2 (static) 211 makefile.intel => Intel C/C++ version 4.0 and later 212 libpng.icc => Project file, IBM VisualAge/C++ 4.0 or later 213 makefile.netbsd => NetBSD/cc makefile, PNGGCCRD, makes libpng.so. 214 makefile.ne12bsd => NetBSD/cc makefile, PNGGCCRD, makes libpng12.so 215 makefile.openbsd => OpenBSD makefile 216 makefile.sgi => Silicon Graphics IRIX (cc, creates static lib) 217 makefile.sggcc => Silicon Graphics 218 (gcc, creates libpng12.so.0.1.2.8) 219 makefile.sunos => Sun makefile 220 makefile.solaris => Solaris 2.X makefile 221 (gcc, creates libpng12.so.0.1.2.8) 222 makefile.so9 => Solaris 9 makefile 223 (gcc, creates libpng12.so.0.1.2.8) 224 makefile.32sunu => Sun Ultra 32-bit makefile 225 makefile.64sunu => Sun Ultra 64-bit makefile 226 makefile.sco => For SCO OSr5 ELF and Unixware 7 with Native cc 227 makefile.mips => MIPS makefile 228 makefile.acorn => Acorn makefile 229 makefile.amiga => Amiga makefile 230 smakefile.ppc => AMIGA smakefile for SAS C V6.58/7.00 PPC 231 compiler (Requires SCOPTIONS, copied from 232 scripts/SCOPTIONS.ppc) 233 makefile.atari => Atari makefile 234 makefile.beos => BEOS makefile for X86 235 makefile.bor => Borland makefile (uses bcc) 236 makefile.bc32 => 32-bit Borland C++ (all modules compiled in C mode) 237 makefile.tc3 => Turbo C 3.0 makefile 238 makefile.dj2 => DJGPP 2 makefile 239 makefile.msc => Microsoft C makefile 240 makefile.vcawin32=> makefile for Microsoft Visual C++ 5.0 and 241 later (uses assembler code tuned for Intel MMX 242 platform) 243 makefile.vcwin32 => makefile for Microsoft Visual C++ 4.0 and 244 later (does not use assembler code) 245 makefile.os2 => OS/2 Makefile (gcc and emx, requires pngos2.def) 246 pngos2.def => OS/2 module definition file used by makefile.os2 247 makefile.watcom => Watcom 10a+ Makefile, 32-bit flat memory model 248 makevms.com => VMS build script 249 SCOPTIONS.ppc => Used with smakefile.ppc 250 251Good luck, and happy coding. 252 253-Glenn Randers-Pehrson (current maintainer) 254 Internet: glennrp at users.sourceforge.net 255 256-Andreas Eric Dilger (former maintainer, 1996-1997) 257 Internet: adilger at enel.ucalgary.ca 258 Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/ 259 260-Guy Eric Schalnat (original author and former maintainer, 1995-1996) 261 (formerly of Group 42, Inc) 262 Internet: gschal at infinet.com 263
