| 1 | README for libpng version 1.2.7 - September 12, 2004 (shared library 12.0) |
| 2 | See the note about version numbers near the top of png.h |
| 3 | |
| 4 | See INSTALL for instructions on how to install libpng. |
| 5 | |
| 6 | Libpng comes in several distribution formats. Get libpng-*.tar.gz |
| 7 | or libpng-*.tar.bz2 if you want UNIX-style line endings in the text |
| 8 | files, or lpng*.zip if you want DOS-style line endings. |
| 9 | |
| 10 | Version 0.89 was the first official release of libpng. Don't let the |
| 11 | fact that it's the first release fool you. The libpng library has been in |
| 12 | extensive use and testing since mid-1995. By late 1997 it had |
| 13 | finally gotten to the stage where there hadn't been significant |
| 14 | changes to the API in some time, and people have a bad feeling about |
| 15 | libraries with versions < 1.0. Version 1.0.0 was released in |
| 16 | March 1998. |
| 17 | |
| 18 | **** |
| 19 | Note that some of the changes to the png_info structure render this |
| 20 | version of the library binary incompatible with libpng-0.89 or |
| 21 | earlier 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 |
| 23 | png_uint_32, which will affect shared-library applications that use |
| 24 | this function. |
| 25 | |
| 26 | To avoid problems with changes to the internals of png_info_struct, |
| 27 | new APIs have been made available in 0.95 to avoid direct application |
| 28 | access to info_ptr. These functions are the png_set_<chunk> and |
| 29 | png_get_<chunk> functions. These functions should be used when |
| 30 | accessing/storing the info_struct data, rather than manipulating it |
| 31 | directly, to avoid such problems in the future. |
| 32 | |
| 33 | It is important to note that the APIs do not make current programs |
| 34 | that access the info struct directly incompatible with the new |
| 35 | library. However, it is strongly suggested that new programs use |
| 36 | the new APIs (as shown in example.c and pngtest.c), and older programs |
| 37 | be converted to the new format, to facilitate upgrades in the future. |
| 38 | **** |
| 39 | |
| 40 | Additions since 0.90 include the ability to compile libpng as a |
| 41 | Windows DLL, and new APIs for accessing data in the info struct. |
| 42 | Experimental functions include the ability to set weighting and cost |
| 43 | factors for row filter selection, direct reads of integers from buffers |
| 44 | on big-endian processors that support misaligned data access, faster |
| 45 | methods of doing alpha composition, and more accurate 16->8 bit color |
| 46 | conversion. |
| 47 | |
| 48 | The additions since 0.89 include the ability to read from a PNG stream |
| 49 | which has had some (or all) of the signature bytes read by the calling |
| 50 | application. This also allows the reading of embedded PNG streams that |
| 51 | do not have the PNG file signature. As well, it is now possible to set |
| 52 | the library action on the detection of chunk CRC errors. It is possible |
| 53 | to set different actions based on whether the CRC error occurred in a |
| 54 | critical or an ancillary chunk. |
| 55 | |
| 56 | The changes made to the library, and bugs fixed are based on discussions |
| 57 | on the PNG-implement mailing list |
| 58 | and not on material submitted privately to Guy, Andreas, or Glenn. They will |
| 59 | forward any good suggestions to the list. |
| 60 | |
| 61 | For a detailed description on using libpng, read libpng.txt. For |
| 62 | examples of libpng in a program, see example.c and pngtest.c. For usage |
| 63 | information and restrictions (what little they are) on libpng, see |
| 64 | png.h. For a description on using zlib (the compression library used by |
| 65 | libpng) and zlib's restrictions, see zlib.h |
| 66 | |
| 67 | I have included a general makefile, as well as several machine and |
| 68 | compiler specific ones, but you may have to modify one for your own needs. |
| 69 | |
| 70 | You should use zlib 1.0.4 or later to run this, but it MAY work with |
| 71 | versions as old as zlib 0.95. Even so, there are bugs in older zlib |
| 72 | versions which can cause the output of invalid compression streams for |
| 73 | some images. You will definitely need zlib 1.0.4 or later if you are |
| 74 | taking advantage of the MS-DOS "far" structure allocation for the small |
| 75 | and medium memory models. You should also note that zlib is a |
| 76 | compression library that is useful for more things than just PNG files. |
| 77 | You can use zlib as a drop-in replacement for fread() and fwrite() if |
| 78 | you are so inclined. |
| 79 | |
| 80 | zlib should be available at the same place that libpng is, or at. |
| 81 | ftp://ftp.info-zip.org/pub/infozip/zlib |
| 82 | |
| 83 | You may also want a copy of the PNG specification. It is available |
| 84 | as an RFC, a W3C Recommendation, and an ISO/IEC Standard. You can find |
| 85 | these at http://www.libpng.org/pub/png/documents/ |
| 86 | |
| 87 | This code is currently being archived at libpng.sf.net in the |
| 88 | [DOWNLOAD] area, and on CompuServe, Lib 20 (PNG SUPPORT) |
| 89 | at GO GRAPHSUP. If you can't find it in any of those places, |
| 90 | e-mail me, and I'll help you find it. |
| 91 | |
| 92 | If you have any code changes, requests, problems, etc., please e-mail |
| 93 | them to me. Also, I'd appreciate any make files or project files, |
| 94 | and any modifications you needed to make to get libpng to compile, |
| 95 | along with a #define variable to tell what compiler/system you are on. |
| 96 | If you needed to add transformations to libpng, or wish libpng would |
| 97 | provide the image in a different way, drop me a note (and code, if |
| 98 | possible), so I can consider supporting the transformation. |
| 99 | Finally, if you get any warning messages when compiling libpng |
| 100 | (note: not zlib), and they are easy to fix, I'd appreciate the |
| 101 | fix. Please mention "libpng" somewhere in the subject line. Thanks. |
| 102 | |
| 103 | This release was created and will be supported by myself (of course |
| 104 | based in a large way on Guy's and Andreas' earlier work), and the PNG group. |
| 105 | |
| 106 | glennrp@users.sourceforge.net |
| 107 | png-implement@ccrc.wustl.edu (subscription required; write to |
| 108 | majordomo@ccrc.wustl.edu with "subscribe png-implement" in the message). |
| 109 | |
| 110 | You can't reach Guy, the original libpng author, at the addresses |
| 111 | given in previous versions of this document. He and Andreas will read mail |
| 112 | addressed to the png-implement list, however. |
| 113 | |
| 114 | Please do not send general questions about PNG. Send them to |
| 115 | the (png-list@ccrc.wustl.edu, subscription required, write to |
| 116 | majordomo@ccrc.wustl.edu with "subscribe png-list" in your message). |
| 117 | On the other hand, |
| 118 | please do not send libpng questions to that address, send them to me |
| 119 | or to the png-implement list. I'll |
| 120 | get them in the end anyway. If you have a question about something |
| 121 | in the PNG specification that is related to using libpng, send it |
| 122 | to me. Send me any questions that start with "I was using libpng, |
| 123 | and ...". If in doubt, send questions to me. I'll bounce them |
| 124 | to others, if necessary. |
| 125 | |
| 126 | Please do not send suggestions on how to change PNG. We have |
| 127 | been discussing PNG for nine years now, and it is official and |
| 128 | finished. If you have suggestions for libpng, however, I'll |
| 129 | gladly listen. Even if your suggestion is not used immediately, |
| 130 | it may be used later. |
| 131 | |
| 132 | Files 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.linux => Linux/ELF makefile |
| 192 | (gcc, creates libpng12.so.0.1.2.7) |
| 193 | makefile.gcmmx => Linux/ELF makefile |
| 194 | (gcc, creates libpng12.so.0.1.2.7, |
| 195 | uses assembler code tuned for Intel MMX platform) |
| 196 | makefile.gcc => Generic makefile (gcc, creates static libpng.a) |
| 197 | makefile.knr => Archaic UNIX Makefile that converts files with |
| 198 | ansi2knr (Requires ansi2knr.c from |
| 199 | ftp://ftp.cs.wisc.edu/ghost) |
| 200 | makefile.aix => AIX makefile |
| 201 | makefile.cygwin => Cygwin/gcc makefile |
| 202 | makefile.darwin => Darwin makefile |
| 203 | makefile.dec => DEC Alpha UNIX makefile |
| 204 | makefile.freebsd => FreeBSD makefile |
| 205 | makefile.hpgcc => HPUX makefile using gcc |
| 206 | makefile.hpux => HPUX (10.20 and 11.00) makefile |
| 207 | makefile.hp64 => HPUX (10.20 and 11.00) makefile, 64 bit |
| 208 | makefile.ibmc => IBM C/C++ version 3.x for Win32 and OS/2 (static) |
| 209 | makefile.intel => Intel C/C++ version 4.0 and later |
| 210 | libpng.icc => Project file, IBM VisualAge/C++ 4.0 or later |
| 211 | makefile.netbsd => NetBSD/cc makefile, PNGGCCRD, makes libpng.so. |
| 212 | makefile.ne12bsd => NetBSD/cc makefile, PNGGCCRD, makes libpng12.so |
| 213 | makefile.openbsd => OpenBSD makefile |
| 214 | makefile.sgi => Silicon Graphics IRIX (cc, creates static lib) |
| 215 | makefile.sggcc => Silicon Graphics |
| 216 | (gcc, creates libpng12.so.0.1.2.7) |
| 217 | makefile.sunos => Sun makefile |
| 218 | makefile.solaris => Solaris 2.X makefile |
| 219 | (gcc, creates libpng12.so.0.1.2.7) |
| 220 | makefile.so9 => Solaris 9 makefile |
| 221 | (gcc, creates libpng12.so.0.1.2.7) |
| 222 | makefile.32sunu => Sun Ultra 32-bit makefile |
| 223 | makefile.64sunu => Sun Ultra 64-bit makefile |
| 224 | makefile.sco => For SCO OSr5 ELF and Unixware 7 with Native cc |
| 225 | makefile.mips => MIPS makefile |
| 226 | makefile.acorn => Acorn makefile |
| 227 | makefile.amiga => Amiga makefile |
| 228 | smakefile.ppc => AMIGA smakefile for SAS C V6.58/7.00 PPC |
| 229 | compiler (Requires SCOPTIONS, copied from |
| 230 | scripts/SCOPTIONS.ppc) |
| 231 | makefile.atari => Atari makefile |
| 232 | makefile.beos => BEOS makefile for X86 |
| 233 | makefile.bor => Borland makefile (uses bcc) |
| 234 | makefile.bc32 => 32-bit Borland C++ (all modules compiled in C mode) |
| 235 | makefile.tc3 => Turbo C 3.0 makefile |
| 236 | makefile.dj2 => DJGPP 2 makefile |
| 237 | makefile.msc => Microsoft C makefile |
| 238 | makefile.vcawin32=> makefile for Microsoft Visual C++ 5.0 and |
| 239 | later (uses assembler code tuned for Intel MMX |
| 240 | platform) |
| 241 | makefile.vcwin32 => makefile for Microsoft Visual C++ 4.0 and |
| 242 | later (does not use assembler code) |
| 243 | makefile.os2 => OS/2 Makefile (gcc and emx, requires pngos2.def) |
| 244 | pngos2.def => OS/2 module definition file used by makefile.os2 |
| 245 | makefile.watcom => Watcom 10a+ Makefile, 32-bit flat memory model |
| 246 | makevms.com => VMS build script |
| 247 | SCOPTIONS.ppc => Used with smakefile.ppc |
| 248 | |
| 249 | Good luck, and happy coding. |
| 250 | |
| 251 | -Glenn Randers-Pehrson (current maintainer) |
| 252 | Internet: glennrp@users.sourceforge.net |
| 253 | |
| 254 | -Andreas Eric Dilger (former maintainer, 1996-1997) |
| 255 | Internet: adilger@enel.ucalgary.ca |
| 256 | Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/ |
| 257 | |
| 258 | -Guy Eric Schalnat (original author and former maintainer, 1995-1996) |
| 259 | (formerly of Group 42, Inc) |
| 260 | Internet: gschal@infinet.com |