Glenn Randers-Pehrson | f7a7bb0 | 2014-10-17 09:06:25 -0500 | [diff] [blame^] | 1 | README for libpng version 1.6.14rc02 - October 17, 2014 (shared library 16.0) |
Glenn Randers-Pehrson | 08a3343 | 1998-03-07 06:06:55 -0600 | [diff] [blame] | 2 | See the note about version numbers near the top of png.h |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 3 | |
Glenn Randers-Pehrson | 08a3343 | 1998-03-07 06:06:55 -0600 | [diff] [blame] | 4 | See INSTALL for instructions on how to install libpng. |
Glenn Randers-Pehrson | 2687fcc | 1998-01-07 20:54:20 -0600 | [diff] [blame] | 5 | |
Glenn Randers-Pehrson | 810b6e5 | 2013-06-05 16:52:41 -0500 | [diff] [blame] | 6 | Libpng comes in several distribution formats. Get libpng-*.tar.gz or |
| 7 | libpng-*.tar.xz or if you want UNIX-style line endings in the text files, |
| 8 | or lpng*.7z or lpng*.zip if you want DOS-style line endings. |
Glenn Randers-Pehrson | 61c32d9 | 2000-02-04 23:40:16 -0600 | [diff] [blame] | 9 | |
Glenn Randers-Pehrson | 860ab2b | 1999-10-14 07:43:10 -0500 | [diff] [blame] | 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 |
Glenn Randers-Pehrson | b6ce43d | 1998-01-01 07:13:13 -0600 | [diff] [blame] | 14 | changes to the API in some time, and people have a bad feeling about |
Glenn Randers-Pehrson | 860ab2b | 1999-10-14 07:43:10 -0500 | [diff] [blame] | 15 | libraries with versions < 1.0. Version 1.0.0 was released in |
| 16 | March 1998. |
Glenn Randers-Pehrson | b6ce43d | 1998-01-01 07:13:13 -0600 | [diff] [blame] | 17 | |
Andreas Dilger | 47a0c42 | 1997-05-16 02:46:07 -0500 | [diff] [blame] | 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 |
Glenn Randers-Pehrson | 2687fcc | 1998-01-07 20:54:20 -0600 | [diff] [blame] | 23 | png_uint_32, which will affect shared-library applications that use |
Andreas Dilger | 47a0c42 | 1997-05-16 02:46:07 -0500 | [diff] [blame] | 24 | this function. |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 25 | |
Andreas Dilger | 47a0c42 | 1997-05-16 02:46:07 -0500 | [diff] [blame] | 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. |
Glenn Randers-Pehrson | b6ce43d | 1998-01-01 07:13:13 -0600 | [diff] [blame] | 32 | |
Glenn Randers-Pehrson | f7a7bb0 | 2014-10-17 09:06:25 -0500 | [diff] [blame^] | 33 | It is important to note that the APIs did not make current programs |
Glenn Randers-Pehrson | 2687fcc | 1998-01-07 20:54:20 -0600 | [diff] [blame] | 34 | that access the info struct directly incompatible with the new |
Glenn Randers-Pehrson | f7a7bb0 | 2014-10-17 09:06:25 -0500 | [diff] [blame^] | 35 | library, through libpng-1.2.x. In libpng-1.4.x, which was meant to |
| 36 | be a transitional release, the png struct and the info struct can still |
| 37 | be accessed, but the compiler will issue a warning about deprecated |
| 38 | usage. Since libpng-1.5.0, direct access to these structs is not |
| 39 | allowed, and the definitions of the structs reside in private |
| 40 | pngstruct.h and pnginfo.h header files that are not accessible to |
| 41 | applications. It is strongly suggested that new programs use the new |
| 42 | APIs (as shown in example.c and pngtest.c), and older programs be |
| 43 | converted to the new format, to facilitate upgrades in the future. |
Andreas Dilger | 47a0c42 | 1997-05-16 02:46:07 -0500 | [diff] [blame] | 44 | **** |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 45 | |
Andreas Dilger | 47a0c42 | 1997-05-16 02:46:07 -0500 | [diff] [blame] | 46 | Additions since 0.90 include the ability to compile libpng as a |
| 47 | Windows DLL, and new APIs for accessing data in the info struct. |
| 48 | Experimental functions include the ability to set weighting and cost |
| 49 | factors for row filter selection, direct reads of integers from buffers |
| 50 | on big-endian processors that support misaligned data access, faster |
| 51 | methods of doing alpha composition, and more accurate 16->8 bit color |
| 52 | conversion. |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 53 | |
Andreas Dilger | 47a0c42 | 1997-05-16 02:46:07 -0500 | [diff] [blame] | 54 | The additions since 0.89 include the ability to read from a PNG stream |
| 55 | which has had some (or all) of the signature bytes read by the calling |
| 56 | application. This also allows the reading of embedded PNG streams that |
| 57 | do not have the PNG file signature. As well, it is now possible to set |
| 58 | the library action on the detection of chunk CRC errors. It is possible |
| 59 | to set different actions based on whether the CRC error occurred in a |
| 60 | critical or an ancillary chunk. |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 61 | |
| 62 | The changes made to the library, and bugs fixed are based on discussions |
Glenn Randers-Pehrson | ce96c3e | 2009-11-27 16:17:19 -0600 | [diff] [blame] | 63 | on the PNG-implement mailing list and not on material submitted |
| 64 | privately to Guy, Andreas, or Glenn. They will forward any good |
| 65 | suggestions to the list. |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 66 | |
Glenn Randers-Pehrson | f3abb2c | 2010-10-17 12:51:53 -0500 | [diff] [blame] | 67 | For a detailed description on using libpng, read libpng-manual.txt. For |
Andreas Dilger | 47a0c42 | 1997-05-16 02:46:07 -0500 | [diff] [blame] | 68 | examples of libpng in a program, see example.c and pngtest.c. For usage |
| 69 | information and restrictions (what little they are) on libpng, see |
| 70 | png.h. For a description on using zlib (the compression library used by |
| 71 | libpng) and zlib's restrictions, see zlib.h |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 72 | |
Andreas Dilger | 47a0c42 | 1997-05-16 02:46:07 -0500 | [diff] [blame] | 73 | I have included a general makefile, as well as several machine and |
| 74 | compiler specific ones, but you may have to modify one for your own needs. |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 75 | |
| 76 | You should use zlib 1.0.4 or later to run this, but it MAY work with |
| 77 | versions as old as zlib 0.95. Even so, there are bugs in older zlib |
| 78 | versions which can cause the output of invalid compression streams for |
| 79 | some images. You will definitely need zlib 1.0.4 or later if you are |
| 80 | taking advantage of the MS-DOS "far" structure allocation for the small |
| 81 | and medium memory models. You should also note that zlib is a |
| 82 | compression library that is useful for more things than just PNG files. |
| 83 | You can use zlib as a drop-in replacement for fread() and fwrite() if |
| 84 | you are so inclined. |
| 85 | |
Glenn Randers-Pehrson | 810b6e5 | 2013-06-05 16:52:41 -0500 | [diff] [blame] | 86 | zlib should be available at the same place that libpng is, or at zlib.net. |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 87 | |
| 88 | You may also want a copy of the PNG specification. It is available |
Glenn Randers-Pehrson | a4981d4 | 2004-08-25 22:00:45 -0500 | [diff] [blame] | 89 | as an RFC, a W3C Recommendation, and an ISO/IEC Standard. You can find |
| 90 | these at http://www.libpng.org/pub/png/documents/ |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 91 | |
Glenn Randers-Pehrson | a4981d4 | 2004-08-25 22:00:45 -0500 | [diff] [blame] | 92 | This code is currently being archived at libpng.sf.net in the |
Glenn Randers-Pehrson | 810b6e5 | 2013-06-05 16:52:41 -0500 | [diff] [blame] | 93 | [DOWNLOAD] area, and at ftp://ftp.simplesystems.org. If you can't find it |
| 94 | in any of those places, e-mail me, and I'll help you find it. |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 95 | |
Glenn Randers-Pehrson | 9782cce | 2014-08-07 19:48:10 -0500 | [diff] [blame] | 96 | I am not a lawyer, but I believe that the Export Control Classification |
| 97 | Number (ECCN) for libpng is EAR99, which means not subject to export |
| 98 | controls or International Traffic in Arms Regulations (ITAR) because it |
| 99 | is open source, publicly available software, that does not contain any |
| 100 | encryption software. See the EAR, paragraphs 734.3(b)(3) and 734.7(b). |
| 101 | |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 102 | If you have any code changes, requests, problems, etc., please e-mail |
| 103 | them to me. Also, I'd appreciate any make files or project files, |
| 104 | and any modifications you needed to make to get libpng to compile, |
| 105 | along with a #define variable to tell what compiler/system you are on. |
| 106 | If you needed to add transformations to libpng, or wish libpng would |
| 107 | provide the image in a different way, drop me a note (and code, if |
| 108 | possible), so I can consider supporting the transformation. |
| 109 | Finally, if you get any warning messages when compiling libpng |
| 110 | (note: not zlib), and they are easy to fix, I'd appreciate the |
| 111 | fix. Please mention "libpng" somewhere in the subject line. Thanks. |
| 112 | |
| 113 | This release was created and will be supported by myself (of course |
Glenn Randers-Pehrson | ce96c3e | 2009-11-27 16:17:19 -0600 | [diff] [blame] | 114 | based in a large way on Guy's and Andreas' earlier work), and the PNG |
| 115 | development group. |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 116 | |
Glenn Randers-Pehrson | ce96c3e | 2009-11-27 16:17:19 -0600 | [diff] [blame] | 117 | Send comments/corrections/commendations to png-mng-implement at |
Glenn Randers-Pehrson | 871b1d0 | 2013-03-02 14:58:22 -0600 | [diff] [blame] | 118 | lists.sourceforge.net (subscription required; visit |
Glenn Randers-Pehrson | 9c3ab68 | 2006-02-20 22:09:05 -0600 | [diff] [blame] | 119 | https://lists.sourceforge.net/lists/listinfo/png-mng-implement |
| 120 | to subscribe) or to glennrp at users.sourceforge.net |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 121 | |
Glenn Randers-Pehrson | c4a2ae6 | 1998-01-16 22:06:18 -0600 | [diff] [blame] | 122 | You can't reach Guy, the original libpng author, at the addresses |
Glenn Randers-Pehrson | ce96c3e | 2009-11-27 16:17:19 -0600 | [diff] [blame] | 123 | given in previous versions of this document. He and Andreas will |
| 124 | read mail addressed to the png-implement list, however. |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 125 | |
| 126 | Please do not send general questions about PNG. Send them to |
Glenn Randers-Pehrson | 36edbb5 | 2011-06-03 07:15:04 -0500 | [diff] [blame] | 127 | png-mng-misc at lists.sf.net (subscription required; visit |
| 128 | https://lists.sourceforge.net/lists/listinfo/png-mng-misc to |
| 129 | subscribe). If you have a question about something |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 130 | in the PNG specification that is related to using libpng, send it |
| 131 | to me. Send me any questions that start with "I was using libpng, |
| 132 | and ...". If in doubt, send questions to me. I'll bounce them |
| 133 | to others, if necessary. |
| 134 | |
| 135 | Please do not send suggestions on how to change PNG. We have |
Glenn Randers-Pehrson | 95a1973 | 2013-12-31 21:10:13 -0600 | [diff] [blame] | 136 | been discussing PNG for nineteen years now, and it is official and |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 137 | finished. If you have suggestions for libpng, however, I'll |
Glenn Randers-Pehrson | a4981d4 | 2004-08-25 22:00:45 -0500 | [diff] [blame] | 138 | gladly listen. Even if your suggestion is not used immediately, |
| 139 | it may be used later. |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 140 | |
| 141 | Files in this distribution: |
| 142 | |
Glenn Randers-Pehrson | 520a764 | 2000-03-21 05:13:06 -0600 | [diff] [blame] | 143 | ANNOUNCE => Announcement of this version, with recent changes |
Andreas Dilger | 47a0c42 | 1997-05-16 02:46:07 -0500 | [diff] [blame] | 144 | CHANGES => Description of changes between libpng versions |
Glenn Randers-Pehrson | 520a764 | 2000-03-21 05:13:06 -0600 | [diff] [blame] | 145 | KNOWNBUG => List of known bugs and deficiencies |
| 146 | LICENSE => License to use and redistribute libpng |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 147 | README => This file |
| 148 | TODO => Things not implemented in the current library |
Glenn Randers-Pehrson | 520a764 | 2000-03-21 05:13:06 -0600 | [diff] [blame] | 149 | Y2KINFO => Statement of Y2K compliance |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 150 | example.c => Example code for using libpng functions |
Glenn Randers-Pehrson | f3abb2c | 2010-10-17 12:51:53 -0500 | [diff] [blame] | 151 | libpng.3 => manual page for libpng (includes libpng-manual.txt) |
| 152 | libpng-manual.txt => Description of libpng and its functions |
Glenn Randers-Pehrson | cbe52d8 | 1998-02-28 07:00:24 -0600 | [diff] [blame] | 153 | libpngpf.3 => manual page for libpng's private functions |
Glenn Randers-Pehrson | cbe52d8 | 1998-02-28 07:00:24 -0600 | [diff] [blame] | 154 | png.5 => manual page for the PNG format |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 155 | png.c => Basic interface functions common to library |
Glenn Randers-Pehrson | 2bc7abf | 2010-03-13 21:36:45 -0600 | [diff] [blame] | 156 | png.h => Library function and interface declarations (public) |
| 157 | pngpriv.h => Library function and interface declarations (private) |
| 158 | pngconf.h => System specific library configuration (public) |
| 159 | pngstruct.h => png_struct declaration (private) |
| 160 | pnginfo.h => png_info struct declaration (private) |
| 161 | pngdebug.h => debugging macros (private) |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 162 | pngerror.c => Error/warning message I/O functions |
Glenn Randers-Pehrson | cbe52d8 | 1998-02-28 07:00:24 -0600 | [diff] [blame] | 163 | pngget.c => Functions for retrieving info from struct |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 164 | pngmem.c => Memory handling functions |
Glenn Randers-Pehrson | a4d54bd | 2000-07-14 08:15:12 -0500 | [diff] [blame] | 165 | pngbar.png => PNG logo, 88x31 |
| 166 | pngnow.png => PNG logo, 98x31 |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 167 | pngpread.c => Progressive reading functions |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 168 | pngread.c => Read data/helper high-level functions |
| 169 | pngrio.c => Lowest-level data read I/O functions |
| 170 | pngrtran.c => Read data transformation functions |
| 171 | pngrutil.c => Read data utility functions |
Andreas Dilger | 47a0c42 | 1997-05-16 02:46:07 -0500 | [diff] [blame] | 172 | pngset.c => Functions for storing data into the info_struct |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 173 | pngtest.c => Library test program |
| 174 | pngtest.png => Library test sample image |
| 175 | pngtrans.c => Common data transformation functions |
| 176 | pngwio.c => Lowest-level write I/O functions |
| 177 | pngwrite.c => High-level write functions |
| 178 | pngwtran.c => Write data transformations |
| 179 | pngwutil.c => Write utility functions |
Glenn Randers-Pehrson | f962512 | 2013-06-03 20:57:45 -0500 | [diff] [blame] | 180 | arm => Contains optimized code for the ARM platform |
Glenn Randers-Pehrson | 860ab2b | 1999-10-14 07:43:10 -0500 | [diff] [blame] | 181 | contrib => Contributions |
Glenn Randers-Pehrson | f962512 | 2013-06-03 20:57:45 -0500 | [diff] [blame] | 182 | examples => Example programs |
Glenn Randers-Pehrson | 860ab2b | 1999-10-14 07:43:10 -0500 | [diff] [blame] | 183 | gregbook => source code for PNG reading and writing, from |
| 184 | Greg Roelofs' "PNG: The Definitive Guide", |
| 185 | O'Reilly, 1999 |
Glenn Randers-Pehrson | f962512 | 2013-06-03 20:57:45 -0500 | [diff] [blame] | 186 | libtests => Test programs |
| 187 | pngminim => Minimal decoder, encoder, and progressive decoder |
| 188 | programs demonstrating use of pngusr.dfa |
| 189 | pngminus => Simple pnm2png and png2pnm programs |
| 190 | pngsuite => Test images |
| 191 | tools => Various tools |
Glenn Randers-Pehrson | db66d44 | 2000-06-23 21:38:16 -0500 | [diff] [blame] | 192 | visupng => Contains a MSVC workspace for VisualPng |
Glenn Randers-Pehrson | ce96c3e | 2009-11-27 16:17:19 -0600 | [diff] [blame] | 193 | projects => Contains project files and workspaces for |
| 194 | building a DLL |
Glenn Randers-Pehrson | f962512 | 2013-06-03 20:57:45 -0500 | [diff] [blame] | 195 | owatcom => Contains a WATCOM project for building libpng |
Glenn Randers-Pehrson | 2bc7abf | 2010-03-13 21:36:45 -0600 | [diff] [blame] | 196 | visualc71 => Contains a Microsoft Visual C++ (MSVC) |
| 197 | workspace for building libpng and zlib |
Glenn Randers-Pehrson | f962512 | 2013-06-03 20:57:45 -0500 | [diff] [blame] | 198 | vstudio => Contains a Microsoft Visual C++ (MSVC) |
Glenn Randers-Pehrson | 2bc7abf | 2010-03-13 21:36:45 -0600 | [diff] [blame] | 199 | workspace for building libpng and zlib |
Glenn Randers-Pehrson | 08a3343 | 1998-03-07 06:06:55 -0600 | [diff] [blame] | 200 | scripts => Directory containing scripts for building libpng: |
Glenn Randers-Pehrson | c9cd65a | 2010-04-17 09:13:37 -0500 | [diff] [blame] | 201 | (see scripts/README.txt for the list of scripts) |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 202 | |
| 203 | Good luck, and happy coding. |
| 204 | |
Glenn Randers-Pehrson | f81b50b | 2009-12-29 16:50:15 -0600 | [diff] [blame] | 205 | -Glenn Randers-Pehrson (current maintainer, since 1998) |
Glenn Randers-Pehrson | 5dd2b8e | 2004-11-24 07:50:16 -0600 | [diff] [blame] | 206 | Internet: glennrp at users.sourceforge.net |
Glenn Randers-Pehrson | c4a2ae6 | 1998-01-16 22:06:18 -0600 | [diff] [blame] | 207 | |
Glenn Randers-Pehrson | a4981d4 | 2004-08-25 22:00:45 -0500 | [diff] [blame] | 208 | -Andreas Eric Dilger (former maintainer, 1996-1997) |
Glenn Randers-Pehrson | 5dd2b8e | 2004-11-24 07:50:16 -0600 | [diff] [blame] | 209 | Internet: adilger at enel.ucalgary.ca |
Andreas Dilger | 47a0c42 | 1997-05-16 02:46:07 -0500 | [diff] [blame] | 210 | Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/ |
Andreas Dilger | 02ad0ef | 1997-01-17 01:34:35 -0600 | [diff] [blame] | 211 | |
Glenn Randers-Pehrson | a4981d4 | 2004-08-25 22:00:45 -0500 | [diff] [blame] | 212 | -Guy Eric Schalnat (original author and former maintainer, 1995-1996) |
Glenn Randers-Pehrson | c4a2ae6 | 1998-01-16 22:06:18 -0600 | [diff] [blame] | 213 | (formerly of Group 42, Inc) |
Glenn Randers-Pehrson | 5dd2b8e | 2004-11-24 07:50:16 -0600 | [diff] [blame] | 214 | Internet: gschal at infinet.com |