michael@0: README for libpng version 1.6.10 - March 6, 2014 (shared library 16.0) michael@0: See the note about version numbers near the top of png.h michael@0: michael@0: See INSTALL for instructions on how to install libpng. michael@0: michael@0: Libpng comes in several distribution formats. Get libpng-*.tar.gz or michael@0: libpng-*.tar.xz or if you want UNIX-style line endings in the text files, michael@0: or lpng*.7z or lpng*.zip if you want DOS-style line endings. michael@0: michael@0: Version 0.89 was the first official release of libpng. Don't let the michael@0: fact that it's the first release fool you. The libpng library has been in michael@0: extensive use and testing since mid-1995. By late 1997 it had michael@0: finally gotten to the stage where there hadn't been significant michael@0: changes to the API in some time, and people have a bad feeling about michael@0: libraries with versions < 1.0. Version 1.0.0 was released in michael@0: March 1998. michael@0: michael@0: **** michael@0: Note that some of the changes to the png_info structure render this michael@0: version of the library binary incompatible with libpng-0.89 or michael@0: earlier versions if you are using a shared library. The type of the michael@0: "filler" parameter for png_set_filler() has changed from png_byte to michael@0: png_uint_32, which will affect shared-library applications that use michael@0: this function. michael@0: michael@0: To avoid problems with changes to the internals of png_info_struct, michael@0: new APIs have been made available in 0.95 to avoid direct application michael@0: access to info_ptr. These functions are the png_set_ and michael@0: png_get_ functions. These functions should be used when michael@0: accessing/storing the info_struct data, rather than manipulating it michael@0: directly, to avoid such problems in the future. michael@0: michael@0: It is important to note that the APIs do not make current programs michael@0: that access the info struct directly incompatible with the new michael@0: library. However, it is strongly suggested that new programs use michael@0: the new APIs (as shown in example.c and pngtest.c), and older programs michael@0: be converted to the new format, to facilitate upgrades in the future. michael@0: **** michael@0: michael@0: Additions since 0.90 include the ability to compile libpng as a michael@0: Windows DLL, and new APIs for accessing data in the info struct. michael@0: Experimental functions include the ability to set weighting and cost michael@0: factors for row filter selection, direct reads of integers from buffers michael@0: on big-endian processors that support misaligned data access, faster michael@0: methods of doing alpha composition, and more accurate 16->8 bit color michael@0: conversion. michael@0: michael@0: The additions since 0.89 include the ability to read from a PNG stream michael@0: which has had some (or all) of the signature bytes read by the calling michael@0: application. This also allows the reading of embedded PNG streams that michael@0: do not have the PNG file signature. As well, it is now possible to set michael@0: the library action on the detection of chunk CRC errors. It is possible michael@0: to set different actions based on whether the CRC error occurred in a michael@0: critical or an ancillary chunk. michael@0: michael@0: The changes made to the library, and bugs fixed are based on discussions michael@0: on the PNG-implement mailing list and not on material submitted michael@0: privately to Guy, Andreas, or Glenn. They will forward any good michael@0: suggestions to the list. michael@0: michael@0: For a detailed description on using libpng, read libpng-manual.txt. For michael@0: examples of libpng in a program, see example.c and pngtest.c. For usage michael@0: information and restrictions (what little they are) on libpng, see michael@0: png.h. For a description on using zlib (the compression library used by michael@0: libpng) and zlib's restrictions, see zlib.h michael@0: michael@0: I have included a general makefile, as well as several machine and michael@0: compiler specific ones, but you may have to modify one for your own needs. michael@0: michael@0: You should use zlib 1.0.4 or later to run this, but it MAY work with michael@0: versions as old as zlib 0.95. Even so, there are bugs in older zlib michael@0: versions which can cause the output of invalid compression streams for michael@0: some images. You will definitely need zlib 1.0.4 or later if you are michael@0: taking advantage of the MS-DOS "far" structure allocation for the small michael@0: and medium memory models. You should also note that zlib is a michael@0: compression library that is useful for more things than just PNG files. michael@0: You can use zlib as a drop-in replacement for fread() and fwrite() if michael@0: you are so inclined. michael@0: michael@0: zlib should be available at the same place that libpng is, or at zlib.net. michael@0: michael@0: You may also want a copy of the PNG specification. It is available michael@0: as an RFC, a W3C Recommendation, and an ISO/IEC Standard. You can find michael@0: these at http://www.libpng.org/pub/png/documents/ michael@0: michael@0: This code is currently being archived at libpng.sf.net in the michael@0: [DOWNLOAD] area, and at ftp://ftp.simplesystems.org. If you can't find it michael@0: in any of those places, e-mail me, and I'll help you find it. michael@0: michael@0: If you have any code changes, requests, problems, etc., please e-mail michael@0: them to me. Also, I'd appreciate any make files or project files, michael@0: and any modifications you needed to make to get libpng to compile, michael@0: along with a #define variable to tell what compiler/system you are on. michael@0: If you needed to add transformations to libpng, or wish libpng would michael@0: provide the image in a different way, drop me a note (and code, if michael@0: possible), so I can consider supporting the transformation. michael@0: Finally, if you get any warning messages when compiling libpng michael@0: (note: not zlib), and they are easy to fix, I'd appreciate the michael@0: fix. Please mention "libpng" somewhere in the subject line. Thanks. michael@0: michael@0: This release was created and will be supported by myself (of course michael@0: based in a large way on Guy's and Andreas' earlier work), and the PNG michael@0: development group. michael@0: michael@0: Send comments/corrections/commendations to png-mng-implement at michael@0: lists.sourceforge.net (subscription required; visit michael@0: https://lists.sourceforge.net/lists/listinfo/png-mng-implement michael@0: to subscribe) or to glennrp at users.sourceforge.net michael@0: michael@0: You can't reach Guy, the original libpng author, at the addresses michael@0: given in previous versions of this document. He and Andreas will michael@0: read mail addressed to the png-implement list, however. michael@0: michael@0: Please do not send general questions about PNG. Send them to michael@0: png-mng-misc at lists.sf.net (subscription required; visit michael@0: https://lists.sourceforge.net/lists/listinfo/png-mng-misc to michael@0: subscribe). If you have a question about something michael@0: in the PNG specification that is related to using libpng, send it michael@0: to me. Send me any questions that start with "I was using libpng, michael@0: and ...". If in doubt, send questions to me. I'll bounce them michael@0: to others, if necessary. michael@0: michael@0: Please do not send suggestions on how to change PNG. We have michael@0: been discussing PNG for nineteen years now, and it is official and michael@0: finished. If you have suggestions for libpng, however, I'll michael@0: gladly listen. Even if your suggestion is not used immediately, michael@0: it may be used later. michael@0: michael@0: Files in this distribution: michael@0: michael@0: ANNOUNCE => Announcement of this version, with recent changes michael@0: CHANGES => Description of changes between libpng versions michael@0: KNOWNBUG => List of known bugs and deficiencies michael@0: LICENSE => License to use and redistribute libpng michael@0: README => This file michael@0: TODO => Things not implemented in the current library michael@0: Y2KINFO => Statement of Y2K compliance michael@0: example.c => Example code for using libpng functions michael@0: libpng.3 => manual page for libpng (includes libpng-manual.txt) michael@0: libpng-manual.txt => Description of libpng and its functions michael@0: libpngpf.3 => manual page for libpng's private functions michael@0: png.5 => manual page for the PNG format michael@0: png.c => Basic interface functions common to library michael@0: png.h => Library function and interface declarations (public) michael@0: pngpriv.h => Library function and interface declarations (private) michael@0: pngconf.h => System specific library configuration (public) michael@0: pngstruct.h => png_struct declaration (private) michael@0: pnginfo.h => png_info struct declaration (private) michael@0: pngdebug.h => debugging macros (private) michael@0: pngerror.c => Error/warning message I/O functions michael@0: pngget.c => Functions for retrieving info from struct michael@0: pngmem.c => Memory handling functions michael@0: pngbar.png => PNG logo, 88x31 michael@0: pngnow.png => PNG logo, 98x31 michael@0: pngpread.c => Progressive reading functions michael@0: pngread.c => Read data/helper high-level functions michael@0: pngrio.c => Lowest-level data read I/O functions michael@0: pngrtran.c => Read data transformation functions michael@0: pngrutil.c => Read data utility functions michael@0: pngset.c => Functions for storing data into the info_struct michael@0: pngtest.c => Library test program michael@0: pngtest.png => Library test sample image michael@0: pngtrans.c => Common data transformation functions michael@0: pngwio.c => Lowest-level write I/O functions michael@0: pngwrite.c => High-level write functions michael@0: pngwtran.c => Write data transformations michael@0: pngwutil.c => Write utility functions michael@0: arm => Contains optimized code for the ARM platform michael@0: contrib => Contributions michael@0: examples => Example programs michael@0: gregbook => source code for PNG reading and writing, from michael@0: Greg Roelofs' "PNG: The Definitive Guide", michael@0: O'Reilly, 1999 michael@0: libtests => Test programs michael@0: pngminim => Minimal decoder, encoder, and progressive decoder michael@0: programs demonstrating use of pngusr.dfa michael@0: pngminus => Simple pnm2png and png2pnm programs michael@0: pngsuite => Test images michael@0: tools => Various tools michael@0: visupng => Contains a MSVC workspace for VisualPng michael@0: projects => Contains project files and workspaces for michael@0: building a DLL michael@0: owatcom => Contains a WATCOM project for building libpng michael@0: visualc71 => Contains a Microsoft Visual C++ (MSVC) michael@0: workspace for building libpng and zlib michael@0: vstudio => Contains a Microsoft Visual C++ (MSVC) michael@0: workspace for building libpng and zlib michael@0: scripts => Directory containing scripts for building libpng: michael@0: (see scripts/README.txt for the list of scripts) michael@0: michael@0: Good luck, and happy coding. michael@0: michael@0: -Glenn Randers-Pehrson (current maintainer, since 1998) michael@0: Internet: glennrp at users.sourceforge.net michael@0: michael@0: -Andreas Eric Dilger (former maintainer, 1996-1997) michael@0: Internet: adilger at enel.ucalgary.ca michael@0: Web: http://www-mddsp.enel.ucalgary.ca/People/adilger/ michael@0: michael@0: -Guy Eric Schalnat (original author and former maintainer, 1995-1996) michael@0: (formerly of Group 42, Inc) michael@0: Internet: gschal at infinet.com