readme.txt - for libpng 0.8 This is the second beta version of libpng 1.0. I've updated most of the stuff I want to before the final 1.0 version. Remaining to do are the medium memory model support (which I'll put in as soon as we test this version), better dithering, and any bug fixes and makefile/include additions. I expect a third (and perhaps final) beta after zlib is officially 1.0. I've tried to incorporate all the changes and makefiles everyone sent me. However, I may of lost some in the flood. If you sent me a change and I didn't put it in, send it again. Sorry. Updates from libpng 0.71 include a new transformation, png_set_filler(), which replaces png_set_rgbx() and png_set_xrgb(). The old functions will be supported for awhile, but I'd suggest changing to the new function. Also, I've added defines in png.h to remove unwanted code from the compiled library. I've added a new field to png_realloc(), and fixed various bugs. I've also split up pngstub.c into pngmem.c, pngio.c, and pngerror.c, in case you need to just change some of these. I've pulled pngconf.h out of png.h, so you don't have to remake your changes every new release. I've added a function to update the png_info structure after you're done setting up your transformations (png_read_update_info()). The complete list of changes is in pngchang.txt. Most of you won't be much affected by any of this. Some of you will want to use the new features. For a detailed description on using libpng, read libpng.txt. 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, but you may have to modify it for your own needs. You will need zlib 0.95 or later to run this. zlib is a compression library that is useful for more things then just png files. If you need a compression library, check out zlib.h zlib should be available at the same place that libpng is. If not, it should be at ftp.uu.net in /graphics/png Eventually, it will be at ftp.uu.net in /pub/archiving/zip/zlib You will also want a copy of the PNG specification. It should be available at the same place you picked up libpng. If it is not there, try ftp.uu.net in the /graphics/png directory. This code is currently being archived at ftp.uu.net in the /graphics/png directory, and at ftp.group42.com (204.94.158.25) in the /pub/png directory, 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. You can reach me at: internet: schalnat@group42.com CompuServe: 75501,1625 Please do not send me general questions about PNG. Send them to the address in the specification. At the same time, please do not send libpng questions to that address, send them to me. 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 9 months 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 for version 1.0, it may be used later. Good luck, and happy coding. -Guy Eric Schalnat Group 42, Inc. Internet: schalnat@group42.com CompuServe: 75501,1625 Web: www.group42.com FTP: ftp.group42.com (204.94.158.25)