91 lines
3.9 KiB
Plaintext
91 lines
3.9 KiB
Plaintext
readme.txt - for libpng 0.87
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This is a bug fix for the second beta version of libpng 1.0, and
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a first try at a progressive (push) reader. It hasn't been
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tested as much as the pull reader, but seems to work ok.
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I've implemented the callback functions for the error/warning
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messages and the input/output. See the libpng.txt
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for details. I've also added defines to support medium memory
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models, so every type now has pointer defines. For example,
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a pointer to the png_struct is now png_structp, while a double
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pointer is now png_structpp. The old way should work, but I'll
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be using the new way from now on in all my examples. Those of
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you doing medium memory model or changing the error/warning
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or input/output functions should try these and report back to
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me any problems.
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I've tried to incorporate all the changes and makefiles everyone
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sent me. However, I may of lost some in the flood. If you sent
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me a change and I didn't put it in, send it again. Sorry.
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For a detailed description on using libpng, read libpng.txt. For
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usage information and restrictions (what little they are) on libpng,
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see png.h. For a description on using zlib (the compression library
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used by libpng) and zlib's restrictions, see zlib.h
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I have included a general makefile, but you may have to modify it
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for your own needs.
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You will need zlib 0.95 or later to run this. zlib is a compression
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library that is useful for more things then just png files. If
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you need a compression library, check out zlib.h
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zlib should be available at the same place that libpng is.
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If not, it should be at ftp.uu.net in /graphics/png
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Eventually, it will be at ftp.uu.net in /pub/archiving/zip/zlib
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You will also want a copy of the PNG specification. It should
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be available at the same place you picked up libpng. If it is
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not there, try ftp.uu.net in the /graphics/png directory.
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This code is currently being archived at ftp.uu.net in the
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/graphics/png directory, and on CompuServe, Lib 20 (PNG SUPPORT)
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at GO GRAPHSUP. If you can't find it in any of those places,
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e-mail me, and I'll help you find it.
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If you have any code changes, requests, problems, etc., please e-mail
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them to me. Also, I'd appreciate any make files or project files,
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and any modifications you needed to make to get libpng to compile,
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along with a #define variable to tell what compiler/system you are on.
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If you needed to add transformations to libpng, or wish libpng would
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provide the image in a different way, drop me a note (and code, if
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possible), so I can consider supporting the transformation.
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Finally, if you get any warning messages when compiling libpng
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(note: not zlib), and they are easy to fix, I'd appreciate the
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fix. Please mention "libpng" somewhere in the subject line. Thanks.
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You can reach me at:
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internet: schalnat@group42.com
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CompuServe: 75501,1625
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I tend to check my CompuServe account very infrequently, so you may
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want to use the internet account. If I don't answer your email
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immediately, please be patient. If you don't receive a reply within
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a week, you may want to write and ask if I got the first email.
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Please do not send me general questions about PNG. Send them to
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the address in the specification. At the same time, please do
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not send libpng questions to that address, send them to me. I'll
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get them in the end anyway. If you have a question about something
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in the PNG specification that is related to using libpng, send it
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to me. Send me any questions that start with "I was using libpng,
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and ...". If in doubt, send questions to me. I'll bounce them
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to others, if necessary.
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Please do not send suggestions on how to change PNG. We have
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been discussing PNG for over a year now, and it is official and
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finished. If you have suggestions for libpng, however, I'll
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gladly listen. Even if your suggestion is not used for version
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1.0, it may be used later.
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Good luck, and happy coding.
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-Guy Eric Schalnat
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Group 42, Inc.
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Internet: schalnat@group42.com
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CompuServe: 75501,1625
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Web: www.group42.com
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