X-Git-Url: https://git.pterodactylus.net/?a=blobdiff_plain;f=gtkmm-osx%2Ftrunk%2Flibpng-1.2.5%2Fcontrib%2Fpngminus%2FREADME;fp=gtkmm-osx%2Ftrunk%2Flibpng-1.2.5%2Fcontrib%2Fpngminus%2FREADME;h=0000000000000000000000000000000000000000;hb=a095981e18cc37a8ecc7cd237cc22b9c10329264;hp=8683a596ae502cfb336ed23493f8cc4864f593aa;hpb=9459638ad6797b8139f1e9f0715c96076dbf0890;p=synfig.git diff --git a/gtkmm-osx/trunk/libpng-1.2.5/contrib/pngminus/README b/gtkmm-osx/trunk/libpng-1.2.5/contrib/pngminus/README deleted file mode 100644 index 8683a59..0000000 --- a/gtkmm-osx/trunk/libpng-1.2.5/contrib/pngminus/README +++ /dev/null @@ -1,153 +0,0 @@ -PngMinus --------- -(copyright Willem van Schaik, 1999) - - -License -------- - -Permission to use, copy, modify, and distribute this software and -its documentation for any purpose and without fee is hereby granted, -provided that the above copyright notice appear in all copies and -that both that copyright notice and this permission notice appear in -supporting documentation. This software is provided "as is" without -express or implied warranty. - - -Some history ------------- -Soon after the creation of PNG in 1995, the need was felt for a set of -pnmtopng / pngtopnm utilities. Independantly Alexander Lehmann and I -(Willem van Schaik) started such a project. Luckily we discovered this -and merged the two together into pnmtopng.tar.gz, which is available -from a/o ftp://swrinde.nde.swri.edu/pub/png/. - -These two utilities have many, many options and make use of most of the -features of PNG, like gamma, alpha, sbit, text-chunks, etc. This makes -the utilities quite complex and by now not anymore very maintainable. -When we wrote these programs, libpng was still in an early stage. -Therefore, lots of the functionality that we put in our software can now -be done using transform-functions in libpng. - -Finally, to compile these programs, you need to have installed and -compiled three libraries: libpng, zlib and netpbm. Especially the latter -makes the whole setup a bit bulky. But that's unavoidable given the many -features of pnmtopng. - - -What now --------- -At this moment libpng is in a very stable state and can do much of the -work done in pnmtopng. Also, pnmtopng needs to be upgraded to the new -interface of libpng. Hence, it is time for a rewrite from the ground up -of pnmtopng and pngtopnm. This will happen in the near future (stay -tuned). The new package will get a different name to distinguish it from -the old one: PngPlus. - -To experiment a bit with the new interface of libpng, I started off with -a small prototype that contains only the basic functionality. It doesn't -have any of the options to read or write special chunks and it will do -no gamma correction. But this makes it also a simple program that is -quite easy to understand and can serve well as a template for other -software developments. (By now there are of course a couple of programs, -like Greg Roelofs' rpng/wpng, that can be used just as good.) - - -Can and can not ---------------- -As this is the small brother of the future PngPlus, I called this fellow -PngMinus. Because I started this development in good-old Turbo-C, I -avoided the use the netpbm library, which requires DOS extenders. Again, -another reason to call it PngMinus (minus netpbm :-). So, part of the -program are some elementary routines to read / write pgm- and ppm-files. -It does not read b&w pbm-files. - -The downside of this approach is that you can not use them on images -that require blocks of memory bigger than 64k (the DOS version). For -larger images you will get an out-of-memory error. - -As said before, PngMinus doesn't correct for gamma. When reading -png-files you can do this just as well by piping the output of png2pnm -to pnmgamma, one of the standard PbmPlus tools. This same scenario will -most probably also be followed in the full-blown future PngPlus, with -the addition of course of the possibility to create gamma-chunks when -writing png-files. - -On the other hand it supports alpha-channels. When reading a png-image -you can write the alpha-channel into a pgm-file. And when creating an -RGB+A png-image, you just combine a ppm-file with a corresponding -pgm-file containing the alpha-channel. When reading, transparency chunks -are converted into an alpha-channel and from there on treated the same -way. - -Finally you can opt for writing ascii or binary pgm- and ppm-files. When -the bit-depth is 16, the format will always be ascii. - - -Using it --------- -To distinguish them from pnmtopng and PngPlus, the utilities are named -png2pnm and pnm2png (2 instead of to). The input- and output-files can -be given as parameters or through redirection. Therefore the programs -can be part of a pipe. - -To list the options type "png2pnm -h" or "pnm2png -h". - - -Just like Scandinavian furniture --------------------------------- -You have to put it together yourself. I did test the software under -MS-DOS with Turbo-C 3.0 and under RedHat Linux 4.2 with gcc. In both -cases I used libpng-1.0.4 and zlib-1.1.3. Later versions should be OK, -however some older libpng versions have a bug in pngmem.c when using -Turbo-C 3.0 (see below). - -You can build it using one of the two makefiles (make -f makefile.###) -or use the batch/script files pngminus.bat / pngminus.sh. This assumes -that you have built the libraries in ../libpng and ../zlib. Using Linux, -make sure that you have built libpng with makefile.std and not -makefile.linux (also called .lnx in earlier versions of libpng). The -latter creates a .so shared-library, while the PngMinus makefile assumes -a normal .a static library. - -If you create a ../pngsuite directory and then store the basn####.png -files from PngSuite (http://www.schaik.com/pngsuite/) in there, you can -test in one go the proper functioning of PngMinus, see png2pnm.bat and -pnm2png.bat (or the .sh versions). - - -Warranty -------- -Please, remember that this was just a small experiment to learn a few -things. It will have many unforeseen features . Who said bugs? Use -it when you are in need for something simple or when you want to start -developing your own stuff. - - -The Turbo bug -------------- -** pngmem.old - hptr = (png_byte huge *)((long)(hptr) & 0xfffffff0L); - hptr += 16L; -** pngmem.c - hptr = (png_byte huge *)((long)(hptr) & 0xfffffff0L); - hptr = hptr + 16L; -** - -** pngmem.old - png_ptr->offset_table_ptr[i] = (png_bytep)hptr; - hptr += (png_uint_32)65536L; -** pngmem.c - png_ptr->offset_table_ptr[i] = (png_bytep)hptr; - hptr = hptr + 65536L; -** - - -The end -------- -Willem van Schaik -mailto:willem@schaik.com -http://www.schaik.com/png/ -------- -Oct 1999 -