"Fossies" - the Fresh Open Source Software Archive

Member "firefox-69.0.1/media/libpng/README" (17 Sep 2019, 9392 Bytes) of package /linux/www/firefox-69.0.1.source.tar.xz:


As a special service "Fossies" has tried to format the requested text file into HTML format (style: standard) with prefixed line numbers. Alternatively you can here view or download the uninterpreted source code file. See also the last Fossies "Diffs" side-by-side code changes reports for "README": 60.7.2_vs_68.0 or 67.0.4_vs_68.0.

    1 README for libpng version 1.6.37 - April 14, 2019
    2 =================================================
    3 
    4 See the note about version numbers near the top of png.h.
    5 See INSTALL for instructions on how to install libpng.
    6 
    7 Libpng comes in several distribution formats.  Get libpng-*.tar.gz or
    8 libpng-*.tar.xz or if you want UNIX-style line endings in the text
    9 files, or lpng*.7z or lpng*.zip if you want DOS-style line endings.
   10 
   11 Version 0.89 was the first official release of libpng.  Don't let the
   12 fact that it's the first release fool you.  The libpng library has been
   13 in extensive use and testing since mid-1995.  By late 1997 it had
   14 finally gotten to the stage where there hadn't been significant
   15 changes to the API in some time, and people have a bad feeling about
   16 libraries with versions < 1.0.  Version 1.0.0 was released in
   17 March 1998.
   18 
   19 ****
   20 Note that some of the changes to the png_info structure render this
   21 version of the library binary incompatible with libpng-0.89 or
   22 earlier versions if you are using a shared library.  The type of the
   23 "filler" parameter for png_set_filler() has changed from png_byte to
   24 png_uint_32, which will affect shared-library applications that use
   25 this function.
   26 
   27 To avoid problems with changes to the internals of the png info_struct,
   28 new APIs have been made available in 0.95 to avoid direct application
   29 access to info_ptr.  These functions are the png_set_<chunk> and
   30 png_get_<chunk> functions.  These functions should be used when
   31 accessing/storing the info_struct data, rather than manipulating it
   32 directly, to avoid such problems in the future.
   33 
   34 It is important to note that the APIs did not make current programs
   35 that access the info struct directly incompatible with the new
   36 library, through libpng-1.2.x.  In libpng-1.4.x, which was meant to
   37 be a transitional release, members of the png_struct and the
   38 info_struct can still be accessed, but the compiler will issue a
   39 warning about deprecated usage.  Since libpng-1.5.0, direct access
   40 to these structs is not allowed, and the definitions of the structs
   41 reside in private pngstruct.h and pnginfo.h header files that are not
   42 accessible to applications.  It is strongly suggested that new
   43 programs use the new APIs (as shown in example.c and pngtest.c), and
   44 older programs be converted to the new format, to facilitate upgrades
   45 in the future.
   46 ****
   47 
   48 Additions since 0.90 include the ability to compile libpng as a
   49 Windows DLL, and new APIs for accessing data in the info struct.
   50 Experimental functions include the ability to set weighting and cost
   51 factors for row filter selection, direct reads of integers from buffers
   52 on big-endian processors that support misaligned data access, faster
   53 methods of doing alpha composition, and more accurate 16->8 bit color
   54 conversion.
   55 
   56 The additions since 0.89 include the ability to read from a PNG stream
   57 which has had some (or all) of the signature bytes read by the calling
   58 application.  This also allows the reading of embedded PNG streams that
   59 do not have the PNG file signature.  As well, it is now possible to set
   60 the library action on the detection of chunk CRC errors.  It is possible
   61 to set different actions based on whether the CRC error occurred in a
   62 critical or an ancillary chunk.
   63 
   64 For a detailed description on using libpng, read libpng-manual.txt.
   65 For examples of libpng in a program, see example.c and pngtest.c.  For
   66 usage information and restrictions (what little they are) on libpng,
   67 see png.h.  For a description on using zlib (the compression library
   68 used by libpng) and zlib's restrictions, see zlib.h
   69 
   70 I have included a general makefile, as well as several machine and
   71 compiler specific ones, but you may have to modify one for your own
   72 needs.
   73 
   74 You should use zlib 1.0.4 or later to run this, but it MAY work with
   75 versions as old as zlib 0.95.  Even so, there are bugs in older zlib
   76 versions which can cause the output of invalid compression streams for
   77 some images.
   78 
   79 You should also note that zlib is a compression library that is useful
   80 for more things than just PNG files.  You can use zlib as a drop-in
   81 replacement for fread() and fwrite(), if you are so inclined.
   82 
   83 zlib should be available at the same place that libpng is, or at
   84 https://zlib.net.
   85 
   86 You may also want a copy of the PNG specification.  It is available
   87 as an RFC, a W3C Recommendation, and an ISO/IEC Standard.  You can find
   88 these at http://www.libpng.org/pub/png/pngdocs.html .
   89 
   90 This code is currently being archived at libpng.sourceforge.io in the
   91 [DOWNLOAD] area, and at http://libpng.download/src .
   92 
   93 This release, based in a large way on Glenn's, Guy's and Andreas'
   94 earlier work, was created and will be supported by myself and the PNG
   95 development group.
   96 
   97 Send comments/corrections/commendations to png-mng-implement at
   98 lists.sourceforge.net (subscription required; visit
   99 https://lists.sourceforge.net/lists/listinfo/png-mng-implement
  100 to subscribe).
  101 
  102 Send general questions about the PNG specification to png-mng-misc
  103 at lists.sourceforge.net (subscription required; visit
  104 https://lists.sourceforge.net/lists/listinfo/png-mng-misc to
  105 subscribe).
  106 
  107 Files in this distribution:
  108 
  109       ANNOUNCE      =>  Announcement of this version, with recent changes
  110       AUTHORS       =>  List of contributing authors
  111       CHANGES       =>  Description of changes between libpng versions
  112       KNOWNBUG      =>  List of known bugs and deficiencies
  113       LICENSE       =>  License to use and redistribute libpng
  114       README        =>  This file
  115       TODO          =>  Things not implemented in the current library
  116       TRADEMARK     =>  Trademark information
  117       example.c     =>  Example code for using libpng functions
  118       libpng.3      =>  manual page for libpng (includes libpng-manual.txt)
  119       libpng-manual.txt  =>  Description of libpng and its functions
  120       libpngpf.3    =>  manual page for libpng's private functions
  121       png.5         =>  manual page for the PNG format
  122       png.c         =>  Basic interface functions common to library
  123       png.h         =>  Library function and interface declarations (public)
  124       pngpriv.h     =>  Library function and interface declarations (private)
  125       pngconf.h     =>  System specific library configuration (public)
  126       pngstruct.h   =>  png_struct declaration (private)
  127       pnginfo.h     =>  png_info struct declaration (private)
  128       pngdebug.h    =>  debugging macros (private)
  129       pngerror.c    =>  Error/warning message I/O functions
  130       pngget.c      =>  Functions for retrieving info from struct
  131       pngmem.c      =>  Memory handling functions
  132       pngbar.png    =>  PNG logo, 88x31
  133       pngnow.png    =>  PNG logo, 98x31
  134       pngpread.c    =>  Progressive reading functions
  135       pngread.c     =>  Read data/helper high-level functions
  136       pngrio.c      =>  Lowest-level data read I/O functions
  137       pngrtran.c    =>  Read data transformation functions
  138       pngrutil.c    =>  Read data utility functions
  139       pngset.c      =>  Functions for storing data into the info_struct
  140       pngtest.c     =>  Library test program
  141       pngtest.png   =>  Library test sample image
  142       pngtrans.c    =>  Common data transformation functions
  143       pngwio.c      =>  Lowest-level write I/O functions
  144       pngwrite.c    =>  High-level write functions
  145       pngwtran.c    =>  Write data transformations
  146       pngwutil.c    =>  Write utility functions
  147       arm           =>  Contains optimized code for the ARM platform
  148       powerpc       =>  Contains optimized code for the PowerPC platform
  149       contrib       =>  Contributions
  150        arm-neon         =>  Optimized code for ARM-NEON platform
  151        powerpc-vsx      =>  Optimized code for POWERPC-VSX platform
  152        examples         =>  Example programs
  153        gregbook         =>  source code for PNG reading and writing, from
  154                             Greg Roelofs' "PNG: The Definitive Guide",
  155                             O'Reilly, 1999
  156        libtests         =>  Test programs
  157        mips-msa         =>  Optimized code for MIPS-MSA platform
  158        pngminim         =>  Minimal decoder, encoder, and progressive decoder
  159                             programs demonstrating use of pngusr.dfa
  160        pngminus         =>  Simple pnm2png and png2pnm programs
  161        pngsuite         =>  Test images
  162        testpngs
  163        tools            =>  Various tools
  164        visupng          =>  Contains a MSVC workspace for VisualPng
  165       intel             =>  Optimized code for INTEL-SSE2 platform
  166       mips              =>  Optimized code for MIPS platform
  167       projects      =>  Contains project files and workspaces for
  168                         building a DLL
  169        owatcom          =>  Contains a WATCOM project for building libpng
  170        visualc71        =>  Contains a Microsoft Visual C++ (MSVC)
  171                             workspace for building libpng and zlib
  172        vstudio          =>  Contains a Microsoft Visual C++ (MSVC)
  173                             workspace for building libpng and zlib
  174       scripts       =>  Directory containing scripts for building libpng:
  175                             (see scripts/README.txt for the list of scripts)
  176 
  177 Good luck, and happy coding!
  178 
  179  * Cosmin Truta (current maintainer, since 2018)
  180  * Glenn Randers-Pehrson (former maintainer, 1998-2018)
  181  * Andreas Eric Dilger (former maintainer, 1996-1997)
  182  * Guy Eric Schalnat (original author and former maintainer, 1995-1996)
  183    (formerly of Group 42, Inc.)