Libpng 1.5.3beta06 - May 6, 2011

This is not intended to be a public release.  It will be replaced
within a few weeks by a public version or by another test version.

Files available for download:

Source files with LF line endings (for Unix/Linux) and with a
"configure" script

   1.5.3beta06.tar.xz (LZMA-compressed, recommended)
   1.5.3beta06.tar.gz
   1.5.3beta06.tar.bz2

Source files with CRLF line endings (for Windows), without the
"configure" script

   lp153b06.7z  (LZMA-compressed, recommended)
   lp153b06.zip

Other information:

   1.5.3beta06-README.txt
   1.5.3beta06-LICENSE.txt

Changes since the last public release (1.5.2):

Version 1.5.3beta01 [April 1, 2011]
  Re-initialize the zlib compressor before compressing non-IDAT chunks.
  Added API functions to set parameters for zlib compression of non-IDAT
    chunks.

Version 1.5.3beta02 [April 3, 2011]
  Updated scripts/symbols.def with new API functions.
  Only compile the new zlib re-initializing code when text or iCCP is
    supported, using PNG_WRITE_COMPRESSED_TEXT_SUPPORTED macro.
  Improved the optimization of the zlib CMF byte (see libpng-1.2.6beta03).
  Optimize the zlib CMF byte in non-IDAT compressed chunks

Version 1.5.3beta03 [April 16, 2011]
  Fixed gcc -ansi -pedantic compile. A strict ANSI system does not have
    snprintf, and the "__STRICT_ANSI__" detects that condition more reliably
    than __STDC__ (John Bowler).
  Removed the PNG_PTR_NORETURN attribute because it too dangerous. It tells
    the compiler that a user supplied callback (the error handler) does not
    return, yet there is no guarantee in practice that the application code
    will correctly implement the error handler because the compiler only
    issues a warning if there is a mistake (John Bowler).
  Removed the no-longer-used PNG_DEPSTRUCT macro.
  Updated the zlib version to 1.2.5 in the VStudio project.
  Fixed 64-bit builds where png_uint_32 is smaller than png_size_t in
    pngwutil.c (John Bowler).
  Fixed bug with stripping the filler or alpha channel when writing, that
    was introduced in libpng-1.5.2beta01 (bug report by Andrew Church).

Version 1.5.3beta04 [April 27, 2011]
  Updated pngtest.png with the new zlib CMF optimization.
  Cleaned up conditional compilation code and of background/gamma handling
    Internal changes only except a new option to avoid compiling the
    png_build_grayscale_palette API (which is not used at all internally.)
    The main change is to move the transform tests (READ_TRANSFORMS,
    WRITE_TRANSFORMS) up one level to the caller of the APIs.  This avoids
    calls to spurious functions if all transforms are disabled and slightly
    simplifies those functions.  Pngvalid modified to handle this.
    A minor change is to stop the strip_16 and expand_16 interfaces from
    disabling each other; this allows the future alpha premultiplication
    code to use 16-bit intermediate values while still producing 8-bit output.
    png_do_background and png_do_gamma have been simplified to take a single
    pointer to the png_struct rather than pointers to every item required
    from the png_struct. This makes no practical difference to the internal
    code.
  A serious bug in the pngvalid internal routine 'standard_display_init' has
    been fixed - this failed to initialize the red channel and accidentally
    initialized the alpha channel twice.
  Changed png_struct jmp_buf member name from png_jmpbuf to tmp_jmpbuf to
    avoid a clash with the png_jmpbuf macro on some platforms.

Version 1.5.3beta05 [May 6, 2011]
  Added appropriate feature test macros to ensure libpng sees the correct API
   _POSIX_SOURCE is defined in pngpriv.h, pngtest.c and pngvalid.c to ensure
    that POSIX conformant systems disable non-POSIX APIs.  _ISOC99_SOURCE is
    defined in pngpriv.h to obtain the ISO C99 snprintf definition, when
    available.
  Removed png_snprintf and added formatted warning messages.  This change adds
    internal APIs to allow png_warning messages to have parameters without
    requiring the host OS to implement snprintf.  As a side effect the
    dependency of the tIME-supporting RFC1132 code on stdio is removed and
    PNG_NO_WARNINGS does actually work now.
  Added PNG_WRITE_OPTIMIZE_CMF_SUPPORTED macro to make the zlib "CMF" byte
    optimization configureable.
  IDAT compression failed if preceded by a compressed text chunk (bug
    introduced in libpng-1.5.3beta01-02).  This was because the attempt to
    reset the zlib stream in png_write_IDAT happened after the first IDAT
    chunk had been deflated - much too late.  In this change internal
    functions were added to claim/release the z_stream and, hopefully, make
    the code more robust.  Also deflateEnd checking is added - previously
    libpng would ignore an error at the end of the stream.

Version 1.5.3beta06 [May 6, 2011]

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Glenn R-P