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libpng-1.6.17/libpng.3  view on Meta::CPAN

png.h and pngconf.h into a new pngpriv.h header file.

Functions png_set_benign_errors(), png_benign_error(), and
png_chunk_benign_error() were added.

Support for setting the maximum amount of memory that the application
will allocate for reading chunks was added, as a security measure.
The functions png_set_chunk_cache_max() and png_get_chunk_cache_max()
were added to the library.

We implemented support for I/O states by adding png_ptr member io_state
and functions png_get_io_chunk_name() and png_get_io_state() in pngget.c

We added PNG_TRANSFORM_GRAY_TO_RGB to the available high-level
input transforms.

Checking for and reporting of errors in the IHDR chunk is more thorough.

Support for global arrays was removed, to improve thread safety.

Some obsolete/deprecated macros and functions have been removed.

Typecasted NULL definitions such as
   #define png_voidp_NULL            (png_voidp)NULL
were eliminated.  If you used these in your application, just use
NULL instead.

The png_struct and info_struct members "trans" and "trans_values" were
changed to "trans_alpha" and "trans_color", respectively.

The obsolete, unused pnggccrd.c and pngvcrd.c files and related makefiles
were removed.

The PNG_1_0_X and PNG_1_2_X macros were eliminated.

The PNG_LEGACY_SUPPORTED macro was eliminated.

Many WIN32_WCE #ifdefs were removed.

The functions png_read_init(info_ptr), png_write_init(info_ptr),
png_info_init(info_ptr), png_read_destroy(), and png_write_destroy()
have been removed.  They have been deprecated since libpng-0.95.

The png_permit_empty_plte() was removed. It has been deprecated
since libpng-1.0.9.  Use png_permit_mng_features() instead.

We removed the obsolete stub functions png_get_mmx_flagmask(),
png_set_mmx_thresholds(), png_get_asm_flags(),
png_get_mmx_bitdepth_threshold(), png_get_mmx_rowbytes_threshold(),
png_set_asm_flags(), and png_mmx_supported()

We removed the obsolete png_check_sig(), png_memcpy_check(), and
png_memset_check() functions.  Instead use !png_sig_cmp(), memcpy(),
and memset(), respectively.

The function png_set_gray_1_2_4_to_8() was removed. It has been
deprecated since libpng-1.0.18 and 1.2.9, when it was replaced with
png_set_expand_gray_1_2_4_to_8() because the former function also
expanded any tRNS chunk to an alpha channel.

Macros for png_get_uint_16, png_get_uint_32, and png_get_int_32
were added and are used by default instead of the corresponding
functions. Unfortunately,
from libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
function) incorrectly returned a value of type png_uint_32.

We changed the prototype for png_malloc() from
    png_malloc(png_structp png_ptr, png_uint_32 size)
to
    png_malloc(png_structp png_ptr, png_alloc_size_t size)

This also applies to the prototype for the user replacement malloc_fn().

The png_calloc() function was added and is used in place of
of "png_malloc(); memset();" except in the case in png_read_png()
where the array consists of pointers; in this case a "for" loop is used
after the png_malloc() to set the pointers to NULL, to give robust.
behavior in case the application runs out of memory part-way through
the process.

We changed the prototypes of png_get_compression_buffer_size() and
png_set_compression_buffer_size() to work with png_size_t instead of
png_uint_32.

Support for numbered error messages was removed by default, since we
never got around to actually numbering the error messages. The function
png_set_strip_error_numbers() was removed from the library by default.

The png_zalloc() and png_zfree() functions are no longer exported.
The png_zalloc() function no longer zeroes out the memory that it
allocates.  Applications that called png_zalloc(png_ptr, number, size)
can call png_calloc(png_ptr, number*size) instead, and can call
png_free() instead of png_zfree().

Support for dithering was disabled by default in libpng-1.4.0, because
it has not been well tested and doesn't actually "dither".
The code was not
removed, however, and could be enabled by building libpng with
PNG_READ_DITHER_SUPPORTED defined.  In libpng-1.4.2, this support
was re-enabled, but the function was renamed png_set_quantize() to
reflect more accurately what it actually does.  At the same time,
the PNG_DITHER_[RED,GREEN_BLUE]_BITS macros were also renamed to
PNG_QUANTIZE_[RED,GREEN,BLUE]_BITS, and PNG_READ_DITHER_SUPPORTED
was renamed to PNG_READ_QUANTIZE_SUPPORTED.

We removed the trailing '.' from the warning and error messages.

.SH XI.  Changes to Libpng from version 1.4.x to 1.5.x

From libpng-1.4.0 until 1.4.4, the png_get_uint_16 macro (but not the
function) incorrectly returned a value of type png_uint_32.
The incorrect macro was removed from libpng-1.4.5.

Checking for invalid palette index on write was added at libpng
1.5.10.  If a pixel contains an invalid (out-of-range) index libpng issues
a benign error.  This is enabled by default because this condition is an
error according to the PNG specification, Clause 11.3.2, but the error can
be ignored in each png_ptr with

   png_set_check_for_invalid_index(png_ptr, allowed);