Corrections for the pngcp minimal configuration in libpng 1.7 and corrections to
the libpng 1.7 code to fix bugs revealed by the reduced configuration.
Signed-off-by: John Bowler <jbowler@acm.org>
Simplified API: change handling of PNG_IMAGE_FLAG_FAST to use
PNG_COMPRESSION_HIGH_SPEED, and PNG_COMPRESSION_HIGH otherwise.
Compression: add missing break statements that caused some compression settings
to fall through to the 'HIGH' setting.
Internal: remove png_struct::flags, it only stored the 'library mismatch' flag
and that could never be accessed (because immediately after it was set the
png_struct, which was on the stack, was eliminated.)
Signed-off-by: John Bowler <jbowler@acm.org>
PNG compression level setting API: this allows the various compression settings
controlling deflate, fitlering, and so on to be set via a single setting with
six values. This is currently documented in png.h ("Write compression
settings").
Internally the compression settings have been tuned both for the overall setting
and for any specific settings made by the original APIs.
APIs to control iCCP chunk compression separately have been added.
contrib/examples/pngcp.c has been modified to accomodate the new compression
setting and to include options for separate control of iCCP chunk compression.
The new ABI, png_setting, has been modified to accomodate a wider range of
settings and most of the old compression control ABIs have been replaced by
function-like macros with the same API which call png_setting. This is an API
check in 1.7.0 for png_setting (alone). png_setting now handles all of
png_set_option. This eliminates 19 ABIs at the cost of adding 1 (png_setting).
CRC and benign error checking has been updated internally to use bit-fields and
the CRC calculation skip when the CRC is not used has been improved slightly to
avoid the initialization of the CRC. A new png_setting based API allows more
detailed control of benign error/warning messages (this may change, the internal
error handling seems too complex.) The ERROR_NUMBERS support has been removed
with the intent of implementing proper i18n.
The memcpy-size-0 issue in png_push_fill_buffer has been fixed, with an
appropriate debug() assert if a fill for 0 bytes occurs.
Most PNG_FLAG_ values for png_struct::flags have been eliminated (as a result of
the benign error handling changes). Only one remains.
Signed-off-by: John Bowler <jbowler@acm.org>
This rewrites the code used previously in the heuristics to make it easier to
debug and introduces the 'methodical' method, which is intended to be an
expensive but reliable way of reducing image size.
The code in this commit does not work; the 'methodical' test for success does
not take account of data buffered inside zlib and, anyway, it changes the
results of pngtest so that the test fails. This commit is just a checkpoint of
the current state; another commit will temporarily disable the 'methodical'
code.
Signed-off-by: John Bowler <jbowler@acm.org>
Unify the compression code so that inflate calls are localized to a common
routine. Ground work for filter selection support. Minor API changes to use
void* not byte* for data parameters. Unification of some of the compression
code with the decompression code; IDAT_size replaces IDAT_read_size and
zbuffer_size, IDAT reading and writing is no longer controlled by the size of
the compression buffer.
Signed-off-by: John Bowler <jbowler@acm.org>
This commit moves code round and changes the filter write interfaces that took
png_uint_32 buffer pixel counts to unsigned int. Also moves compression code
and definitions into pngwutil.c so that the compression code is isolated from
other definitions.
Signed-off-by: John Bowler <jbowler@acm.org>
