The LOW_MEMORY PNG_COMPRESSION option should not be setting HUFFMAN_ONLY or
using a low deflate 'level'; according to the comments in zconf.h only
windowBits and memLevel affect the memory. pngwutil.c has been changed to use
the same values as HIGH compression.
The COMPAT option turned on the old optimize_cmf code (now in fix_cinfo),
however there was a serious bug in that code; it put the wrong value in z_cmf.
The setting was also not handled correctly in pz_compression_settings.
pngtest now verifies the operation of COMPAT and, as a result, pngtest.png has
been reverted to the libpng 1.6 (etc) version.
IDAT size handling has been improved; if not explicitly set values appropriate
to png_level are now chosen (in addition to the handling for the COMPAT
setting). HIGH and HIGH_READ_SPEED now create unlimited size IDAT chunks, which
requires buffering the whole of the IDAT data in memory but reflects what other
programs and optimizers do.
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settings and most of the old compression control ABIs have been replaced by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>
Palette index checking: checking on read was erroneously skipped. pngcp can now
turn off the palette index checking or fix the errors (mainly to allow
comparison with libpng 1.6, which defaulted to ignoring it). The API now
documents how the 'enabled' parameter works. On read the check is on by default
(it was apparently off in libpng 1.6) however now if explicitly turned on the
warning message is stopped, this provides better interaction with
get_palette_max at the cost of a small API change (may need to be reviewed.)
Palette size errors: invalid entries in the palette are now set to #beaded to
make the errors more obvious and allow easy detection in memory.
Read transform pipeline caching: changes to fix the palette index check (which
are erroneously cached), the pipeline can now contain multiple caches. E.g.
caching of packing of palette indices can be combined with caching of palette
RGB transforms.
Read code now checks for callbacks to read 0 data (and faults them). Fixed the
reading of PNGs with multiple 0 length IDATs that failed as a result plus the
handling of zero length unknown. (Which occurs, validly; the spurious warning
has been removed).
filter selection: the 1.6 and earlier sum of absolute differences algorithm has
been reintroduced with an option to disfavor some filters over others where the
sums are close (not yet exposed). The selection code also logs the last known
occurence of each possible byte code across multiple lines. This allows
detection of PNG images with lower bit depth than the format implies and,
therefore, allows the filtering to be turned off in those cases as well.
The default write zlib settings are still lower than libpng16. The selection
algorithm is being refined (the overall results are worse than not doing any
filtering).
Signed-off-by: John Bowler <jbowler@acm.org>
This implements the code for row-by-row filter selection but does not provide an
actual implementation; the selection function just chooses the lowest set filter
bit.
Signed-off-by: John Bowler <jbowler@acm.org>
A debug() assert fired if windowBits was set to 8 for the Huffman only and
no-compression cases. This commit changes it to do some extra checking. Remove
unreachable code in pz_default_settings, eliminate a spurious warning in pngcp
for small files.
Signed-off-by: John Bowler <jbowler@acm.org>
Implemented better defaulting of zlib settings based on image properties.
Implemented pass-through of png_write_rows when the rows can be used directly (a
common case) optimizing the handling of previous-row buffering.
Removed the METHODICAL filter selection method and disabled the HEURISTIC one;
the first was ridiculously slow (though useful for experiments) the second
doesn't work. Filter selection is temporarily disabled (it defaults to the
lowest numbered filter in the list; typically 'none').
New handling of compression settings (incomplete), new PNG compression level
(not yet visible in an API).
Back ported 'PNG_FAST_FILTERS' from 1.6 (in png.h).
There are minimal API changes beyond removal of the selection options. Work is
still to be done to investigate a filter selection mechanism that is at least as
good as the previous one.
Signed-off-by: John Bowler <jbowler@acm.org>
Batched fixes from libpng16: PNG_IMAGE_PNG_SIZE_MAX macro fix, contrib/libtests
exit(77) change to just do that for configure and changes to pngstest to
(by default) make random backgrounds on a per-file, not per-session, basis.
Signed-off-by: John Bowler <jbowler@acm.org>
This is an API change for 1.7, albeit a quiet one; it may produce compiler
warnings but should not result in errors, unless warnings are treated as errors.
On 64-bit systems it widens the results of the various PNG_IMAGE_ macros that
return size values (component counts, byte sizes) to 64 bits. It also changes
the row_stride parameter, which is the pointer difference between adjacent rows
of the image buffer, to ptrdiff_t which is the ANSI-C90 defined type of the
difference of two pointers. The existing (1.6.22) checks for overflow are
preserved but now accomdate images that require more than 32 bits of address
space when size_t/ptrdiff_t are 64 bit types.
Signed-off-by: John Bowler <jbowler@acm.org>
This implements an API and provides a number of assist macros to allow an
application which uses the simplified API write to bypass stdio and write
directly to memory.
It also includes some warnings (png.h) and some check code to detect *possible*
overflow in the ROW_STRIDE and simplified image SIZE macros. This disallows
image width/height/format that *might* overflow. A quiet API change that limits
in-memory image size (uncompressed) to less that 4GByte and image row size
(stride) to less than 2GByte.
Signed-off-by: John Bowler <jbowler@acm.org>
The sequential read code failed to read to the end of the IDAT stream in about
1/820 cases, resulting in a spurious warning. The
png_set_compression_buffer_size API also would not work (or do bad things) if
the size of a zlib uInt was less than 32 bits.
This includes a quiet API change to alter png_set_compression_buffer_size to use
a png_alloc_size_t, not png_size_t and implement the correct checks.
Signed-off-by: John Bowler <jbowler@acm.org>
The handling of tIME and text chunks on read now records the location of the
chunks relative to PLTE and IDAT. Behavior on write is unchanged except that if
the position was recorded on read it will be re-used.
This involves an ABI change to the png_text_struct; a one byte location field is
added (with the same meaning as the one used to record unknown chunk location.)
Because this field is only used on read there is no API change unless a png_info
from a libpng read is passed to a subsequent libpng write (this did not work
very well before 1.7; the tIME chunk could get duplicated.)
png_set_text ignores the new field, resetting it to the current position in the
read or write stream. On write the position is set to the next location to be
written unless the write has not started (the position is before the signature)
in which case the location is set to PNG_HAVE_PLTE|PNG_AFTER_IDAT. When the
chunk is written the position is set to the actual write location (effectively
the position is frozen.)
Signed-off-by: John Bowler <jbowler@acm.org>
The filter selection options are made more intuitive (IMO, but I am not an
Intuitive User). Dummy code added for methodical filter selection.
Signed-off-by: John Bowler <jbowler@acm.org>
This implements the heuristic part of filter selction, the methodic testing
approach is still not implemented. png_set_option methods are incomplete.
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>
