configurations don't build because of missing contrib/libtests test programs
and overly complex dependencies in scripts/pnglibconf.dfa. This change adds
contrib/conftest/*.dfa files that can be used in automatic build
scripts to ensure that these configurations continue to build.
requirements of png_modifier are greater than that of png_store and as a
consequence compilation of pngvalid.c results in a warning about increased
alignment requirements because of the bare cast to (png_modifier*). The code
is safe, because the pointer is known to point to a stack allocated
png_modifier, but this change avoids the warning.
Fixed default behavior of ARM_NEON_API. If the ARM NEON API option was
compiled without the CHECK option it defaulted to on, not off.
Check user callback behavior in pngunknown.c. Previous versions compiled
if SAVE_UNKNOWN was not available but did nothing since the callback
was never implemented.
Merged pngunknown.c with 1.7 version and back ported 1.7 improvements/fixes
READ_GAMMA. Prior to 1.6.0 switching off READ_GAMMA did unpredictable things
to the interfaces that use it (specifically, png_do_background in 1.4 would
simply display composite for grayscale images but do composition
with the incorrect arithmetic for color ones). In 1.6 the semantic
of -DPNG_NO_READ_GAMMA is changed to simply disable any interface that
depends on it; this obliges people who set it to consider whether they
really want it off if they happen to use any of the interfaces in
question (typically most users who disable it won't).
support. Now "make check" will succeed even if libpng is compiled with
-DPNG_NO_READ or -DPNG_NO_WRITE. The tests performed are reduced, but the
basic reading and writing of a PNG file is always tested by one or more of
the tests.
The compiler performs an optimization which is safe; however it then warns
about it. Changing the type of 'palette_number' in pngvalid.c removes the
warning.
compiler issues slightly different warnings from those issued by the
current vesions of GCC. This eliminates those warnings by
adding/removing casts and small code rewrites.
