from pngwrite.c

(Contributed by Philip Lowman)

in png_handle_sPLT().

to check info_ptr members instead of the contents of the returned parameters.

to add a test for user passing a 16-bit height varible to png_get_IHDR()
which causes an overflow into the high bytes of the width variable.

and mentioned use of 2-space indentation in macro definitions in
the libpng style guide.

to eliminate bogus complaint about filter_type.

in png_set_gAMA_and_cHRM() where we supply the cHRM constants and
therefore we know they are OK.

Move redundant IHDR checking into new png_check_IHDR() in png.c
and report all errors found in the IHDR data.  Report problems
with width and height separately.

and revised libpng style to mention not using the TAB character.

to avoid compiler complaints about doubly declaring things "const".

about fixing the "#if def " bug

to give Dennis Gustafsson credit for noticing the incorrect typecast
of "filler".

and always use png_calloc().  The macros were only there for testing,
since libpng-1.4.0beta48 and no problems have been reported.

Always use local arrays, which has been the default behavior
for a long time.

instead of memset to zero in png_read_png().

They were only useful for obtaining compatibility for old applications
that used libpng-1.0.x versions prior to the implementation of "free_me".

It does not seem to promise any benefit to libpng.

To try this, configure libpng using PNG_USE_MEMSET_LOOP.  Initial testing
with pngcrush was not promising, although it does save a hundred bytes or
so of executable size.