On 9 Nov 2008, at 10:57, Fabien Costantini wrote: > IMHO, what we should do is : > - Getting these png flags forced to yes when localpng is on as > Ian does, > this implies that we figure out why one of it has been forced to no > in configure.in when localpng is set to yes, because it may > hide some trouble (?). Anyway, testing will help.
I'm looking into this now. > - We should not force this flags when using a system lib. > Al is right that it seems to work for long in fltk2 without > checking that flags, but ; unless it is obsoleted by the PNG team > itself, we should care about these flags. I.e. It could happen that > they decide to use it differently in future lib implementations. These flags are fltk specific, they are not part of PNG per se. They were added at some point in our past to discriminate between early variants of libpng that did not support png_set_tRNS_to_alpha stuff. AFAIK all the "recent" libpng versions seem to. The flags are used exactly once in the code, at line 116 of Fl_PNG_Image.cxx. They are both used together, never apart (so only one flag is actually logically required, but *both* must be set to make it work...) The alternative fix, then, might be just to remove the flags altogether, if we assume they are always "true" with any recent PNG lib. This seems to be what fltk-2 does. IIRC the fltk-2 configure script does test for these flags (with the same bugs as the fltk-1 tests) but the fltk-2 code does not use these flags at all, so it Just Works. _______________________________________________ fltk-dev mailing list [email protected] http://lists.easysw.com/mailman/listinfo/fltk-dev
