diff options
| -rw-r--r-- | converter/other/pngx.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/converter/other/pngx.c b/converter/other/pngx.c index dfc74485..b96857e9 100644 --- a/converter/other/pngx.c +++ b/converter/other/pngx.c @@ -467,6 +467,15 @@ pngx_setIhdr(struct pngx * const pngxP, void pngx_setInterlaceHandling(struct pngx * const pngxP) { + /* It isn't clear what this does. The documentation is contradictory, + saying in some places that it gets the number of passes required. and + in others that it sets the interlacing scheme. In practice, whether + the compressor generates an interlaced image or not appears to be + controlled by png_set_IHDR and unaffected by this. + + Also, documentation says this returns 7 if the compressor is + interlacing, but it always returns 1 in practice. + */ pngxP->numPassesRequired = png_set_interlace_handling(pngxP->png_ptr); } |