Hi, Greg > o png alpha channel and BGR handling > There is currently alpha channel support in > 0.92RC2 that should work. However, there > isn't support for conversion to BGR format. > Is this to guarantee quick drawing the > GdDrawImage routine, or for another reason? > I would like a sample .png for testing. image_png.c:GdDecodePNG() has some inconsistent part. ( it works well, but inconsistent. ) In spite of MWIMAGEHDR that returned from image_png.c:GdDecodePNG() has RGB RGB RGB ..., MWIMAGEHDR's compression field has not MWIMAGE_RGB flag.( only if alpha channel exist.) I attach modified diff file. -------------------------------------------------------------------------- Hi, yut616 > [TAO] this png is 24bit, but with "tRNS Transparency" > This is related to the libpng, just a special case for 24bit png (IHDR > Bitdepth: 8 ). > refer: > http://www.libpng.org/pub/png/spec/1.1/png-1.1.pdf > 4.2.12 tRNS Transparency > According to PNG_EXPAND_tRNS to build in an alpha channel using trans_value. > When the RGB is same as trans_value's RGB, it will set ALPHA to 0, otherwise > it will set 0xFF. > ====================== > libpng-1.2.14/pngrtran.c > png_do_expand() > (row_info->color_type == PNG_COLOR_TYPE_RGB && trans_value) > ====================== I guess that 0.92RC2 do support that. I think that the following code work for that. ( image_png.c:GdDecodePNG() ) ============================================ if (png_get_valid(state, pnginfo, PNG_INFO_tRNS)) // if 'trans_value' exist, then this condition is true. png_set_tRNS_to_alpha(state); ============================================ But, I am not sure. Can you suggest some sample png? Regards.
git-vs-sjbyun-20100226.diff.tar.gz
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