png_set_background_fixed 1457 3rdparty/libpng/png.h PNG_FIXED_EXPORT(215, void, png_set_background_fixed, (png_structp png_ptr,
png_set_background_fixed  129 3rdparty/libpng/pngrtran.c    png_set_background_fixed(png_ptr, background_color, background_gamma_code,