png_set_bKGD     2335 third_party/libpng/png.h extern PNG_EXPORT(void,png_set_bKGD) PNGARG((png_structp png_ptr,
png_set_bKGD     1511 third_party/libpng/pngrutil.c    png_set_bKGD(png_ptr, info_ptr, &(png_ptr->background));