From 5fbfd76293e7ce2d189e6742f0a957e538d76036 Mon Sep 17 00:00:00 2001 From: Leonardo Hernández Hernández Date: Fri, 14 Jun 2024 14:04:03 -0600 Subject: jxl: do alpha pre-multiplication manually some images does not render correctly if we rely in libjxl doing the pre-multiplication --- jxl.c | 25 ++++++++++++++++++++++--- 1 file changed, 22 insertions(+), 3 deletions(-) diff --git a/jxl.c b/jxl.c index 6c1ac4d..57dca49 100644 --- a/jxl.c +++ b/jxl.c @@ -68,9 +68,6 @@ jxl_load(FILE *fp, const char *path) JxlDecoderSetParallelRunner(decoder, JxlResizableParallelRunner, runner); #endif - /* pixman expects premultiplied alpha */ - JxlDecoderSetUnpremultiplyAlpha(decoder, JXL_FALSE); - JxlDecoderSubscribeEvents(decoder, JXL_DEC_BASIC_INFO | JXL_DEC_FULL_IMAGE); JxlDecoderSetInput(decoder, file_data, file_size); @@ -133,6 +130,28 @@ jxl_load(FILE *fp, const char *path) } } + for (uint32_t *abgr = (uint32_t *)image; + abgr < (uint32_t *)(image + (size_t)width * (size_t)height * 4); + abgr++) { + uint8_t alpha = (*abgr >> 24) & 0xff; + uint8_t red = (*abgr >> 16) & 0xff; + uint8_t green = (*abgr >> 8) & 0xff; + uint8_t blue = (*abgr >> 0) & 0xff; + + if (alpha == 0xff) + continue; + + if (alpha == 0x00) + blue = green = red = 0x00; + else { + blue = blue * alpha / 0xff; + green = green * alpha / 0xff; + red = red * alpha / 0xff; + } + + *abgr = (uint32_t)alpha << 24 | red << 16 | green << 8 | blue; + } + pix = pixman_image_create_bits_no_clear(format, width, height, (uint32_t *)image, stride); ok = pix != NULL; -- cgit v1.2.3