From ae0b7c4466f32a6ff1d3ead57cecf8b2bd14e2d8 Mon Sep 17 00:00:00 2001
From: Sam Lantinga <slouken@libsdl.org>
Date: Thu, 26 Dec 2024 12:28:58 -0800
Subject: [PATCH] Expand PNG_COLOR_TYPE_GRAY_ALPHA to RGBA

Fixes https://github.com/libsdl-org/SDL_image/issues/494
---
 src/IMG_png.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/src/IMG_png.c b/src/IMG_png.c
index 6947be39..c667b90a 100644
--- a/src/IMG_png.c
+++ b/src/IMG_png.c
@@ -306,8 +306,11 @@ static void LIBPNG_LoadPNG_IO(SDL_IOStream *src, struct loadpng_vars *vars)
     lib.png_set_packing(vars->png_ptr);
 
     /* scale greyscale values to the range 0..255 */
-    if (color_type == PNG_COLOR_TYPE_GRAY)
+    if (color_type == PNG_COLOR_TYPE_GRAY) {
         lib.png_set_expand(vars->png_ptr);
+    } else if (color_type == PNG_COLOR_TYPE_GRAY_ALPHA) {
+        lib.png_set_gray_to_rgb(vars->png_ptr);
+    }
 
     /* For images with a single "transparent colour", set colour key;
        if more than one index has transparency, or if partially transparent