pixel-buffer: Fix overflow in blend_two_pixel_values

It was using 16bit types to hold the intermiediate
results of the blend, but for high intensity,
low opacity input values it could need up to
17 bits to prevent overflow.

https://bugs.freedesktop.org/show_bug.cgi?id=33129

diff --git a/src/libply-splash-core/ply-pixel-buffer.c b/src/libply-splash-core/ply-pixel-buffer.c
index 038601e65621fd13133ec0d6a08e3920b47a8e29..a612990a58a50604216ba4346e4ba02ab122c179 100644 (file)
--- a/src/libply-splash-core/ply-pixel-buffer.c
+++ b/src/libply-splash-core/ply-pixel-buffer.c
@@ -65,7 +65,7 @@ blend_two_pixel_values (uint32_t pixel_value_1,
     {
       uint8_t alpha_1, red_1, green_1, blue_1;
       uint8_t red_2, green_2, blue_2;
-      uint_least16_t red, green, blue;
+      uint_least32_t red, green, blue;
 
       alpha_1 = (uint8_t) (pixel_value_1 >> 24);
       red_1 = (uint8_t) (pixel_value_1 >> 16);