[gtk/modern-testsuite: 7/23] reftests: Make diff pixels always opaque

[Benjamin Otte <otte src gnome org>]

commit 3a8ec683d3477a1f914b9c7fec427b323249179a
Author: Benjamin Otte <otte redhat com>
Date:   Wed Sep 15 16:39:09 2021 +0200

    reftests: Make diff pixels always opaque
    
    We had pixels that did not differ in alpha and we then set 0 alpha
    difference hich made the pixel invisible. Oops.

 testsuite/reftests/reftest-compare.c | 2 ++
 1 file changed, 2 insertions(+)
---
diff --git a/testsuite/reftests/reftest-compare.c b/testsuite/reftests/reftest-compare.c
index 5bccb697b8..a24ab337a6 100644
--- a/testsuite/reftests/reftest-compare.c
+++ b/testsuite/reftests/reftest-compare.c
@@ -143,6 +143,8 @@ buffer_diff_core (const guchar *buf_a,
               guint8 alpha = diff_pixel >> 24;
               diff_pixel = alpha * 0x010101;
             }
+          /* make the pixel fully opaque */
+          diff_pixel |= 0xff000000;
           
           row[x] = diff_pixel;
       }