[gtk/clipboard-test: 2/2] Compare images as pixels

[Matthias Clasen <matthiasc src gnome org>]

commit 1db999018283a80031cd13a8148b1588eaf1afb3
Author: Matthias Clasen <mclasen redhat com>
Date:   Thu Apr 29 08:48:40 2021 -0400

    Compare images as pixels
    
    The byte streams may be different because we
    serialize and deserialize to png format a few
    times here.

 testsuite/gdk/clipboard.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 49 insertions(+)
---
diff --git a/testsuite/gdk/clipboard.c b/testsuite/gdk/clipboard.c
index 03973c2103..9569de927b 100644
--- a/testsuite/gdk/clipboard.c
+++ b/testsuite/gdk/clipboard.c
@@ -88,6 +88,35 @@ read_upto_done (GObject      *source,
   g_main_context_wakeup (NULL);
 }
 
+static void
+assert_texture_equal (GdkTexture *t1,
+                      GdkTexture *t2)
+{
+  int width;
+  int height;
+  int stride;
+  guchar *d1;
+  guchar *d2;
+
+  width = gdk_texture_get_width (t1);
+  height = gdk_texture_get_height (t1);
+  stride = 4 * width;
+
+  g_assert_cmpint (width, ==, gdk_texture_get_width (t2));
+  g_assert_cmpint (height, ==, gdk_texture_get_height (t2));
+
+  d1 = g_malloc (stride * height);
+  d2 = g_malloc (stride * height);
+
+  gdk_texture_download (t1, d1, stride);
+  gdk_texture_download (t2, d2, stride);
+
+  g_assert_cmpmem (d1, stride * height, d2, stride * height);
+
+  g_free (d1);
+  g_free (d2);
+}
+
 static void
 test_clipboard_roundtrip (const char *type,
                           const char *value,
@@ -149,6 +178,26 @@ test_clipboard_roundtrip (const char *type,
     {
       g_test_fail ();
     }
+  else if (g_str_has_suffix (value, ".png"))
+    {
+      GFile *f1, *f2;
+      GdkTexture *t1, *t2;
+
+      f1 = g_file_new_for_path (value);
+      f2 = g_file_new_for_path (stdout_buf);
+
+      t1 = gdk_texture_new_from_file (f1, &error);
+      g_assert_no_error (error);
+      t2 = gdk_texture_new_from_file (f2, &error);
+      g_assert_no_error (error);
+
+      assert_texture_equal (t1, t2);
+
+      g_object_unref (t1);
+      g_object_unref (t2);
+      g_object_unref (f1);
+      g_object_unref (f2);
+    }
   else
     {
       char *m1, *m2;