[gtk+] image: Warn when attempting to load pixdata GResources

[Bastien Nocera <hadess src gnome org>]

commit eb338feff9689625bb70eea82c24d1f0191ae53a
Author: Bastien Nocera <hadess hadess net>
Date:   Wed Jul 5 23:01:26 2017 +0200

    image: Warn when attempting to load pixdata GResources
    
    GdkPixdata is deprecated. Warn when the application tries to load
    pixdata embedded resources. The application developer will have to
    remove the "to-pixdata" keyword from the GResource definition file.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=781583

 gtk/gtkimage.c |   42 ++++++++++++++++++++++++++++++++++++++++--
 1 files changed, 40 insertions(+), 2 deletions(-)
---
diff --git a/gtk/gtkimage.c b/gtk/gtkimage.c
index bc47eee..0d536ce 100644
--- a/gtk/gtkimage.c
+++ b/gtk/gtkimage.c
@@ -860,6 +860,36 @@ gtk_image_set_from_file   (GtkImage    *image,
   g_object_thaw_notify (G_OBJECT (image));
 }
 
+#ifndef GDK_PIXBUF_MAGIC_NUMBER
+#define GDK_PIXBUF_MAGIC_NUMBER (0x47646b50)    /* 'GdkP' */
+#endif
+
+static gboolean
+resource_is_pixdata (const gchar *resource_path)
+{
+  const guint8 *stream;
+  guint32 magic;
+  gsize data_size;
+  GBytes *bytes;
+  gboolean ret = FALSE;
+
+  bytes = g_resources_lookup_data (resource_path, 0, NULL);
+  if (bytes == NULL)
+    return FALSE;
+
+  stream = g_bytes_get_data (bytes, &data_size);
+  if (data_size < sizeof(guint32))
+    goto out;
+
+  magic = (stream[0] << 24) + (stream[1] << 16) + (stream[2] << 8) + stream[3];
+  if (magic == GDK_PIXBUF_MAGIC_NUMBER)
+    ret = TRUE;
+
+out:
+  g_bytes_unref (bytes);
+  return ret;
+}
+
 /**
  * gtk_image_set_from_resource:
  * @image: a #GtkImage
@@ -873,7 +903,7 @@ gtk_image_set_from_resource (GtkImage    *image,
 {
   GtkImagePrivate *priv;
   GdkPixbufAnimation *animation;
-  gint scale_factor;
+  gint scale_factor = 1;
 
   g_return_if_fail (GTK_IS_IMAGE (image));
 
@@ -889,7 +919,15 @@ gtk_image_set_from_resource (GtkImage    *image,
       return;
     }
 
-  animation = load_scalable_with_loader (image, NULL, resource_path, &scale_factor);
+  if (resource_is_pixdata (resource_path))
+    {
+      g_warning ("GdkPixdata format images are not supported, remove the \"to-pixdata\" option from your 
GResource files");
+      animation = NULL;
+    }
+  else
+    {
+      animation = load_scalable_with_loader (image, NULL, resource_path, &scale_factor);
+    }
 
   if (animation == NULL)
     {