[mutter] cursor: Load cursor images lazily

[Jasper St. Pierre <jstpierre src gnome org>]

commit fd1243d881efa52f42700e5bc1f70c07c1f3a005
Author: Jasper St. Pierre <jstpierre mecheye net>
Date:   Thu Nov 27 14:34:25 2014 -0800

    cursor: Load cursor images lazily
    
    It doesn't make sense to load cursor textures that we might not ever
    use. Since the code here also uses CoglTexture2D, and cursors tend
    to be NPOT textures, then we won't crash users of cards without
    NPOT support. At least until they open the magnifier. :)

 src/backends/meta-cursor.c |   33 ++++++++++++++++++++++++---------
 1 files changed, 24 insertions(+), 9 deletions(-)
---
diff --git a/src/backends/meta-cursor.c b/src/backends/meta-cursor.c
index 22a8a76..e70b328 100644
--- a/src/backends/meta-cursor.c
+++ b/src/backends/meta-cursor.c
@@ -255,22 +255,30 @@ meta_cursor_image_load_from_xcursor_image (MetaCursorImage   *image,
 #endif
 }
 
-MetaCursorReference *
-meta_cursor_reference_from_theme (MetaCursor cursor)
+static void
+load_cursor_image (MetaCursorReference *cursor)
 {
-  MetaCursorReference *self;
   XcursorImage *image;
 
-  image = load_cursor_on_client (cursor);
+  /* Either cursors are loaded from X cursors or buffers. Since
+   * buffers are converted over immediately, we can make sure to
+   * load this directly. */
+  g_assert (cursor->cursor != META_CURSOR_NONE);
+
+  image = load_cursor_on_client (cursor->cursor);
   if (!image)
-    return NULL;
+    return;
 
-  self = g_slice_new0 (MetaCursorReference);
+  meta_cursor_image_load_from_xcursor_image (&cursor->image, image);
+  XcursorImageDestroy (image);
+}
+
+MetaCursorReference *
+meta_cursor_reference_from_theme (MetaCursor cursor)
+{
+  MetaCursorReference *self = g_slice_new0 (MetaCursorReference);
   self->ref_count = 1;
   self->cursor = cursor;
-  meta_cursor_image_load_from_xcursor_image (&self->image, image);
-
-  XcursorImageDestroy (image);
   return self;
 }
 
@@ -380,10 +388,14 @@ meta_cursor_reference_get_cogl_texture (MetaCursorReference *cursor,
                                         int                 *hot_x,
                                         int                 *hot_y)
 {
+  if (!cursor->image.texture)
+    load_cursor_image (cursor);
+
   if (hot_x)
     *hot_x = cursor->image.hot_x;
   if (hot_y)
     *hot_y = cursor->image.hot_y;
+
   return COGL_TEXTURE (cursor->image.texture);
 }
 
@@ -393,6 +405,9 @@ meta_cursor_reference_get_gbm_bo (MetaCursorReference *cursor,
                                   int                 *hot_x,
                                   int                 *hot_y)
 {
+  if (!cursor->image.bo)
+    load_cursor_image (cursor);
+
   if (hot_x)
     *hot_x = cursor->image.hot_x;
   if (hot_y)