backends: Only reload sprite cursor on changes

Let the meta_cursor_sprite_realize() function return a boolean value
telling whether there was an actual change in the sprite cursor. E.g.
the surface/icon for it changed in between.

This is used in the native backend to avoid converting/uploading again
the cursor surface.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1915>

src/backends/meta-cursor-sprite-xcursor.c

@@ -316,13 +316,15 @@ load_cursor_from_theme (MetaCursorSprite *sprite)
   load_from_current_xcursor_image (sprite_xcursor);
 }
 
-static void
+static gboolean
 meta_cursor_sprite_xcursor_realize_texture (MetaCursorSprite *sprite)
 {
   MetaCursorSpriteXcursor *sprite_xcursor = META_CURSOR_SPRITE_XCURSOR (sprite);
 
   if (sprite_xcursor->theme_dirty)
     load_cursor_from_theme (sprite);
+
+  return TRUE;
 }
 
 MetaCursorSpriteXcursor *

src/backends/meta-cursor-tracker.c

@@ -130,6 +130,7 @@ update_displayed_cursor (MetaCursorTracker *tracker)
 
   if (cursor)
     {
+      meta_cursor_sprite_invalidate (cursor);
       g_signal_connect (cursor, "texture-changed",
                         G_CALLBACK (cursor_texture_updated), tracker);
     }

src/backends/meta-cursor.c

@@ -81,6 +81,7 @@ meta_cursor_sprite_clear_texture (MetaCursorSprite *sprite)
     meta_cursor_sprite_get_instance_private (sprite);
 
   g_clear_pointer (&priv->texture, cogl_object_unref);
+  meta_cursor_sprite_invalidate (sprite);
 }
 
 void
@@ -98,6 +99,8 @@ meta_cursor_sprite_set_texture (MetaCursorSprite *sprite,
   priv->hot_x = hot_x;
   priv->hot_y = hot_y;
 
+  meta_cursor_sprite_invalidate (sprite);
+
   g_signal_emit (sprite, signals[TEXTURE_CHANGED], 0);
 }
 
@@ -108,6 +111,9 @@ meta_cursor_sprite_set_texture_scale (MetaCursorSprite *sprite,
   MetaCursorSpritePrivate *priv =
     meta_cursor_sprite_get_instance_private (sprite);
 
+  if (priv->texture_scale != scale)
+    meta_cursor_sprite_invalidate (sprite);
+
   priv->texture_scale = scale;
 }
 
@@ -118,6 +124,9 @@ meta_cursor_sprite_set_texture_transform (MetaCursorSprite     *sprite,
   MetaCursorSpritePrivate *priv =
     meta_cursor_sprite_get_instance_private (sprite);
 
+  if (priv->texture_transform != transform)
+    meta_cursor_sprite_invalidate (sprite);
+
   priv->texture_transform = transform;
 }
 
@@ -187,10 +196,19 @@ meta_cursor_sprite_prepare_at (MetaCursorSprite   *sprite,
   g_signal_emit (sprite, signals[PREPARE_AT], 0, best_scale, x, y);
 }
 
-void
+gboolean
 meta_cursor_sprite_realize_texture (MetaCursorSprite *sprite)
 {
-  META_CURSOR_SPRITE_GET_CLASS (sprite)->realize_texture (sprite);
+  return META_CURSOR_SPRITE_GET_CLASS (sprite)->realize_texture (sprite);
+}
+
+void
+meta_cursor_sprite_invalidate (MetaCursorSprite *sprite)
+{
+  MetaCursorSpriteClass *sprite_class = META_CURSOR_SPRITE_GET_CLASS (sprite);
+
+  if (sprite_class->invalidate)
+    sprite_class->invalidate (sprite);
 }
 
 static void

src/backends/meta-cursor.h

@@ -36,7 +36,8 @@ struct _MetaCursorSpriteClass
 {
   GObjectClass parent_class;
 
-  void (* realize_texture) (MetaCursorSprite *sprite);
+  void (* invalidate) (MetaCursorSprite *sprite);
+  gboolean (* realize_texture) (MetaCursorSprite *sprite);
   gboolean (* is_animated) (MetaCursorSprite *sprite);
   void (* tick_frame) (MetaCursorSprite *sprite);
   unsigned int (* get_current_frame_time) (MetaCursorSprite *sprite);
@@ -47,7 +48,8 @@ void meta_cursor_sprite_prepare_at (MetaCursorSprite *sprite,
                                     int               x,
                                     int               y);
 
-void meta_cursor_sprite_realize_texture (MetaCursorSprite *sprite);
+void meta_cursor_sprite_invalidate (MetaCursorSprite *sprite);
+gboolean meta_cursor_sprite_realize_texture (MetaCursorSprite *sprite);
 
 void meta_cursor_sprite_clear_texture (MetaCursorSprite *sprite);
 

src/backends/native/meta-cursor-renderer-native.c

@@ -1074,9 +1074,13 @@ meta_cursor_renderer_native_update_cursor (MetaCursorRenderer *renderer,
 
   if (cursor_sprite)
     {
-      meta_cursor_sprite_realize_texture (cursor_sprite);
+      gboolean realized;
+
+      realized = meta_cursor_sprite_realize_texture (cursor_sprite);
       gpus = calculate_cursor_sprite_gpus (renderer, cursor_sprite);
-      realize_cursor_sprite (renderer, cursor_sprite, gpus);
+
+      if (realized)
+        realize_cursor_sprite (renderer, cursor_sprite, gpus);
     }
 
   maybe_schedule_cursor_sprite_animation_frame (native, cursor_sprite);

src/backends/x11/cm/meta-cursor-sprite-xfixes.c

@@ -52,9 +52,10 @@ G_DEFINE_TYPE_WITH_CODE (MetaCursorSpriteXfixes,
                          G_IMPLEMENT_INTERFACE (G_TYPE_INITABLE,
                                                 meta_screen_cast_xfixes_init_initable_iface))
 
-static void
+static gboolean
 meta_cursor_sprite_xfixes_realize_texture (MetaCursorSprite *sprite)
 {
+  return TRUE;
 }
 
 static gboolean

src/wayland/meta-cursor-sprite-wayland.c

@@ -31,9 +31,10 @@ G_DEFINE_TYPE (MetaCursorSpriteWayland,
                meta_cursor_sprite_wayland,
                META_TYPE_CURSOR_SPRITE)
 
-static void
+static gboolean
 meta_cursor_sprite_wayland_realize_texture (MetaCursorSprite *sprite)
 {
+  return TRUE;
 }
 
 static gboolean