[gnome-shell] st-icon: Create shadow pipeline only at paint

[Jonas Ådahl <jadahl src gnome org>]

commit e522e2e804725ee67837fcb0ad7a9428baef40c3
Author: Marco Trevisan (Treviño) <mail 3v1n0 net>
Date:   Wed Oct 18 06:32:22 2017 -0400

    st-icon: Create shadow pipeline only at paint
    
    Don't try to allocate the shadow after allocation, just do it at paint
    as it's done by other shadowed widgets

 src/st/st-icon.c | 48 +++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 41 insertions(+), 7 deletions(-)
---
diff --git a/src/st/st-icon.c b/src/st/st-icon.c
index 988070cd7..5892f8a52 100644
--- a/src/st/st-icon.c
+++ b/src/st/st-icon.c
@@ -56,12 +56,15 @@ struct _StIconPrivate
 
   CoglPipeline *shadow_pipeline;
   StShadow     *shadow_spec;
+  ClutterSize   shadow_size;
 };
 
 G_DEFINE_TYPE_WITH_PRIVATE (StIcon, st_icon, ST_TYPE_WIDGET)
 
 static void st_icon_update               (StIcon *icon);
 static gboolean st_icon_update_icon_size (StIcon *icon);
+static void st_icon_update_shadow_pipeline (StIcon *icon);
+static void st_icon_clear_shadow_pipeline (StIcon *icon);
 
 #define DEFAULT_ICON_SIZE 48
 
@@ -158,12 +161,15 @@ st_icon_dispose (GObject *gobject)
 static void
 st_icon_paint (ClutterActor *actor)
 {
-  StIconPrivate *priv = ST_ICON (actor)->priv;
+  StIcon *icon = ST_ICON (actor);
+  StIconPrivate *priv = icon->priv;
 
   st_widget_paint_background (ST_WIDGET (actor));
 
   if (priv->icon_texture)
     {
+      st_icon_update_shadow_pipeline (icon);
+
       if (priv->shadow_pipeline)
         {
           ClutterActorBox allocation;
@@ -186,7 +192,7 @@ st_icon_style_changed (StWidget *widget)
   StThemeNode *theme_node = st_widget_get_theme_node (widget);
   StIconPrivate *priv = self->priv;
 
-  g_clear_pointer (&priv->shadow_pipeline, cogl_object_unref);
+  st_icon_clear_shadow_pipeline (self);
   g_clear_pointer (&priv->shadow_spec, st_shadow_unref);
 
   priv->shadow_spec = st_theme_node_get_shadow (theme_node, "icon-shadow");
@@ -265,21 +271,49 @@ st_icon_init (StIcon *self)
 }
 
 static void
-st_icon_update_shadow_pipeline (StIcon *icon)
+st_icon_clear_shadow_pipeline (StIcon *icon)
 {
   StIconPrivate *priv = icon->priv;
 
   g_clear_pointer (&priv->shadow_pipeline, cogl_object_unref);
+  clutter_size_init (&priv->shadow_size, 0, 0);
+}
+
+static void
+st_icon_update_shadow_pipeline (StIcon *icon)
+{
+  StIconPrivate *priv = icon->priv;
+
+  if (priv->icon_texture && priv->shadow_spec)
+    {
+      ClutterActorBox box;
+      float width, height;
+
+      clutter_actor_get_allocation_box (CLUTTER_ACTOR (icon), &box);
+      clutter_actor_box_get_size (&box, &width, &height);
+
+      if (priv->shadow_pipeline == NULL ||
+          priv->shadow_size.width != width ||
+          priv->shadow_size.height != height)
+        {
+          st_icon_clear_shadow_pipeline (icon);
+
+          priv->shadow_pipeline =
+            _st_create_shadow_pipeline_from_actor (priv->shadow_spec,
+                                                   priv->icon_texture);
 
-  if (priv->shadow_spec)
-   priv->shadow_pipeline = _st_create_shadow_pipeline_from_actor (priv->shadow_spec, priv->icon_texture);
+          if (priv->shadow_pipeline)
+            clutter_size_init (&priv->shadow_size, width, height);
+        }
+    }
 }
 
 static void
 on_pixbuf_changed (ClutterTexture *texture,
                    StIcon         *icon)
 {
-  st_icon_update_shadow_pipeline (icon);
+  st_icon_clear_shadow_pipeline (icon);
+  clutter_actor_queue_redraw (CLUTTER_ACTOR (icon));
 }
 
 static void
@@ -304,7 +338,7 @@ st_icon_finish_update (StIcon *icon)
       /* Remove the temporary ref we added */
       g_object_unref (priv->icon_texture);
 
-      st_icon_update_shadow_pipeline (icon);
+      st_icon_clear_shadow_pipeline (icon);
 
       /* "pixbuf-change" is actually a misnomer for "texture-changed" */
       g_signal_connect_object (priv->icon_texture, "pixbuf-change",