[gnome-shell] st/icon: Rebuild shadows when the texture dimensions change

[Marge Bot <marge-bot src gnome org>]

commit a21058e6c9008bb6145e6c8e48e3c2f5452e68e8
Author: Daniel van Vugt <daniel van vugt canonical com>
Date:   Thu Jun 3 20:16:12 2021 +0800

    st/icon: Rebuild shadows when the texture dimensions change
    
    Not when the main actor dimensions change. So now the shadows don't get
    constantly regenerated during the overview animation. In my case this
    reduces the render time of the overview animation (tapping Super) by
    approximately 10% with 2 windows, or 20% with 10 windows.
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1869>

 src/st/st-icon.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/src/st/st-icon.c b/src/st/st-icon.c
index c9d7a85e52..c43d7c91bd 100644
--- a/src/st/st-icon.c
+++ b/src/st/st-icon.c
@@ -359,7 +359,8 @@ st_icon_update_shadow_pipeline (StIcon *icon)
       ClutterActorBox box;
       float width, height;
 
-      clutter_actor_get_allocation_box (CLUTTER_ACTOR (icon), &box);
+      clutter_actor_get_allocation_box (CLUTTER_ACTOR (priv->icon_texture),
+                                        &box);
       clutter_actor_box_get_size (&box, &width, &height);
 
       if (priv->shadow_pipeline == NULL ||