[gnome-shell/gnome-40] st/label: Compare shadow spec before invalidating shadow on style change

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

commit a73b1b131c1316be15b6e7a4674b080ec779c814
Author: Jonas Dreßler <verdre v0yd nl>
Date:   Fri Mar 5 12:49:36 2021 +0100

    st/label: Compare shadow spec before invalidating shadow on style change
    
    Just like with the last commit for StEntry, check whether the text
    shadow actually changed before invalidating the pipeline on style
    changes of StLabel.
    
    (cherry picked from commit 09903b6426cbed58ebc316f51378e6525e80caec)
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/2181>

 src/st/st-label.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)
---
diff --git a/src/st/st-label.c b/src/st/st-label.c
index d531dc038c..0d48a47060 100644
--- a/src/st/st-label.c
+++ b/src/st/st-label.c
@@ -62,6 +62,8 @@ struct _StLabelPrivate
 {
   ClutterActor *label;
 
+  StShadow *shadow_spec;
+
   CoglPipeline *text_shadow_pipeline;
   float         shadow_width;
   float         shadow_height;
@@ -119,8 +121,21 @@ static void
 st_label_style_changed (StWidget *self)
 {
   StLabelPrivate *priv = ST_LABEL(self)->priv;
+  StThemeNode *theme_node;
+  StShadow *shadow_spec;
 
-  g_clear_pointer (&priv->text_shadow_pipeline, cogl_object_unref);
+  theme_node = st_widget_get_theme_node (self);
+
+  shadow_spec = st_theme_node_get_text_shadow (theme_node);
+  if (!priv->shadow_spec || !shadow_spec ||
+      !st_shadow_equal (shadow_spec, priv->shadow_spec))
+    {
+      g_clear_pointer (&priv->text_shadow_pipeline, cogl_object_unref);
+
+      g_clear_pointer (&priv->shadow_spec, st_shadow_unref);
+      if (shadow_spec)
+        priv->shadow_spec = st_shadow_ref (shadow_spec);
+    }
 
   _st_set_text_from_style ((ClutterText *)priv->label, st_widget_get_theme_node (self));
 
@@ -194,12 +209,10 @@ st_label_paint (ClutterActor        *actor,
                 ClutterPaintContext *paint_context)
 {
   StLabelPrivate *priv = ST_LABEL (actor)->priv;
-  StThemeNode *theme_node = st_widget_get_theme_node (ST_WIDGET (actor));
-  StShadow *shadow_spec = st_theme_node_get_text_shadow (theme_node);
 
   st_widget_paint_background (ST_WIDGET (actor), paint_context);
 
-  if (shadow_spec)
+  if (priv->shadow_spec)
     {
       ClutterActorBox allocation;
       float width, height;
@@ -222,7 +235,7 @@ st_label_paint (ClutterActor        *actor,
           priv->shadow_width = width;
           priv->shadow_height = height;
           priv->text_shadow_pipeline =
-            _st_create_shadow_pipeline_from_actor (shadow_spec,
+            _st_create_shadow_pipeline_from_actor (priv->shadow_spec,
                                                    priv->label);
         }
 
@@ -232,7 +245,7 @@ st_label_paint (ClutterActor        *actor,
 
           framebuffer =
             clutter_paint_context_get_framebuffer (paint_context);
-          _st_paint_shadow_with_opacity (shadow_spec,
+          _st_paint_shadow_with_opacity (priv->shadow_spec,
                                          framebuffer,
                                          priv->text_shadow_pipeline,
                                          &allocation,