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

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

commit 09903b6426cbed58ebc316f51378e6525e80caec
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.
    
    Part-of: <https://gitlab.gnome.org/GNOME/gnome-shell/-/merge_requests/1744>

 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 1cf0859dfb..e9893fe01e 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,