[mutter/gnome-3-28] clutter: Avoid unnecessary relayouts in ClutterText

[Carlos Garnacho <carlosg src gnome org>]

commit 31779404f0e083fba11d1d263f278154e0580374
Author: Yussuf Khalil <dev pp3345 net>
Date:   Sun Feb 18 21:21:44 2018 +0100

    clutter: Avoid unnecessary relayouts in ClutterText
    
    We can save an unnecessary relayout if the required size to fully draw the text
    is equal to the currently allocated size after the underlying text buffer or
    attributes that only affect the PangoLayout have changed.

 clutter/clutter/clutter-text.c | 43 ++++++++++++++++++++++++++----------------
 1 file changed, 27 insertions(+), 16 deletions(-)
---
diff --git a/clutter/clutter/clutter-text.c b/clutter/clutter/clutter-text.c
index 4828a4cbd..4a6a74a0c 100644
--- a/clutter/clutter/clutter-text.c
+++ b/clutter/clutter/clutter-text.c
@@ -4511,6 +4511,27 @@ buffer_deleted_text (ClutterTextBuffer *buffer,
     }
 }
 
+static void
+clutter_text_queue_redraw_or_relayout (ClutterText *self)
+{
+  ClutterActor *actor = CLUTTER_ACTOR (self);
+  gfloat preferred_width;
+  gfloat preferred_height;
+
+  clutter_text_dirty_cache (self);
+
+  /* we're using our private implementations here to avoid the caching done by ClutterActor */
+  clutter_text_get_preferred_width (actor, -1, NULL, &preferred_width);
+  clutter_text_get_preferred_height (actor, preferred_width, NULL, &preferred_height);
+
+  if (clutter_actor_has_allocation (actor) &&
+      (fabsf (preferred_width - clutter_actor_get_width (actor)) > 0.001 ||
+       fabsf (preferred_height - clutter_actor_get_height (actor)) > 0.001))
+    clutter_actor_queue_relayout (actor);
+  else
+    clutter_text_queue_redraw (actor);
+}
+
 static void
 buffer_notify_text (ClutterTextBuffer *buffer,
                     GParamSpec        *spec,
@@ -4518,9 +4539,7 @@ buffer_notify_text (ClutterTextBuffer *buffer,
 {
   g_object_freeze_notify (G_OBJECT (self));
 
-  clutter_text_dirty_cache (self);
-
-  clutter_actor_queue_relayout (CLUTTER_ACTOR (self));
+  clutter_text_queue_redraw_or_relayout (self);
 
   g_signal_emit (self, text_signals[TEXT_CHANGED], 0);
   g_object_notify_by_pspec (G_OBJECT (self), obj_props[PROP_TEXT]);
@@ -4872,8 +4891,7 @@ clutter_text_set_cursor_visible (ClutterText *self,
     {
       priv->cursor_visible = cursor_visible;
 
-      clutter_text_dirty_cache (self);
-      clutter_actor_queue_relayout (CLUTTER_ACTOR (self));
+      clutter_text_queue_redraw_or_relayout (self);
 
       g_object_notify_by_pspec (G_OBJECT (self), obj_props[PROP_CURSOR_VISIBLE]);
     }
@@ -5774,9 +5792,7 @@ clutter_text_set_line_alignment (ClutterText    *self,
     {
       priv->alignment = alignment;
 
-      clutter_text_dirty_cache (self);
-
-      clutter_actor_queue_relayout (CLUTTER_ACTOR (self));
+      clutter_text_queue_redraw_or_relayout (self);
 
       g_object_notify_by_pspec (G_OBJECT (self), obj_props[PROP_LINE_ALIGNMENT]);
     }
@@ -5831,9 +5847,7 @@ clutter_text_set_use_markup (ClutterText *self,
   if (setting)
     clutter_text_set_markup_internal (self, text);
 
-  clutter_text_dirty_cache (self);
-
-  clutter_actor_queue_relayout (CLUTTER_ACTOR (self));
+  clutter_text_queue_redraw_or_relayout (self);
 }
 
 /**
@@ -5880,9 +5894,7 @@ clutter_text_set_justify (ClutterText *self,
     {
       priv->justify = justify;
 
-      clutter_text_dirty_cache (self);
-
-      clutter_actor_queue_relayout (CLUTTER_ACTOR (self));
+      clutter_text_queue_redraw_or_relayout (self);
 
       g_object_notify_by_pspec (G_OBJECT (self), obj_props[PROP_JUSTIFY]);
     }
@@ -6449,8 +6461,7 @@ clutter_text_set_preedit_string (ClutterText   *self,
       priv->preedit_set = TRUE;
     }
 
-  clutter_text_dirty_cache (self);
-  clutter_actor_queue_relayout (CLUTTER_ACTOR (self));
+  clutter_text_queue_redraw_or_relayout (self);
 }