[metacity] compositor: add ready_to_redraw vfunc

[Alberts Muktupāvels <muktupavels src gnome org>]

commit 3a787346ffae95a3cf26aa847fa3937349c29e30
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Sat Sep 12 19:26:40 2020 +0300

    compositor: add ready_to_redraw vfunc

 src/compositor/meta-compositor-private.h |  2 ++
 src/compositor/meta-compositor.c         | 14 ++++++++++++++
 2 files changed, 16 insertions(+)
---
diff --git a/src/compositor/meta-compositor-private.h b/src/compositor/meta-compositor-private.h
index baa60554..93400b6b 100644
--- a/src/compositor/meta-compositor-private.h
+++ b/src/compositor/meta-compositor-private.h
@@ -44,6 +44,8 @@ struct _MetaCompositorClass
   void          (* sync_window_geometry)   (MetaCompositor  *compositor,
                                             MetaSurface     *surface);
 
+  gboolean      (* ready_to_redraw)        (MetaCompositor  *compositor);
+
   void          (* pre_paint)              (MetaCompositor  *compositor);
 
   void          (* redraw)                 (MetaCompositor  *compositor,
diff --git a/src/compositor/meta-compositor.c b/src/compositor/meta-compositor.c
index 25fad9e5..f5ad2bc0 100644
--- a/src/compositor/meta-compositor.c
+++ b/src/compositor/meta-compositor.c
@@ -173,6 +173,13 @@ redraw_idle_cb (gpointer user_data)
   compositor = META_COMPOSITOR (user_data);
   priv = meta_compositor_get_instance_private (compositor);
 
+  if (!META_COMPOSITOR_GET_CLASS (compositor)->ready_to_redraw (compositor))
+    {
+      priv->redraw_id = 0;
+
+      return G_SOURCE_REMOVE;
+    }
+
   META_COMPOSITOR_GET_CLASS (compositor)->pre_paint (compositor);
 
   if (priv->all_damage != None)
@@ -337,6 +344,12 @@ meta_compositor_set_property (GObject      *object,
     }
 }
 
+static gboolean
+meta_compositor_ready_to_redraw (MetaCompositor *compositor)
+{
+  return TRUE;
+}
+
 static void
 meta_compositor_pre_paint (MetaCompositor *compositor)
 {
@@ -379,6 +392,7 @@ meta_compositor_class_init (MetaCompositorClass *compositor_class)
   object_class->get_property = meta_compositor_get_property;
   object_class->set_property = meta_compositor_set_property;
 
+  compositor_class->ready_to_redraw = meta_compositor_ready_to_redraw;
   compositor_class->pre_paint = meta_compositor_pre_paint;
 
   install_properties (object_class);