[gimp/wip/animation: 312/373] plug-ins: only run the idle source on the renderer when needed.

[Jehan Pagès <jehanp src gnome org>]

commit a8c5768104980eb66968202bbe82ad2ca7a407c9
Author: Jehan <jehan girinstud io>
Date:   Sun May 21 23:20:19 2017 +0200

    plug-ins: only run the idle source on the renderer when needed.
    
    Running it continuously was eating the processor. Just run it
    temporarily when we are still waiting for renders to be done.

 plug-ins/animation-play/core/animation-renderer.c |   28 +++++++++++++++++---
 1 files changed, 23 insertions(+), 5 deletions(-)
---
diff --git a/plug-ins/animation-play/core/animation-renderer.c 
b/plug-ins/animation-play/core/animation-renderer.c
index 0417180..507ca81 100644
--- a/plug-ins/animation-play/core/animation-renderer.c
+++ b/plug-ins/animation-play/core/animation-renderer.c
@@ -163,7 +163,8 @@ animation_renderer_finalize (GObject *object)
   g_thread_unref (renderer->priv->queue_thread);
 
   /* Clean remaining data. */
-  g_source_remove (renderer->priv->idle_id);
+  if (renderer->priv->idle_id)
+    g_source_remove (renderer->priv->idle_id);
   g_mutex_lock (&renderer->priv->lock);
   for (i = 0; i < animation_get_duration (animation); i++)
     {
@@ -335,6 +336,7 @@ static gboolean
 animation_renderer_idle_update (AnimationRenderer *renderer)
 {
   gpointer p;
+  gboolean retval;
 
   while ((p = g_async_queue_try_pop (renderer->priv->ack_queue)))
     {
@@ -345,7 +347,21 @@ animation_renderer_idle_update (AnimationRenderer *renderer)
   while (g_main_context_pending (NULL))
     g_main_context_iteration (NULL, FALSE);
 
-  return G_SOURCE_CONTINUE;
+  /* If nothing is being rendered (negative queue length, meaning the
+   * renderer is waiting), nor is there anything in the ACK queue, just
+   * stop the idle source. */
+  if (g_async_queue_length (renderer->priv->queue) < 0 &&
+      g_async_queue_length (renderer->priv->ack_queue) == 0)
+    {
+      retval = G_SOURCE_REMOVE;
+      renderer->priv->idle_id = 0;
+    }
+  else
+    {
+      retval = G_SOURCE_CONTINUE;
+    }
+
+  return retval;
 }
 
 static void
@@ -371,6 +387,10 @@ on_frames_changed (Animation         *animation,
                                   * sorting it from the current position.
                                   */
                                  0);
+      if (renderer->priv->idle_id == 0)
+        renderer->priv->idle_id = g_idle_add_full (G_PRIORITY_HIGH_IDLE,
+                                                   (GSourceFunc) animation_renderer_idle_update,
+                                                   renderer, NULL);
     }
 }
 
@@ -426,9 +446,7 @@ on_animation_loaded (Animation         *animation,
   renderer->priv->queue_thread = g_thread_new ("gimp-animation-process-queue",
                                                (GThreadFunc) animation_renderer_process_queue,
                                                renderer);
-  renderer->priv->idle_id = g_idle_add_full (G_PRIORITY_HIGH_IDLE,
-                                             (GSourceFunc) animation_renderer_idle_update,
-                                             renderer, NULL);
+  renderer->priv->idle_id = 0;
 }
 
 /**** Public Functions ****/