[gtk+] Avoid spurious operations on destroy

[Matthias Clasen <matthiasc src gnome org>]

commit 4e155d784dda384cd4bba6653134b1a0542ee569
Author: Paolo Borelli <pborelli gnome org>
Date:   Sun Feb 16 22:22:59 2014 +0100

    Avoid spurious operations on destroy
    
    When the stack is destroyed we do not want to waste time running
    animations and notifying listeners about which is our current
    visible child.
    
    This is not only an optimization, but it is important for the stack
    switcher widgets: since they are in another branch of the hieratchy
    we do not want to get notifications while the stack is being destroyed.
    
    Based on a patch by Paolo Borelli
    https://bugzilla.gnome.org/show_bug.cgi?id=724506

 gtk/gtkstack.c |   20 ++++++++++++++++++++
 1 files changed, 20 insertions(+), 0 deletions(-)
---
diff --git a/gtk/gtkstack.c b/gtk/gtkstack.c
index 7752689..e1e4f3b 100644
--- a/gtk/gtkstack.c
+++ b/gtk/gtkstack.c
@@ -141,6 +141,8 @@ typedef struct {
   gint last_visible_widget_height;
 
   GtkStackTransitionType active_transition_type;
+
+  gboolean destroying;
 } GtkStackPrivate;
 
 static GParamSpec *stack_props[LAST_PROP] = { NULL, };
@@ -174,6 +176,7 @@ static void     gtk_stack_get_preferred_width_for_height (GtkWidget     *widget,
                                                           gint           height,
                                                           gint          *minimum_width,
                                                           gint          *natural_width);
+static void     gtk_stack_destroy                        (GtkWidget     *widget);
 static void     gtk_stack_finalize                       (GObject       *obj);
 static void     gtk_stack_get_property                   (GObject       *object,
                                                           guint          property_id,
@@ -399,6 +402,7 @@ gtk_stack_class_init (GtkStackClass *klass)
   widget_class->get_preferred_width = gtk_stack_get_preferred_width;
   widget_class->get_preferred_width_for_height = gtk_stack_get_preferred_width_for_height;
   widget_class->compute_expand = gtk_stack_compute_expand;
+  widget_class->destroy = gtk_stack_destroy;
 
   container_class->add = gtk_stack_add;
   container_class->remove = gtk_stack_remove;
@@ -1012,6 +1016,11 @@ set_visible_child (GtkStack               *stack,
   GtkWidget *focus;
   gboolean contains_focus = FALSE;
 
+  /* if we are being destroyed, do not bother with transitions
+   * and notifications */
+  if (priv->destroying)
+    return;
+
   /* If none, pick first visible */
   if (child_info == NULL)
     {
@@ -1843,6 +1852,17 @@ gtk_stack_compute_expand (GtkWidget *widget,
 }
 
 static void
+gtk_stack_destroy (GtkWidget *widget)
+{
+  GtkStack *stack = GTK_STACK (widget);
+  GtkStackPrivate *priv = gtk_stack_get_instance_private (stack);
+
+  priv->destroying = TRUE;
+
+  GTK_WIDGET_CLASS (gtk_stack_parent_class)->destroy (widget);
+}
+
+static void
 gtk_stack_draw_crossfade (GtkWidget *widget,
                           cairo_t   *cr)
 {