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

diff --git a/gtk/gtkstack.c b/gtk/gtkstack.c
index 775268999129d7204d13e644b71b9089cb70c559..e1e4f3b4446ca90456c470ed5a9d295094031f5c 100644 (file)
--- 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)
     {
@@ -1842,6 +1851,17 @@ gtk_stack_compute_expand (GtkWidget *widget,
   *vexpand_p = vexpand;
 }
 
+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)