[gnome-builder] util: ensure IdeWidgetContextHandler is emitted only once per change

[Christian Hergert <chergert src gnome org>]

commit 373b7a305b354be07bebc6737e6c32a4919b1c1b
Author: Christian Hergert <chergert redhat com>
Date:   Tue Jan 9 15:39:40 2018 -0800

    util: ensure IdeWidgetContextHandler is emitted only once per change
    
    It was possible previously that we could notify multiple times for the same
    IdeContext. This stashes a pointer (only for comparison) in quark data like
    we do with our handler. It then only notifies when that has changed.
    
    Additionally, we move to using the Quark API instead of the string-based
    API.

 src/libide/util/ide-gtk.c |   47 +++++++++++++++++++++++++++++++++++++-------
 1 files changed, 39 insertions(+), 8 deletions(-)
---
diff --git a/src/libide/util/ide-gtk.c b/src/libide/util/ide-gtk.c
index f004cb6..0f0c349 100644
--- a/src/libide/util/ide-gtk.c
+++ b/src/libide/util/ide-gtk.c
@@ -21,25 +21,48 @@
 #include "application/ide-application.h"
 #include "util/ide-gtk.h"
 
+static GQuark quark_handler;
+static GQuark quark_where_context_was;
+
 static void
 ide_widget_notify_context (GtkWidget  *toplevel,
                            GParamSpec *pspec,
                            GtkWidget  *widget)
 {
   IdeWidgetContextHandler handler;
-  g_autoptr(IdeContext) context = NULL;
+  IdeContext *old_context;
+  IdeContext *context;
+
+  g_assert (GTK_IS_WIDGET (toplevel));
+  g_assert (GTK_IS_WIDGET (widget));
+
+  handler = g_object_get_qdata (G_OBJECT (widget), quark_handler);
+  old_context = g_object_get_qdata (G_OBJECT (widget), quark_where_context_was);
 
-  handler = g_object_get_data (G_OBJECT (widget), "IDE_CONTEXT_HANDLER");
   if (handler == NULL)
     return;
 
-  g_object_get (toplevel,
-                "context", &context,
-                NULL);
+  context = ide_widget_get_context (toplevel);
+
+  if (context == old_context)
+    return;
+
+  g_object_set_qdata (G_OBJECT (widget), quark_where_context_was, context);
 
   handler (widget, context);
 }
 
+static gboolean
+has_context_property (GtkWidget *widget)
+{
+  GParamSpec *pspec;
+
+  g_assert (GTK_IS_WIDGET (widget));
+
+  pspec = g_object_class_find_property (G_OBJECT_GET_CLASS (widget), "context");
+  return pspec != NULL && g_type_is_a (pspec->value_type, IDE_TYPE_CONTEXT);
+}
+
 static void
 ide_widget_hierarchy_changed (GtkWidget *widget,
                               GtkWidget *previous_toplevel,
@@ -56,7 +79,7 @@ ide_widget_hierarchy_changed (GtkWidget *widget,
 
   toplevel = gtk_widget_get_toplevel (widget);
 
-  if (GTK_IS_WINDOW (toplevel))
+  if (GTK_IS_WINDOW (toplevel) && has_context_property (toplevel))
     {
       g_signal_connect_object (toplevel,
                                "notify::context",
@@ -82,14 +105,22 @@ ide_widget_set_context_handler (gpointer                widget,
 
   g_return_if_fail (GTK_IS_WIDGET (widget));
 
-  g_object_set_data (G_OBJECT (widget), "IDE_CONTEXT_HANDLER", handler);
+  /* Ensure we have our quarks for quick key lookup */
+  if G_UNLIKELY (quark_handler == 0)
+    quark_handler = g_quark_from_static_string ("IDE_CONTEXT_HANDLER");
+  if G_UNLIKELY (quark_where_context_was == 0)
+    quark_where_context_was = g_quark_from_static_string ("IDE_CONTEXT");
+
+  g_object_set_qdata (G_OBJECT (widget), quark_handler, handler);
 
   g_signal_connect (widget,
                     "hierarchy-changed",
                     G_CALLBACK (ide_widget_hierarchy_changed),
                     NULL);
 
-  if ((toplevel = gtk_widget_get_toplevel (widget)))
+  toplevel = gtk_widget_get_toplevel (widget);
+
+  if (GTK_IS_WINDOW (toplevel))
     ide_widget_hierarchy_changed (widget, NULL, NULL);
 }