[gtk+/wip/window-scales] widget: Track when the window scale factor changes and notify

[Alexander Larsson <alexl src gnome org>]

commit a612037883996ff66bdb72f0aa8605cc6277bf5d
Author: Alexander Larsson <alexl redhat com>
Date:   Fri Jun 28 10:39:52 2013 +0200

    widget: Track when the window scale factor changes and notify
    
    The scale-factor property on the widgets will be notified, and the
    scale will change on the style property, causing us to pick up
    new css assets.

 gtk/gtkwidget.c        |   29 ++++++++++++++++++++++++++++-
 gtk/gtkwidgetprivate.h |    2 ++
 gtk/gtkwindow.c        |   22 ++++++++++++++++++++++
 3 files changed, 52 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 971b188..1b42636 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -10001,10 +10001,33 @@ gtk_widget_has_screen (GtkWidget *widget)
   return (gtk_widget_get_screen_unchecked (widget) != NULL);
 }
 
+void
+_gtk_widget_scale_changed (GtkWidget *widget)
+{
+  GtkWidgetPrivate *priv;
+
+  g_return_if_fail (GTK_IS_WIDGET (widget));
+
+  priv = widget->priv;
+
+  if (priv->context)
+    gtk_style_context_set_scale (priv->context, gtk_widget_get_scale_factor (widget));
+
+  g_object_notify (G_OBJECT (widget), "scale-factor");
+
+  gtk_widget_queue_draw (widget);
+
+  if (GTK_IS_CONTAINER (widget))
+    gtk_container_forall (GTK_CONTAINER (widget),
+                          (GtkCallback) _gtk_widget_scale_changed,
+                          NULL);
+}
+
 gint
 gtk_widget_get_scale_factor (GtkWidget *widget)
 {
   GtkWidget *toplevel;
+  GdkScreen *screen;
 
   g_return_val_if_fail (GTK_IS_WIDGET (widget), 1);
 
@@ -10018,7 +10041,11 @@ gtk_widget_get_scale_factor (GtkWidget *widget)
   /* else fall back to something that is more likely to be right than
    * just returning 1:
    */
-  return gdk_screen_get_monitor_scale_factor (gtk_widget_get_screen (widget), 0);
+  screen = gtk_widget_get_screen (widget);
+  if (screen)
+    return gdk_screen_get_monitor_scale_factor (screen, 0);
+
+  return 1;
 }
 
 /**
diff --git a/gtk/gtkwidgetprivate.h b/gtk/gtkwidgetprivate.h
index 045c08a..7cf15f8 100644
--- a/gtk/gtkwidgetprivate.h
+++ b/gtk/gtkwidgetprivate.h
@@ -47,6 +47,8 @@ void         _gtk_widget_set_alloc_needed   (GtkWidget *widget,
                                              gboolean   alloc_needed);
 void         _gtk_widget_draw               (GtkWidget *widget,
                                             cairo_t   *cr);
+void          _gtk_widget_scale_changed     (GtkWidget *widget);
+
 
 void         _gtk_widget_add_sizegroup         (GtkWidget    *widget,
                                                gpointer      group);
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index bbec07e..9b8e4ce 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -147,6 +147,8 @@ struct _GtkWindowPrivate
 
   guint    mnemonics_display_timeout_id;
 
+  gint     scale;
+
   gint title_height;
   GtkWidget *title_box;
   GtkWidget *title_icon;
@@ -1321,6 +1323,8 @@ gtk_window_init (GtkWindow *window)
 
   context = gtk_widget_get_style_context (GTK_WIDGET (window));
   gtk_style_context_add_class (context, GTK_STYLE_CLASS_BACKGROUND);
+
+  priv->scale = gtk_widget_get_scale_factor (GTK_WIDGET (window));
 }
 
 static void
@@ -5654,6 +5658,7 @@ gtk_window_realize (GtkWidget *widget)
   gint attributes_mask;
   GtkWindowPrivate *priv;
   gint i;
+  int old_scale;
 
   window = GTK_WINDOW (widget);
   priv = window->priv;
@@ -5883,6 +5888,11 @@ gtk_window_realize (GtkWidget *widget)
 
   if (priv->has_resize_grip)
     resize_grip_create_window (window);
+
+  old_scale = priv->scale;
+  priv->scale = gtk_widget_get_scale_factor (widget);
+  if (old_scale != priv->scale)
+    _gtk_widget_scale_changed (widget);
 }
 
 static void
@@ -6480,6 +6490,12 @@ gtk_window_configure_event (GtkWidget         *widget,
   GtkWindow *window = GTK_WINDOW (widget);
   GtkWindowPrivate *priv = window->priv;
   gboolean expected_reply = priv->configure_request_count > 0;
+  int old_scale;
+
+  old_scale = priv->scale;
+  priv->scale = gtk_widget_get_scale_factor (widget);
+  if (old_scale != priv->scale)
+    _gtk_widget_scale_changed (window);
 
   if (!gtk_widget_is_toplevel (GTK_WIDGET (widget)))
     {
@@ -9653,6 +9669,7 @@ gtk_window_set_screen (GtkWindow *window,
   GtkWidget *widget;
   GdkScreen *previous_screen;
   gboolean was_mapped;
+  int old_scale;
 
   g_return_if_fail (GTK_IS_WINDOW (window));
   g_return_if_fail (GDK_IS_SCREEN (screen));
@@ -9700,6 +9717,11 @@ gtk_window_set_screen (GtkWindow *window,
 
   if (was_mapped)
     gtk_widget_map (widget);
+
+  old_scale = priv->scale;
+  priv->scale = gtk_widget_get_scale_factor (widget);
+  if (old_scale != priv->scale)
+    _gtk_widget_scale_changed (window);
 }
 
 static void