API: Add gdk_window_get_visual() and gdk_window_get_screen()

Now that we store the visual in the GdkWindow, these are rather trivial
accessors.

docs/reference/gdk/gdk3-sections.txt

@@ -363,6 +363,8 @@ GdkWindowAttributesType
 gdk_window_new
 gdk_window_destroy
 gdk_window_get_window_type
+gdk_window_get_screen
+gdk_window_get_visual
 gdk_window_at_pointer
 gdk_window_show
 gdk_window_show_unraised

gdk/gdk.symbols

@@ -581,6 +581,8 @@ gdk_window_get_origin
 gdk_window_get_root_coords
 gdk_window_set_support_multidevice
 gdk_window_get_support_multidevice
+gdk_window_get_screen
+gdk_window_get_visual
 gdk_window_has_native
 gdk_window_set_background
 gdk_window_set_background_pattern

gdk/gdkwindow.c

@@ -2172,6 +2172,46 @@ gdk_window_get_window_type (GdkWindow *window)
   return GDK_WINDOW_TYPE (window);
 }
 
+/**
+ * gdk_window_get_visual:
+ * @window: a #GdkWindow
+ * 
+ * Gets the #GdkVisual describing the pixel format of @window.
+ * 
+ * Return value: a #GdkVisual
+ **/
+GdkVisual*
+gdk_window_get_visual (GdkWindow *window)
+{
+  GdkWindowObject *private;
+
+  g_return_val_if_fail (GDK_IS_WINDOW (window), NULL);
+  
+  private = (GdkWindowObject *) window;
+
+  return private->visual;
+}
+
+/**
+ * gdk_window_get_screen:
+ * @window: a #GdkWindow
+ * 
+ * Gets the #GdkScreen associated with a #GdkWindow.
+ * 
+ * Return value: the #GdkScreen associated with @window
+ **/
+GdkScreen*
+gdk_window_get_screen (GdkWindow *window)
+{
+  GdkWindowObject *private;
+
+  g_return_val_if_fail (GDK_IS_WINDOW (window), NULL);
+
+  private = (GdkWindowObject *) window;
+
+  return gdk_visual_get_screen (private->visual);
+}
+
 /**
  * gdk_window_is_destroyed:
  * @window: a #GdkWindow

gdk/gdkwindow.h

@@ -505,6 +505,8 @@ void          gdk_window_destroy               (GdkWindow     *window);
 GdkWindowType gdk_window_get_window_type       (GdkWindow     *window);
 gboolean      gdk_window_is_destroyed          (GdkWindow     *window);
 
+GdkVisual *   gdk_window_get_visual            (GdkWindow     *window);
+GdkScreen *   gdk_window_get_screen            (GdkWindow     *window);
 #ifndef GDK_MULTIDEVICE_SAFE
 GdkWindow*    gdk_window_at_pointer            (gint          *win_x,
                                                 gint          *win_y);