gdk: add gdk_window_set_shadow_width()

And deprecate the X11-specific version of it.

We call this new API _set_shadow_width() and not _set_frame_extents()
because we already have a gdk_window_get_frame_extents() with a
different meaning and different type of value.

https://bugzilla.gnome.org/show_bug.cgi?id=720374

docs/reference/gdk/gdk3-sections.txt

@@ -450,6 +450,7 @@ gdk_window_set_modal_hint
 gdk_window_get_modal_hint
 gdk_window_set_type_hint
 gdk_window_get_type_hint
+gdk_window_set_shadow_width
 gdk_window_set_skip_taskbar_hint
 gdk_window_set_skip_pager_hint
 gdk_window_set_urgency_hint

gdk/gdkwindow.c

@@ -10872,3 +10872,42 @@ gdk_window_set_opaque_region (GdkWindow      *window,
   if (impl_class->set_opaque_region)
     return impl_class->set_opaque_region (window, region);
 }
+
+/**
+ * gdk_window_set_shadow_width:
+ * @window: a #GdkWindow
+ * @left: The left extent
+ * @right: The right extent
+ * @top: The top extent
+ * @bottom: The bottom extent
+ *
+ * Newer GTK+ windows using client-side decorations use extra geometry
+ * around their frames for effects like shadows and invisible borders.
+ * Window managers that want to maximize windows or snap to edges need
+ * to know where the extents of the actual frame lie, so that users
+ * don't feel like windows are snapping against random invisible edges.
+ *
+ * Note that this property is automatically updated by GTK+, so this
+ * function should only be used by applications which do not use GTK+
+ * to create toplevel windows.
+ *
+ * Since: 3.12
+ */
+void
+gdk_window_set_shadow_width (GdkWindow *window,
+                             gint       left,
+                             gint       right,
+                             gint       top,
+                             gint       bottom)
+{
+  GdkWindowImplClass *impl_class;
+
+  g_return_if_fail (GDK_IS_WINDOW (window));
+  g_return_if_fail (!GDK_WINDOW_DESTROYED (window));
+  g_return_if_fail (left >= 0 && right >= 0 && top >= 0 && bottom >= 0);
+
+  impl_class = GDK_WINDOW_IMPL_GET_CLASS (window->impl);
+
+  if (impl_class->set_shadow_width)
+    impl_class->set_shadow_width (window, left, right, top, bottom);
+}

gdk/gdkwindow.h

@@ -1096,6 +1096,13 @@ void       gdk_window_set_event_compression    (GdkWindow      *window,
 GDK_AVAILABLE_IN_3_12
 gboolean   gdk_window_get_event_compression    (GdkWindow      *window);
 
+GDK_AVAILABLE_IN_3_12
+void       gdk_window_set_shadow_width         (GdkWindow      *window,
+                                                gint            left,
+                                                gint            right,
+                                                gint            top,
+                                                gint            bottom);
+
 G_END_DECLS
 
 #endif /* __GDK_WINDOW_H__ */

gdk/gdkwindowimpl.h

@@ -295,6 +295,11 @@ struct _GdkWindowImplClass
 
   void         (* set_opaque_region)      (GdkWindow      *window,
                                            cairo_region_t *region);
+  void         (* set_shadow_width)       (GdkWindow      *window,
+                                           gint            left,
+                                           gint            right,
+                                           gint            top,
+                                           gint            bottom);
 };
 
 /* Interface Functions */

gdk/x11/gdkwindow-x11.c

@@ -3660,32 +3660,12 @@ gdk_x11_window_set_hide_titlebar_when_maximized (GdkWindow *window,
     }
 }
 
-/**
+static void
- * gdk_x11_window_set_frame_extents:
+gdk_x11_window_set_shadow_width (GdkWindow *window,
- * @window: (type GdkX11Window): a #GdkWindow
+                                 int        left,
- * @left: The left extent
+                                 int        right,
- * @right: The right extent
+                                 int        top,
- * @top: The top extent
+                                 int        bottom)
- * @bottom: The bottom extent
- *
- * Newer GTK+ windows using client-side decorations use extra geometry
- * around their frames for effects like shadows and invisible borders.
- * Window managers that want to maximize windows or snap to edges need
- * to know where the extents of the actual frame lie, so that users
- * don't feel like windows are snapping against random invisible edges.
- *
- * Note that this property is automatically updated by GTK+, so this
- * function should only be used by applications which do not use GTK+
- * to create toplevel windows.
- *
- * Since: 3.10
- */
-void
-gdk_x11_window_set_frame_extents (GdkWindow *window,
-                                  int        left,
-                                  int        right,
-                                  int        top,
-                                  int        bottom)
 {
   Atom frame_extents;
   gulong data[4] = { left, right, top, bottom };
@@ -3699,6 +3679,31 @@ gdk_x11_window_set_frame_extents (GdkWindow *window,
                    (guchar *) &data, 4);
 }
 
+/**
+ * gdk_x11_window_set_frame_extents:
+ * @window: (type GdkX11Window): a #GdkWindow
+ * @left: The left extent
+ * @right: The right extent
+ * @top: The top extent
+ * @bottom: The bottom extent
+ *
+ * This is the same as gdk_window_set_shadow_width() but it only works
+ * on GdkX11Window.
+ *
+ * Since: 3.10
+ *
+ * Deprecated: 3.12: Use gdk_window_set_shadow_width() instead.
+ */
+void
+gdk_x11_window_set_frame_extents (GdkWindow *window,
+                                  int        left,
+                                  int        right,
+                                  int        top,
+                                  int        bottom)
+{
+  gdk_x11_window_set_shadow_width (window, left, right, top, bottom);
+}
+
 /**
  * gdk_x11_window_set_theme_variant:
  * @window: (type GdkX11Window): a #GdkWindow
@@ -5712,4 +5717,5 @@ gdk_window_impl_x11_class_init (GdkWindowImplX11Class *klass)
   impl_class->delete_property = _gdk_x11_window_delete_property;
   impl_class->get_scale_factor = gdk_x11_window_get_scale_factor;
   impl_class->set_opaque_region = gdk_x11_window_set_opaque_region;
+  impl_class->set_shadow_width = gdk_x11_window_set_shadow_width;
 }

gdk/x11/gdkx11window.h

@@ -65,7 +65,7 @@ void     gdk_x11_window_set_utf8_property    (GdkWindow *window,
 GDK_AVAILABLE_IN_3_2
 void     gdk_x11_window_set_theme_variant (GdkWindow   *window,
                                            char        *variant);
-GDK_AVAILABLE_IN_3_10
+GDK_DEPRECATED_IN_3_12_FOR(gdk_window_set_shadow_width)
 void     gdk_x11_window_set_frame_extents (GdkWindow *window,
                                            int        left,
                                            int        right,

gtk/gtkwindow.c

@@ -6422,21 +6422,19 @@ update_border_windows (GtkWindow *window)
 }
 
 static void
-update_frame_extents (GtkWindow *window,
+update_shadow_width (GtkWindow *window,
-                      GtkBorder *border)
+                     GtkBorder *border)
 {
-#ifdef GDK_WINDOWING_X11
   GdkWindow *gdk_window;
 
   gdk_window = gtk_widget_get_window (GTK_WIDGET (window));
 
-  if (GDK_IS_X11_WINDOW (gdk_window))
+  if (gdk_window)
-    gdk_x11_window_set_frame_extents (gdk_window,
+    gdk_window_set_shadow_width (gdk_window,
-                                      border->left,
+                                 border->left,
-                                      border->right,
+                                 border->right,
-                                      border->top,
+                                 border->top,
-                                      border->bottom);
+                                 border->bottom);
-#endif
 }
 
 static void
@@ -6571,7 +6569,7 @@ _gtk_window_set_allocation (GtkWindow           *window,
   priv->title_height = 0;
 
   if (priv->client_decorated)
-    update_frame_extents (window, &window_border);
+    update_shadow_width (window, &window_border);
 
   update_opaque_region (window, &window_border, &child_allocation);