Support bypass compositor hints

Add support for _NET_WM_BYPASS_COMPOSITOR and _NET_WM_DONT_BYPASS_COMPOSITOR
as proposed here: https://mail.gnome.org/archives/wm-spec-list/2012-February/msg00010.html

https://bugzilla.gnome.org/show_bug.cgi?id=683020

src/compositor/meta-window-actor.c

@@ -1193,18 +1193,26 @@ meta_window_actor_should_unredirect (MetaWindowActor *self)
   int num_monitors = meta_screen_get_n_monitors (screen);
   int i;
 
-  if (!meta_window_is_override_redirect (metaWindow))
+  if (meta_window_requested_dont_bypass_compositor (metaWindow))
+    return FALSE;
+
+  if (!meta_window_is_override_redirect (metaWindow) &&
+      !meta_window_requested_bypass_compositor (metaWindow))
     return FALSE;
 
   if (priv->opacity != 0xff)
     return FALSE;
 
-  if (priv->argb32)
+  if (priv->argb32 && !meta_window_requested_bypass_compositor (metaWindow))
     return FALSE;
 
   if (metaWindow->has_shape)
     return FALSE;
 
+  if (meta_window_requested_bypass_compositor (metaWindow) &&
+      meta_window_is_fullscreen (metaWindow))
+    return TRUE;
+
   meta_screen_get_size (screen, &screen_width, &screen_height);
   meta_window_get_outer_rect (metaWindow, &window_rect);
 

src/core/window-private.h

@@ -413,6 +413,10 @@ struct _MetaWindow
 
   /* The currently complementary tiled window, if any */
   MetaWindow *tile_match;
+
+  /* Bypass compositor hints */
+  guint bypass_compositor : 1;
+  guint dont_bypass_compositor : 1;
 };
 
 struct _MetaWindowClass

src/core/window-props.c

@@ -1584,6 +1584,58 @@ reload_gtk_hide_titlebar_when_maximized (MetaWindow    *window,
     }
 }
 
+static void
+reload_bypass_compositor (MetaWindow    *window,
+                          MetaPropValue *value,
+                          gboolean       initial)
+{
+  gboolean requested_value = FALSE;
+  gboolean current_value = window->bypass_compositor;
+
+  if (value->type != META_PROP_VALUE_INVALID)
+    {
+      requested_value = ((int) value->v.cardinal == 1);
+      meta_verbose ("Request to bypass compositor for window %s.\n", window->desc);
+    }
+
+  if (requested_value == current_value)
+    return;
+
+  if (requested_value && window->dont_bypass_compositor)
+    {
+      meta_verbose ("Setting bypass and dont compositor for same window (%s) makes no sense, ignoring.\n", window->desc);
+      return;
+    }
+
+  window->bypass_compositor = requested_value;
+}
+
+static void
+reload_dont_bypass_compositor (MetaWindow    *window,
+                               MetaPropValue *value,
+                               gboolean       initial)
+{
+  gboolean requested_value = FALSE;
+  gboolean current_value = window->dont_bypass_compositor;
+
+  if (value->type != META_PROP_VALUE_INVALID)
+    {
+      requested_value = ((int) value->v.cardinal == 1);
+      meta_verbose ("Request to don't bypass compositor for window %s.\n", window->desc);
+    }
+
+  if (requested_value == current_value)
+    return;
+
+  if (requested_value && window->bypass_compositor)
+    {
+      meta_verbose ("Setting bypass and dont compositor for same window (%s) makes no sense, ignoring.\n", window->desc);
+      return;
+    }
+
+  window->dont_bypass_compositor = requested_value;
+}
+
 #define RELOAD_STRING(var_name, propname) \
   static void                                       \
   reload_ ## var_name (MetaWindow    *window,       \
@@ -1683,6 +1735,8 @@ meta_display_init_window_prop_hooks (MetaDisplay *display)
     { display->atom__NET_WM_WINDOW_TYPE, META_PROP_VALUE_INVALID, reload_net_wm_window_type,  FALSE, TRUE },
     { display->atom__NET_WM_STRUT,         META_PROP_VALUE_INVALID, reload_struts,            FALSE, FALSE },
     { display->atom__NET_WM_STRUT_PARTIAL, META_PROP_VALUE_INVALID, reload_struts,            FALSE, FALSE },
+    { display->atom__NET_WM_BYPASS_COMPOSITOR, META_PROP_VALUE_CARDINAL,  reload_bypass_compositor, FALSE, FALSE },
+    { display->atom__NET_WM_DONT_BYPASS_COMPOSITOR, META_PROP_VALUE_CARDINAL,  reload_dont_bypass_compositor, FALSE, FALSE },
     { 0 },
   };
 

src/core/window.c

@@ -3640,6 +3640,28 @@ meta_window_is_on_primary_monitor (MetaWindow *window)
   return window->monitor->is_primary;
 }
 
+/**
+ * meta_window_requested_bypass_compositor:
+ *
+ * Return value: %TRUE if the window requested to bypass the compositor
+ */
+gboolean
+meta_window_requested_bypass_compositor (MetaWindow *window)
+{
+  return window->bypass_compositor;
+}
+
+/**
+ * meta_window_requested_dont_bypass_compositor:
+ *
+ * Return value: %TRUE if the window requested to opt out of unredirecting
+ */
+gboolean
+meta_window_requested_dont_bypass_compositor (MetaWindow *window)
+{
+  return window->dont_bypass_compositor;
+}
+
 void
 meta_window_tile (MetaWindow *window)
 {

src/meta/atomnames.h

@@ -172,6 +172,8 @@ item(_NET_WM_ACTION_BELOW)
 item(_NET_WM_STATE_STICKY)
 item(_NET_WM_FULLSCREEN_MONITORS)
 item(_NET_WM_STATE_FOCUSED)
+item(_NET_WM_BYPASS_COMPOSITOR)
+item(_NET_WM_DONT_BYPASS_COMPOSITOR)
 
 #if 0
 /* We apparently never use: */

src/meta/window.h

@@ -140,6 +140,8 @@ void     meta_window_foreach_ancestor         (MetaWindow            *window,
 MetaMaximizeFlags meta_window_get_maximized (MetaWindow *window);
 gboolean          meta_window_is_fullscreen (MetaWindow *window);
 gboolean          meta_window_is_on_primary_monitor (MetaWindow *window);
+gboolean          meta_window_requested_bypass_compositor (MetaWindow *window);
+gboolean          meta_window_requested_dont_bypass_compositor (MetaWindow *window);
 
 gboolean meta_window_is_mapped (MetaWindow  *window);
 gboolean meta_window_toplevel_is_mapped (MetaWindow  *window);