wayland: Make window opacity work

Under wayland, the compositor doesn't have a 'overall window alpha'
knob, we just need to add the alpha to the buffers we send.
Client-side alpha, if you want to call it that.

Implement this by reusing the existing alpha support for non-toplevel
widgets. As a side-effect of the implementation, windows with RGBA
visual under X will now also use per-pixel alpha, instead of
overall alpha.

2 files changed, 8 insertions, 3 deletions

diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index 9565439..f3e4958 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -7122,8 +7122,9 @@ _gtk_widget_draw (GtkWidget *widget,
   cairo_save (cr);
 
   push_group =
-    (widget->priv->alpha != 255 &&
-     !gtk_widget_is_toplevel (widget));
+    widget->priv->alpha != 255 &&
+    (!gtk_widget_is_toplevel (widget) ||
+     gtk_widget_get_visual (widget) == gdk_screen_get_rgba_visual (gtk_widget_get_screen (widget)));
 
   if (push_group)
     cairo_push_group (cr);
@@ -15958,7 +15959,8 @@ gtk_widget_update_alpha (GtkWidget *widget)
 
   if (gtk_widget_get_realized (widget))
     {
-      if (gtk_widget_is_toplevel (widget))
+      if (gtk_widget_is_toplevel (widget) &&
+          gtk_widget_get_visual (widget) != gdk_screen_get_rgba_visual (gtk_widget_get_screen (widget)))
 	gdk_window_set_opacity (priv->window, priv->alpha / 255.0);
 
       gtk_widget_queue_draw (widget);
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index 0b0365f..6bfe836 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -6761,6 +6761,9 @@ update_opaque_region (GtkWindow           *window,
       is_opaque = (color->alpha >= 1.0);
     }
 
+  if (gtk_widget_get_opacity (widget) < 1.0)
+    is_opaque = FALSE;
+
   if (is_opaque)
     {
       cairo_rectangle_int_t rect;