viewport: Set the pixel cache background from the child

The viewport itself doesn't move, so we cannot use it as the pixel
cache's background. Use the bottommost using element instead, which is
the viewport's child.

This might need adaptations in themes as we want the backgroud to be
opaque to speed up pixel cache performance.

1 files changed, 20 insertions, 5 deletions

diff --git a/gtk/gtkviewport.c b/gtk/gtkviewport.c
index 7a67fb8de9..3edf5ec47d 100644
--- a/gtk/gtkviewport.c
+++ b/gtk/gtkviewport.c
@@ -109,6 +109,8 @@ static void gtk_viewport_map                      (GtkWidget        *widget);
 static void gtk_viewport_unmap                    (GtkWidget        *widget);
 static gint gtk_viewport_draw                     (GtkWidget        *widget,
 						   cairo_t          *cr);
+static void gtk_viewport_remove                   (GtkContainer     *container,
+						   GtkWidget        *widget);
 static void gtk_viewport_add                      (GtkContainer     *container,
 						   GtkWidget        *widget);
 static void gtk_viewport_size_allocate            (GtkWidget        *widget,
@@ -387,6 +389,7 @@ gtk_viewport_class_init (GtkViewportClass *class)
   
   gtk_widget_class_set_accessible_role (widget_class, ATK_ROLE_VIEWPORT);
 
+  container_class->remove = gtk_viewport_remove;
   container_class->add = gtk_viewport_add;
   gtk_container_class_handle_border_width (container_class);
 
@@ -488,7 +491,6 @@ gtk_viewport_init (GtkViewport *viewport)
 {
   GtkWidget *widget;
   GtkViewportPrivate *priv;
-  GtkStyleContext *style_context;
   GtkCssNode *widget_node;
 
   viewport->priv = gtk_viewport_get_instance_private (viewport);
@@ -506,9 +508,6 @@ gtk_viewport_init (GtkViewport *viewport)
 
   priv->pixel_cache = _gtk_pixel_cache_new ();
 
-  style_context = gtk_widget_get_style_context (widget);
-  _gtk_pixel_cache_set_style_context (priv->pixel_cache, style_context);
-
   widget_node = gtk_widget_get_css_node (widget);
   priv->gadget = gtk_css_custom_gadget_new_for_node (widget_node,
                                                      widget,
@@ -517,7 +516,7 @@ gtk_viewport_init (GtkViewport *viewport)
                                                      gtk_viewport_render,
                                                      NULL, NULL);
 
-  gtk_style_context_add_class (style_context, GTK_STYLE_CLASS_FRAME);
+  gtk_css_gadget_add_class (priv->gadget, GTK_STYLE_CLASS_FRAME);
   viewport_set_adjustment (viewport, GTK_ORIENTATION_HORIZONTAL, NULL);
   viewport_set_adjustment (viewport, GTK_ORIENTATION_VERTICAL, NULL);
 }
@@ -941,6 +940,19 @@ gtk_viewport_draw (GtkWidget *widget,
 }
 
 static void
+gtk_viewport_remove (GtkContainer *container,
+		     GtkWidget    *child)
+{
+  GtkViewport *viewport = GTK_VIEWPORT (container);
+  GtkViewportPrivate *priv = viewport->priv;
+
+  GTK_CONTAINER_CLASS (gtk_viewport_parent_class)->remove (container, child);
+
+  _gtk_pixel_cache_set_style_context (priv->pixel_cache, NULL);
+
+}
+
+static void
 gtk_viewport_add (GtkContainer *container,
 		  GtkWidget    *child)
 {
@@ -952,6 +964,9 @@ gtk_viewport_add (GtkContainer *container,
 
   gtk_widget_set_parent_window (child, priv->bin_window);
 
+  _gtk_pixel_cache_set_style_context (priv->pixel_cache,
+                                      gtk_widget_get_style_context (child));
+
   GTK_CONTAINER_CLASS (gtk_viewport_parent_class)->add (container, child);
 }