[gtk+] viewport: Set the pixel cache background from the child

[Benjamin Otte <otte src gnome org>]

commit 9cb0a97bb56ef904e7518a8b3bd722acd8515773
Author: Benjamin Otte <otte redhat com>
Date:   Wed Jan 20 04:35:04 2016 +0100

    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.

 gtk/gtkviewport.c |   25 ++++++++++++++++++++-----
 1 files changed, 20 insertions(+), 5 deletions(-)
---
diff --git a/gtk/gtkviewport.c b/gtk/gtkviewport.c
index 7a67fb8..3edf5ec 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);
 }