Gtk: improve performance of tab dragging.

Remove two server trips and two byte swizzles by keeping the tab image server side (instead of piping it through an SkBitmap). This creates noticeably better performance on drawing attached dragged tabs (i.e. when you drag a tab to reorder it, but don't drag out of the tab strip) on non-compositing WMs (I suspect it is better for compositing as well, but did not test it).

BUG=21657
TEST=see above

Review URL: http://codereview.chromium.org/496002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@34488 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 10 insertions, 15 deletions

diff --git a/chrome/browser/gtk/tabs/dragged_tab_gtk.cc b/chrome/browser/gtk/tabs/dragged_tab_gtk.cc
index 1764578..40127ca 100644
--- a/chrome/browser/gtk/tabs/dragged_tab_gtk.cc
+++ b/chrome/browser/gtk/tabs/dragged_tab_gtk.cc
@@ -241,7 +241,7 @@ void DraggedTabGtk::SetContainerTransparency() {
   cairo_destroy(cairo_context);
 }
 
-void DraggedTabGtk::SetContainerShapeMask(GdkPixbuf* pixbuf) {
+void DraggedTabGtk::SetContainerShapeMask(cairo_surface_t* surface) {
   // Create a 1bpp bitmap the size of |container_|.
   gfx::Size size = bounds().size();
   GdkPixmap* pixmap = gdk_pixmap_new(NULL, size.width(), size.height(), 1);
@@ -255,7 +255,7 @@ void DraggedTabGtk::SetContainerShapeMask(GdkPixbuf* pixbuf) {
   cairo_set_operator(cairo_context, CAIRO_OPERATOR_SOURCE);
   if (!attached_)
     cairo_scale(cairo_context, kScalingFactor, kScalingFactor);
-  gdk_cairo_set_source_pixbuf(cairo_context, pixbuf, 0, 0);
+  cairo_set_source_surface(cairo_context, surface, 0, 0);
   cairo_paint(cairo_context);
 
   if (!attached_) {
@@ -264,7 +264,7 @@ void DraggedTabGtk::SetContainerShapeMask(GdkPixbuf* pixbuf) {
     cairo_identity_matrix(cairo_context);
     cairo_set_source_rgba(cairo_context, 1.0f, 1.0f, 1.0f, 1.0f);
     int tab_height = static_cast<int>(kScalingFactor *
-                                      gdk_pixbuf_get_height(pixbuf) -
+                                      renderer_->height() -
                                       kDragFrameBorderSize);
     cairo_rectangle(cairo_context,
                     0, tab_height,
@@ -279,27 +279,22 @@ void DraggedTabGtk::SetContainerShapeMask(GdkPixbuf* pixbuf) {
   g_object_unref(pixmap);
 }
 
-GdkPixbuf* DraggedTabGtk::PaintTab() {
-  SkBitmap bitmap = renderer_->PaintBitmap();
-  return gfx::GdkPixbufFromSkBitmap(&bitmap);
-}
-
 // static
 gboolean DraggedTabGtk::OnExposeEvent(GtkWidget* widget,
                                       GdkEventExpose* event,
                                       DraggedTabGtk* dragged_tab) {
-  GdkPixbuf* pixbuf = dragged_tab->PaintTab();
+  cairo_surface_t* surface = dragged_tab->renderer_->PaintToSurface();
   if (gtk_util::IsScreenComposited()) {
     dragged_tab->SetContainerTransparency();
   } else {
-    dragged_tab->SetContainerShapeMask(pixbuf);
+    dragged_tab->SetContainerShapeMask(surface);
   }
 
   // Only used when not attached.
-  int tab_height = static_cast<int>(kScalingFactor *
-                                    gdk_pixbuf_get_height(pixbuf));
   int tab_width = static_cast<int>(kScalingFactor *
-                                   gdk_pixbuf_get_width(pixbuf));
+      dragged_tab->renderer_->width());
+  int tab_height = static_cast<int>(kScalingFactor *
+      dragged_tab->renderer_->height());
 
   // Draw the render area.
   if (dragged_tab->backing_store_ && !dragged_tab->attached_) {
@@ -341,12 +336,12 @@ gboolean DraggedTabGtk::OnExposeEvent(GtkWidget* widget,
   // Draw the tab.
   if (!dragged_tab->attached_)
     cairo_scale(cr, kScalingFactor, kScalingFactor);
-  gdk_cairo_set_source_pixbuf(cr, pixbuf, 0, 0);
+  cairo_set_source_surface(cr, surface, 0, 0);
   cairo_paint(cr);
 
   cairo_destroy(cr);
 
-  g_object_unref(pixbuf);
+  cairo_surface_destroy(surface);
 
   // We've already drawn the tab, so don't propagate the expose-event signal.
   return TRUE;