From 77b09771989874184cbe3884d5b93be5b9a61cbe Mon Sep 17 00:00:00 2001
From: Matt Woodrow <mwoodrow@mozilla.com>
Date: Mon, 13 Aug 2012 22:10:10 +1200
Subject: [PATCH] Bug 539356 - Part 13 - Only repaint widgets that have had
 changes since the last paint. r=roc

---
 view/src/nsViewManager.cpp | 7 +++++--
 widget/nsIWidget.h         | 5 +++++
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/view/src/nsViewManager.cpp b/view/src/nsViewManager.cpp
index e339e90a2b66..50e7970cf03e 100644
--- a/view/src/nsViewManager.cpp
+++ b/view/src/nsViewManager.cpp
@@ -23,6 +23,7 @@
 #include "nsEventStateManager.h"
 #include "mozilla/StartupTimeline.h"
 #include "sampler.h"
+#include "nsRefreshDriver.h"
 
 /**
    XXX TODO XXX
@@ -377,7 +378,9 @@ void nsViewManager::ProcessPendingUpdatesForView(nsView* aView,
   // damage is applied based on the final widget geometry
   if (aFlushDirtyRegion) {
     nsIWidget *widget = aView->GetWidget();
-    if (widget) {
+    if (widget && widget->NeedsPaint() && aView->HasNonEmptyDirtyRegion()) {
+      FlushDirtyRegionToWidget(aView);
+      SetPainting(true);
 #ifdef DEBUG_INVALIDATIONS
       printf("---- PAINT START ----PresShell(%p), nsView(%p), nsIWidget(%p)\n", mPresShell, aView, widget);
 #endif
@@ -386,8 +389,8 @@ void nsViewManager::ProcessPendingUpdatesForView(nsView* aView,
 #ifdef DEBUG_INVALIDATIONS
       printf("---- PAINT END ----\n");
 #endif
+      SetPainting(false);
     }
-    FlushDirtyRegionToWidget(aView);
   }
 }
 
diff --git a/widget/nsIWidget.h b/widget/nsIWidget.h
index e03aaca87462..b4bfb119f865 100644
--- a/widget/nsIWidget.h
+++ b/widget/nsIWidget.h
@@ -409,6 +409,7 @@ class nsIWidget : public nsISupports {
     nsIWidget()
       : mLastChild(nullptr)
       , mPrevSibling(nullptr)
+      , mNeedsPaint(false)
     {}
 
         
@@ -1593,6 +1594,9 @@ class nsIWidget : public nsISupports {
      */
     virtual bool WidgetPaintsBackground() { return false; }
 
+    bool NeedsPaint() { 
+      return true;
+    }
     /**
      * Get the natural bounds of this widget.  This method is only
      * meaningful for widgets for which Gecko implements screen
@@ -1643,6 +1647,7 @@ protected:
     nsIWidget* mLastChild;
     nsCOMPtr<nsIWidget> mNextSibling;
     nsIWidget* mPrevSibling;
+    bool mNeedsPaint;
 };
 
 NS_DEFINE_STATIC_IID_ACCESSOR(nsIWidget, NS_IWIDGET_IID)