Bug 810470. Part 3: Remove code for invalidating background-attachment:fixed content when scrolling. r=mattwoodrow

New invalidation logic takes care of this automatically.

--HG--
extra : rebase_source : f598635e58390ef868a057e8ea8ab0cf2410b8a9

layout/base/FrameLayerBuilder.cpp

@@ -2314,33 +2314,6 @@ ContainerState::InvalidateForLayerChange(nsDisplayItem* aItem,
   }
 }
 
-bool
-FrameLayerBuilder::NeedToInvalidateFixedDisplayItem(nsDisplayListBuilder* aBuilder,
-                                                    nsDisplayItem* aItem)
-{
-  if (!aItem->ShouldFixToViewport(aBuilder)) {
-    return true;
-  }
-
-  nsRefPtr<LayerManager> layerManager;
-  nsIFrame* referenceFrame = aBuilder->RootReferenceFrame();
-  NS_ASSERTION(referenceFrame == nsLayoutUtils::GetDisplayRootFrame(referenceFrame),
-               "Reference frame must be a display root for us to use the layer manager");
-  nsIWidget* window = referenceFrame->GetNearestWidget();
-  if (window) {
-    layerManager = window->GetLayerManager();
-  }
-
-  if (layerManager) {
-    DisplayItemData* data = GetDisplayItemDataForManager(aItem, layerManager);
-    if (data) {
-      return false;
-    }
-  }
-
-  return true;
-}
-
 void
 FrameLayerBuilder::AddThebesDisplayItem(ThebesLayer* aLayer,
                                         nsDisplayItem* aItem,

layout/base/FrameLayerBuilder.h

@@ -321,16 +321,6 @@ public:
 
   LayerManager* GetRetainingLayerManager() { return mRetainingManager; }
 
-  /**
-   * Returns true if the given item (which we assume here is
-   * background-attachment:fixed) needs to be repainted as we scroll in its
-   * document.
-   * Returns false if it doesn't need to be repainted because the layer system
-   * is ensuring its fixed-ness for us.
-   */
-  static bool NeedToInvalidateFixedDisplayItem(nsDisplayListBuilder* aBuilder,
-                                                 nsDisplayItem* aItem);
-
   /**
    * Returns true if the given display item was rendered during the previous
    * paint. Returns false otherwise.

layout/generic/nsGfxScrollFrame.cpp

@@ -1671,56 +1671,6 @@ CanScrollWithBlitting(nsIFrame* aFrame)
   return true;
 }
 
-static void
-InvalidateFixedBackgroundFramesFromList(nsDisplayListBuilder* aBuilder,
-                                        nsIFrame* aMovingFrame,
-                                        const nsDisplayList& aList)
-{
-  for (nsDisplayItem* item = aList.GetBottom(); item; item = item->GetAbove()) {
-    nsDisplayList* sublist = item->GetSameCoordinateSystemChildren();
-    if (sublist) {
-      InvalidateFixedBackgroundFramesFromList(aBuilder, aMovingFrame, *sublist);
-      continue;
-    }
-    nsIFrame* f = item->GetUnderlyingFrame();
-    if (f &&
-        item->IsVaryingRelativeToMovingFrame(aBuilder, aMovingFrame)) {
-      if (FrameLayerBuilder::NeedToInvalidateFixedDisplayItem(aBuilder, item)) {
-        // FrameLayerBuilder does not take care of scrolling this one
-        f->InvalidateFrame();
-      }
-    }
-  }
-}
-
-static void
-InvalidateFixedBackgroundFrames(nsIFrame* aRootFrame,
-                                nsIFrame* aMovingFrame,
-                                const nsRect& aUpdateRect)
-{
-  if (!aMovingFrame->PresContext()->MayHaveFixedBackgroundFrames())
-    return;
-
-  NS_ASSERTION(aRootFrame != aMovingFrame,
-               "The root frame shouldn't be the one that's moving, that makes no sense");
-
-  // Build the 'after' display list over the whole area of interest.
-  nsDisplayListBuilder builder(aRootFrame, nsDisplayListBuilder::OTHER, true);
-  builder.EnterPresShell(aRootFrame, aUpdateRect);
-  nsDisplayList list;
-  nsresult rv =
-    aRootFrame->BuildDisplayListForStackingContext(&builder, aUpdateRect, &list);
-  builder.LeavePresShell(aRootFrame, aUpdateRect);
-  if (NS_FAILED(rv))
-    return;
-
-  nsRegion visibleRegion(aUpdateRect);
-  list.ComputeVisibilityForRoot(&builder, &visibleRegion);
-
-  InvalidateFixedBackgroundFramesFromList(&builder, aMovingFrame, list);
-  list.DeleteAll();
-}
-
 bool nsGfxScrollFrameInner::IsIgnoringViewportClipping() const
 {
   if (!mIsRoot)
@@ -1796,14 +1746,11 @@ void nsGfxScrollFrameInner::ScrollVisual(nsPoint aOldScrolledFramePos)
   AdjustViews(mScrolledFrame);
   // We need to call this after fixing up the view positions
   // to be consistent with the frame hierarchy.
-  bool invalidate = false;
   bool canScrollWithBlitting = CanScrollWithBlitting(mOuter);
   mOuter->RemoveStateBits(NS_SCROLLFRAME_INVALIDATE_CONTENTS_ON_SCROLL);
   if (IsScrollingActive()) {
     if (!canScrollWithBlitting) {
       MarkInactive();
-    } else {
-      invalidate = true;
     }
   }
   if (canScrollWithBlitting) {
@@ -1811,16 +1758,6 @@ void nsGfxScrollFrameInner::ScrollVisual(nsPoint aOldScrolledFramePos)
   }
 
   mOuter->SchedulePaint();
-
-  if (invalidate) {
-    nsIFrame* displayRoot = nsLayoutUtils::GetDisplayRootFrame(mOuter);
-    nsRect update =
-      GetScrollPortRect() + mOuter->GetOffsetToCrossDoc(displayRoot);
-    nsRect displayRootUpdate = update.ConvertAppUnitsRoundOut(
-      mOuter->PresContext()->AppUnitsPerDevPixel(),
-      displayRoot->PresContext()->AppUnitsPerDevPixel());
-    InvalidateFixedBackgroundFrames(displayRoot, mScrolledFrame, displayRootUpdate);
-  }
 }
 
 /**