Backed out changeset f67228df9ae0 (bug 1022612)

layout/base/nsDisplayList.cpp

@@ -2246,6 +2246,23 @@ nsDisplayBackgroundImage::IsUniform(nsDisplayListBuilder* aBuilder, nscolor* aCo
   return false;
 }
 
+bool
+nsDisplayBackgroundImage::IsVaryingRelativeToMovingFrame(nsDisplayListBuilder* aBuilder,
+                                                         nsIFrame* aFrame)
+{
+  if (!mBackgroundStyle)
+    return false;
+  if (!mBackgroundStyle->HasFixedBackground())
+    return false;
+
+  // If aFrame is mFrame or an ancestor in this document, and aFrame is
+  // not the viewport frame, then moving aFrame will move mFrame
+  // relative to the viewport, so our fixed-pos background will change.
+  return aFrame->GetParent() &&
+    (aFrame == mFrame ||
+     nsLayoutUtils::IsProperAncestorFrame(aFrame, mFrame));
+}
+
 nsRect
 nsDisplayBackgroundImage::GetPositioningArea()
 {
@@ -3102,6 +3119,13 @@ bool nsDisplayWrapList::IsUniform(nsDisplayListBuilder* aBuilder, nscolor* aColo
   return false;
 }
 
+bool nsDisplayWrapList::IsVaryingRelativeToMovingFrame(nsDisplayListBuilder* aBuilder,
+                                                         nsIFrame* aFrame) {
+  NS_WARNING("nsDisplayWrapList::IsVaryingRelativeToMovingFrame called unexpectedly");
+  // We could try to do something but let's conservatively just return true.
+  return true;
+}
+
 void nsDisplayWrapList::Paint(nsDisplayListBuilder* aBuilder,
                               nsRenderingContext* aCtx) {
   NS_ERROR("nsDisplayWrapList should have been flattened away for painting");

layout/base/nsDisplayList.h

@@ -1101,6 +1101,16 @@ public:
    * bounds with the same (possibly translucent) color
    */
   virtual bool IsUniform(nsDisplayListBuilder* aBuilder, nscolor* aColor) { return false; }
+  /**
+   * @return false if the painting performed by the item is invariant
+   * when the item's underlying frame is moved relative to aFrame.
+   * In other words, if you render the item at locations P and P', the rendering
+   * only differs by the translation.
+   * It return true for all wrapped lists.
+   */
+  virtual bool IsVaryingRelativeToMovingFrame(nsDisplayListBuilder* aBuilder,
+                                                nsIFrame* aFrame)
+  { return false; }
   /**
    * @return true if the contents of this item are rendered fixed relative
    * to the nearest viewport.
@@ -2169,6 +2179,8 @@ public:
                                    const nsRect& aAllowVisibleRegionExpansion) MOZ_OVERRIDE;
   virtual nsRegion GetOpaqueRegion(nsDisplayListBuilder* aBuilder,
                                    bool* aSnap) MOZ_OVERRIDE;
+  virtual bool IsVaryingRelativeToMovingFrame(nsDisplayListBuilder* aBuilder,
+                                                nsIFrame* aFrame) MOZ_OVERRIDE;
   virtual bool IsUniform(nsDisplayListBuilder* aBuilder, nscolor* aColor) MOZ_OVERRIDE;
   /**
    * GetBounds() returns the background painting area.
@@ -2583,6 +2595,8 @@ public:
   virtual nsRegion GetOpaqueRegion(nsDisplayListBuilder* aBuilder,
                                    bool* aSnap) MOZ_OVERRIDE;
   virtual bool IsUniform(nsDisplayListBuilder* aBuilder, nscolor* aColor) MOZ_OVERRIDE;
+  virtual bool IsVaryingRelativeToMovingFrame(nsDisplayListBuilder* aBuilder,
+                                                nsIFrame* aFrame) MOZ_OVERRIDE;
   virtual void Paint(nsDisplayListBuilder* aBuilder, nsRenderingContext* aCtx) MOZ_OVERRIDE;
   virtual bool ComputeVisibility(nsDisplayListBuilder* aBuilder,
                                  nsRegion* aVisibleRegion,

layout/tables/nsTableFrame.cpp

@@ -1088,6 +1088,20 @@ nsDisplayTableItem::GetBounds(nsDisplayListBuilder* aBuilder, bool* aSnap) {
   return mFrame->GetVisualOverflowRectRelativeToSelf() + ToReferenceFrame();
 }
 
+bool
+nsDisplayTableItem::IsVaryingRelativeToMovingFrame(nsDisplayListBuilder* aBuilder,
+                                                   nsIFrame* aFrame)
+{
+  if (!mPartHasFixedBackground)
+    return false;
+
+  // If aFrame is mFrame or an ancestor in this document, and aFrame is
+  // not the viewport frame, then moving aFrame will move mFrame
+  // relative to the viewport, so our fixed-pos background will change.
+  return mFrame == aFrame ||
+    nsLayoutUtils::IsProperAncestorFrame(aFrame, mFrame);
+}
+
 /* static */ void
 nsDisplayTableItem::UpdateForFrameBackground(nsIFrame* aFrame)
 {

layout/tables/nsTableFrame.h

@@ -50,6 +50,8 @@ public:
       nsDisplayItem(aBuilder, aFrame),
       mPartHasFixedBackground(false) {}
 
+  virtual bool IsVaryingRelativeToMovingFrame(nsDisplayListBuilder* aBuilder,
+                                                nsIFrame* aFrame) MOZ_OVERRIDE;
   // With collapsed borders, parts of the collapsed border can extend outside
   // the table part frames, so allow this display element to blow out to our
   // overflow rect. This is also useful for row frames that have spanning