Bug 539356 - Part 18 - Mark frames with only invalid children as an optimization to use when invalidating further frames. r=roc

layout/generic/nsFrame.cpp

@@ -4754,6 +4754,12 @@ void
 nsIFrame::InvalidateFrameSubtree(uint32_t aFlags)
 {
   InvalidateFrame(aFlags);
+
+  if (HasAnyStateBits(NS_FRAME_ALL_DESCENDANTS_NEED_PAINT)) {
+    return;
+  }
+
+  AddStateBits(NS_FRAME_ALL_DESCENDANTS_NEED_PAINT);
   
   nsAutoTArray<nsIFrame::ChildList,4> childListArray;
   GetCrossDocChildLists(&childListArray);
@@ -4784,7 +4790,9 @@ nsIFrame::ClearInvalidationStateBits()
     }
   }
 
-  RemoveStateBits(NS_FRAME_NEEDS_PAINT | NS_FRAME_DESCENDANT_NEEDS_PAINT);
+  RemoveStateBits(NS_FRAME_NEEDS_PAINT | 
+                  NS_FRAME_DESCENDANT_NEEDS_PAINT | 
+                  NS_FRAME_ALL_DESCENDANTS_NEED_PAINT);
 }
 
 void
@@ -7991,6 +7999,13 @@ nsFrame::SetParent(nsIFrame* aParent)
   } else {
     RemoveInPopupStateBitFromDescendants(this);
   }
+  
+  // If our new parent only has invalid children, then we just invalidate
+  // ourselves too. This is probably faster than clearing the flag all
+  // the way up the frame tree.
+  if (aParent->HasAnyStateBits(NS_FRAME_ALL_DESCENDANTS_NEED_PAINT)) {
+    InvalidateFrame(INVALIDATE_DONT_SCHEDULE_PAINT);
+  }
 }
 
 void

layout/generic/nsIFrame.h

@@ -313,6 +313,12 @@ typedef uint64_t nsFrameState;
 // Frame is a descendant of a popup
 #define NS_FRAME_IN_POPUP                           NS_FRAME_STATE_BIT(50)
 
+// Frame has only descendant frames that needs painting - This includes
+// cross-doc children. This guarantees that all descendents have 
+// NS_FRAME_NEEDS_PAINT and NS_FRAME_ALL_DESCENDANTS_NEED_PAINT, or they 
+// have no display items.
+#define NS_FRAME_ALL_DESCENDANTS_NEED_PAINT         NS_FRAME_STATE_BIT(51)
+
 // Box layout bits
 #define NS_STATE_IS_HORIZONTAL                      NS_FRAME_STATE_BIT(22)
 #define NS_STATE_IS_DIRECTION_NORMAL                NS_FRAME_STATE_BIT(31)