Bug 617152. Part 11: Invalidate the ThebesLayers for an active-scroll-root using the scroll position at the last layer tree update, and do the rest of the invalidation using the current scroll position. r=tnikkel

layout/generic/nsGfxScrollFrame.cpp

@@ -190,26 +190,43 @@ nsHTMLScrollFrame::InvalidateInternal(const nsRect& aDamageRect,
 {
   if (aForChild) {
     if (aForChild == mInner.mScrolledFrame) {
-      // restrict aDamageRect to the scrollable view's bounds
       nsRect damage = aDamageRect + nsPoint(aX, aY);
-      // damage is now in our coordinate system, which means it was
-      // translated using the current scroll position. Adjust it to
-      // reflect the scroll position at last paint, since that's what
-      // the layer system wants us to invalidate.
-      damage += GetScrollPosition() - mInner.mScrollPosAtLastPaint;
-      nsRect r;
-      r.IntersectRect(damage, mInner.mScrollPort);
-      PRBool seperateThebes = IsScrollingActive() &&
-        !(aFlags & INVALIDATE_NO_THEBES_LAYERS) && r != damage;
-      if (seperateThebes) {
-        nsHTMLContainerFrame::InvalidateInternal(damage, 0, 0, aForChild,
-          aFlags | INVALIDATE_ONLY_THEBES_LAYERS);
+      // This is the damage rect that we're going to pass up to our parent.
+      nsRect parentDamage;
+      parentDamage.IntersectRect(damage, mInner.mScrollPort);
+
+      if (IsScrollingActive()) {
+        // This is the damage rect that we're going to pass up and
+        // only request invalidation of ThebesLayers for.
+        // damage is now in our coordinate system, which means it was
+        // translated using the current scroll position. Adjust it to
+        // reflect the scroll position at last paint, since that's what
+        // the ThebesLayers are currently set up for.
+        // This should not be clipped to the scrollport since ThebesLayers
+        // can contain content outside the scrollport that may need to be
+        // invalidated.
+        nsRect thebesLayerDamage = damage + GetScrollPosition() - mInner.mScrollPosAtLastPaint;
+        if (parentDamage == thebesLayerDamage) {
+          // This single call will take care of both rects
+          nsHTMLContainerFrame::InvalidateInternal(parentDamage, 0, 0, aForChild, aFlags);
+        } else {
+          // Invalidate rects separately
+          if (!(aFlags & INVALIDATE_NO_THEBES_LAYERS)) {
+            nsHTMLContainerFrame::InvalidateInternal(thebesLayerDamage, 0, 0, aForChild,
+                                                     aFlags | INVALIDATE_ONLY_THEBES_LAYERS);
+          }
+          if (!(aFlags & INVALIDATE_ONLY_THEBES_LAYERS) && !parentDamage.IsEmpty()) {
+            nsHTMLContainerFrame::InvalidateInternal(parentDamage, 0, 0, aForChild,
+                                                     aFlags | INVALIDATE_NO_THEBES_LAYERS);
+          }
+        }
+      } else {
+        if (!parentDamage.IsEmpty()) {
+          nsHTMLContainerFrame::InvalidateInternal(parentDamage, 0, 0, aForChild, aFlags);
+        }
       }
-      if (!r.IsEmpty()) {
-        nsHTMLContainerFrame::InvalidateInternal(r, 0, 0, aForChild,
-          aFlags | (seperateThebes ? INVALIDATE_NO_THEBES_LAYERS : 0));
-      }
-      if (mInner.mIsRoot && r != damage) {
+
+      if (mInner.mIsRoot && parentDamage != damage) {
         // Make sure we notify our prescontext about invalidations outside
         // viewport clipping.
         // This is important for things that are snapshotting the viewport,