Bug 893330. Invalidate the frame area for box shadow display list items with border radius. r=mattwoodrow

layout/base/nsDisplayList.cpp

@@ -2619,6 +2619,33 @@ nsDisplayBoxShadowOuter::ComputeVisibility(nsDisplayListBuilder* aBuilder,
   return !RoundedRectContainsRect(frameRect, twipsRadii, visibleBounds);
 }
 
+void
+nsDisplayBoxShadowOuter::ComputeInvalidationRegion(nsDisplayListBuilder* aBuilder,
+                                                   const nsDisplayItemGeometry* aGeometry,
+                                                   nsRegion* aInvalidRegion)
+{
+  const nsDisplayItemGenericGeometry* geometry =
+    static_cast<const nsDisplayItemGenericGeometry*>(aGeometry);
+  bool snap;
+  if (!geometry->mBounds.IsEqualInterior(GetBounds(aBuilder, &snap)) ||
+      !geometry->mBorderRect.IsEqualInterior(GetBorderRect())) {
+    nsRegion oldShadow, newShadow;
+    nscoord dontCare[8];
+    bool hasBorderRadius = mFrame->GetBorderRadii(dontCare);
+    if (hasBorderRadius) {
+      // If we have rounded corners then we need to invalidate the frame area
+      // too since we paint into it.
+      oldShadow = geometry->mBounds;
+      newShadow = GetBounds(aBuilder, &snap);
+    } else {
+      oldShadow = oldShadow.Sub(geometry->mBounds, geometry->mBorderRect);
+      newShadow = newShadow.Sub(GetBounds(aBuilder, &snap), GetBorderRect());
+    }
+    aInvalidRegion->Or(oldShadow, newShadow);
+  }
+}
+
+
 void
 nsDisplayBoxShadowInner::Paint(nsDisplayListBuilder* aBuilder,
                                nsRenderingContext* aCtx) {

layout/base/nsDisplayList.h

@@ -2204,18 +2204,7 @@ public:
   
   virtual void ComputeInvalidationRegion(nsDisplayListBuilder* aBuilder,
                                          const nsDisplayItemGeometry* aGeometry,
-                                         nsRegion* aInvalidRegion)
-  {
-    const nsDisplayItemGenericGeometry* geometry = static_cast<const nsDisplayItemGenericGeometry*>(aGeometry);
-    bool snap;
-    if (!geometry->mBounds.IsEqualInterior(GetBounds(aBuilder, &snap)) ||
-        !geometry->mBorderRect.IsEqualInterior(GetBorderRect())) {
-      nsRegion oldShadow, newShadow;
-      oldShadow = oldShadow.Sub(geometry->mBounds, geometry->mBorderRect);
-      newShadow = newShadow.Sub(GetBounds(aBuilder, &snap), GetBorderRect());
-      aInvalidRegion->Or(oldShadow, newShadow);
-    }
-  }
+                                         nsRegion* aInvalidRegion);
 
   nsRect GetBoundsInternal();