Bug 822141 - Invalidate bullet display items when their value changes. r=roc

layout/generic/nsBulletFrame.cpp

@@ -170,6 +170,19 @@ nsBulletFrame::DidSetStyleContext(nsStyleContext* aOldStyleContext)
 #endif
 }
 
+class nsDisplayBulletGeometry : public nsDisplayItemGenericGeometry
+{
+public:
+  nsDisplayBulletGeometry(nsDisplayItem* aItem, nsDisplayListBuilder* aBuilder)
+    : nsDisplayItemGenericGeometry(aItem, aBuilder)
+  {
+    nsBulletFrame* f = static_cast<nsBulletFrame*>(aItem->GetUnderlyingFrame());
+    mOrdinal = f->GetOrdinal();
+  }
+
+  int32_t mOrdinal;
+};
+
 class nsDisplayBullet : public nsDisplayItem {
 public:
   nsDisplayBullet(nsDisplayListBuilder* aBuilder, nsBulletFrame* aFrame) :
@@ -200,6 +213,27 @@ public:
     bool snap;
     return GetBounds(aBuilder, &snap);
   }
+
+  virtual nsDisplayItemGeometry* AllocateGeometry(nsDisplayListBuilder* aBuilder)
+  {
+    return new nsDisplayBulletGeometry(this, aBuilder);
+  }
+
+  virtual void ComputeInvalidationRegion(nsDisplayListBuilder* aBuilder,
+                                         const nsDisplayItemGeometry* aGeometry,
+                                         nsRegion *aInvalidRegion)
+  {
+    const nsDisplayBulletGeometry* geometry = static_cast<const nsDisplayBulletGeometry*>(aGeometry);
+    nsBulletFrame* f = static_cast<nsBulletFrame*>(mFrame);
+
+    if (f->GetOrdinal() != geometry->mOrdinal) {
+      bool snap;
+      aInvalidRegion->Or(geometry->mBounds, GetBounds(aBuilder, &snap));
+      return;
+    }
+
+    return nsDisplayItem::ComputeInvalidationRegion(aBuilder, aGeometry, aInvalidRegion);
+  }
 };
 
 void nsDisplayBullet::Paint(nsDisplayListBuilder* aBuilder,