diff -r 000000000000 -r 6474c204b198 layout/base/nsDisplayListInvalidation.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/base/nsDisplayListInvalidation.h	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,133 @@
+/*-*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef NSDISPLAYLISTINVALIDATION_H_
+#define NSDISPLAYLISTINVALIDATION_H_
+
+#include "mozilla/Attributes.h"
+#include "nsRect.h"
+#include "nsColor.h"
+
+class nsDisplayItem;
+class nsDisplayListBuilder;
+class nsDisplayBackgroundImage;
+class nsDisplayThemedBackground;
+
+/**
+ * This stores the geometry of an nsDisplayItem, and the area
+ * that will be affected when painting the item.
+ *
+ * It is used to retain information about display items so they
+ * can be compared against new display items in the next paint.
+ */
+class nsDisplayItemGeometry
+{
+public:
+  nsDisplayItemGeometry(nsDisplayItem* aItem, nsDisplayListBuilder* aBuilder);
+  virtual ~nsDisplayItemGeometry();
+  
+  /**
+   * Compute the area required to be invalidated if this
+   * display item is removed.
+   */
+  const nsRect& ComputeInvalidationRegion() { return mBounds; }
+  
+  /**
+   * Shifts all retained areas of the nsDisplayItemGeometry by the given offset.
+   * 
+   * This is used to compensate for scrolling, since the destination buffer
+   * can scroll without requiring a full repaint.
+   *
+   * @param aOffset Offset to shift by.
+   */
+  virtual void MoveBy(const nsPoint& aOffset) = 0;
+
+  /**
+   * Bounds of the display item
+   */
+  nsRect mBounds;
+};
+
+/**
+ * A default geometry implementation, used by nsDisplayItem. Retains
+ * and compares the bounds, and border rect.
+ *
+ * This should be sufficient for the majority of display items.
+ */
+class nsDisplayItemGenericGeometry : public nsDisplayItemGeometry
+{
+public:
+  nsDisplayItemGenericGeometry(nsDisplayItem* aItem, nsDisplayListBuilder* aBuilder);
+
+  virtual void MoveBy(const nsPoint& aOffset) MOZ_OVERRIDE;
+
+  nsRect mBorderRect;
+};
+
+class nsDisplayItemBoundsGeometry : public nsDisplayItemGeometry
+{
+public:
+  nsDisplayItemBoundsGeometry(nsDisplayItem* aItem, nsDisplayListBuilder* aBuilder);
+
+  virtual void MoveBy(const nsPoint& aOffset) MOZ_OVERRIDE;
+
+  bool mHasRoundedCorners;
+};
+
+class nsDisplayBorderGeometry : public nsDisplayItemGeometry
+{
+public:
+  nsDisplayBorderGeometry(nsDisplayItem* aItem, nsDisplayListBuilder* aBuilder);
+
+  virtual void MoveBy(const nsPoint& aOffset) MOZ_OVERRIDE;
+
+  nsRect mContentRect;
+};
+
+class nsDisplayBackgroundGeometry : public nsDisplayItemGeometry
+{
+public:
+  nsDisplayBackgroundGeometry(nsDisplayBackgroundImage* aItem, nsDisplayListBuilder* aBuilder);
+
+  virtual void MoveBy(const nsPoint& aOffset) MOZ_OVERRIDE;
+
+  nsRect mPositioningArea;
+};
+
+class nsDisplayThemedBackgroundGeometry : public nsDisplayItemGeometry
+{
+public:
+  nsDisplayThemedBackgroundGeometry(nsDisplayThemedBackground* aItem, nsDisplayListBuilder* aBuilder);
+
+  virtual void MoveBy(const nsPoint& aOffset) MOZ_OVERRIDE;
+
+  nsRect mPositioningArea;
+  bool mWindowIsActive;
+};
+
+class nsDisplayBoxShadowInnerGeometry : public nsDisplayItemGeometry
+{
+public:
+  nsDisplayBoxShadowInnerGeometry(nsDisplayItem* aItem, nsDisplayListBuilder* aBuilder);
+  
+  virtual void MoveBy(const nsPoint& aOffset) MOZ_OVERRIDE;
+
+  nsRect mPaddingRect;
+};
+
+class nsDisplaySolidColorGeometry : public nsDisplayItemBoundsGeometry
+{
+public:
+  nsDisplaySolidColorGeometry(nsDisplayItem* aItem,
+                              nsDisplayListBuilder* aBuilder,
+                              nscolor aColor)
+    : nsDisplayItemBoundsGeometry(aItem, aBuilder)
+    , mColor(aColor)
+  { }
+
+  nscolor mColor;
+};
+
+#endif /*NSDISPLAYLISTINVALIDATION_H_*/