1 files changed, 36 insertions, 0 deletions
diff --git a/cc/scrollbar_geometry_fixed_thumb.h b/cc/scrollbar_geometry_fixed_thumb.h
index 638cbb2..fe0db12 100644
--- a/cc/scrollbar_geometry_fixed_thumb.h
+++ b/cc/scrollbar_geometry_fixed_thumb.h
@@ -1,3 +1,39 @@
 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
+
+#ifndef CCScrollbarGeometryFixedThumb_h
+#define CCScrollbarGeometryFixedThumb_h
+
+#include "CCScrollbarGeometryStub.h"
+#include "IntSize.h"
+
+namespace cc {
+
+// This scrollbar geometry class behaves exactly like a normal geometry except
+// it always returns a fixed thumb length. This allows a page to zoom (changing
+// the total size of the scrollable area, changing the thumb length) while not
+// requiring the thumb resource to be repainted.
+class CCScrollbarGeometryFixedThumb : public CCScrollbarGeometryStub {
+public:
+    static PassOwnPtr<CCScrollbarGeometryFixedThumb> create(PassOwnPtr<WebKit::WebScrollbarThemeGeometry>);
+    virtual ~CCScrollbarGeometryFixedThumb();
+
+    // Update thumb length from scrollbar
+    void update(WebKit::WebScrollbar*);
+
+    // WebScrollbarThemeGeometry interface
+    virtual WebKit::WebScrollbarThemeGeometry* clone() const OVERRIDE;
+    virtual int thumbLength(WebKit::WebScrollbar*) OVERRIDE;
+    virtual int thumbPosition(WebKit::WebScrollbar*) OVERRIDE;
+    virtual void splitTrack(WebKit::WebScrollbar*, const WebKit::WebRect& track, WebKit::WebRect& startTrack, WebKit::WebRect& thumb, WebKit::WebRect& endTrack) OVERRIDE;
+
+private:
+    explicit CCScrollbarGeometryFixedThumb(PassOwnPtr<WebKit::WebScrollbarThemeGeometry>);
+
+    IntSize m_thumbSize;
+};
+
+}
+
+#endif