cc/scrollbar_geometry_fixed_thumb.h

// 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 CC_SCROLLBAR_GEOMETRY_FIXED_THUMB_H_
#define CC_SCROLLBAR_GEOMETRY_FIXED_THUMB_H_

#include "cc/cc_export.h"
#include "cc/scrollbar_geometry_stub.h"
#include "ui/gfx/size.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 CC_EXPORT ScrollbarGeometryFixedThumb : public ScrollbarGeometryStub {
public:
    static scoped_ptr<ScrollbarGeometryFixedThumb> create(scoped_ptr<WebKit::WebScrollbarThemeGeometry>);
    virtual ~ScrollbarGeometryFixedThumb();

    // 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 ScrollbarGeometryFixedThumb(scoped_ptr<WebKit::WebScrollbarThemeGeometry>);

    gfx::Size m_thumbSize;
};

}

#endif  // CC_SCROLLBAR_GEOMETRY_FIXED_THUMB_H_