Source/WebCore/platform/WheelFlingPlatformGestureCurve.h

/*
 * Copyright (C) 2012 Google Inc. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1.  Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 * 2.  Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#ifndef WheelFlingPlatformGestureCurve_h
#define WheelFlingPlatformGestureCurve_h

#include "FloatPoint.h"
#include "PlatformGestureCurve.h"
#include <wtf/OwnPtr.h>
#include <wtf/PassOwnPtr.h>

namespace WebCore {

class PlatformGestureCurveTarget;

// Implementation of PlatformGestureCurve suitable for mouse wheel-based fling
// scroll. A Rayleigh distribtution curve is used to define the velocity profile,
// so velocity starts at zero, accelerates to a maximum proportional to 'velocity',
// then gently tails off to zero again.
class WheelFlingPlatformGestureCurve : public PlatformGestureCurve {
public:
    static PassOwnPtr<PlatformGestureCurve> create(const FloatPoint& velocity);
    virtual ~WheelFlingPlatformGestureCurve();

    virtual const char* debugName() const OVERRIDE;
    virtual bool apply(double time, PlatformGestureCurveTarget*) OVERRIDE;

private:
    explicit WheelFlingPlatformGestureCurve(const FloatPoint& velocity);

    FloatPoint m_velocity;
    IntPoint m_cumulativeScroll;
};

} // namespace WebCore

#endif