KineticScroller.h

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/* @@@LICENSE
*
*      Copyright (c) 2010-2012 Hewlett-Packard Development Company, L.P.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* LICENSE@@@ */




#ifndef KINETIC_SCROLLER_H_
#define KINETIC_SCROLLER_H_

#include <QObject>
#include <QTimer>
#include <QTime>
#include <QEasingCurve>
#include <QPointer>
#include <QTextStream>
#include <QFile>

#include <limits>

QT_BEGIN_NAMESPACE
class QPropertyAnimation;
QT_END_NAMESPACE

class KineticScroller : public QObject
{
        Q_OBJECT
        Q_PROPERTY(qreal scrollOffset READ scrollOffset WRITE setScrollOffset)
Q_SIGNALS:
        void scrolled(qreal oldScroll);

public:
        KineticScroller(qreal minValue = -std::numeric_limits<qreal>::infinity(),
                        qreal maxValue = std::numeric_limits<qreal>::infinity());
        ~KineticScroller();

        void setMaxOverscroll(qreal overscroll);
        void setMinValue(qreal minValue);
        void setMaxValue(qreal maxValue);

        qreal scrollOffset() const;
        qreal getMinScrollValue() const;
        void scrollBy(qreal offset);

        void setScrollOffset(qreal offset);

        void handleFlick(qreal velocity);
        void handleMouseDown();
        void handleMouseUp();
        void stopImmediately();
        void correctOverscroll();

        bool animatingFlick() const;

private Q_SLOTS:
        void flickAnimationTick();
        void overscrollTrigger();
        void flickTransitionToOverscroll();
        void stopFlickAnimation();

private:
        enum FlickState {
                FlickNormal,
                FlickOverScroll,
                FlickOverscrollCorrection,
        };

        enum FlickDirection {
                FlickUp = 1,
                FlickDown = -1,
        };

        static FlickDirection direction(qreal x)
        {
                return x >= 0 ? FlickUp : FlickDown;
        }

        void zizz(qreal inV);
        bool inOverscroll() const;
        bool inOverscroll(qreal scrollOffset) const;
        void checkUserActionOnOverscroll();

        qreal amountInOverscroll() const;
        qreal instantaneousVelocity() const;
        qreal easingCubicCoEfficient(qreal index) const;

        QTimer m_flickAnimationTimer;
        QTimer m_flickFilter;
        QTimer m_overscroll;
        QTime m_clock;
        QEasingCurve m_easing;
        qreal m_minScroll;
        qreal m_maxScroll;
        qreal m_maxOverscroll;
        qreal m_scrollOffset;
        //static qreal m_scrollOffsetChecker;
        qreal m_previousVelocity;
        qreal m_accumulatedScroll;
        QPointer<QPropertyAnimation> m_flickAnimation;
        QPointer<QPropertyAnimation> m_flickOverscrollAnimation;
        QPointer<QPropertyAnimation> m_overscrollAnimation;
        FlickDirection m_flickEventDirection;
        FlickState m_flickState;
        qreal m_flickVelocity;
        qreal m_friction;
        qreal m_restoreForce;
        qreal m_flickStopOffset;
        qreal m_tRegularScrollingTime;
        qreal m_s0;
        qreal m_sp;
        qreal m_s1;
        qreal m_sReferenceTime;
        qreal m_sReferenceTime1;
        qreal m_v0;
        qreal m_overScrollCorrectionStart;
        bool m_BypassOverScrollInfo;
        bool m_OverScrollCorrectionInterrupted;
#if TRACE_SCROLLER
        QFile m_plotFile;
        QFile m_plotFile2;
        QTextStream *m_plot;
        QTextStream *m_plotMouse;
#endif
        bool m_flickAnimationTimerActive;
};

#endif