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/****************************************************************************
**
** Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies).
** All rights reserved.
** Contact: qt-info@nokia.com
**
** This software, including documentation, is protected by copyright
** controlled by Nokia Corporation. You may use this software in
** accordance with the terms and conditions contained in the Qt Phone
** Demo License Agreement.
**
****************************************************************************/
#include <QTime>
#include <QTimer>
#include "kineticscroll.h"
#define MAX_SPEED 2000
class KineticScrollPrivate
{
public:
QTimer *animation;
qreal animationSpeed;
QTime animationITime;
qreal animationAccel;
qreal accelConstant;
QTime time;
QTime lastTime;
int value;
int lastValue;
};
KineticScroll::KineticScroll(QObject *parent)
: QObject(parent), d(new KineticScrollPrivate)
{
d->animation = 0;
d->accelConstant = 0.3;
d->value = d->lastValue = -1;
d->time = d->lastTime = QTime::currentTime();
}
KineticScroll::~KineticScroll()
{
delete d;
}
void KineticScroll::mouseUp(int value)
{
if (d->lastValue < 0 || d->animation)
return;
QTime t = QTime::currentTime();
qreal dv = value - d->lastValue;
qreal dt = (qreal)d->lastTime.msecsTo(t) / 1000;
if (dt == 0)
return;
kineticStart(dv / dt);
mouseCancel();
}
bool KineticScroll::mouseDown(int value)
{
bool r = true;
if (d->animation) {
d->animation->stop();
d->animation->deleteLater();
d->animation = 0;
r = false;
}
d->lastValue = d->value = value;
d->lastTime = d->time = QTime::currentTime();
return r;
}
void KineticScroll::mouseMove(int value)
{
if (d->lastValue < 0)
return;
int dv = value - d->value;
QTime t = QTime::currentTime();
d->lastValue = d->value;
d->lastTime = d->time;
d->value = value;
d->time = t;
emit signalMoveOffset(dv);
}
void KineticScroll::mouseCancel()
{
d->value = -1;
d->lastValue = -1;
}
void KineticScroll::kineticStop()
{
if (d->animation) {
d->animation->stop();
d->animation->deleteLater();
}
d->animation = 0;
}
void KineticScroll::kineticStart(qreal speed)
{
d->animationSpeed = qBound<qreal>(-MAX_SPEED, speed, MAX_SPEED);
d->animationITime = QTime::currentTime();
d->animationAccel = -d->animationSpeed * d->accelConstant;
d->animation = new QTimer();
connect(d->animation, SIGNAL(timeout()), this, SLOT(animator()));
d->animation->start(10);
}
void KineticScroll::animator()
{
QTime now = QTime::currentTime();
qreal dt = (qreal)d->animationITime.msecsTo(now) / 1000;
qreal speed = d->animationSpeed + d->animationAccel * dt;
qreal value = d->animationSpeed * dt + d->animationAccel * dt * dt / 2;
if (d->animationAccel * speed > 0) {
// just to notify animation finish
emit signalMoveOffset(0);
kineticStop();
} else {
emit signalMoveOffset(qRound(value));
d->animationSpeed = speed;
d->animationITime = now;
}
}
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