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+/****************************************************************************
+**
+** Copyright (C) 2011 Nokia Corporation and/or its subsidiary(-ies).
+** All rights reserved.
+** Contact: Nokia Corporation (qt-info@nokia.com)
+**
+** This file is part of the demonstration applications of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:LGPL$
+** No Commercial Usage
+** This file contains pre-release code and may not be distributed.
+** You may use this file in accordance with the terms and conditions
+** contained in the Technology Preview License Agreement accompanying
+** this package.
+**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 2.1 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 2.1 requirements
+** will be met: http://www.gnu.org/licenses/old-licenses/lgpl-2.1.html.
+**
+** In addition, as a special exception, Nokia gives you certain additional
+** rights. These rights are described in the Nokia Qt LGPL Exception
+** version 1.1, included in the file LGPL_EXCEPTION.txt in this package.
+**
+** If you have questions regarding the use of this file, please contact
+** Nokia at qt-info@nokia.com.
+**
+**
+**
+**
+**
+**
+**
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#include "flickable.h"
+
+#include <QtCore>
+#include <QtGui>
+
+class FlickableTicker: QObject
+{
+public:
+ FlickableTicker(Flickable *scroller) {
+ m_scroller = scroller;
+ }
+
+ void start(int interval) {
+ if (!m_timer.isActive())
+ m_timer.start(interval, this);
+ }
+
+ void stop() {
+ m_timer.stop();
+ }
+
+protected:
+ void timerEvent(QTimerEvent *event) {
+ Q_UNUSED(event);
+ m_scroller->tick();
+ }
+
+private:
+ Flickable *m_scroller;
+ QBasicTimer m_timer;
+};
+
+class FlickablePrivate
+{
+public:
+ typedef enum {
+ Steady,
+ Pressed,
+ ManualScroll,
+ AutoScroll,
+ Stop
+ } State;
+
+ State state;
+ int threshold;
+ QPoint pressPos;
+ QPoint offset;
+ QPoint delta;
+ QPoint speed;
+ FlickableTicker *ticker;
+ QTime timeStamp;
+ QWidget *target;
+ QList<QEvent*> ignoreList;
+};
+
+Flickable::Flickable()
+{
+ d = new FlickablePrivate;
+ d->state = FlickablePrivate::Steady;
+ d->threshold = 10;
+ d->ticker = new FlickableTicker(this);
+ d->timeStamp = QTime::currentTime();
+ d->target = 0;
+}
+
+Flickable::~Flickable()
+{
+ delete d;
+}
+
+void Flickable::setThreshold(int th)
+{
+ if (th >= 0)
+ d->threshold = th;
+}
+
+int Flickable::threshold() const
+{
+ return d->threshold;
+}
+
+void Flickable::setAcceptMouseClick(QWidget *target)
+{
+ d->target = target;
+}
+
+static QPoint deaccelerate(const QPoint &speed, int a = 1, int max = 64)
+{
+ int x = qBound(-max, speed.x(), max);
+ int y = qBound(-max, speed.y(), max);
+ x = (x == 0) ? x : (x > 0) ? qMax(0, x - a) : qMin(0, x + a);
+ y = (y == 0) ? y : (y > 0) ? qMax(0, y - a) : qMin(0, y + a);
+ return QPoint(x, y);
+}
+
+void Flickable::handleMousePress(QMouseEvent *event)
+{
+ event->ignore();
+
+ if (event->button() != Qt::LeftButton)
+ return;
+
+ if (d->ignoreList.removeAll(event))
+ return;
+
+ switch (d->state) {
+
+ case FlickablePrivate::Steady:
+ event->accept();
+ d->state = FlickablePrivate::Pressed;
+ d->pressPos = event->pos();
+ break;
+
+ case FlickablePrivate::AutoScroll:
+ event->accept();
+ d->state = FlickablePrivate::Stop;
+ d->speed = QPoint(0, 0);
+ d->pressPos = event->pos();
+ d->offset = scrollOffset();
+ d->ticker->stop();
+ break;
+
+ default:
+ break;
+ }
+}
+
+void Flickable::handleMouseRelease(QMouseEvent *event)
+{
+ event->ignore();
+
+ if (event->button() != Qt::LeftButton)
+ return;
+
+ if (d->ignoreList.removeAll(event))
+ return;
+
+ QPoint delta;
+
+ switch (d->state) {
+
+ case FlickablePrivate::Pressed:
+ event->accept();
+ d->state = FlickablePrivate::Steady;
+ if (d->target) {
+ QMouseEvent *event1 = new QMouseEvent(QEvent::MouseButtonPress,
+ d->pressPos, Qt::LeftButton,
+ Qt::LeftButton, Qt::NoModifier);
+ QMouseEvent *event2 = new QMouseEvent(*event);
+ d->ignoreList << event1;
+ d->ignoreList << event2;
+ QApplication::postEvent(d->target, event1);
+ QApplication::postEvent(d->target, event2);
+ }
+ break;
+
+ case FlickablePrivate::ManualScroll:
+ event->accept();
+ delta = event->pos() - d->pressPos;
+ if (d->timeStamp.elapsed() > 100) {
+ d->timeStamp = QTime::currentTime();
+ d->speed = delta - d->delta;
+ d->delta = delta;
+ }
+ d->offset = scrollOffset();
+ d->pressPos = event->pos();
+ if (d->speed == QPoint(0, 0)) {
+ d->state = FlickablePrivate::Steady;
+ } else {
+ d->speed /= 4;
+ d->state = FlickablePrivate::AutoScroll;
+ d->ticker->start(20);
+ }
+ break;
+
+ case FlickablePrivate::Stop:
+ event->accept();
+ d->state = FlickablePrivate::Steady;
+ d->offset = scrollOffset();
+ break;
+
+ default:
+ break;
+ }
+}
+
+void Flickable::handleMouseMove(QMouseEvent *event)
+{
+ event->ignore();
+
+ if (!(event->buttons() & Qt::LeftButton))
+ return;
+
+ if (d->ignoreList.removeAll(event))
+ return;
+
+ QPoint delta;
+
+ switch (d->state) {
+
+ case FlickablePrivate::Pressed:
+ case FlickablePrivate::Stop:
+ delta = event->pos() - d->pressPos;
+ if (delta.x() > d->threshold || delta.x() < -d->threshold ||
+ delta.y() > d->threshold || delta.y() < -d->threshold) {
+ d->timeStamp = QTime::currentTime();
+ d->state = FlickablePrivate::ManualScroll;
+ d->delta = QPoint(0, 0);
+ d->pressPos = event->pos();
+ event->accept();
+ }
+ break;
+
+ case FlickablePrivate::ManualScroll:
+ event->accept();
+ delta = event->pos() - d->pressPos;
+ setScrollOffset(d->offset - delta);
+ if (d->timeStamp.elapsed() > 100) {
+ d->timeStamp = QTime::currentTime();
+ d->speed = delta - d->delta;
+ d->delta = delta;
+ }
+ break;
+
+ default:
+ break;
+ }
+}
+
+void Flickable::tick()
+{
+ if (d->state == FlickablePrivate:: AutoScroll) {
+ d->speed = deaccelerate(d->speed);
+ setScrollOffset(d->offset - d->speed);
+ d->offset = scrollOffset();
+ if (d->speed == QPoint(0, 0)) {
+ d->state = FlickablePrivate::Steady;
+ d->ticker->stop();
+ }
+ } else {
+ d->ticker->stop();
+ }
+}