294 lines
7.8 KiB
C++
294 lines
7.8 KiB
C++
/****************************************************************************
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**
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** Copyright (C) 2016 The Qt Company Ltd.
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** Contact: https://www.qt.io/licensing/
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**
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** This file is part of the demonstration applications of the Qt Toolkit.
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**
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** $QT_BEGIN_LICENSE:BSD$
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** Commercial License Usage
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** Licensees holding valid commercial Qt licenses may use this file in
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** accordance with the commercial license agreement provided with the
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** Software or, alternatively, in accordance with the terms contained in
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** a written agreement between you and The Qt Company. For licensing terms
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** and conditions see https://www.qt.io/terms-conditions. For further
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** information use the contact form at https://www.qt.io/contact-us.
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**
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** BSD License Usage
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** Alternatively, you may use this file under the terms of the BSD license
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** as follows:
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**
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** "Redistribution and use in source and binary forms, with or without
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** modification, are permitted provided that the following conditions are
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** met:
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** * Redistributions of source code must retain the above copyright
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** notice, this list of conditions and the following disclaimer.
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** * Redistributions in binary form must reproduce the above copyright
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** notice, this list of conditions and the following disclaimer in
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** the documentation and/or other materials provided with the
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** distribution.
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** * Neither the name of The Qt Company Ltd nor the names of its
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** contributors may be used to endorse or promote products derived
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** from this software without specific prior written permission.
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**
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**
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** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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** DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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** (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
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**
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** $QT_END_LICENSE$
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**
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****************************************************************************/
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#include "flickable.h"
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#include <QtCore>
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#include <QtWidgets>
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class FlickableTicker: QObject
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{
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public:
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FlickableTicker(Flickable *scroller) {
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m_scroller = scroller;
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}
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void start(int interval) {
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if (!m_timer.isActive())
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m_timer.start(interval, this);
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}
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void stop() {
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m_timer.stop();
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}
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protected:
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void timerEvent(QTimerEvent *event) {
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Q_UNUSED(event);
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m_scroller->tick();
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}
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private:
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Flickable *m_scroller;
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QBasicTimer m_timer;
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};
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class FlickablePrivate
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{
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public:
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typedef enum {
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Steady,
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Pressed,
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ManualScroll,
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AutoScroll,
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Stop
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} State;
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State state;
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int threshold;
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QPoint pressPos;
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QPoint offset;
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QPoint delta;
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QPoint speed;
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FlickableTicker *ticker;
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QElapsedTimer timeStamp;
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QWidget *target;
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QList<QEvent*> ignoreList;
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};
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Flickable::Flickable()
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{
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d = new FlickablePrivate;
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d->state = FlickablePrivate::Steady;
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d->threshold = 10;
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d->ticker = new FlickableTicker(this);
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d->timeStamp.start();
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d->target = 0;
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}
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Flickable::~Flickable()
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{
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delete d;
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}
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void Flickable::setThreshold(int th)
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{
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if (th >= 0)
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d->threshold = th;
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}
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int Flickable::threshold() const
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{
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return d->threshold;
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}
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void Flickable::setAcceptMouseClick(QWidget *target)
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{
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d->target = target;
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}
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static QPoint deaccelerate(const QPoint &speed, int a = 1, int max = 64)
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{
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int x = qBound(-max, speed.x(), max);
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int y = qBound(-max, speed.y(), max);
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x = (x == 0) ? x : (x > 0) ? qMax(0, x - a) : qMin(0, x + a);
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y = (y == 0) ? y : (y > 0) ? qMax(0, y - a) : qMin(0, y + a);
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return QPoint(x, y);
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}
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void Flickable::handleMousePress(QMouseEvent *event)
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{
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event->ignore();
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if (event->button() != Qt::LeftButton)
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return;
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if (d->ignoreList.removeAll(event))
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return;
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switch (d->state) {
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case FlickablePrivate::Steady:
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event->accept();
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d->state = FlickablePrivate::Pressed;
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d->pressPos = event->pos();
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break;
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case FlickablePrivate::AutoScroll:
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event->accept();
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d->state = FlickablePrivate::Stop;
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d->speed = QPoint(0, 0);
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d->pressPos = event->pos();
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d->offset = scrollOffset();
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d->ticker->stop();
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break;
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default:
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break;
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}
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}
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void Flickable::handleMouseRelease(QMouseEvent *event)
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{
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event->ignore();
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if (event->button() != Qt::LeftButton)
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return;
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if (d->ignoreList.removeAll(event))
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return;
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QPoint delta;
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switch (d->state) {
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case FlickablePrivate::Pressed:
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event->accept();
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d->state = FlickablePrivate::Steady;
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if (d->target) {
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QMouseEvent *event1 = new QMouseEvent(QEvent::MouseButtonPress,
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d->pressPos, Qt::LeftButton,
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Qt::LeftButton, Qt::NoModifier);
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QMouseEvent *event2 = new QMouseEvent(*event);
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d->ignoreList << event1;
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d->ignoreList << event2;
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QApplication::postEvent(d->target, event1);
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QApplication::postEvent(d->target, event2);
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}
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break;
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case FlickablePrivate::ManualScroll:
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event->accept();
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delta = event->pos() - d->pressPos;
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if (d->timeStamp.elapsed() > 100) {
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d->timeStamp.start();
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d->speed = delta - d->delta;
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d->delta = delta;
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}
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d->offset = scrollOffset();
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d->pressPos = event->pos();
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if (d->speed == QPoint(0, 0)) {
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d->state = FlickablePrivate::Steady;
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} else {
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d->speed /= 4;
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d->state = FlickablePrivate::AutoScroll;
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d->ticker->start(20);
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}
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break;
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case FlickablePrivate::Stop:
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event->accept();
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d->state = FlickablePrivate::Steady;
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d->offset = scrollOffset();
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break;
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default:
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break;
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}
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}
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void Flickable::handleMouseMove(QMouseEvent *event)
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{
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event->ignore();
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if (!(event->buttons() & Qt::LeftButton))
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return;
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if (d->ignoreList.removeAll(event))
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return;
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QPoint delta;
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switch (d->state) {
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case FlickablePrivate::Pressed:
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case FlickablePrivate::Stop:
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delta = event->pos() - d->pressPos;
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if (delta.x() > d->threshold || delta.x() < -d->threshold ||
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delta.y() > d->threshold || delta.y() < -d->threshold) {
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d->timeStamp.start();
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d->state = FlickablePrivate::ManualScroll;
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d->delta = QPoint(0, 0);
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d->pressPos = event->pos();
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event->accept();
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}
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break;
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case FlickablePrivate::ManualScroll:
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event->accept();
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delta = event->pos() - d->pressPos;
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setScrollOffset(d->offset - delta);
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if (d->timeStamp.elapsed() > 100) {
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d->timeStamp.start();
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d->speed = delta - d->delta;
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d->delta = delta;
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}
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break;
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default:
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break;
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}
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}
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void Flickable::tick()
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{
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if (d->state == FlickablePrivate:: AutoScroll) {
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d->speed = deaccelerate(d->speed);
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setScrollOffset(d->offset - d->speed);
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d->offset = scrollOffset();
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if (d->speed == QPoint(0, 0)) {
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d->state = FlickablePrivate::Steady;
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d->ticker->stop();
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}
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} else {
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d->ticker->stop();
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}
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}
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