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| ** Copyright (C) 2016 The Qt Company Ltd. |
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| ** This file is part of the demonstration applications of the Qt Toolkit. |
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| ****************************************************************************/ |
| |
| #include "flickable.h" |
| |
| #include <QtCore> |
| #include <QtWidgets> |
| |
| 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; |
| QElapsedTimer 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.start(); |
| 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.start(); |
| 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.start(); |
| 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.start(); |
| 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(); |
| } |
| } |
