flickable.cpp Example File
demos/embedded/flickable/flickable.cpp
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#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();
}
}
