QGestureRecognizer::Result QSwipeGestureRecognizer::recognize(QGesture *state,
QObject *,
QEvent *event)
{
QSwipeGesture *q = static_cast<QSwipeGesture *>(state);
QSwipeGesturePrivate *d = q->d_func();
const QTouchEvent *ev = static_cast<const QTouchEvent *>(event);
QGestureRecognizer::Result result;
switch (event->type()) {
case QEvent::TouchBegin: {
d->velocityValue = 1;
d->time.start();
d->started = true;
result = QGestureRecognizer::MayBeGesture;
break;
}
case QEvent::TouchEnd: {
if (q->state() != Qt::NoGesture) {
result = QGestureRecognizer::FinishGesture;
} else {
result = QGestureRecognizer::CancelGesture;
}
break;
}
case QEvent::TouchUpdate: {
if (!d->started)
result = QGestureRecognizer::CancelGesture;
else if (ev->touchPoints().size() == 3) {
QTouchEvent::TouchPoint p1 = ev->touchPoints().at(0);
QTouchEvent::TouchPoint p2 = ev->touchPoints().at(1);
QTouchEvent::TouchPoint p3 = ev->touchPoints().at(2);
if (d->lastPositions[0].isNull()) {
d->lastPositions[0] = p1.startScreenPos().toPoint();
d->lastPositions[1] = p2.startScreenPos().toPoint();
d->lastPositions[2] = p3.startScreenPos().toPoint();
}
d->hotSpot = p1.screenPos();
d->isHotSpotSet = true;
int xDistance = (p1.screenPos().x() - d->lastPositions[0].x() +
p2.screenPos().x() - d->lastPositions[1].x() +
p3.screenPos().x() - d->lastPositions[2].x()) / 3;
int yDistance = (p1.screenPos().y() - d->lastPositions[0].y() +
p2.screenPos().y() - d->lastPositions[1].y() +
p3.screenPos().y() - d->lastPositions[2].y()) / 3;
const int distance = xDistance >= yDistance ? xDistance : yDistance;
int elapsedTime = d->time.restart();
if (!elapsedTime)
elapsedTime = 1;
d->velocityValue = 0.9 * d->velocityValue + distance / elapsedTime;
d->swipeAngle = QLineF(p1.startScreenPos(), p1.screenPos()).angle();
static const int MoveThreshold = 50;
if (xDistance > MoveThreshold || yDistance > MoveThreshold) {
// measure the distance to check if the direction changed
d->lastPositions[0] = p1.screenPos().toPoint();
d->lastPositions[1] = p2.screenPos().toPoint();
d->lastPositions[2] = p3.screenPos().toPoint();
QSwipeGesture::SwipeDirection horizontal =
xDistance > 0 ? QSwipeGesture::Right : QSwipeGesture::Left;
QSwipeGesture::SwipeDirection vertical =
yDistance > 0 ? QSwipeGesture::Down : QSwipeGesture::Up;
if (d->verticalDirection == QSwipeGesture::NoDirection)
d->verticalDirection = vertical;
if (d->horizontalDirection == QSwipeGesture::NoDirection)
d->horizontalDirection = horizontal;
if (d->verticalDirection != vertical || d->horizontalDirection != horizontal) {
// the user has changed the direction!
result = QGestureRecognizer::CancelGesture;
}
result = QGestureRecognizer::TriggerGesture;
} else {
if (q->state() != Qt::NoGesture)
result = QGestureRecognizer::TriggerGesture;
else
result = QGestureRecognizer::MayBeGesture;
}
} else if (ev->touchPoints().size() > 3) {
result = QGestureRecognizer::CancelGesture;
} else { // less than 3 touch points
if (d->started && (ev->touchPointStates() & Qt::TouchPointPressed))
result = QGestureRecognizer::CancelGesture;
else if (d->started)
result = QGestureRecognizer::Ignore;
else
result = QGestureRecognizer::MayBeGesture;
}
break;
}
case QEvent::MouseButtonPress:
case QEvent::MouseMove:
case QEvent::MouseButtonRelease:
result = QGestureRecognizer::Ignore;
break;
default:
result = QGestureRecognizer::Ignore;
break;
}
return result;
}
