Qt for android触摸手势事件QGestureEvent「建议收藏」

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在触摸设备上可以使用Qt的手势事件

要激活手势事件，需要执行以下操作：

第一步，为QWidget控件注册手势事件

QList<Qt::GestureType> gestures;

    gestures << Qt::PanGesture;

    gestures << Qt::PinchGesture;

    gestures << Qt::SwipeGesture;

    gestures << Qt::TapGesture;

    gestures << Qt::TapAndHoldGesture;

    MainWindow w;

    w.grabGestures(gestures);

第二步，在QWidget控件类中过滤事件

bool MainWindow::event(QEvent *event)

{
 
 

    if (event->type() == QEvent::Gesture)

        return gestureEvent(static_cast<QGestureEvent*>(event));

    return QWidget::event(event);

}

bool MainWindow::gestureEvent(QGestureEvent *event)

{
 
 

    qCDebug(lcExample) << "gestureEvent():" << event->gestures().size();

    if (QGesture *swipe = event->gesture(Qt::SwipeGesture))

        swipeTriggered(static_cast<QSwipeGesture *>(swipe));

    else if (QGesture *pan = event->gesture(Qt::PanGesture))

        panTriggered(static_cast<QPanGesture *>(pan));

    else if (QGesture *tap = event->gesture(Qt::TapGesture))

        tapTriggered(static_cast<QTapGesture *>(tap));

    else if (QGesture *tapAndHold = event->gesture(Qt::TapAndHoldGesture))

        tapAndHoldTriggered(static_cast<QTapAndHoldGesture *>(tapAndHold));

    if (QGesture *pinch = event->gesture(Qt::PinchGesture))

        pinchTriggered(static_cast<QPinchGesture *>(pinch));

    return true;

}

//! [gesture event handler]

void MainWindow::panTriggered(QPanGesture *gesture)

{
 
 

#ifndef QT_NO_CURSOR

    switch (gesture->state()) {
 
 

        case Qt::GestureStarted:

        case Qt::GestureUpdated:

            setCursor(Qt::SizeAllCursor);

            break;

        default:

            setCursor(Qt::ArrowCursor);

    }

#endif

    QPointF delta = gesture->delta();

    qCDebug(lcExample) << "panTriggered():" << delta;

    horizontalOffset += delta.x();

    verticalOffset += delta.y();

}

void MainWindow::pinchTriggered(QPinchGesture *gesture)

{
 
 

    QPinchGesture::ChangeFlags changeFlags = gesture->changeFlags();

    if (changeFlags & QPinchGesture::RotationAngleChanged) {
 
 

        const qreal value = gesture->property("rotationAngle").toReal();

        const qreal lastValue = gesture->property("lastRotationAngle").toReal();

        const qreal rotationAngleDelta = value - lastValue;

        rotationAngle += rotationAngleDelta;

        qCDebug(lcExample) << "pinchTriggered(): rotation by" << rotationAngleDelta << rotationAngle;

    }

    if (changeFlags & QPinchGesture::ScaleFactorChanged) {
 
 

        qreal value = gesture->property("scaleFactor").toReal();

        currentStepScaleFactor = value;

        qCDebug(lcExample) << "pinchTriggered(): " << currentStepScaleFactor;

    }

    if (gesture->state() == Qt::GestureFinished) {
 
 

        scaleFactor *= currentStepScaleFactor;

        currentStepScaleFactor = 1;

    }

    update();

}

//! [swipe function]

void MainWindow::swipeTriggered(QSwipeGesture *gesture)

{
 
 

    if (gesture->state() == Qt::GestureFinished) {
 
 

        if (gesture->horizontalDirection() == QSwipeGesture::Left

            || gesture->verticalDirection() == QSwipeGesture::Up) {
 
 

            qCDebug(lcExample) << "swipeTriggered(): swipe to previous";

        } else {
 
 

            qCDebug(lcExample) << "swipeTriggered(): swipe to next";

        }

    }

}

//! [swipe function]

void MainWindow::tapTriggered(QTapGesture *gesture)

{
 
 

    qCDebug(lcExample) << "tapTriggered():" ;

}

void MainWindow::tapAndHoldTriggered(QTapAndHoldGesture *gesture)

{
 
 

    qCDebug(lcExample) << "tapAndHoldTriggered():";

}