C++ QPinchGesture::state方法代码示例

void CanvasView::gestureEvent(QGestureEvent *event)
{
	QPinchGesture *pinch = static_cast<QPinchGesture*>(event->gesture(Qt::PinchGesture));
	if(pinch) {
		if(pinch->state() == Qt::GestureStarted) {
			_gestureStartZoom = _zoom;
			_gestureStartAngle = _rotate;
		}

		if((pinch->changeFlags() & QPinchGesture::ScaleFactorChanged))
			setZoom(_gestureStartZoom * pinch->scaleFactor());

		if((pinch->changeFlags() & QPinchGesture::RotationAngleChanged))
			setRotation(_gestureStartAngle + pinch->rotationAngle());
	}
}

bool HPiano::gestureEvent(QGestureEvent *event)
      {
      if (QGesture *gesture = event->gesture(Qt::PinchGesture)) {
            // Zoom in/out when receiving a pinch gesture
            QPinchGesture *pinch = static_cast<QPinchGesture *>(gesture);

            static qreal magStart = 1.0;
            if (pinch->state() == Qt::GestureStarted) {
                  magStart = scaleVal;
                  }
            if (pinch->changeFlags() & QPinchGesture::ScaleFactorChanged) {
                  // On Windows, totalScaleFactor() contains the net magnification.
                  // On OS X, totalScaleFactor() is 1, and scaleFactor() contains the net magnification.
                  qreal value = pinch->totalScaleFactor();
                  if (value == 1) {
                        value = pinch->scaleFactor();
                        }
                  // Qt 5.4 doesn't report pinch->centerPoint() correctly
                  setScale(magStart*value);
                  }
            }
      return true;
      }

QGestureRecognizer::Result QPinchGestureRecognizer::recognize(QGesture *state,
                                                              QObject *,
                                                              QEvent *event)
{
    QPinchGesture *q = static_cast<QPinchGesture *>(state);
    QPinchGesturePrivate *d = q->d_func();

    const QTouchEvent *ev = static_cast<const QTouchEvent *>(event);

    QGestureRecognizer::Result result;

    switch (event->type()) {
    case QEvent::TouchBegin: {
        result = QGestureRecognizer::MayBeGesture;
        break;
    }
    case QEvent::TouchEnd: {
        if (q->state() != Qt::NoGesture) {
            result = QGestureRecognizer::FinishGesture;
        } else {
            result = QGestureRecognizer::CancelGesture;
        }
        break;
    }
    case QEvent::TouchUpdate: {
        d->changeFlags = 0;
        if (ev->touchPoints().size() == 2) {
            QTouchEvent::TouchPoint p1 = ev->touchPoints().at(0);
            QTouchEvent::TouchPoint p2 = ev->touchPoints().at(1);

            d->hotSpot = p1.screenPos();
            d->isHotSpotSet = true;

            QPointF centerPoint = (p1.screenPos() + p2.screenPos()) / 2.0;
            if (d->isNewSequence) {
                d->startPosition[0] = p1.screenPos();
                d->startPosition[1] = p2.screenPos();
                d->lastCenterPoint = centerPoint;
            } else {
                d->lastCenterPoint = d->centerPoint;
            }
            d->centerPoint = centerPoint;

            d->changeFlags |= QPinchGesture::CenterPointChanged;

            if (d->isNewSequence) {
                d->scaleFactor = 1.0;
                d->lastScaleFactor = 1.0;
            } else {
                d->lastScaleFactor = d->scaleFactor;
                QLineF line(p1.screenPos(), p2.screenPos());
                QLineF lastLine(p1.lastScreenPos(),  p2.lastScreenPos());
                d->scaleFactor = line.length() / lastLine.length();
            }
            d->totalScaleFactor = d->totalScaleFactor * d->scaleFactor;
            d->changeFlags |= QPinchGesture::ScaleFactorChanged;

            qreal angle = QLineF(p1.screenPos(), p2.screenPos()).angle();
            if (angle > 180)
                angle -= 360;
            qreal startAngle = QLineF(p1.startScreenPos(), p2.startScreenPos()).angle();
            if (startAngle > 180)
                startAngle -= 360;
            const qreal rotationAngle = startAngle - angle;
            if (d->isNewSequence)
                d->lastRotationAngle = 0.0;
            else
                d->lastRotationAngle = d->rotationAngle;
            d->rotationAngle = rotationAngle;
            d->totalRotationAngle += d->rotationAngle - d->lastRotationAngle;
            d->changeFlags |= QPinchGesture::RotationAngleChanged;

            d->totalChangeFlags |= d->changeFlags;
            d->isNewSequence = false;
            result = QGestureRecognizer::TriggerGesture;
        } else {
            d->isNewSequence = true;
            if (q->state() == Qt::NoGesture)
                result = QGestureRecognizer::Ignore;
            else
                result = QGestureRecognizer::FinishGesture;
        }
        break;
    }
    case QEvent::MouseButtonPress:
    case QEvent::MouseMove:
    case QEvent::MouseButtonRelease:
        result = QGestureRecognizer::Ignore;
        break;
    default:
        result = QGestureRecognizer::Ignore;
        break;
    }
    return result;
}

//===============================================================
bool MousePanNZoomNavigator::eventFilter(QObject *widget, QEvent *e) {
// according to Qt's doc, this constant has been defined by wheel mouse vendors
// we need it to interpret the value of QWheelEvent->delta()
#define WHEEL_DELTA 120
  if (e->type() == QEvent::Wheel &&
      (((QWheelEvent *) e)->orientation() == Qt::Vertical)) {

    GlMainWidget *g = (GlMainWidget *) widget;

    if(((QWheelEvent *) e)->delta() < 0 && g->getScene()->getCamera().getZoomFactor() < 0.5f) {
      return true;
    }

    g->getScene()->zoomXY(((QWheelEvent *) e)->delta() / WHEEL_DELTA,
                          ((QWheelEvent *) e)->x(), ((QWheelEvent *) e)->y());
    g->draw(false);
    return true;
  }

  if(e->type() == QEvent::Gesture) {
    GlMainWidget *g = (GlMainWidget *) widget;
    QGestureEvent* gesture = (QGestureEvent*)e;
    QPointF center;
    //swipe events and pan events are never fired, known Qt bug
    /*if(gesture->gesture(Qt::SwipeGesture)) {
      QSwipeGesture* swipe = (QSwipeGesture*)gesture->gesture(Qt::SwipeGesture);
      int x = cos(swipe->swipeAngle()) * swipe->property("velocity").toFloat();
      int y = sin(swipe->swipeAngle()) * swipe->property("velocity").toFloat();
      g->getScene()->translateCamera(x, y, 0);
    }*/

    if(gesture->gesture(Qt::PinchGesture)) {
      QPinchGesture* pinch = (QPinchGesture*)gesture->gesture(Qt::PinchGesture);
      Camera& camera = g->getScene()->getCamera();

      //store the camera scale factor when starting the gesture
      if(pinch->state() == Qt::GestureStarted) {
        cameraScaleFactor = camera.getZoomFactor();
        isGesturing = true;
      }

      if(pinch->changeFlags() & QPinchGesture::ScaleFactorChanged) {
        //only set the zoom factor if two events in a row were in the same direction (zoom in or out) to smooth a bit the effect.
        if((pinch->lastScaleFactor() > 1 && pinch->scaleFactor() > 1) || (pinch->lastScaleFactor() <= 1 && pinch->scaleFactor() <= 1)) {
          camera.setZoomFactor(cameraScaleFactor * pinch->totalScaleFactor());
        }
      }

      if(pinch->changeFlags() & QPinchGesture::RotationAngleChanged) {
        /*//backup the current camera center
              Coord oldCenter = camera.getCenter();
              Coord oldEye = camera.getEyes();
        //sets the camera center to the center of the pich gesture
              Coord rotationCenter(g->mapFromGlobal(pinch->centerPoint().toPoint()).x(), g->mapFromGlobal(pinch->centerPoint().toPoint()).y(), oldCenter.getZ());
              Coord rotationEye=camera.getEyes()+(rotationCenter-oldCenter);
              camera.setCenter(rotationCenter);
              camera.setEyes(rotationEye);*/
        //rotates the camera
        camera.rotate((pinch->rotationAngle() - pinch->lastRotationAngle())/180*M_PI, 0, 0, 1);
        /*
        //restore old camera center and eyes
              camera.setCenter(oldCenter);
              camera.setEyes(oldEye); */
      }

      if(pinch->state() == Qt::GestureFinished) {
        isGesturing = false;
      }

      if(gesture->gesture(Qt::PanGesture)) {
        QPanGesture* pan = (QPanGesture*)gesture->gesture(Qt::PanGesture);

        if(pan->state() == Qt::GestureStarted) {
          isGesturing = true;
        }

        if(pan->state() == Qt::GestureFinished) {
          isGesturing = false;
        }

        center = pan->delta();
        g->getScene()->translateCamera(pan->delta().x(), -pan->delta().y(), 0);
      }
    }

    g->draw(false);
    return true;
  }

  return false;
}