C++ QPinchGesture::totalScaleFactor方法代码示例

bool View::gestureEvent(QGestureEvent* event)
{   
    //
    // pinch has precedence
    if (QGesture *pinchEvent = event->gesture(Qt::PinchGesture)) {
        QPinchGesture* pinch = static_cast<QPinchGesture*>(pinchEvent);

        //
        // only pinch if the fingers have already moved a significant amount
        qreal totalScaleFactor = pinch->totalScaleFactor();
        if((totalScaleFactor < 0.66) || (totalScaleFactor > 1.5)){
            qreal zoomDelta = pinch->scaleFactor();
            qreal resultZoom = m_zoomFactor * zoomDelta;
            if(resultZoom > s_maxZoomFactor){
                zoomDelta = s_maxZoomFactor / m_zoomFactor;
            }else if(resultZoom < s_minZoomFactor){
                zoomDelta = s_minZoomFactor / m_zoomFactor;
            }

            // scale the view
            scale(zoomDelta,zoomDelta);
            m_zoomFactor *= zoomDelta;

            return true;
        }
    }

    //
    // pan
    if (QGesture *panEvent = event->gesture(Qt::PanGesture)) {
        QPanGesture* pan = static_cast<QPanGesture*>(panEvent);
        QPointF delta = pan->delta();
        qreal factor = (1.0 / m_zoomFactor) * 0.9;

        QScrollBar* vScrollBar = verticalScrollBar();
        vScrollBar->setValue(vScrollBar->value() - int(delta.y()/factor));

        QScrollBar* hScrollBar = horizontalScrollBar();
        hScrollBar->setValue(hScrollBar->value() - int(delta.x()/factor));
    }

    return true;
}

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;
      }

//===============================================================
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;
}