pinch

void MyBrowser::paintEvent(QPaintEvent *event)
{
  if (!_pixmap.isNull()) {
    QPainter p(this);
    QRect picR = rect();
    if (_target.width() <  picR.width()) { // zoom out
      QBrush b(Qt::white);
      p.setBrush(b);
      p.drawRect(picR);
      p.drawPixmap(_target, _pixmap, picR);
    }
    else { // zoom in
      p.drawPixmap(picR, _pixmap, _source);
    }
  }
  else
    QWebView::paintEvent(event);
}

bool MyBrowser::gestureEvent(QGestureEvent *event)
{
  if (QGesture *pinch = event->gesture(Qt::PinchGesture)) {
    if (_pixmap.isNull()) {
      _scrollPos.hide();
      _pixmap = QPixmap::grabWidget (this, rect()) ;
    }
    pinchTriggered(static_cast<QPinchGesture *>(pinch));
    return true;
  }
  return false;
}


void MyBrowser::pinchTriggered(QPinchGesture *gesture)
{
  QPinchGesture::ChangeFlags changeFlags = gesture->changeFlags();
  if (changeFlags & QPinchGesture::ScaleFactorChanged) {
    qreal value = gesture->property("scaleFactor").toReal();
    _target = rect();
    QPoint cp = _target.center();
    _target.setWidth(_target.width()*value);
    if (value > 1) { // zoomin in
      _source = rect();
      _source.setWidth(_source.width()/value);
      _source.setHeight(_source.height()/value);
    }
    else
      _target.setHeight(_target.height()*value);
  }
  if (gesture->state() == Qt::GestureFinished) {
    qreal value = gesture->property("scaleFactor").toReal();
    setZoomFactor(value);
    _pixmap = QPixmap();
  }
  update();
}