protected virtual void OnKeyboardStartZoom(KeyRoutedEventArgs e)
        {
            var f = IsCtrlKeyPressed() ? 0.25f : 1;

            switch (e.Key)
            {
            case VirtualKey.PageUp:
                OnAddZoomForce?.Invoke(Viewport, new AddForceEventArgs(new Vector2(-0.1f * f * (float)Viewport.PageUpDownZoomSensitivity, 0)));
                e.Handled = true;
                break;

            case VirtualKey.PageDown:
                OnAddZoomForce?.Invoke(Viewport, new AddForceEventArgs(new Vector2(0.1f * f * (float)Viewport.PageUpDownZoomSensitivity, 0)));
                e.Handled = true;
                break;

            case VirtualKey.Back:
                OnRestoreCameraSettings?.Invoke(Viewport, EventArgs.Empty);
                e.Handled = true;
                break;
            }
        }
 protected void RaiseOnAddZoomForce(AddForceEventArgs args)
 {
     OnAddZoomForce?.Invoke(Viewport, args);
 }