onTouch(event) {
    if (new Date().valueOf() - this.touchTime > 50) {
      this.drag.pointer = this.getPointer(event.center);
      this.drag.pinched = false;
      this.pinch.scale = this.body.view.scale;
      // to avoid double fireing of this event because we have two hammer instances. (on canvas and on frame)
      this.touchTime = new Date().valueOf();
    }
  }
On start of a touch gesture, store the pointer
@param {Event}  event   The event
@private