Fabric JS；如何使对象不可移动，直到对象被“完全”单击(鼠标按下和鼠标向上移动)

var canvas = new fabric.Canvas('canvas');

var rect = new fabric.Rect({
  left: 100,
  top: 100,
  width: 100,
  height: 100,
  fill: 'red'
});
canvas.add(rect);

rect.selectable = false;

rect.on('mousedown', function(options) {
  if (options.e.button === 0) { // 判断是否为鼠标左键单击
    // 执行对象被完全单击后的操作
    console.log('Object clicked!');
  }
});