fabric.js阻止对象移动到画布外

canvas.on('object:moving', (e) => {
      // 阻止对象移动到画布外面
      let padding = 10; // 内容距离画布的空白宽度，主动设置
      var obj = e.target;
      if (obj.currentHeight > obj.canvas.height - padding * 2 ||
        obj.currentWidth > obj.canvas.width - padding * 2) {
        return;
      }
      obj.setCoords();
      if (obj.getBoundingRect().top < padding || obj.getBoundingRect().left < padding) {
        obj.top = Math.max(obj.top, obj.top - obj.getBoundingRect().top + padding);
        obj.left = Math.max(obj.left, obj.left - obj.getBoundingRect().left + padding);
      }
      if (obj.getBoundingRect().top + obj.getBoundingRect().height > obj.canvas.height - padding || obj.getBoundingRect().left + obj.getBoundingRect().width > obj.canvas.width - padding) {
        obj.top = Math.min(
          obj.top,
          obj.canvas.height - obj.getBoundingRect().height + obj.top - obj.getBoundingRect().top - padding
        );
        obj.left = Math.min(
          obj.left,
          obj.canvas.width - obj.getBoundingRect().width + obj.left - obj.getBoundingRect().left - padding
        );
      }
    });

原文：使用fabricjs在画布上添加“出血区域”