Fabricjs 橡皮擦、取消橡皮擦、绘画、选择和喷雾

    case "select": //选择
      canvas.isDrawingMode = false //取消绘画模式
      break;
    case "erase": //橡皮擦
      canvas.freeDrawingBrush = new fabric.EraserBrush(canvas);
      canvas.freeDrawingBrush.width = 10;
      canvas.isDrawingMode = true;
      break;
    case "undo": //取消橡皮擦
      canvas.freeDrawingBrush = new fabric.EraserBrush(canvas);
      canvas.freeDrawingBrush.width = 10;
      canvas.freeDrawingBrush.inverted = true //倒转的
      canvas.isDrawingMode = true
      break;
    case "draw": //绘画
      canvas.freeDrawingBrush = new fabric.PencilBrush(canvas);
      canvas.freeDrawingBrush.width = 5;
      canvas.isDrawingMode = true;
      break;
    case "spray": //喷雾器
      canvas.freeDrawingBrush = new fabric.SprayBrush(canvas);
      canvas.freeDrawingBrush.width = 35
      canvas.isDrawingMode = true;

代码是直接复制的，重点是canvas的属性值