canvas实现图片裁剪

getList() {
  let pilotRect = {
    left: 190,
    right: 290,
    top: 160,
    bottom: 260
  };
  this.initPicture('/static/images/car.png', pilotRect);
},
initPicture(imgUrl, rect) {
  let img = new Image();
  img.src = imgUrl;
  img.setAttribute('crossOrigin', 'Anonymous');

  let imgW = Math.abs(rect.right - rect.left);
  let imgH = Math.abs(rect.bottom - rect.top);

  let canvas = document.createElement('canvas');
  let context = canvas.getContext('2d');
  canvas.width = imgW;
  canvas.height = imgH;
  context.fillStyle = '#FFF';
  context.fillRect(0, 0, imgW, imgH);

  img.onload = () => {
    context.drawImage(img, -rect.left, -rect.top);
    this.imgTest = canvas.toDataURL('image/jpeg');
  };
},

例如裁剪出抓拍车辆图片中的主驾驶和副驾驶人员图片等