function drawImage(config) {

  const { top, left, width, height, url, round } = config

​

  const img = canvas.createImage()

  img.src = url

  return new Promise((resolve, reject) => {

    // 绘制图片时宽度 100% 垂直方向居中截取

    img.onload = () => {

      CTX.save()

      CTX.beginPath()

      CTX.rect(left, top, width, height)

      CTX.clip()

      const newHeight = width / img.width * img.height

      const topOffset = (newHeight - height) / 2

      CTX.drawImage(img, left, top - topOffset, width, newHeight)

      CTX.restore()

      resolve()

    }

    img.onerror = reject

  })

}