// 图片转为base64格式
export const imageToBase64 = (img) => {
  var canvas = document.createElement('canvas')
  canvas.width = img.width
  canvas.height = img.height
  var ctx = canvas.getContext('2d')
  ctx.drawImage(img, 0, 0, img.width, img.height)
  var ext = img.src.substring(img.src.lastIndexOf('.') + 1).toLowerCase()
  var dataURL = canvas.toDataURL('image/jpeg' + ext)
  return dataURL
}

export const base64ToFile = (urlData, fileName) => {
  const arr = urlData.split(',')
  const mime = arr[0].match(/:(.*?);/)[1]
  const bytes = atob(arr[1]) // 解码base64
  let n = bytes.length
  const ia = new Uint8Array(n)
  while (n--) {
    ia[n] = bytes.charCodeAt(n)
  }
  return new File([ia], fileName, { type: mime })
}