运用canvas完成照片免费下载作用来完成访问器适

<a href="#" @click.prevent="downloadIamge(imgsrc, name)"><span>{{name}}</span></a>

downloadIamge (imgsrc, name) {
      const url = imgsrc
      this.convertUrlToBase64(url).then((base64) => {
        const blob = this.convertBase64UrlToBlob(base64)
        if (getBrowser() === 'IE' || getBrowser() === 'Edge') {
          window.navigator.msSaveBlob(blob, name)
        } else {
          const a = document.createElement('a')
          const body = document.querySelector('body')
          a.download = name || 'image'
          a.href = URL.createObjectURL(blob)
          a.style.display = 'none'
          body.appendChild(a)
          a.click()
          body.removeChild(a)
          window.URL.revokeObjectURL(a.href)
        }
      })
    },

convertUrlToBase64 (url) {
      return new Promise((resolve, reject) => {
        const img = new Image()
        img.crossOrigin = 'Anonymous'
        img.src = url
        img.onload = function () {
          const canvas = document.createElement('canvas')
          canvas.width = img.width
          canvas.height = img.height
          const ctx = canvas.getContext('2d')
          ctx.drawImage(img, 0, 0, img.width, img.height)
          const ext = img.src.substring(img.src.lastIndexOf('.') + 1).toLowerCase()
          const dataURL = canvas.toDataURL('image/' + ext)
          const base64 = {
            dataURL: dataURL,
            type: 'image/' + ext,
            ext: ext
          }
          resolve(base64)
        }
      })
    },

convertBase64UrlToBlob (base64) {
      const parts = base64.dataURL.split('base64,')
      const contentType = parts[0].split(':')[1]
      const raw = window.atob(parts[1])
      const rawLength = raw.length
      const uInt8Array = new Uint8Array(rawLength)
      for (let i = 0; i < rawLength; i++) {
        uInt8Array[i] = raw.charCodeAt(i)
      }
      return new Blob([uInt8Array], { type: contentType })
    },

import { getBrowser } from '@/utils/utils'
export function getBrowser () {
  const userAgent = navigator.userAgent
  if (userAgent.indexOf('OPR') > ⑴) {
    return 'Opera'
  }
  if (userAgent.indexOf('Firefox') > ⑴) {
    return 'FF'
  }
  if (userAgent.indexOf('Trident') > ⑴) {
    return 'IE'
  }
  if (userAgent.indexOf('Edge') > ⑴) {
    return 'Edge'
  }
  if (userAgent.indexOf('Chrome') > ⑴) {
    return 'Chrome'
  }
  if (userAgent.indexOf('Safari') > ⑴) {
    return 'Safari'
  }
}