html2canvas 图片转 base64

toSave() {
    
    
      html2canvas(‘照片路径’).then(canvas => {
    
    
        let saveUrl = canvas.toDataURL('image/png')
        let aLink = document.createElement('a')
        let blob = this.base64ToBlob(saveUrl)
        let evt = document.createEvent('HTMLEvents')
        evt.initEvent('click', true, true)
        aLink.download = '二维码.jpg'
        aLink.href = URL.createObjectURL(blob)
        aLink.click()
      });
    },
 //这里把图片转base64
    base64ToBlob (code) {
    
    
       let parts = code.split(';base64,')
       let contentType = parts[0].split(':')[1]
       let raw = window.atob(parts[1])
       let rawLength = raw.length
       let uInt8Array = new Uint8Array(rawLength)
       for (let i = 0; i < rawLength; ++i) {
    
    
           uInt8Array[i] = raw.charCodeAt(i)
       }
       return new Blob([uInt8Array], {
    
    type: contentType})
   },