How can I resize the image? about react-s3-uploader HOT 7 OPEN

<ReactS3Uploader
            getSignedUrl={this._signUrl}
            accept='image/*'
            uploadRequestHeaders={{ 'x-amz-acl': 'public-read' }}
            preprocess={this._onUploadStart}
            onError={this._uploadOnError}
            onFinish={this._uploadOnFinish}
            contentDisposition='auto'
            className='file-input__file'
            id='input-file' />

_onUploadStart (file, cb) {
    this.props.startImageUpload(file)
    let fileName = file.name.replace(/\.[^/.]+$/, '')
    // Load the image
    let reader = new FileReader()
    reader.onload = (readerEvent) => {
      let image = new Image()
      image.onload = (imageEvent) => {
        // Resize the image
        let canvas = document.createElement('canvas')
        let maxSize = 1050
        let width = image.width
        let height = image.height
        if (width > height) {
          if (width > maxSize) {
            height *= maxSize / width
            width = maxSize
          }
        } else {
          if (height > maxSize) {
            width *= maxSize / height
            height = maxSize
          }
        }
        canvas.width = width
        canvas.height = height
        canvas.getContext('2d').drawImage(image, 0, 0, width, height)
        let dataUrl = canvas.toDataURL('image/jpeg')
        let resizedImage = this._dataURLToBlob(dataUrl)
        resizedImage.lastModifiedDate = new Date()
        resizedImage.name = file.name
        cb(resizedImage)
      }
      image.src = readerEvent.target.result
    }
    reader.readAsDataURL(file)
  }
  _dataURLToBlob (dataURL) {
    if(typeof window !== 'undefined'){
      let BASE64_MARKER = ';base64,'
      if (dataURL.indexOf(BASE64_MARKER) === -1) {
        let parts = dataURL.split(',')
        let contentType = parts[0].split(':')[1]
        let raw = parts[1]
        return new Blob([raw], {type: contentType})
      }

      let parts = dataURL.split(BASE64_MARKER)
      let contentType = parts[0].split(':')[1]
      let raw = window.atob(parts[1])
      let rawLength = raw.length
      let uInt8Array = new Uint8Array(rawLength)

      for (var i = 0; i < rawLength; ++i) {
        uInt8Array[i] = raw.charCodeAt(i)
      }
      return new Blob([uInt8Array], {type: contentType})
    }
  }