从Amazon S3将图像编码为Base64

Encode image to Base64 from Amazon S3

本文关键字：Base64 图像编码 Amazon S3      更新时间：2023-09-26

我有一个包含图像的iframe。图像源链接到S3桶中的图像。我需要在Base64中编码此图像，并将iframe的主体保存在数据库中。

我该怎么做?

试试这个如何访问<在文件从iframe?>

$('#Iframe1').contents().find('img').css({'width':'100%','height':'90%'});

然后使用这个函数从这里得到JavaScript中的图像数据?

function getBase64Image(img) {
    // Create an empty canvas element
    var canvas = document.createElement("canvas");
    canvas.width = img.width;
    canvas.height = img.height;
    // Copy the image contents to the canvas
    var ctx = canvas.getContext("2d");
    ctx.drawImage(img, 0, 0);
    // Get the data-URL formatted image
    // Firefox supports PNG and JPEG. You could check img.src to
    // guess the original format, but be aware the using "image/jpg"
    // will re-encode the image.
    var dataURL = canvas.toDataURL("image/png");
    return dataURL.replace(/^data:image'/(png|jpg);base64,/, "");
}

如果您将s3存储在binary/blob中，例如，你在服务器端做了如下操作:

...
//event.body - base64 received from client or REST
       
let decodedImage = Buffer.from(event.body.replace(/^data:(image|application)'/'w+;base64,/, ""), "base64")
        var params = {
          Bucket: bucket,
          Key: key, // 
          Body: decodedImage,
          ContentEncoding: 'base64',
          ACL: 'public-read',
          ContentType: event.headers["Content-Type"],
        }

        // Uploading files to the bucket :
...
        s3.putObject(params, function (err, data) {

接收它并将其转换回base64可以在前端用代码完成(在示例中是React hook):

const blobToBase64 = (blob) => {
  const reader = new FileReader()
  reader.readAsDataURL(blob)
  return new Promise((rs, rj) => {
    reader.onloadend = () => {
      rs(reader.result)
    }
    reader.onerror = rj
  })
}
function useImage({s3Link}) {
  const [src, setSrc] = React.useState(null)
  React.useEffect(() => {
    async function query({link}) {
      //link is link to s3 bucket URL link e.g
      // const link = s3.getSignedUrl('getObject', {
      //   Bucket: bucketnamw,
      //   Key: key,
      //   Expires: 30,
      // })
      const r = await fetch(link)
      const blob = await r.blob()
      const base64 = await blobToBase64(blob)
      console.log(`base64!`, base64)
      setSrc(base64)
    }
    if (s3Link) {
      query({link: s3Link})
    }
  }, [s3Link, setSrc])
  return [{src}]
}

…

const [hookImage] = useImage({s3Link})

视图:

 {hookImage.src ? <img src={hookImage.src} /> : null}

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