AngularJS show image from byte array sent in response

Question

I have a service which adds some properties to file and sends it back in a response as byte array, but i have hard time displaying it as it is bytes, i tried to convert it to base64 but it still didn't worked. It shows raw bytes

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IHDR&��LCv�IDATx��......

What would be best solution to solve this maybe i should change response type is it possible to send not bytes?

@RequestMapping(path = "image/decode", method = POST, consumes = "multipart/form-data", produces = {"image/png", "image/jpeg"})
public byte[] decodeImage(@RequestParam("file") MultipartFile file) throws Exception {
    File file1 = addProperties(file);
    return FileUtils.readFileToByteArray(file1);
}

Js code

$scope.extractImage = function (sourceFile) {
    Upload.upload({
        url: '/image/decode',
        objectKey: '',
        data: {
            file: sourceFile
        }
    }).then(function (response) {
        console.log('Success ' +'Response: ' + response);
        $scope.image = response.data;
    }, function (response) {
        console.log('Error status: ' + response);
    });
};

Html code

<img class="thumb image-properties" ng-if="image" ng-src="{{image}}" />

Try converting it to a data uri: data:image/png;base64,<data converted to Base64> — Riiverside
– Riiverside, Commented May 1, 2017 at 16:40
Possible duplicate of Javascript : How to display image from byte array using Javascript or Servlet? — adam-beck
– adam-beck, Commented May 1, 2017 at 16:42
Actually a better duplicate would be: stackoverflow.com/questions/14979791/… — adam-beck
– adam-beck, Commented May 1, 2017 at 16:44
I added <img ng-src="data:image/JPEG;base64,{{image}}"> as it says in the answer but still image is not displayed, where to put this $compileProvider.aHrefSanitizationWhitelist(/^\s*(https?|file|ftp|blob):|data:image\//);? — DanJo
– DanJo, Commented May 1, 2017 at 16:53

alizelzele · Accepted Answer · 2017-12-01 07:09:31Z

0

surely you already find the solution. if not

  var bytes = response.data;
  var base64String = btoa(String.fromCharCode.apply(null, new Uint8Array(bytes)));
  $scope.image = "data:image/png;base64," + base64String;

for other people with the same issue, this problem have a far easier solution:

@GetMapping(path = "image/decode/{img}", produces = {"image/png", "image/jpeg"})
public byte[] decodeImage(@PathVariable String img) throws Exception {
  // return your file's bytes
}

and in JS:

$scope.extractImage = function (sourceFile) {
  $scope.image = `/image/decode/$sourceFile`;
};

answered Dec 1, 2017 at 7:09

alizelzele

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Comments

jpllosa · Accepted Answer · 2020-06-17 09:57:25Z

Ok, my search led me here. Here's how I solve the "show image from byte array sent in response" problem. The comment from @amdev from show-byte-array-content-as-image was particularly helpful. Here are the key points:

The backend must return a base 64 encoded string.
Send the string as a response body and not a string response. If you send it as a string response straight away, there is a possibility that the image will be incomplete because it is too large.
The frontend displays it using data URL.

Java Spring Backend

@RequestMapping(value = "/**")
public @ResponseBody JsonResponse getImage(...) throws URISyntaxException {
    ...
    // the meat
    RestTemplate restTemplate = new RestTemplate();
    JsonResponse response = new JsonResponse(); // our own JSON marshaller class

    try {
        // pull image from a web api returning a byte array but this could be a call
        // to a database returning a byte array
        ResponseEntity<byte[]> imageBytes = restTemplate.exchange(url, method, httpEntity, byte[].class);
        byte[] imageBytesBody = imageBytes.getBody();
        String b64 = Base64.encodeBase64String(imageBytesBody);
        response.setSuccess(b64);
        // JSON message is {status: 'success', result: 'b64 - the image in base 64 format'}
    }
    catch(RestClientException x) {
        response.setError(x);
        // JSON message is {status: 'error', result: 'error blah blah blah'}
    }

    return response;
}

Javascript jQuery Frontend

$.ajax({
  type: 'GET',
  url: '/image',
  ...
})
.done(function(response) {
  $('body').append('<img src="data:image/png;base64,' + response.result + '" />');
});

Hope this helps.

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