How do bind content retrieved from an ApiController to an Angular element using data URIs?

Question

I have a html page that looks like so:

<div ng-controller="DocumentCtrl">
    <img ng-src="data:image/tiff;base64,{{image}}" />
</div>

My Angular controller looks like this:

angular.controller('DocumentCtrl', ['$scope', '$http', function ($scope, $http) {

    $http.get('/api/Image').
        then(function (response) {
            $scope.image = response.data;
        });
}]);

And my ApiController GET like this:

public HttpResponseMessage Get()
{
    var file = HttpContext.Current.Server.MapPath("~/Images/docs/example.TIF");

    var stream = new FileStream(file, FileMode.Open);
    var content = new HttpResponseMessage(HttpStatusCode.OK)
    {
        Content = new StreamContent(stream)
    };

    content.Content.Headers.ContentType = new MediaTypeHeaderValue("image/tiff");
    return content;
}

Inspecting the element in Chrome gives me this:

enter image description here

Now the data is binding to the UI correctly, but it always shows as a broken image link icon. I've tried various things, like changing the data type to image/* and using application/octet as the Content-Type, but nothing seems to make a difference.

Also, if I inspect the request with Fiddler and look at the ImageView of the response content, the image shows up there as I expect, so that portion of the process seems to be working correctly.

Is there something obvious I'm missing?

Thanks.

when you inspect the HTML, what is {{image}} replaced with? <img ng-src="data:image/tiff;base64,{{image}}" /> — SoluableNonagon
– SoluableNonagon, Commented May 6, 2014 at 19:03

Community · Accepted Answer · 2017-05-23 12:33:00Z

3

It appears your server does not render the image base64 encoded (from what I can see), if you base64 encode the image before sending it back then it should be fine.

Take a look at the below fiddle, the same request is used however I base64 encode the response on the 2nd image before assigning it to the scope (used the technique provided by Getting BLOB data from XHR request).

http://jsfiddle.net/kW4aV/2/

$http.get('http://lorempixel.com/50/50/', {responseType: "arraybuffer"}).success(function (resp) {
    $scope.image = resp;

    // Prep the response for Base64 encoding
    var uInt8Array = new Uint8Array(resp);
    var i = uInt8Array.length;
    var binaryString = new Array(i);
    while (i--)
    {
        binaryString[i] = String.fromCharCode(uInt8Array[i]);
    }
    var data = binaryString.join('');

    // Base64 encoded image and assign it to the scope
    $scope.image2 = window.btoa(data);
});

Note: that the fiddle will only work in Chrome and I do not suggest doing base64 encoding client side, best to do it on the server.

edited May 23, 2017 at 12:33

CommunityBot

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answered May 6, 2014 at 21:27

AndrewMerrell

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1 Comment

Andrew Over a year ago

This was the conclusion I had come to, I'm just now trying to figure out if it's possible to keep the GET function as is and render the image, before I go about modifying my server side code to do Base64 encoding.

SoluableNonagon · Accepted Answer · 2014-05-06 19:18:08Z

1

http://plnkr.co/edit/fa3owvnzZLBa72pDCeB5?p=preview

I created a plunker showing a working example:

<body ng-app="app" ng-controller="MainCtrl">

  <img ng-src="data:image/png;base64,{{image}}"  />

</body>

and

$scope.image = "iVBORw0KGgoAAAANSUhEUgAAAAUAAAAFCAYAAACNbyblAAAAHElEQVQI12P4//8/w38GIAXDIBKE0DHxgljNBAAO9TXL0Y4OHwAAAABJRU5ErkJggg==";

answered May 6, 2014 at 19:18

SoluableNonagon

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