How to download an image by clicking on button into our local using angularjs?

Hi I am new to angularjs and I saw lot of questions on stackoverflow regarding this,but not able to find a good solution.

<button ng-click="download()">download</button>

My requirement is (1) I don't want to use <a> tag

(2) I don't want to use <download> attribute, because it should support in all browsers.

When user clicks on download button the image should get download to clients local machine.

Assume the image is coming through some url

<script>
angular.module('myApp', []);

angular.module('myApp').controller('HomeCtrl', ['$scope', '$http', function($scope, $http) {

  $scope.download=function()
  {
      $http.get(url).success(function(data){
             // code to download image here
        }).error(function(err, status){})
  }

}]);
</script>

You can achieve this with the help of BLOB object

HTML

<body ng-app="myApp">
 <div  ng-controller="HomeCtrl">
<button ng-click="download()">download</button>
    <img id="photo"/>
</div>
</body>

Angular code:

angular.module('myApp', []);

angular.module('myApp').controller('HomeCtrl', ['$scope', '$http', function($scope, $http) {

  $scope.download=function()
  {
      $http.get('https://placeholdit.imgix.net/~text?txtsize=15&txt=image1&w=120&h=120', {responseType: "arraybuffer"}).success(function(data){

           var arrayBufferView = new Uint8Array( data );
    var blob = new Blob( [ arrayBufferView ], { type: "image/png" } );
    var urlCreator = window.URL || window.webkitURL;
    var imageUrl = urlCreator.createObjectURL( blob );
    var img = document.querySelector( "#photo" );
    img.src = imageUrl;
             // code to download image here
        }).error(function(err, status){})
  }



function SaveToDisk(fileURL, fileName) {
    // for non-IE
    if (!window.ActiveXObject) {
        var save = document.createElement('a');
        save.href = fileURL;
        save.target = '_blank';
        save.download = fileName || 'unknown';

        var event = document.createEvent('Event');
        event.initEvent('click', true, true);
        save.dispatchEvent(event);
        (window.URL || window.webkitURL).revokeObjectURL(save.href);
    }

    // for IE
    else if ( !! window.ActiveXObject && document.execCommand)     {
        var _window = window.open(fileURL, '_blank');
        _window.document.close();
        _window.document.execCommand('SaveAs', true, fileName || fileURL)
        _window.close();
    }
}
    }]);

Plunker for the solution:http://plnkr.co/edit/IKQKWkY6YMwodzpByx0f?p=preview New Pluncker Auto download: http://plnkr.co/edit/eevPO2fh3F37Yhvchnol?p=preview