title: How to show jquery-upload thumbnails through Ember
body: <p>when jquery-file-upload processes images to thumbnails, it does not show them correctly when I use Ember to render view. There is either an empty canvas shown or Ember tries to fetch blob:http that is not found.</p>
  
  <p>So when jquery-upload has processed image resize and calls <strong>on('fileuploadprocessdone')</strong></p>
  
  <pre><code>App.VideosNewView = Ember.View.extend(
    didInsertElement: -&gt;
      self = this
      $("#fileupload").fileupload(
        dataType: "json"
        autoUpload: false
        previewCanvas: false
      ).on('fileuploadprocessdone', (e, data) -&gt;
        console.log "DONE"
        file = data.files[0]
        self.get('controller').set('addFile', file);
     )
  )
  </code></pre>
  
  <p>the corresponding file is added to file-array in EmberController:</p>
  
  <pre><code>App.VideosNewController = Ember.ObjectController.extend(
    files: []
  
    actions:
      addFile: (file) -&gt;
        @files.pushObject file
  )
  </code></pre>
  
  <p>and the template gets updated:</p>
  
  <pre><code>{{#each file in files}}
    {{{file.preview.outerHTML}}}
  {{/each}}
  </code></pre>
  
  <p>Depending on jquery-file-upload setting (previewCanvas) Ember either tries to fetch an blob:http reference that is 404 not found</p>
  
  <pre><code>previewCanvas: false
  ...
  
  GET blob:http%3A//localhost%3A3000/8e2869ad-8e44-4701-a56c-a2ad2fdafa07 404 (Not Found)
  </code></pre>
  
  <p>or it renders an empty HTML-canvas element</p>
  
  <pre><code>previewCanvas: true
  ...
  
  &lt;canvas width="80" height="45"&gt;&lt;/canvas&gt;&lt;!-- THIS DOES NOT SHOW ANYTHING --&gt;
  </code></pre>
  
  <p>If I render these straight from jquery then everything shows correctly.</p>
  
  <pre><code> .on('fileuploadprocessdone', (e, data) -&gt;
     node = data.context.children()
     node.prepend('&lt;br&gt;').prepend(file.preview) if file.preview
  </code></pre>
  
  <p>I don't quite understand why these are shown correctly when inserted with jquery but not with Ember. How do I get these previews to show correctly with Ember? </p>