title: Xamarin Forms image binding on url with default on embedded resource
body: <p>i have a Xamarin ListView with images from internet. I would to show a default image (from embedded resource), and, when present, the image from an url.</p>
  
  <p>I've tryied with this code but works only with UriImageSource, not for the embedded resource:</p>
  
  <pre><code>    &lt;ListView ItemsSource="{Binding Data}"&gt;
          &lt;ListView.ItemTemplate&gt;
            &lt;DataTemplate&gt;
               &lt;ViewCell&gt;
                  &lt;Image&gt;
                    &lt;Image.Source&gt;
                      &lt;!-- does not works
                      &lt;ImageSource&gt;
         {utils:ImageResource Namespace.Assets.img-placeholder.png}
                      &lt;/ImageSource&gt;
                      --&gt;
                      &lt;UriImageSource Uri="{Binding ImageUri}"&gt;&lt;/UriImageSource&gt;
                    &lt;/Image.Source&gt;
                  &lt;/Image&gt;
               &lt;/ViewCell&gt;
           &lt;/DataTemplate&gt;
        &lt;/ListView.ItemTemplate&gt;
      &lt;/ListView&gt;
  </code></pre>
  
  <p>if i use </p>
  
  <pre><code>&lt;Image Source="{utils:ImageResource Namespace.Assets.img-placeholder.png}" /&gt;
  </code></pre>
  
  <p>this works showing the embedded resource default image</p>
  
  <p>The model:</p>
  
  <pre><code>    public Uri ImageUri =&gt; Image != null ?
          new Uri($"http://www.example.com/{Image}")
          : null;
  </code></pre>
  
  <p>Any help? Thanks</p>