title: How to make an image provider from an Icon in flutter for FadeInImage widget?
body: <p>I want to use <code>FadeInImage</code> with an icon as a placeholder.</p>
  
  <p><code>FadeInImage</code> has few constructors.</p>
  
  <p>In a default constructor it takes <code>ImageProvider</code> as a placeholder, and in <code>FadeInImage.MemoryNetwork(</code> it takes <code>Uint8List</code> as a memory placeholder.</p>
  
  <p>The third constructor creates AssetImage, but I doubt that is useful here.</p>
  
  <p>Is there any way to convert an Icon to one of those data types?</p>
  
  <p>Example signature:</p>
  
  <p><code>FadeInImage(placeholder: iconPlaceholder, image: NetworkImage("url"))</code></p>