title: Make AppBar transparent and show background image which is set to whole screen
body: <p>I have added <strong>AppBar</strong> in my flutter application. My screen already have a background image, where i don't want to set appBar color or don't want set separate background image to appBar. </p>
  
  <p>I want show same screen background image to appBar also.</p>
  
  <p>I already tried by setting appBar color as transparent but it shows color like gray. </p>
  
  <p><strong>Example code:</strong></p>
  
  <pre><code>appBar: new AppBar(
          centerTitle: true,
  //        backgroundColor: Color(0xFF0077ED),
          elevation: 0.0,
          title: new Text(
              "DASHBOARD",
              style: const TextStyle(
                  color:  const Color(0xffffffff),
                  fontWeight: FontWeight.w500,
                  fontFamily: "Roboto",
                  fontStyle:  FontStyle.normal,
                  fontSize: 19.0
              )),
        )
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/Rt8uv.png" rel="noreferrer"><img src="https://i.stack.imgur.com/Rt8uv.png" alt="enter image description here"></a></p>