title: Flutter cut rectangle from widget?
body: <p>How can I clip a rectangle from an image/widget?
  I want something like this:</p>
  <p><a href="https://i.stack.imgur.com/Uyt4B.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Uyt4B.jpg" alt="enter image description here" /></a></p>
  <p>I can add a blur overlay, but I need to &quot;cut&quot; a rectangle in the middle.
  How can I do this?</p>
  <pre class="lang-dart prettyprint-override"><code> Scaffold(
    body: Stack(
      children: [
        LastQrScannerPreview(
          onQRViewCreated: _onQRViewCreated,
        ),
        Center(
          child: BackdropFilter(
            filter: ImageFilter.blur(sigmaX: 3, sigmaY: 3),
            child: Container(
              color: Colors.black.withOpacity(0.0),
            ),
          ),
        )
      ],
    ),
  );
  </code></pre>