title: How can I catch a button clicked on mobile device with Flutter
body: <p>I am new to Flutter. I've been trying to develop an android application for a handheld terminal which model is ZEBRA.</p>
  <p>I need to catch when a user clicks the barcode scanner button on the handled terminal.
  If the User focuses on TextField, the Barcode value appears in the text field. But If it's not focused I need to catch what the barcode scanner read and get the value.</p>
  <p>I found a package in Flutter --&gt; hardware_buttons: ^1.0.0</p>
  <p>But It gives only those 3 buttons</p>
  <ul>
  <li>VolumeButton</li>
  <li>HomeButton</li>
  <li>LockButton</li>
  </ul>
  <p>How can I do that? or Is there any workaround method to achieve this?</p>