title: Flutter, scroll, pinch and zoom large image
body: <p>I need to show a large image (or pdf) that the user can then scroll around and pinch &amp; zoom.</p>
  
  <p>In iOS / Android, I'd just show it in a WebView.
  Note: the file to display is from the filesystem (an asset), not from the internet.</p>
  
  <p>Is there a way of doing this in Flutter?</p>