title: Read QR Code from file in Flutter
body: <p>I'm developing a mobile app using the Flutter framework.</p>
  
  <p>I need to read QR Codes, and I have successfully implemented the <a href="https://pub.dartlang.org/packages/barcode_scan" rel="noreferrer">Barcode Scan</a> library, based on <a href="https://github.com/zxing/zxing" rel="noreferrer">ZXing</a> to <a href="https://pub.dartlang.org/documentation/zxing/latest/zxing/Zxing/scan.html" rel="noreferrer">decode</a> one through the camera.</p>
  
  <p>Now I would also like to add the chance to pick an image containing a QR code from the gallery and decoding, without having to go through the camera.</p>
  
  <p>I checked the library I'm using and also this one without finding any reference to such functionality: <a href="https://pub.dartlang.org/packages/qrcode_reader" rel="noreferrer">qrcode_reader</a>, <a href="https://pub.dartlang.org/packages/qr" rel="noreferrer">qr</a>.
  but in vain.</p>
  
  <p>A solution that would imply serializing and decoding byte by byte an image using pure Dart would be acceptable as well.</p>