Overlay example does not apply background opacity correctly

[IanVS]

I'm using the overlay example as a guide for building a feature in my app, and I noticed that the background opacity is not being applied outside of the scan window correctly:

I'm a beginner flutter dev, so I don't know what might be causing this.

[navaronbracke]

This could be a bug in the example. Although, I think that the example just draws the white rectangle, and nothing else.

[IanVS]

From what I can tell, it does try to apply some opacity.

https://github.com/juliansteenbakker/mobile_scanner/blob/c3271f0cda3df5594a4cebc02696007657785861/example/lib/mobile_scanner_overlay.dart#L147C21-L147C41

    // First, draw the background,
    // with a cutout area that is a bit larger than the scan window.
    // Finally, draw the scan window itself.
    canvas.drawPath(backgroundWithCutout, backgroundPaint);
    canvas.drawRRect(borderRect, borderPaint);

[RobertCer]

In ScannerOverlay example class, changing from:

final backgroundPaint = Paint()
  ..color = Colors.black.withOpacity(0.5)
  ..style = PaintingStyle.fill
  ..blendMode = BlendMode.dstOut;

to

final backgroundPaint = Paint()
  ..color = Colors.black.withOpacity(0.5)
  ..style = PaintingStyle.fill
  ..blendMode = BlendMode.srcOver; // <- This line

will add the background opacity.