Access control: open'ed things that was private

[neoneye]

RSBarcodes_Swift is a great framework. I use it in 2 projects. It's robust and easy.

In this PR I have inserted the open keyword a few places. In particular I need to access the internal videoPreviewLayer ivar and I need to override the reloadVideoOrientation() function.

Yesterday+today I have been writing code that restricts the scanning area to a tiny box centered on the screen. For this purpose Apple provides AVCaptureMetadataOutput.rectOfInterest. I had to figure out how to compute the rectOfInterest using camera coordinates in the range 0..1. It was especially challenging dealing with orientation changes on iPad. Invoking updateRectOfInterest() too early and then the coordinates would be wrong. I have tested on iPad Pro and on iPhone6s and the rectOfInterest is working.

My subclass looks like this:

class MyScannerViewController: RSCodeReaderViewController {
    @IBOutlet weak var restrictedScanArea: UIView!

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()
        updateRectOfInterest()
    }

    override func reloadVideoOrientation() {
        super.reloadVideoOrientation()
        updateRectOfInterest()
    }

    func updateRectOfInterest() {
        guard let videoPreviewLayer: AVCaptureVideoPreviewLayer = self.videoPreviewLayer else {
            return
        }
        let scanRect = self.restrictedScanArea.frame
        /// Convert from display coordinates (pixels) to camera coordinates (0..1 range)
        /// scanRect: (515.0, 443.0, 336.0, 138.0)  rectOfInterest: (0.408, 0.433, 0.185, 0.135)
        output.rectOfInterest = videoPreviewLayer.metadataOutputRectConverted(fromLayerRect: scanRect)
    }
}

---

I can see that there are other people that have asked about rectOfInterest, see issue 76 and issue 110.

[codecov-io]

Codecov Report

Merging #113 into master will decrease coverage by 0.55%.
The diff coverage is 25%.

@@            Coverage Diff             @@
##           master     #113      +/-   ##
==========================================
- Coverage   49.49%   48.94%   -0.56%     
==========================================
  Files          23       23              
  Lines        1388     1706     +318     
  Branches        0       53      +53     
==========================================
+ Hits          687      835     +148     
- Misses        701      846     +145     
- Partials        0       25      +25

Impacted Files	Coverage Δ
Source/RSCodeReaderViewController.swift	12.25% <25%> (-1.09%)	⬇️
.../RSBarcodesSampleTests/RSBarcodesSampleTests.swift	76.54% <0%> (-23.46%)	⬇️
...RSBarcodesSample/BarcodeReaderViewController.swift	40.54% <0%> (-4.46%)	⬇️
Source/RSUnifiedCodeGenerator.swift	76.56% <0%> (-3.44%)	⬇️
...SBarcodesSample/RSBarcodesSample/AppDelegate.swift	36.36% <0%> (-1.14%)	⬇️
Source/RSEANGenerator.swift	96.96% <0%> (-0.99%)	⬇️
Source/RSUnifiedCodeValidator.swift	0% <0%> (ø)	⬆️
Source/RSFocusMarkLayer.swift	0% <0%> (ø)	⬆️
...SBarcodesSample/BarcodeDisplayViewController.swift	0% <0%> (ø)	⬆️
... and 13 more

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