我正在寻找制作条形码扫描仪应用程序。由于我是 Swift 和 Xcode 的新手，因此我设法从其他 stackoverflow 文章（this和this one）中获得帮助，以创建一个页面，我可以在其中扫描 rectOfInterestArea（带角）而不是全景相机中的条形码。但是，除了 rectOfInterestArea 之外，我很难使该区域的其余部分更暗。我让整个区域变暗。不知道我做错了什么。这是结果：
我基本上希望实现类似的目标
下面是我的代码
import AVFoundation
import UIKit
class TestViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
var captureSession: AVCaptureSession!
var previewLayer: AVCaptureVideoPreviewLayer!
var rectOfInterestArea = UIView()
var darkView = UIView()
var scanRect:CGRect = CGRect(x: 0, y: 0, width: 0, height: 0)
let metadataOutput = AVCaptureMetadataOutput()
override func viewDidLoad() {
super.viewDidLoad()
captureSession = AVCaptureSession()
guard let videoCaptureDevice = AVCaptureDevice.default(for: .video) else { return }
let videoInput: AVCaptureDeviceInput
do {
videoInput = try AVCaptureDeviceInput(device: videoCaptureDevice)
} catch {
return
}
if (captureSession.canAddInput(videoInput)) {
captureSession.addInput(videoInput)
} else {
failed()
return
}
if (captureSession.canAddOutput(metadataOutput)) {
captureSession.addOutput(metadataOutput)
metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
metadataOutput.metadataObjectTypes = [.qr]
} else {
failed()
return
}
let size = 300
let screenWidth = self.view.frame.size.width
let xPos = (CGFloat(screenWidth) / CGFloat(2)) - (CGFloat(size) / CGFloat(2))
scanRect = CGRect(x: Int(xPos), y: 150, width: size, height: size)
rectOfInterestArea.frame = scanRect
view.addSubview(rectOfInterestArea)
print(rectOfInterestArea.frame.size.height, " ", rectOfInterestArea.frame.size.width )
previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
previewLayer.frame = view.layer.bounds
previewLayer.videoGravity = .resizeAspectFill
view.layer.addSublayer(previewLayer)
print(previewLayer.frame.size.height, " ", previewLayer.frame.size.width )
view.addSubview(rectOfInterestArea)
captureSession.startRunning()
metadataOutput.rectOfInterest = previewLayer.metadataOutputRectConverted(fromLayerRect: scanRect)
}
func failed() {
let ac = UIAlertController(title: "Scanning not supported", message: "Your device does not support scanning a code from an item. Please use a device with a camera.", preferredStyle: .alert)
ac.addAction(UIAlertAction(title: "OK", style: .default))
present(ac, animated: true)
captureSession = nil
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
self.rectOfInterestArea.layer.addSublayer(self.createFrame())
if (captureSession?.isRunning == false) {
captureSession.startRunning()
}
}
override func viewWillDisappear(_ animated: Bool) {
super.viewWillDisappear(animated)
if (captureSession?.isRunning == true) {
captureSession.stopRunning()
}
}
func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection) {
captureSession.stopRunning()
if let metadataObject = metadataObjects.first {
guard let readableObject = metadataObject as? AVMetadataMachineReadableCodeObject else { return }
guard let stringValue = readableObject.stringValue else { return }
found(code: stringValue)
}
dismiss(animated: true)
}
func found(code: String) {
print(code)
}
override var prefersStatusBarHidden: Bool {
return true
}
override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
return .portrait
}
func createFrame() -> CAShapeLayer {
let height: CGFloat = self.rectOfInterestArea.frame.size.height
let width: CGFloat = self.rectOfInterestArea.frame.size.width
print(height, " " , width)
//let h = previewLayer.frame.size.height
let path = UIBezierPath()
path.move(to: CGPoint(x: 5, y: 50))
path.addLine(to: CGPoint(x: 5, y: 5))
path.addLine(to: CGPoint(x: 50, y: 5))
path.move(to: CGPoint(x: height - 55, y: 5))
path.addLine(to: CGPoint(x: height - 5, y: 5))
path.addLine(to: CGPoint(x: height - 5, y: 55))
path.move(to: CGPoint(x: 5, y: width - 55))
path.addLine(to: CGPoint(x: 5, y: width - 5))
path.addLine(to: CGPoint(x: 55, y: width - 5))
path.move(to: CGPoint(x: width - 55, y: height - 5))
path.addLine(to: CGPoint(x: width - 5, y: height - 5))
path.addLine(to: CGPoint(x: width - 5, y: height - 55))
let shape = CAShapeLayer()
shape.path = path.cgPath
shape.strokeColor = UIColor.white.cgColor
shape.lineWidth = 5
shape.fillColor = UIColor.clear.cgColor
return shape
}
}
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