iPhone Xs Max：添加到View子层时，AVCaptureVideoPreviewLayer占用的空间少于iPhone X的安全区域-为什么？

Question

我正在尝试使用带有新iPhone Xs Max的单视图应用程序构建自定义相机。参考下面的屏幕截图，可以看出AVCaptureVideoPreviewLayer中显示的视频输出占用的空间小于iPhone x上屏幕的安全区域。如何计算尚未占用的空间？

我怎么知道AVCaptureVideoPreviewLayer占用的空间少于安全区域？好吧，顶部“按钮”的顶部边界固定在安全区域的顶部边界。底部按钮类似地锚定在底部安全区域的底部。但是有很多重叠！

问题：

单视图应用程序的布局：按钮顶部约束

底部白色按钮底部约束：

所有其他布局约束：

SWIFT：

class ViewController: UIViewController, UIImagePickerControllerDelegate, AVCaptureVideoDataOutputSampleBufferDelegate  {

var previewLayer = AVCaptureVideoPreviewLayer.init()
var captureSession: AVCaptureSession!
var previewFrame = CGRect.init()
var safeAreaFrame: CGRect = CGRect.init()



override func viewDidLoad() {
    super.viewDidLoad()

      let screenSize = UIScreen.main.bounds
      // This is (0.0, 0.0, 414.0, 896.0)

      startAVCaptureSession()

}



override func viewDidLayoutSubviews() {
    print("viewDidLayoutSubviews ...")

    let sAreaFrame = UIApplication.shared.windows[0].safeAreaLayoutGuide.layoutFrame
    self.safeAreaFrame = sAreaFrame

    // self.safeAreaFrame - This is (0.0, 44.0, 414.0, 818.0)


    self.previewLayer.frame = view.bounds // // I have tried  self.previewLayer.frame = self.safeAreaFrame 
    self.previewFrame = previewLayer.frame
}




func startAVCaptureSession() {
    print("START CAPTURE SESSION!!")

    // Setting Up a Capture Session
    self.captureSession = AVCaptureSession()
    captureSession.beginConfiguration()

    // Configure input
    let videoDevice = AVCaptureDevice.default(for: .video)

    guard
        let videoDeviceInput = try? AVCaptureDeviceInput.init(device: videoDevice!) as AVCaptureInput,
        self.captureSession.canAddInput(videoDeviceInput)else {return}

    self.captureSession.addInput(videoDeviceInput)

    // Capture video output
    let videoOutput = AVCaptureVideoDataOutput.init()
    guard self.captureSession.canAddOutput(videoOutput) else {return}
    videoOutput.setSampleBufferDelegate(self, queue: DispatchQueue.init(label: "videoQueue"))
    self.captureSession.addOutput(videoOutput)


    // start
    self.captureSession.commitConfiguration()
    self.captureSession.startRunning()


    // Display camera preview
    self.previewLayer = AVCaptureVideoPreviewLayer.init(session: self.captureSession)

    // Use 'insertSublayer' to enable button to be viewable
    view.layer.insertSublayer(self.previewLayer, at: 0)



}





}

项目链接： https://github.com/babylon123/RectangleCapture

Answer 1

与长宽比有关。如果添加此行，它将正常工作：

self.previewLayer.videoGravity = AVLayerVideoGravity.resizeAspectFill