如何将 AVCaptureVideoPreviewLayer 旋转 90 度以在 iOS11 中更正它？

Posted 2023-02-23

【中文标题】如何将 AVCaptureVideoPreviewLayer 旋转 90 度以在 iOS11 中更正它？

【英文标题】：How to rotate a AVCaptureVideoPreviewLayer by 90 degrees to correct it in iOS11?

【发布时间】：2018-03-25 07:04:56

【问题描述】：

我有一个AVCaptureVideoPreviewLayer，它被设置为使用前置摄像头捕捉会话的实时预览。但是，输出旋转了 90 度，我试图让图层与我的应用程序的其余部分对齐，即Landscape 方向。有没有办法通过90 degrees 旋转它以纠正它？

到目前为止，这是我的代码：

override func viewDidLoad() 
    super.viewDidLoad()

    let captureSession = AVCaptureSession()

    guard let captureDevice = getDevice(position: .front) else  return 
    guard let input = try? AVCaptureDeviceInput(device: captureDevice) else  return 
    captureSession.addInput(input)

    captureSession.startRunning()

    let previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
    view.layer.addSublayer(previewLayer)
    previewLayer.frame = view.frame
    previewLayer.videoGravity = .resizeAspectFill
    previewLayer.connection?.automaticallyAdjustsVideoMirroring = false
    previewLayer.connection?.isVideoMirrored = false


func getDevice(position: AVCaptureDevice.Position) -> AVCaptureDevice? 
    let devices = AVCaptureDevice.devices() as NSArray;
    for de in devices 
        let deviceConverted = de as! AVCaptureDevice
        if(deviceConverted.position == position)
            return deviceConverted
        
    
    return nil

【参考方案1】：

您能否将previewLayer 添加到另一个UIView，然后尝试像这样旋转：

private var captureView: UIView!

override func viewDidLoad() 
    super.viewDidLoad()

    self.captureView = UIView(frame: self.view.bounds)
    self.captureView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
    self.view.addSubview(captureView)

    // ...
    captureView.layer.addSublayer(previewLayer)
    // ...

    self.rotateView(animated: false)


// Rotating captureView based on device orientation
func rotateView(animated: Bool) 
    var transform: CGAffineTransform?
    switch UIDevice.current.orientation 
    case .portraitUpsideDown:
        transform = CGAffineTransform(rotationAngle: CGFloat.pi)
    case .landscapeLeft:
        transform = CGAffineTransform(rotationAngle: CGFloat.pi / 2)
    case .landscapeRight:
        transform = CGAffineTransform(rotationAngle: -CGFloat.pi / 2)
    default:
        break
    

    guard animated else 
        self.captureView.transform(transform)
        return
    

    UIView.animate(withDuration: 0.5, animations: [weak self] in
        self?.captureView.transform(transform)
    )