AVCaptureVideoPreviewLayer 横向

Question

如何让“AVCaptureVideoPreviewLayer”以横向正确显示？它在纵向上可以正常工作，但不会旋转，并且当父视图控制器处于横向时会显示旋转的相机捕获。

Answer 1

仅仅改变 AVCaptureVideoPreviewLayer 的连接方向是不够的。 这只会更新您在屏幕上看到的图像。

但实际图像仍将保持不变。您可以在不同方向打印输出图像大小并检查结果。

要使旋转真正起作用，您还需要更改 AVCaptureSession 连接的方向。

func updateVideoOrientation() {
    if let previewLayerConnection = previewLayer.connection, previewLayerConnection.isVideoOrientationSupported {
        previewLayerConnection.videoOrientation = currentVideoOrientation
    }
    if let captureSessionConnection = captureSession.connections.first, captureSessionConnection.isVideoOrientationSupported {
        captureSessionConnection.videoOrientation = currentVideoOrientation
    }
}

Answer 2

Jacksanford 和 NeonEye 的回答很棒。不过，我有一个快速的建议。

因为 statusBarOrientation 在 iOS 13 中已弃用，所以我最终使用了

connection.videoOrientation = self.interfaceOrientation(toVideoOrientation: UIApplication.shared.windows.first?.windowScene?.interfaceOrientation ?? .portrait

Answer 3

Swift 5 (iOS 13.0+)：

    func updateVideoOrientation() {
        guard let videoPreviewLayer = self.videoPreviewLayer else {
            return
        }
        guard videoPreviewLayer.connection!.isVideoOrientationSupported else {
            print("isVideoOrientationSupported is false")
            return
        }
        let statusBarOrientation = UIApplication.shared.windows.first?.windowScene?.interfaceOrientation
        let videoOrientation: AVCaptureVideoOrientation = statusBarOrientation?.videoOrientation ?? .portrait
        videoPreviewLayer.frame = view.layer.bounds
        videoPreviewLayer.connection?.videoOrientation = videoOrientation
        videoPreviewLayer.removeAllAnimations()
    }

    override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
        super.viewWillTransition(to: size, with: coordinator)

        coordinator.animate(alongsideTransition: nil, completion: { [weak self] (context) in
            DispatchQueue.main.async(execute: {
                self?.updateVideoOrientation()
            })
        })
    }

extension UIInterfaceOrientation {
    var videoOrientation: AVCaptureVideoOrientation? {
        switch self {
        case .portraitUpsideDown: return .portraitUpsideDown
        case .landscapeRight: return .landscapeRight
        case .landscapeLeft: return .landscapeLeft
        case .portrait: return .portrait
        default: return nil
        }
    }
}

Answer 4

override func viewWillLayoutSubviews() {
    self.previewLayer.frame = self.view.bounds
    if previewLayer.connection.isVideoOrientationSupported {
        self.previewLayer.connection.videoOrientation = self.interfaceOrientation(toVideoOrientation: UIApplication.shared.statusBarOrientation)
    }
}

func interfaceOrientation(toVideoOrientation orientation: UIInterfaceOrientation) -> AVCaptureVideoOrientation {
    switch orientation {
    case .portrait:
        return .portrait
    case .portraitUpsideDown:
        return .portraitUpsideDown
    case .landscapeLeft:
        return .landscapeLeft
    case .landscapeRight:
        return .landscapeRight
    default:
        break
    }

    print("Warning - Didn't recognise interface orientation (\(orientation))")
    return .portrait
}

//SWIFT 3 转换

Answer 5

Swift3

func updateVideoOrientation() {
    guard let previewLayer = self.previewLayer else {
        return
    }
    guard previewLayer.connection.isVideoOrientationSupported else {
        print("isVideoOrientationSupported is false")
        return
    }

    let statusBarOrientation = UIApplication.shared.statusBarOrientation
    let videoOrientation: AVCaptureVideoOrientation = statusBarOrientation.videoOrientation ?? .portrait

    if previewLayer.connection.videoOrientation == videoOrientation {
        print("no change to videoOrientation")
        return
    }

    previewLayer.frame = cameraView.bounds
    previewLayer.connection.videoOrientation = videoOrientation
    previewLayer.removeAllAnimations()
}

override func viewWillTransition(to size: CGSize, with coordinator: UIViewControllerTransitionCoordinator) {
    super.viewWillTransition(to: size, with: coordinator)

    coordinator.animate(alongsideTransition: nil, completion: { [weak self] (context) in
        DispatchQueue.main.async(execute: {
            self?.updateVideoOrientation()
        })
    })
}

---

extension UIInterfaceOrientation {
    var videoOrientation: AVCaptureVideoOrientation? {
        switch self {
        case .portraitUpsideDown: return .portraitUpsideDown
        case .landscapeRight: return .landscapeRight
        case .landscapeLeft: return .landscapeLeft
        case .portrait: return .portrait
        default: return nil
        }
    }
}

Answer 6

除了 viewWillLayoutSubviews()，你还必须实现 didRotateFromInterfaceOrientation()。

这是因为如果设备从纵向模式旋转到纵向倒置模式，子视图布局将不会更新（显然是出于效率原因）。

Answer 7

首先，答案

- (void)viewWillLayoutSubviews {
  _captureVideoPreviewLayer.frame = self.view.bounds;
  if (_captureVideoPreviewLayer.connection.supportsVideoOrientation) {
    _captureVideoPreviewLayer.connection.videoOrientation = [self interfaceOrientationToVideoOrientation:[UIApplication sharedApplication].statusBarOrientation];
  }
}

- (AVCaptureVideoOrientation)interfaceOrientationToVideoOrientation:(UIInterfaceOrientation)orientation {
  switch (orientation) {
    case UIInterfaceOrientationPortrait:
        return AVCaptureVideoOrientationPortrait;
    case UIInterfaceOrientationPortraitUpsideDown:
        return AVCaptureVideoOrientationPortraitUpsideDown;
    case UIInterfaceOrientationLandscapeLeft:
        return AVCaptureVideoOrientationLandscapeLeft;
    case UIInterfaceOrientationLandscapeRight:
        return AVCaptureVideoOrientationLandscapeRight;
    default:
        break;
  }
  NSLog(@"Warning - Didn't recognise interface orientation (%d)",orientation);
  return AVCaptureVideoOrientationPortrait;
}

我遇到了几篇关于这个问题的 SO 帖子，但找不到任何简单的解释，所以我想分享我自己的。

如果您在这件事上遵循 Apple 的示例，当您将 iOS 设备旋转到横向时会遇到两个潜在问题

1. 捕捉将显示为旋转（就像您将相机保持 90 度关闭一样）
2. 它不会完全跨越其设定的界限

这里的问题是“CALayer”不支持自动旋转，因此，与您添加为子视图的“UIView”不同，它不会在其父“UIView”旋转时旋转。因此，每次父视图的边界发生变化时，您都必须手动更新其框架（不是父视图的框架，因为框架在旋转后保持不变）。这是通过覆盖容器视图控制器中的“viewWillLayoutSubviews”来实现的。

其次，您应该使用“videoOrientation”属性通知 AVFoundation 方向，以便它正确进行预览。

希望这会有所帮助。