AVLayerVideoGravityResizeAspectFill在哪里裁剪

Question

我正在使用AVCaptureSession AVCaptureVideoPreviewLayer AVLayerVideoGravityResizeAspectFill重力。

self.captureSession =[[AVCaptureSession alloc] init];
captureSession.sessionPreset = AVCaptureSessionPresetPhoto;
self.previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.captureSession];
[self.previewLayer setVideoGravity: AVLayerVideoGravityResizeAspectFill];

如何知道如何调整视频大小以适应AVLayerVideoGravityResizeAspectFill的预览区域？在预览区域中可以看到图像的哪一部分？

来自the doc：

  

AVLayerVideoGravityResizeAspectFill：这会保留宽高比，但会填充可用的屏幕区域，必要时裁剪视频

基本上，如何准确获取previewLayer中显示的内容？

Answer 1

AVCaptureVideoPreviewLayer

中的iOS 6 SDK I can use the following

(CGPoint)captureDevicePointOfInterestForPoint:(CGPoint)pointInLayer