AVLayerVideoGravityResizeAspectFill在哪里裁剪

Question

我使用的是AVCaptureSession具有AVCaptureVideoPreviewLayer与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预览区域AVLayerVideoGravityResizeAspectFill？在预览区域中可以看到图像的哪个部分？

来自doc:

AVLayerVideoGravityResizeAspectFill:这会保留纵横比,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

通过iOS 6 SDK，我可以使用以下内容AVCaptureVideoPreviewLayer

(CGPoint)captureDevicePointOfInterestForPoint:(CGPoint)pointInLayer