ios AVCaptureVideoPreviewLayer捕获当前图像

一旦默认的iPhone相机应用程序拍摄照片，预览出现，图像animation到相机滚动button。 我正试图复制这个animation。

session = [[AVCaptureSession alloc] init]; session.sessionPreset = AVCaptureSessionPresetPhoto; CALayer *viewLayer = self.vImagePreview.layer; NSLog(@"viewLayer = %@", viewLayer); captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session]; captureVideoPreviewLayer.frame = CGRectMake(0, 0, 322, 425); [self.vImagePreview.layer addSublayer:captureVideoPreviewLayer]; device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo]; NSError *error = nil; AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error]; if (!input) { // Handle the error appropriately. NSLog(@"ERROR: trying to open camera: %@", error); } [session addInput:input]; _stillImageOutput = [[AVCaptureStillImageOutput alloc] init]; NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys: AVVideoCodecJPEG, AVVideoCodecKey, nil]; [_stillImageOutput setOutputSettings:outputSettings]; [session addOutput:_stillImageOutput]; 

这是我如何形象：

 AVCaptureConnection *videoConnection = nil; for (AVCaptureConnection *connection in _stillImageOutput.connections) { for (AVCaptureInputPort *port in [connection inputPorts]) { if ([[port mediaType] isEqual:AVMediaTypeVideo] ) { videoConnection = connection; break; } } if (videoConnection) { break; } } NSLog(@"about to request a capture from: %@", _stillImageOutput); [_stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error) { CFDictionaryRef exifAttachments = CMGetAttachment( imageSampleBuffer, kCGImagePropertyExifDictionary, NULL); if (exifAttachments) { // Do something with the attachments. NSLog(@"attachements: %@", exifAttachments); } else NSLog(@"no attachments"); NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer]; UIImage *image = [[UIImage alloc] initWithData:imageData]; UIImageWriteToSavedPhotosAlbum(image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil); }]; 

这需要完整的照片图像，但我也需要从AVCaptureVideoPreviewLayer的图像，所以我可以用它来复制animation。 如何获取AVCaptureVideoPreviewLayer中当前显示的图像？

Answer 1

要做到这一点的方法是将另一个输出添加到会话：

  frameOutput = [[AVCaptureVideoDataOutput alloc] init]; frameOutput.videoSettings = @{(id)kCVPixelBufferPixelFormatTypeKey : @(kCVPixelFormatType_32BGRA)}; [frameOutput setSampleBufferDelegate:self queue:dispatch_get_main_queue()]; 

一旦你有了，你可以得到缓冲区上的当前图像：

  - (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection{ // Create a UIImage from the sample buffer data UIImage *image = [self imageFromSampleBuffer:sampleBuffer]; rotatedScreenImage = rotateUIImage(image, 90.0);} - (UIImage *) imageFromSampleBuffer:(CMSampleBufferRef) sampleBuffer{ CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer); CVPixelBufferLockBaseAddress(imageBuffer, 0); // Get the number of bytes per row for the pixel buffer void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer); // Get the number of bytes per row for the pixel buffer size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer); // Get the pixel buffer width and height size_t width = CVPixelBufferGetWidth(imageBuffer); size_t height = CVPixelBufferGetHeight(imageBuffer); // Create a device-dependent RGB color space CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); // Create a bitmap graphics context with the sample buffer data CGContextRef context = CGBitmapContextCreate(baseAddress, width, height, 8, bytesPerRow, colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst); // Create a Quartz image from the pixel data in the bitmap graphics context CGImageRef quartzImage = CGBitmapContextCreateImage(context); // Unlock the pixel buffer CVPixelBufferUnlockBaseAddress(imageBuffer,0); // Free up the context and color space CGContextRelease(context); CGColorSpaceRelease(colorSpace); // Create an image object from the Quartz image UIImage *image = [UIImage imageWithCGImage:quartzImage]; // Release the Quartz image CGImageRelease(quartzImage); return (image); 

}

而那个返回（图像）实际上是在屏幕缓冲区中。