iphone - AVCaptureStillImageOutput 的 UIImage 方向不正确

Question

我正在尝试从 AVCaptureStillImageOutput 捕获像素数据，并注意到在将图像裁剪为 CGImage 后，它会重新定向。为了对此进行测试，我将临时图像输出到照片库。现在我注意到，即使在裁剪图像之前，它的缩略图也会旋转，而完整图像不会。 (当我将 UIImage 传递到需要正确尺寸图像的自定义 pixelDataManager 时，这后来成为一个问题。)

设置 captureVideoPreviewLayer.orientation = AVCaptureVideoOrientationPortrait; 和 [videoConnection setVideoOrientation:AVCaptureVideoOrientationPortrait]; 似乎没有任何改变。

有什么想法吗？？？我会把它分成几个部分...

1) 设置 session 、输入和输出:

    // Create a capture session
    AVCaptureSession *session = [[AVCaptureSession alloc] init];
    session.sessionPreset = AVCaptureSessionPresetMedium;

    AVCaptureVideoPreviewLayer *captureVideoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];

    // Add capture layer to visible view    
    captureVideoPreviewLayer.videoGravity = AVLayerVideoGravityResize;
    captureVideoPreviewLayer.frame = screenBounds;
    captureVideoPreviewLayer.bounds = screenBounds;
    captureVideoPreviewLayer.orientation = AVCaptureVideoOrientationPortrait;
    [self.vImagePreview.layer addSublayer:captureVideoPreviewLayer];

    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    // Setup error handling
    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];

    // Start session
    [session startRunning];

    // Output image data 
    stillImageOutput = [[AVCaptureStillImageOutput alloc] init];
    NSDictionary *outputSettings = [[NSDictionary alloc] initWithObjectsAndKeys: AVVideoCodecJPEG, AVVideoCodecKey, nil];
    [stillImageOutput setOutputSettings:outputSettings];

    [session addOutput:stillImageOutput];

2) 设置视频连接:

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; }
}

if ([videoConnection isVideoOrientationSupported])
{
    [videoConnection setVideoOrientation:AVCaptureVideoOrientationPortrait];
}

3)输出抓取的图片:

NSLog(@"about to request a capture from: %@", stillImageOutput);
[stillImageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error)
{         
    NSData *imageData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];
    UIImage *image = [[UIImage alloc] initWithData:imageData];
    UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
    //......
}

Answer 1

当你这样做时，虽然图像是作为 UIImage 提供给你的，但它实际上使用了底层的 Quartz CGImage 数据，它具有不同的原点(我认为是左下角)，这意味着当你使用图像时它会旋转到一边。

我找到了一个 C 函数，您可以使用 UIImage 作为参数调用它来修复它并返回固定的 UIImage。

http://blog.logichigh.com/2008/06/05/uiimage-fix/