显示实时视频流，但无法通过 UIGraphicsGetCurrentContext 捕获图像？
我使用 AVCaptureVideoPreviewLayer 来显示实时视频流，如下所示：
AVCaptureSession *captureSession = yourcapturesession;
previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:captureSession];
UIView *aView = theViewYouWantTheLayerIn;
previewLayer.frame = aView.bounds;
[aView.layer addSublayer:previewLayer];
然后我用它来捕获图像。我得到一个 UIImage 对象，但图像是黑色的：
UIGraphicsBeginImageContext(self.previewLayer.bounds.size);
[self.previewLayer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
NSLog("%@",image);
这里有什么问题？
I use AVCaptureVideoPreviewLayer to display the live video streaming, something like this:
AVCaptureSession *captureSession = yourcapturesession;
previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:captureSession];
UIView *aView = theViewYouWantTheLayerIn;
previewLayer.frame = aView.bounds;
[aView.layer addSublayer:previewLayer];
then I use this to capture the image. I get a UIImage object but the image is black:
UIGraphicsBeginImageContext(self.previewLayer.bounds.size);
[self.previewLayer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
NSLog("%@",image);
What is the problem here?
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也尝试这样做，结果相同 - 没有图像。
我认为答案是这是不可行的，因为它并没有真正将 RGB 图像移交给上下文，只是“通过视口显示它”或类似的东西，如果这有意义的话。
Tried doing this too, w/ the same results - no image.
I think the answer is that it's just not doable because it's not really handing over the RGB image to the context, just "showing it through a viewport" or something similar, if that makes sense.