objective-c metadataOutputRectOfInterestForRect返回{{0,0}，{0,0}}

Question

更新!!!

我正在使用metadataOutputRectOfInterestForRect转换矩形以使用AVCaptureMetadataOutput rectOfInterest。但是当翻译为CGRect时，它总是返回0.

这是我的代码：

NSError *error;

AVCaptureDevice *captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:&error];

if (!input) {
    NSLog(@"%@", [error localizedDescription]);
    return NO;
}

_captureSession = [[AVCaptureSession alloc] init];
[_captureSession addInput:input];

_videoPreviewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:_captureSession];
[_videoPreviewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
[_videoPreviewLayer setFrame:_viewPreview.bounds];
[_viewPreview.layer addSublayer:_videoPreviewLayer];
[_viewPreview bringSubviewToFront:_lblGuide];
[_viewPreview bringSubviewToFront:_vFocus];

CGRect visibleMetadataOutputRect = [_videoPreviewLayer metadataOutputRectOfInterestForRect:CGRectMake(0, 0, 100, 100)];
NSLog(@"--- log convert: %@", NSStringFromCGRect(visibleMetadataOutputRect));
NSLog(@"--- log _videoPreviewLayer: %@", NSStringFromCGRect(_videoPreviewLayer.bounds));
NSLog(@"--- log _viewPreview: %@", NSStringFromCGRect(_viewPreview.bounds));

_captureMetadataOutput = [[AVCaptureMetadataOutput alloc] init];
[_captureSession addOutput:_captureMetadataOutput];

_dispatchQueue = dispatch_queue_create("myQueue", NULL);
[_captureMetadataOutput setMetadataObjectsDelegate:self queue:_dispatchQueue];
[_captureMetadataOutput setMetadataObjectTypes:[NSArray arrayWithObject:AVMetadataObjectTypeQRCode]];
[_captureMetadataOutput setRectOfInterest:visibleMetadataOutputRect];

[_captureSession startRunning];

return YES;

并且NSlog重新开始：

[5082:1768978] --- log convert: {{0, 0}, {0, 0}}
[5082:1768978] --- log _videoPreviewLayer: {{0, 0}, {320, 468}}
[5082:1768978] --- log _viewPreview: {{0, 0}, {320, 468}}

请帮我解决。

Answer 1

我找到了一个简单的解决方案，它对我有用。

在[_captureSession startRunning]

之后立即移动2行代码

CGRect visibleMetadataOutputRect = [_videoPreviewLayer metadataOutputRectOfInterestForRect:self.vFocus.frame];
    [_captureMetadataOutput setRectOfInterest:visibleMetadataOutputRect];

效果很好！