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我正在使用zxing库读取QR码的应用程序。我有ZxingWidgetController
问题 - 显示视图时,应用程序处于后台/未激活状态(例如屏幕锁定),相机中的图像未显示在屏幕上 - 只有背景可见,并且扫描仪看起来不工作。zXing(iOS版)黑白屏幕错误
当我再次调用initCapture
方法,从相机一点点延迟视频显示后,但在这种情况下,每次当应用程序失去活性,我需要时间来重新初始化扫描仪 - 这种行为是不舒服的。
这个bug可以在几乎所有的应用上重复使用zXing,所以我想这是一些zXing的bug。
斑马线initCapture方法的代码是:
- (void)initCapture {
#if HAS_AVFF
AVCaptureDeviceInput *captureInput =
[AVCaptureDeviceInput deviceInputWithDevice:
[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo]
error:nil];
if(!captureInput)
{
NSLog(@"ERROR - CaptureInputNotInitialized");
}
AVCaptureVideoDataOutput *captureOutput = [[AVCaptureVideoDataOutput alloc] init];
captureOutput.alwaysDiscardsLateVideoFrames = YES;
if(!captureOutput)
{
NSLog(@"ERROR - CaptureOutputNotInitialized");
}
[captureOutput setSampleBufferDelegate:self queue:dispatch_get_main_queue()];
NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey;
NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];
NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key];
[captureOutput setVideoSettings:videoSettings];
self.captureSession = [[[AVCaptureSession alloc] init] autorelease];
self.captureSession.sessionPreset = AVCaptureSessionPresetMedium; // 480x360 on a 4
if([self.captureSession canAddInput:captureInput])
{
[self.captureSession addInput:captureInput];
}
else
{
NSLog(@"ERROR - cannot add input");
}
if([self.captureSession canAddOutput:captureOutput])
{
[self.captureSession addOutput:captureOutput];
}
else
{
NSLog(@"ERROR - cannot add output");
}
[captureOutput release];
if (!self.prevLayer)
{
[self.prevLayer release];
}
self.prevLayer = [AVCaptureVideoPreviewLayer layerWithSession:self.captureSession];
// NSLog(@"prev %p %@", self.prevLayer, self.prevLayer);
self.prevLayer.frame = self.view.bounds;
self.prevLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
[self.view.layer addSublayer: self.prevLayer];
[self.captureSession startRunning];
#endif
}
也许你们知道什么是错的?
你有权利 - 我正在写关于情况,当应用程序在后台,而zxing初始化,然后移动到前面。 – Thaven