我正在创建一个应用程序,用户可以在其中拍摄带有文本的图像并上传到服务器。我使用 AVCaptureSession
打开相机并放置了一个条形按钮,用于捕获最新帧并将其上传到服务器。在此应用中,用户可以通过单击条形按钮将多张图片一张一张地发送到服务器。
我想知道是否有可能用户不必按下按钮来捕获帧。是否有可能使用自动对焦自动捕获当前帧?就像用户只需将相机放在图像上一秒钟,当图像对焦良好时,它就会自动拍摄,这样用户就可以移动到下一张图像,而无需按任何按钮?
我捕获帧的代码如下:
- (void)initCapture {
AVCaptureDeviceInput *captureInput = [AVCaptureDeviceInput
deviceInputWithDevice:[AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo]
error:nil];
AVCaptureVideoDataOutput *captureOutput = [[AVCaptureVideoDataOutput alloc] init];
captureOutput.alwaysDiscardsLateVideoFrames = YES;
/*We create a serial queue to handle the processing of our frames*/
dispatch_queue_t queue;
queue = dispatch_queue_create("cameraQueue", NULL);
[captureOutput setSampleBufferDelegate:self queue:queue];
dispatch_release(queue);
// Set the video output to store frame in BGRA (It is supposed to be faster)
NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey;
NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];
NSDictionary* videoSettings = [NSDictionary dictionaryWithObject:value forKey:key];
[captureOutput setVideoSettings:videoSettings];
/*And we create a capture session*/
captureSession = [[AVCaptureSession alloc] init];
/*We add input and output*/
[captureSession addInput:captureInput];
[captureSession addOutput:captureOutput];
AVCaptureConnection *conn = [captureOutput connectionWithMediaType:AVMediaTypeVideo];
if (conn.supportsVideoMinFrameDuration)
conn.videoMinFrameDuration = CMTimeMake(5,1);
if (conn.supportsVideoMaxFrameDuration)
conn.videoMaxFrameDuration = CMTimeMake(5,1);
[captureSession setSessionPreset:AVCaptureSessionPresetPhoto];
customLayer = [CALayer layer];
customLayer.frame = self.view.bounds;
customLayer.transform = CATransform3DRotate(CATransform3DIdentity, M_PI/2.0f, 0, 0, 1);
customLayer.contentsGravity = kCAGravityResizeAspectFill;
//[self.view.layer addSublayer:customLayer];
/*We add the imageView*/
imageView = [[UIImageView alloc] init];
imageView.frame = CGRectMake(0, 0, 100, 100);
//imageView.frame = self.view.bounds;
[self.view addSubview:imageView];
[captureSession startRunning];
}
我会很感激你的帮助。 谢谢。
最佳答案
您必须将 adjustingFocus
观察器添加到您的视频输入中:
[[[captureManager videoInput] device] addObserver:self forKeyPath:@"adjustingFocus" options:NSKeyValueObservingOptionNew context:nil];
然后添加observeValueForKeyPath
方法,调焦完成后拍照:
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context {
if( [keyPath isEqualToString:@"adjustingFocus"] ){
BOOL adjustingFocus = [ [change objectForKey:NSKeyValueChangeNewKey] isEqualToNumber:[NSNumber numberWithInt:1] ];
if (!adjustingFocus) {
[[self captureManager] captureStillImage:self];
}
}
}
关于objective-c - iPhone SDK 中如何实现对焦自动拍照?,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/11423538/