Capture images in the background?

Question

I'm trying to capture images in the background from the camera without loading a camera or preview interface.

In my app photos are taken in the background with no preview screen, just the normal app screen and then shown to the user later.

Can someone please point me in the right direction?

Answer 1

In a (game ) application on ones phone.. example android cell phone; is it.. you push the camera button and the frontal power button at the same time.. volume up and or down button with the frontal power button or volume up / down side power button? To capture image of application (app) for like extra points? via that games contest rules.

Answer 2

You have to use AVCaptureSession & AVCaptureDeviceInput.

This is part of code may help you:

@interface MyViewController : UIViewController
{
    AVCaptureStillImageOutput *_output;
    AVCaptureConnection *_videoConnection;
    bool _isCaptureSessionStarted;
}

@property (retain, nonatomic) AVCaptureDevice *frontalCamera;

- (void)takePhoto;

Implementation:

@interface MyViewController ()

@end

@implementation MyViewController

- (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil
{
    self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil];
    if (self) {
        _isCaptureSessionStarted = false;
    }
    return self;
}

- (void)viewDidLoad
{
    [super viewDidLoad];

    // Finding frontal camera
    NSArray *cameras = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];

    for (int i = 0; i < cameras.count; i++) {
        AVCaptureDevice *camera = [cameras objectAtIndex:i];

        if (camera.position == AVCaptureDevicePositionFront) {
            self.frontalCamera = camera;

            [self.frontalCamera addObserver:self forKeyPath:@"adjustingExposure" options:NSKeyValueObservingOptionNew context:nil];
            [self.frontalCamera addObserver:self forKeyPath:@"adjustingWhiteBalance" options:NSKeyValueObservingOptionNew context:nil];
        }
    }
}

- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
    if (!self.frontalCamera.adjustingExposure && !self.frontalCamera.adjustingWhiteBalance) {
        if (_isCaptureSessionStarted) {
            [self captureStillImage];
        }
    }
}

- (void)takePhoto
{
    if (self.frontalCamera != nil) {
        // Add camera to session
        AVCaptureSession *session = [[AVCaptureSession alloc] init];

        NSError *error;
        AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:self.frontalCamera error:&error];

        if (!error && [session canAddInput:input]) {
            [session addInput:input];

            // Capture still image
            _output = [[AVCaptureStillImageOutput alloc] init];

            // Captured image settings
            [_output setOutputSettings:[[NSDictionary alloc] initWithObjectsAndKeys:AVVideoCodecJPEG, AVVideoCodecKey, nil]];

            if ([session canAddOutput:_output]) {
                [session addOutput:_output];

                _videoConnection = nil;

                for (AVCaptureConnection *connection in _output.connections) {
                    for (AVCaptureInputPort *port in [connection inputPorts]) {
                        if ([[port mediaType] isEqual:AVMediaTypeVideo]) {
                            _videoConnection = connection;
                            break;
                        }
                    }
                    if (_videoConnection) {
                        break;
                    }
                }

                if (_videoConnection) {
                    [session startRunning];
                    NSLock *lock = [[[NSLock alloc] init] autorelease];
                    [lock lock];
                    _isCaptureSessionStarted = true;
                    [lock unlock];
                }
            }
        } else {
            NSLog(@"%@",[error localizedDescription]);
        }
    }
}

- (void) captureStillImage
{
    [_output captureStillImageAsynchronouslyFromConnection:_videoConnection completionHandler:^(CMSampleBufferRef imageDataSampleBuffer, NSError *error) {

        NSLock *lock = [[[NSLock alloc] init] autorelease];
        [lock lock];
        _isCaptureSessionStarted = false;
        [lock unlock];

        if (imageDataSampleBuffer != NULL) {
            NSData *bitmap = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageDataSampleBuffer];

//            You can get image here via [[UIImage alloc] initWithData:bitmap]
        }
    }];
}