XCode条形码扫描仪Phonegap自动对焦

Question

I develop phonegap ios application.I used barcode scanner zxing library. But I have a problem How to implement camera auto focus ?

thank you

My Code:

-(NSString*)setUpCaptureSession {
    NSError* error = nil;

    AVCaptureSession* captureSession = [[[AVCaptureSession alloc] init] autorelease];
    self.captureSession = captureSession;

    AVCaptureDevice* device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    if (!device) return @"unable to obtain video capture device";

    AVCaptureDeviceInput* input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
    if (!input) return @"unable to obtain video capture device input";

    AVCaptureVideoDataOutput* output = [[[AVCaptureVideoDataOutput alloc] init] autorelease];
    if (!output) return @"unable to obtain video capture output";

    NSDictionary* videoOutputSettings = [NSDictionary
                                         dictionaryWithObject:[NSNumber numberWithInt:kCVPixelFormatType_32BGRA]
                                         forKey:(id)kCVPixelBufferPixelFormatTypeKey
                                         ];


    output.alwaysDiscardsLateVideoFrames = YES;
    output.videoSettings = videoOutputSettings;

    [output setSampleBufferDelegate:self queue:dispatch_get_main_queue()];

    if (![captureSession canSetSessionPreset:AVCaptureSessionPresetMedium]) {
        return @"unable to preset medium quality video capture";
    }

    captureSession.sessionPreset = AVCaptureSessionPresetMedium;

    if ([captureSession canAddInput:input]) {
        [captureSession addInput:input];
    }
    else {
        return @"unable to add video capture device input to session";
    }

    if ([captureSession canAddOutput:output]) {
        [captureSession addOutput:output];
    }
    else {
        return @"unable to add video capture output to session";
    }

    // setup capture preview layer
    self.previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:captureSession];

    // run on next event loop pass [captureSession startRunning]
    [captureSession performSelector:@selector(startRunning) withObject:nil afterDelay:0];
    return nil;
}

Answer 1

Unfortunately it appears that the plugin you are using doesn't expose the capture device directly. It does, however, expose the AVCaptureSession via the captureSession property. From this property you should be able to work backwards to get the AVCaptureInputDevice

AVCaptureSession *session=[zxing captureSession];  //Assuming zxing the variable holding a reference to your zxing instance
NSArray *inputs= [session inputs];
AVCaptureInputDevice *input=(AVCaptureInputDevice *)inputs[0];   // Obtain first input device
AVCaptureDevice *device=input.device;

NSError *error;

if ([device lockForConfiguration:&error])
{
    device.focusMode=AVCaptureFocusModeContinuousAutoFocus;
   [device unlockForConfiguration];
}
else
{
  // TODO Handle the device lock error
}