非全屏模式下的iOS 5后置摄像头预览

Question

just wondering if this is possible:

I've been looking at various solutions for displaying the camera preview; and while doing so in full-screen mode is relatively straight-forward, what I'd like to do is to have it scaled to 50% of the screen and presented side by side with a graphic (not an overlay, but a separate graphic to the left of the camera preview which takes up equal space). Basically the purpose is to allow the user to compare the camera preview with the graphic.

So, what I need to know is: a) is it possible to scale the camera preview to a lower resolution b) can it share the screen on an iPad with another graphic which isn't an overlay c) if a and b are true, is there any example source I might be pointed to please?

Thanks!

Answer 1

You can just use next code:

previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:captureSession];
previewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
previewLayer.opaque = YES;
previewLayer.contentsScale = self.view.contentScaleFactor;
previewLayer.frame = self.view.bounds;
previewLayer.needsDisplayOnBoundsChange = YES;
[self.view.layer addSublayer:previewLayer];

Just replace line 5 to set preview layer another frame. You can create captureSession with this code

captureSession = [[AVCaptureSession alloc] init];

if(!captureSession)
{
    NSLog(@"Failed to create video capture session");
    return NO;
}

[captureSession beginConfiguration];

captureSession.sessionPreset = AVCaptureSessionPreset640x480;

AVCaptureDevice *videoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
videoDevice.position = AVCaptureDevicePositionFront;

if(!videoDevice)
{
    NSLog(@"Couldn't create video capture device");
    [captureSession release];
    captureSession = nil;
    return NO;
}

if([videoDevice isFocusModeSupported:AVCaptureFocusModeContinuousAutoFocus])
{
    NSError *deviceError = nil;

    if([videoDevice lockForConfiguration:&deviceError])
    {
        [videoDevice setFocusMode:AVCaptureFocusModeContinuousAutoFocus];
        [videoDevice unlockForConfiguration];
    }
    else
    {
        NSLog(@"Couldn't lock device for configuration");
    }
}

NSError *error;
AVCaptureDeviceInput *videoIn = [AVCaptureDeviceInput deviceInputWithDevice:videoDevice error:&error];

if(!videoIn)
{
    NSLog(@"Couldn't create video capture device input: %@ - %@", [error localizedDescription], [error localizedFailureReason]);
    [captureSession release];
    captureSession = nil;
    return NO;
}

if(![captureSession canAddInput:videoIn])
{
    NSLog(@"Couldn't add video capture device input");
    [captureSession release];
    captureSession = nil;
    return NO;
}

[captureSession addInput:videoIn];
[captureSession commitConfiguration];