Cropping a captured image exactly to how it looks in AVCaptureVideoPreviewLayer

Question

I have a photo app that is using AV Foundation. I have setup a preview layer using AVCaptureVideoPreviewLayer that takes up the top half of the screen. So when the user is tryin

Answer 1

@Cabus has a solution that works and you should up-vote his answer. However, I did my own version in Swift with the following:

// The image returned in initialImageData will be larger than what
//  is shown in the AVCaptureVideoPreviewLayer, so we need to crop it.
let image : UIImage = UIImage(data: initialImageData)!

let originalSize : CGSize
let visibleLayerFrame = self.previewView!.bounds // THE ACTUAL VISIBLE AREA IN THE LAYER FRAME

// Calculate the fractional size that is shown in the preview
let metaRect : CGRect = (self.videoPreviewLayer?.metadataOutputRectOfInterestForRect(visibleLayerFrame))!
if (image.imageOrientation == UIImageOrientation.Left || image.imageOrientation == UIImageOrientation.Right) {
    // For these images (which are portrait), swap the size of the
    // image, because here the output image is actually rotated
    // relative to what you see on screen.
    originalSize = CGSize(width: image.size.height, height: image.size.width)
}
else {
    originalSize = image.size
}

// metaRect is fractional, that's why we multiply here.
let cropRect : CGRect = CGRectIntegral(
        CGRect( x: metaRect.origin.x * originalSize.width,
                y: metaRect.origin.y * originalSize.height,
                width: metaRect.size.width * originalSize.width,
                height: metaRect.size.height * originalSize.height))

let finalImage : UIImage = 
    UIImage(CGImage: CGImageCreateWithImageInRect(image.CGImage, cropRect)!, 
        scale:1, 
        orientation: image.imageOrientation )