Crop Image after taking from custom camera in Swift

Question

I have custom camera view and on top of that I have guides I want to crop the taken photo to that guide, when I get the cropped image I get of different section, I want to get the area inside the guides.

func imageByCropToRect(rect:CGRect, scale:Bool) -> UIImage {

    var rect = rect
    var scaleFactor: CGFloat = 1.0
    if scale  {
        scaleFactor = self.scale
        rect.origin.x *= scaleFactor
        rect.origin.y *= scaleFactor
        rect.size.width *= scaleFactor
        rect.size.height *= scaleFactor
    }

    var image: UIImage? = nil;
    if rect.size.width > 0 && rect.size.height > 0 {
        let imageRef = self.cgImage!.cropping(to: rect)
        image = UIImage(cgImage: imageRef!, scale: scaleFactor, orientation: self.imageOrientation)
    }

    return image!
}


if let image = self.getImageFromSampleBuffer(buffer: sampleBuffer, orientation: orientation) {
let newImage = image.imageByCropToRect(rect: self.guideImageView.frame, scale: true)
selectedPropertyImage = newImage
stopCaptureSession()}

Answer 1

You have to map coordinate of current view layer to camera preview layer using captureDevicePointConverted. For example:

    let previewImageLayerBounds = previewLayer.bounds
    let originalWidth = original.size.width
    let originalHeight = original.size.height

    let A = previewImageLayerBounds.origin
    let B = CGPoint(x: previewImageLayerBounds.size.width, y: previewImageLayerBounds.origin.y)
    let D = CGPoint(x: previewImageLayerBounds.size.width, y: previewImageLayerBounds.size.height)

    let a = previewLayer.captureDevicePointConverted(fromLayerPoint: A)
    let b = previewLayer.captureDevicePointConverted(fromLayerPoint: B)
    let d = previewLayer.captureDevicePointConverted(fromLayerPoint: D)

    let posX = floor(b.x * originalHeight)
    let posY = floor(b.y * originalWidth)

    let width: CGFloat = d.x * originalHeight - b.x * originalHeight
    let height: CGFloat = a.y * originalWidth - b.y * originalWidth

    let cropRect = CGRect(x: posX, y: posY, width: width, height: height)