Cropping Cgrect from Avcapturephotooutput (Resizeaspectfill)

Cropping CGRect from AVCapturePhotoOutput (resizeAspectFill)

I managed to solve the issue with this code.

private func cropToPreviewLayer(from originalImage: UIImage, toSizeOf rect: CGRect) -> UIImage? {
    guard let cgImage = originalImage.cgImage else { return nil }

    // This previewLayer is the AVCaptureVideoPreviewLayer which the resizeAspectFill and videoOrientation portrait has been set.
    let outputRect = previewLayer.metadataOutputRectConverted(fromLayerRect: rect)

    let width = CGFloat(cgImage.width)
    let height = CGFloat(cgImage.height)

    let cropRect = CGRect(x: (outputRect.origin.x * width), y: (outputRect.origin.y * height), width: (outputRect.size.width * width), height: (outputRect.size.height * height))

    if let croppedCGImage = cgImage.cropping(to: cropRect) {
        return UIImage(cgImage: croppedCGImage, scale: 1.0, orientation: originalImage.imageOrientation)
    }

    return nil
}

usage of the piece of code for my case:

let rect = CGRect(x: 25, y: 150, width: 325, height: 230)
let croppedImage = self.cropToPreviewLayer(from: image, toSizeOf: rect)
self.imageView.image = croppedImage

metadataOutputRectConverted(fromLayerRect:) in Android

I figured it out with the following code.

private fun cropImage(bitmap: Bitmap, cameraFrame: View, cropRectFrame: View): Bitmap {
    val scaleFactor: Double; val widthOffset: Double; val heightOffset: Double

    if (cameraFrame.height * bitmap.width > cameraFrame.height * bitmap.width) {
        scaleFactor = (bitmap.width).toDouble() / (cameraFrame.width).toDouble()
        widthOffset = 0.0
        heightOffset = (bitmap.height - cameraFrame.height * scaleFactor) / 2
    } else {
        scaleFactor = (bitmap.height).toDouble() / (cameraFrame.height).toDouble()
        widthOffset = (bitmap.width - cameraFrame.width * scaleFactor) / 2
        heightOffset = 0.0
    }

    val newX = cropRectFrame.left * scaleFactor + widthOffset
    val newY = cropRectFrame.top * scaleFactor + heightOffset
    val width = cropRectFrame.width * scaleFactor
    val height = cropRectFrame.height * scaleFactor

    return Bitmap.createBitmap(bitmap, (newX).toInt(), (newY).toInt(), (width).toInt(), (height).toInt())

}

cropping an area CGRect from UIGraphicsImageContext

The CGRect called objectBounds has two components, an origin and a size. In order the draw the object correctly as a thumbnail, the code needs to scale the image (to get the size right) and translate the image (to move the origin to {0,0}). So the code looks like this

- (UIImage *)getThumbnailOfSize:(CGSize)size forObject:(UIBezierPath *)object
{
    // to maintain the aspect ratio, we need to compute the scale
    // factors for x and y, and then use the smaller of the two
    CGFloat xscale = size.width / object.bounds.size.width;
    CGFloat yscale = size.height / object.bounds.size.height;
    CGFloat scale = (xscale < yscale) ? xscale : yscale;

    // start a graphics context with the thumbnail size
    UIGraphicsBeginImageContext( size );
    CGContextRef context = UIGraphicsGetCurrentContext();

    // here's where we scale and translate to make the image fit
    CGContextScaleCTM( context, scale, scale );
    CGContextTranslateCTM( context, -object.bounds.origin.x, -object.bounds.origin.y );

    // draw the object and get the resulting image
    [object stroke];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return image;
}

AVCapturePhotoOutput iOS Camera Super Dark

It appears as though I have too many async pieces. I broke the code into separate functions for each major piece - async or not and put them all into a DispatchGroup. That seems to have solved the issue.

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