How to zoom crop image in selected area - swift

Question

I want to crop image from selected area this is the image area i want to crop
this is the result i try to crop
the image i crop is not like in the crop area.
i use scrollview to zoom and pan the imageView, this is how setup to crop image.
i use this method from this stackoverflow
class ALCroppedPhotoViewController: UIViewController {
#IBOutlet weak var containerImage: UIView!
#IBOutlet weak var overlayView: UIView!
#IBOutlet weak var previewImageView: UIImageView!
#IBOutlet weak var rectHoleView: UIView!
#IBOutlet weak var scrollView: UIScrollView!
var data: Data?
var rect: CGRect!
override func viewDidLoad() {
super.viewDidLoad()
previewImageView.image = UIImage(data: data ?? Data())
setupScrollView()
}
override func viewDidLayoutSubviews() {
super.viewDidLayoutSubviews()
let midX = overlayView.bounds.midX
let midY = overlayView.bounds.midY
let center = CGPoint(x: midX, y: midY)
let size: CGFloat = 312
// Create the initial layer from the view bounds.
let maskLayer = CAShapeLayer()
maskLayer.frame = overlayView.bounds
// Create the path.
rect = CGRect(x: center.x - size / 2, y: center.y - size / 2, width: size, height: size)
let path = UIBezierPath(rect: overlayView.bounds)
maskLayer.fillRule = .evenOdd
// Append the overlay image to the path so that it is subtracted.
path.append(UIBezierPath(roundedRect: rect, cornerRadius: 20))
maskLayer.path = path.cgPath
// Set the mask of the view.
overlayView.layer.mask = maskLayer
}
private func setupScrollView() {
scrollView.minimumZoomScale = 1.0
scrollView.maximumZoomScale = 2.0
scrollView.delegate = self
}
func snapshot(in imageView: UIImageView, rect: CGRect) -> UIImage {
assert(imageView.contentMode == .scaleAspectFit)
let image = imageView.image!
// figure out what the scale is
let imageRatio = imageView.bounds.width / imageView.bounds.height
let imageViewRatio = image.size.width / image.size.height
let scale: CGFloat
if imageRatio > imageViewRatio {
scale = image.size.height / imageView.bounds.height
} else {
scale = image.size.width / imageView.bounds.width
}
// convert the `rect` into coordinates within the image, itself
let size = rect.size * scale
let origin = CGPoint(x: image.size.width / 2 - (imageView.bounds.midX - rect.minX) * scale,
y: image.size.height / 2 - (imageView.bounds.midY - rect.minY) * scale)
let scaledRect = CGRect(origin: origin, size: size)
// now render the image and grab the appropriate rectangle within
// the image’s coordinate system
let format = UIGraphicsImageRendererFormat()
format.scale = image.scale
format.opaque = false
return UIGraphicsImageRenderer(bounds: scaledRect, format: format).image { _ in
image.draw(at: .zero)
}
}
extension CGSize {
static func * (lhs: CGSize, rhs: CGFloat) -> CGSize {
return CGSize(width: lhs.width * rhs, height: lhs.height * rhs)
}
}
}
The image actually crop successfully, but failed if i try to zoom really closely. How i can crop if try to zoom closely.
This is where the crash start when i try to print
scrollView.zoomScale
extension ALCroppedPhotoViewController: UIScrollViewDelegate {
func viewForZooming(in scrollView: UIScrollView) -> UIView? {
print(scrollView.zoomScale)
return previewImageView
}
}

Answer 1

UIScrollView has a property zoomScale that tells you how much you are currently zoomed in. You'll need to use that to adjust your scale property.