ios - Cropping image with Swift and put it on center position

Question

In Swift programming , how do you crop an image and put it on the center afterwards?

This is what I've got so far ... I've successfully crop the image but I want to put it on the center after

ImgView.image = OrigImage
var masklayer = CAShapeLayer()
masklayer.frame = ImgView.frame
masklayer.path = path.CGPath
masklayer.fillColor = UIColor.whiteColor().CGColor
masklayer.backgroundColor = UIColor.clearColor().CGColor

ImgView.layer.mask = masklayer

UIGraphicsBeginImageContext(ImgView.bounds.size);
ImgView.layer.renderInContext(UIGraphicsGetCurrentContext())
var image = UIGraphicsGetImageFromCurrentImageContext()
ImgView.image = image
UIGraphicsEndImageContext();

UPDATE :

let rect: CGRect = CGRectMake(path.bounds.minX, path.bounds.minY, path.bounds.width, path.bounds.height)

// Create bitmap image from context using the rect
let imageRef: CGImageRef = CGImageCreateWithImageInRect(image.CGImage, rect)
ImgView.bounds = rect
ImgView.image = UIImage(CGImage: imageRef)

I was able to center it by getting the path.bound and size and change the bounds of my ImageView. :)

Answer 1

To get a centered position for your crop, you can halve the difference of the height and width. Then you can assign the bounds for the new width and height after checking the orientation of the image (which part is longer)

func cropToBounds(image: UIImage, width: Double, height: Double) -> UIImage {

    let contextImage: UIImage = UIImage(CGImage: image.CGImage)!

    let contextSize: CGSize = contextImage.size

    var posX: CGFloat = 0.0
    var posY: CGFloat = 0.0
    var cgwidth: CGFloat = CGFloat(width)
    var cgheight: CGFloat = CGFloat(height)

    // See what size is longer and create the center off of that
    if contextSize.width > contextSize.height {
        posX = ((contextSize.width - contextSize.height) / 2)
        posY = 0
        cgwidth = contextSize.height
        cgheight = contextSize.height
    } else {
        posX = 0
        posY = ((contextSize.height - contextSize.width) / 2)
        cgwidth = contextSize.width
        cgheight = contextSize.width
    }

    let rect: CGRect = CGRectMake(posX, posY, cgwidth, cgheight)

    // Create bitmap image from context using the rect
    let imageRef: CGImageRef = CGImageCreateWithImageInRect(contextImage.CGImage, rect)

    // Create a new image based on the imageRef and rotate back to the original orientation
    let image: UIImage = UIImage(CGImage: imageRef, scale: image.scale, orientation: image.imageOrientation)!

    return image
}

I found most of this info over at this website in case you wanted to read further.

Updated for Swift 4

func cropToBounds(image: UIImage, width: Double, height: Double) -> UIImage {

        let cgimage = image.cgImage!
        let contextImage: UIImage = UIImage(cgImage: cgimage)
        let contextSize: CGSize = contextImage.size
        var posX: CGFloat = 0.0
        var posY: CGFloat = 0.0
        var cgwidth: CGFloat = CGFloat(width)
        var cgheight: CGFloat = CGFloat(height)

        // See what size is longer and create the center off of that
        if contextSize.width > contextSize.height {
            posX = ((contextSize.width - contextSize.height) / 2)
            posY = 0
            cgwidth = contextSize.height
            cgheight = contextSize.height
        } else {
            posX = 0
            posY = ((contextSize.height - contextSize.width) / 2)
            cgwidth = contextSize.width
            cgheight = contextSize.width
        }

        let rect: CGRect = CGRect(x: posX, y: posY, width: cgwidth, height: cgheight)

        // Create bitmap image from context using the rect
        let imageRef: CGImage = cgimage.cropping(to: rect)!

        // Create a new image based on the imageRef and rotate back to the original orientation
        let image: UIImage = UIImage(cgImage: imageRef, scale: image.scale, orientation: image.imageOrientation)

        return image
    }