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 t

Answer 1

You can also, very simply, put the concerned ImageView in "Aspect Fill" mode from the Storyboard, and add this in the code :

imageView.layer.masksToBounds = true
imageView.clipsToBounds = true

Answer 2

I came up with a code that will give a desired cropped aspect ratio, regardless of original video frame size (adapted from @Cole's answer):

func cropImage(uncroppedImage: UIImage, cropWidth: CGFloat, cropHeight: CGFloat) -> UIImage {

        let contextImage: UIImage = UIImage(cgImage: uncroppedImage.cgImage!)

        let contextSize: CGSize = contextImage.size
        var cropX: CGFloat = 0.0
        var cropY: CGFloat = 0.0
        var cropRatio: CGFloat = CGFloat(cropWidth/cropHeight)
        var originalRatio: CGFloat = contextSize.width/contextSize.height
        var scaledCropHeight: CGFloat = 0.0
        var scaledCropWidth: CGFloat = 0.0

        // See what size is longer and set crop rect parameters
        if originalRatio > cropRatio {

            scaledCropHeight = contextSize.height
            scaledCropWidth = (contextSize.height/cropHeight) * cropWidth
            cropX = (contextSize.width - scaledCropWidth) / 2
            cropY = 0

        } else {
            scaledCropWidth = contextSize.width
            scaledCropHeight = (contextSize.width/cropWidth) * cropHeight
            cropY = (contextSize.height / scaledCropHeight) / 2
            cropX = 0
        }

        let rect: CGRect = CGRect(x: cropX, y: cropY, width: scaledCropWidth, height: scaledCropHeight)

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

        // Create a new image based on the imageRef and rotate back to the original orientation

        let croppedImage: UIImage = UIImage(cgImage: imageRef, scale: uncroppedImage.scale, orientation: uncroppedImage.imageOrientation)

        return croppedImage
    }

Hope it helps!

Answer 3

In swift 4.1 I would do simply:

imageView.clipsToBounds = true
imageView.contentMode = .scaleAspectFill
imageView.layer.cornerRadius = 20

Credits to Stretching, Redrawing and Positioning with contentMode

Answer 4

you can also use Alamofire and AlamofireImage to crop your image.

https://github.com/Alamofire/AlamofireImage

Installing using CocoaPods pod 'AlamofireImage'

Usage:

let image = UIImage(named: "unicorn")!
let size = CGSize(width: 100.0, height: 100.0)
// Scale image to size disregarding aspect ratio
let scaledImage = image.af_imageScaled(to: size)
let aspectScaledToFitImage = image.af_imageAspectScaled(toFit: size)

// Scale image to fill specified size while maintaining aspect ratio
let aspectScaledToFillImage = image.af_imageAspectScaled(toFill: size)

Answer 5

Accepted answer did not work for me, so I tried wrote my own. Here is an effect of my work:

import UIKit

extension UIImage {

    func cropedToRatio(ratio: CGFloat) -> UIImage? {
        let newImageWidth = size.height * ratio

        let cropRect = CGRect(x: ((size.width - newImageWidth) / 2.0) * scale,
                              y: 0.0,
                              width: newImageWidth * scale,
                              height: size.height * scale)

        guard let cgImage = cgImage else {
            return nil
        }
        guard let newCgImage = cgImage.cropping(to: cropRect) else {
            return nil
        }

        return UIImage(cgImage: newCgImage, scale: scale, orientation: imageOrientation)
    }
}

This function crop image to given ratio. It keeps image scale. Cropped image is always center of original image.

Answer 6

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
    }