Resize Image without distorting or cropping it - ios

Question

Users upload an image of any size and we need to resize it so it becomes a square without distorting or cropping the image. Basically, it should do something similar to the "Aspect Fit" content mode in an image view. So if we have a 200x100px png image, I want to make it 200x200px and have the extra 100px in the height be transparent space. It should not crop the image to 200x200.
I tried to use this image processor but it does not do what I want. https://github.com/gavinbunney/Toucan. It only crops the image.
How would I do this in swift and is there a framework that is better than the one I mentioned above to make doing this easier. Basically, I am looking for the simplest way to do this.

Answer 1

Posting this as an answer, along with example usage...
The scaling code is not mine, it's from: https://gist.github.com/tomasbasham/10533743#gistcomment-1988471
Here is code you can run in a playground to test:
import UIKit
import PlaygroundSupport
let container = UIView(frame: CGRect(x: 0, y: 0, width: 800, height: 800))
container.backgroundColor = UIColor.blue
PlaygroundPage.current.liveView = container
// MARK: - Image Scaling.
extension UIImage {
/// Represents a scaling mode
enum ScalingMode {
case aspectFill
case aspectFit
/// Calculates the aspect ratio between two sizes
///
/// - parameters:
/// - size: the first size used to calculate the ratio
/// - otherSize: the second size used to calculate the ratio
///
/// - return: the aspect ratio between the two sizes
func aspectRatio(between size: CGSize, and otherSize: CGSize) -> CGFloat {
let aspectWidth = size.width/otherSize.width
let aspectHeight = size.height/otherSize.height
switch self {
case .aspectFill:
return max(aspectWidth, aspectHeight)
case .aspectFit:
return min(aspectWidth, aspectHeight)
}
}
}
/// Scales an image to fit within a bounds with a size governed by the passed size. Also keeps the aspect ratio.
///
/// - parameter:
/// - newSize: the size of the bounds the image must fit within.
/// - scalingMode: the desired scaling mode
///
/// - returns: a new scaled image.
func scaled(to newSize: CGSize, scalingMode: UIImage.ScalingMode = .aspectFill) -> UIImage {
let aspectRatio = scalingMode.aspectRatio(between: newSize, and: size)
/* Build the rectangle representing the area to be drawn */
var scaledImageRect = CGRect.zero
scaledImageRect.size.width = size.width * aspectRatio
scaledImageRect.size.height = size.height * aspectRatio
scaledImageRect.origin.x = (newSize.width - size.width * aspectRatio) / 2.0
scaledImageRect.origin.y = (newSize.height - size.height * aspectRatio) / 2.0
/* Draw and retrieve the scaled image */
UIGraphicsBeginImageContext(newSize)
draw(in: scaledImageRect)
let scaledImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return scaledImage!
}
}
if let srcimg = UIImage(named: "flags") {
let w = srcimg.size.width
let h = srcimg.size.height
// determine whether width or height is greater
let longer = max(w, h)
// create a Square size
let sz = CGSize(width: longer, height: longer)
// call scaling function to scale the image to the Square dimensions,
// using "aspect fit"
let newImage = srcimg.scaled(to: sz, scalingMode: .aspectFit)
// create a UIImageView with the resulting image
let v = UIImageView(image: newImage)
v.backgroundColor = UIColor.white
// add it to the container view
container.addSubview(v)
}