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jeffaburt/ImageScaling.swift

Last active October 10, 2017 01:12
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Revisions

  1. jeffaburt revised this gist Oct 10, 2017. 1 changed file with 3 additions and 1 deletion.
    4 changes: 3 additions & 1 deletion ImageScaling.swift
    View file
    Original file line number Diff line number Diff line change
    @@ -1,3 +1,5 @@
    import UIKit

    extension UIImage {
    /**
    Returns a new UIImage instance by applying the new size.
    @@ -53,7 +55,7 @@ extension UIImage {
    UIGraphicsEndImageContext()

    if newImage == nil {
    DDLogWarn("Could not scale image to size: \(targetSize.debugDescription)")
    print("Could not scale image to size: \(targetSize.debugDescription)")
    }

    return newImage!
  2. jeffaburt created this gist Oct 10, 2017.
    61 changes: 61 additions & 0 deletions ImageScaling.swift
    View file
    Original file line number Diff line number Diff line change
    @@ -0,0 +1,61 @@
    extension UIImage {
    /**
    Returns a new UIImage instance by applying the new size.

    - discussion: http://stackoverflow.com/a/2025413/1926015

    - parameter targetSize: the new size

    - returns: a UIImage with the new size
    */
    func imageByScalingProportionallyToSize(_ targetSize: CGSize) -> UIImage {
    let sourceImage = self
    var newImage: UIImage?
    let imageSize = sourceImage.size
    let width = imageSize.width
    let height = imageSize.height
    let targetWidth = targetSize.width
    let targetHeight = targetSize.height
    var scaleFactor = CGFloat(0)
    var scaledWidth = targetWidth
    var scaledHeight = targetHeight
    var thumbnailPoint = CGPoint(x: 0.0, y: 0.0)

    if !imageSize.equalTo(targetSize) {
    let widthFactor = targetWidth / width
    let heightFactor = targetHeight / height
    if widthFactor < heightFactor {
    scaleFactor = widthFactor
    }
    else {
    scaleFactor = heightFactor
    }
    scaledWidth = width * scaleFactor
    scaledHeight = height * scaleFactor

    // center the image
    if widthFactor < heightFactor {
    thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5
    }
    else if widthFactor > heightFactor {
    thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5
    }
    }

    // this is actually the interesting part:
    UIGraphicsBeginImageContextWithOptions(targetSize, false, 0)
    var thumbnailRect: CGRect = .zero
    thumbnailRect.origin = thumbnailPoint
    thumbnailRect.size.width = scaledWidth
    thumbnailRect.size.height = scaledHeight
    sourceImage.draw(in: thumbnailRect)
    newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    if newImage == nil {
    DDLogWarn("Could not scale image to size: \(targetSize.debugDescription)")
    }

    return newImage!
    }
    }