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Scale a UIImage to any given rect keeping the aspect ratio
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| @implementation UIImage (scale) | |
| /** | |
| * Scales an image to fit within a bounds with a size governed by | |
| * the passed size. Also keeps the aspect ratio. | |
| * | |
| * Switch MIN to MAX for aspect fill instead of fit. | |
| * | |
| * @param newSize the size of the bounds the image must fit within. | |
| * @return a new scaled image. | |
| */ | |
| - (UIImage *)scaleImageToSize:(CGSize)newSize { | |
| CGRect scaledImageRect = CGRectZero; | |
| CGFloat aspectWidth = newSize.width / self.size.width; | |
| CGFloat aspectHeight = newSize.height / self.size.height; | |
| CGFloat aspectRatio = MIN ( aspectWidth, aspectHeight ); | |
| scaledImageRect.size.width = self.size.width * aspectRatio; | |
| scaledImageRect.size.height = self.size.height * aspectRatio; | |
| scaledImageRect.origin.x = (newSize.width - scaledImageRect.size.width) / 2.0f; | |
| scaledImageRect.origin.y = (newSize.height - scaledImageRect.size.height) / 2.0f; | |
| UIGraphicsBeginImageContextWithOptions( newSize, NO, 0 ); | |
| [self drawInRect:scaledImageRect]; | |
| UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext(); | |
| UIGraphicsEndImageContext(); | |
| return scaledImage; | |
| } | |
| @end |
Swift 4
extension UIImage {
func scale(with size: CGSize) -> UIImage? {
var scaledImageRect = CGRect.zero
let aspectWidth:CGFloat = size.width / self.size.width
let aspectHeight:CGFloat = size.height / self.size.height
let aspectRatio:CGFloat = min(aspectWidth, aspectHeight)
scaledImageRect.size.width = self.size.width * aspectRatio
scaledImageRect.size.height = self.size.height * aspectRatio
scaledImageRect.origin.x = (size.width - scaledImageRect.size.width) / 2.0
scaledImageRect.origin.y = (size.height - scaledImageRect.size.height) / 2.0
UIGraphicsBeginImageContextWithOptions(size, false, 0)
self.draw(in: scaledImageRect)
let scaledImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return scaledImage
}
}
@shinrikiken - your code is not giving me the perfect image which should fits to the image size.
@lee-ho, perhaps you can replace this line
UIGraphicsBeginImageContext(newSize)
with this
UIGraphicsBeginImageContextWithOptions(newSize, false, UIScreen.main.scale)
and try?
Does anyone have the version of this to work in NSImage (for MacOS)?
Swift 5 (Mac Os)
This working for me but I'm sure if is the best approach
extension NSImage {
/// 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: ScalingMode = .aspectFill) -> NSImage {
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
let scaledImage = NSImage(size: newSize)
scaledImage.lockFocus()
draw(in: scaledImageRect)
scaledImage.unlockFocus()
return scaledImage
}
}
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Thank you for your work, guys!
@akshaynhegde, @Oyvindkg, the method returns a blurry version of the original image, it is scaled, but blurry. Any idea how to fix it?