Comment redimensionner une image dans Swift?
Je crée une application pour iOS avec Swift et Parse.com.
J'essaie de laisser l'utilisateur sélectionner une image à partir d'un sélecteur d'images, puis redimensionner l'image sélectionnée à 200x200 pixels avant de la télécharger sur mon backend.
Parse.com propose un tutoriel pour une application de copie Instagram appelée "AnyPic" qui donne ce code pour le redimensionnement des images, mais il se trouve en Objective-C ....
// Resize the image to be square (what is shown in the preview)
UIImage *resizedImage = [anImage resizedImageWithContentMode:UIViewContentModeScaleAspectFit
bounds:CGSizeMake(560.0f, 560.0f)
interpolationQuality:kCGInterpolationHigh];
// Create a thumbnail and add a corner radius for use in table views
UIImage *thumbnailImage = [anImage thumbnailImage:86.0f
transparentBorder:0.0f
cornerRadius:10.0f
interpolationQuality:kCGInterpolationDefault];
Comment créer une version 200x200px de la photo sélectionnée (à télécharger ensuite dans Swift?)
Et que fait la fonction thumbnailImage?
Voir mon article de blog, Redimensionner l'image dans Swift et l'objectif C , pour plus de détails.
Fonction de redimensionnement de l'image dans Swift comme ci-dessous.
func resizeImage(image: UIImage, targetSize: CGSize) -> UIImage {
let size = image.size
let widthRatio = targetSize.width / size.width
let heightRatio = targetSize.height / size.height
// Figure out what our orientation is, and use that to form the rectangle
var newSize: CGSize
if(widthRatio > heightRatio) {
newSize = CGSizeMake(size.width * heightRatio, size.height * heightRatio)
} else {
newSize = CGSizeMake(size.width * widthRatio, size.height * widthRatio)
}
// This is the rect that we've calculated out and this is what is actually used below
let rect = CGRectMake(0, 0, newSize.width, newSize.height)
// Actually do the resizing to the rect using the ImageContext stuff
UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
image.drawInRect(rect)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage
}
Utilisez la fonction ci-dessus et redimensionnez l'image avec 200 * 200 comme ci-dessous
self.resizeImage(UIImage(named: "yourImageName")!, targetSize: CGSizeMake(200.0, 200.0))
Swift3 mis à jour
func resizeImage(image: UIImage, targetSize: CGSize) -> UIImage {
let size = image.size
let widthRatio = targetSize.width / size.width
let heightRatio = targetSize.height / size.height
// Figure out what our orientation is, and use that to form the rectangle
var newSize: CGSize
if(widthRatio > heightRatio) {
newSize = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
} else {
newSize = CGSize(width: size.width * widthRatio, height: size.height * widthRatio)
}
// This is the rect that we've calculated out and this is what is actually used below
let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)
// Actually do the resizing to the rect using the ImageContext stuff
UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
image.draw(in: rect)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}
Puisque la réponse de @KiritModi date de 2015, voici la version de Swift 3.0:
func resizeImage(image: UIImage, targetSize: CGSize) -> UIImage {
let size = image.size
let widthRatio = targetSize.width / image.size.width
let heightRatio = targetSize.height / image.size.height
// Figure out what our orientation is, and use that to form the rectangle
var newSize: CGSize
if(widthRatio > heightRatio) {
newSize = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
} else {
newSize = CGSize(width: size.width * widthRatio, height: size.height * widthRatio)
}
// This is the rect that we've calculated out and this is what is actually used below
let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)
// Actually do the resizing to the rect using the ImageContext stuff
UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
image.draw(in: rect)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}
Pour Swift 4.0 et iOS 10
extension UIImage {
func resizeImage(_ dimension: CGFloat, opaque: Bool, contentMode: UIViewContentMode = .scaleAspectFit) -> UIImage {
var width: CGFloat
var height: CGFloat
var newImage: UIImage
let size = self.size
let aspectRatio = size.width/size.height
switch contentMode {
case .scaleAspectFit:
if aspectRatio > 1 { // Landscape image
width = dimension
height = dimension / aspectRatio
} else { // Portrait image
height = dimension
width = dimension * aspectRatio
}
default:
fatalError("UIIMage.resizeToFit(): FATAL: Unimplemented ContentMode")
}
if #available(iOS 10.0, *) {
let renderFormat = UIGraphicsImageRendererFormat.default()
renderFormat.opaque = opaque
let renderer = UIGraphicsImageRenderer(size: CGSize(width: width, height: height), format: renderFormat)
newImage = renderer.image {
(context) in
self.draw(in: CGRect(x: 0, y: 0, width: width, height: height))
}
} else {
UIGraphicsBeginImageContextWithOptions(CGSize(width: width, height: height), opaque, 0)
self.draw(in: CGRect(x: 0, y: 0, width: width, height: height))
newImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
}
return newImage
}
}
Il est également possible d'utiliser AlamofireImage ( https://github.com/Alamofire/AlamofireImage )
let size = CGSize(width: 30.0, height: 30.0)
let aspectScaledToFitImage = image.af_imageAspectScaled(toFit: size)
La fonction dans le post précédent m'a donné un résultat flou.
Pour Swift 4, je voudrais juste faire une extension sur UIImage avec un référencement à soi.
import UIKit
extension UIImage {
func resizeImage(targetSize: CGSize) -> UIImage {
let size = self.size
let widthRatio = targetSize.width / size.width
let heightRatio = targetSize.height / size.height
let newSize = widthRatio > heightRatio ? CGSize(width: size.width * heightRatio, height: size.height * heightRatio) : CGSize(width: size.width * widthRatio, height: size.height * widthRatio)
let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)
UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
self.draw(in: rect)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}
}
style Swift 3 et style d'extension
Cette réponse provient de @Kirit Modi.
extension UIImage {
func resizeImage(targetSize: CGSize) -> UIImage {
let size = self.size
let widthRatio = targetSize.width / size.width
let heightRatio = targetSize.height / size.height
// Figure out what our orientation is, and use that to form the rectangle
var newSize: CGSize
if(widthRatio > heightRatio) {
newSize = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
} else {
newSize = CGSize(width: size.width * widthRatio, height: size.height * widthRatio)
}
// This is the rect that we've calculated out and this is what is actually used below
let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)
// Actually do the resizing to the rect using the ImageContext stuff
UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
self.draw(in: rect)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}
}
Version Swift 4
extension UIImage {
func resizeImage(_ newSize: CGSize) -> UIImage? {
func isSameSize(_ newSize: CGSize) -> Bool {
return size == newSize
}
func scaleImage(_ newSize: CGSize) -> UIImage? {
func getScaledRect(_ newSize: CGSize) -> CGRect {
let ratio = max(newSize.width / size.width, newSize.height / size.height)
let width = size.width * ratio
let height = size.height * ratio
return CGRect(x: 0, y: 0, width: width, height: height)
}
func _scaleImage(_ scaledRect: CGRect) -> UIImage? {
UIGraphicsBeginImageContextWithOptions(scaledRect.size, false, 0.0);
draw(in: scaledRect)
let image = UIGraphicsGetImageFromCurrentImageContext() ?? UIImage()
UIGraphicsEndImageContext()
return image
}
return _scaleImage(getScaledRect(newSize))
}
return isSameSize(newSize) ? self : scaleImage(newSize)!
}
}
Swift 4, version d'extension, PAS DE LIGNE BLANCHE SUR LES BORDS.
Personne ne semble mentionner que si image.draw() est appelée avec des valeurs non entières, l'image résultante peut afficher un artefact de ligne blanche sur le bord droit ou inférieur.
extension UIImage {
func scaled(with scale: CGFloat) -> UIImage? {
// size has to be integer, otherwise it could get white lines
let size = CGSize(width: floor(self.size.width * scale), height: floor(self.size.height * scale))
UIGraphicsBeginImageContext(size)
draw(in: CGRect(x: 0, y: 0, width: size.width, height: size.height))
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image
}
Swift 4.2 version de @KiritModi answer
func resizeImage(image: UIImage, targetSize: CGSize) -> UIImage {
let size = image.size
let widthRatio = targetSize.width / size.width
let heightRatio = targetSize.height / size.height
var newSize: CGSize
if(widthRatio > heightRatio) {
newSize = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
} else {
newSize = CGSize(width: size.width * widthRatio, height: size.height * widthRatio)
}
let rect = CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height)
UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
image.draw(in: rect)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}
Détails
- Xcode 10.2.1 (10E1001), Swift 5
Liens
- https://Gist.github.com/eugenebokhan/5e62a0155754ae6aa6c3c13cf17449
- Techniques de redimensionnement de l'image
Solution
import UIKit
import CoreGraphics
import Accelerate
extension UIImage {
public enum ResizeFramework {
case uikit, coreImage, coreGraphics, imageIO, accelerate
}
/// Resize image with ScaleAspectFit mode and given size.
///
/// - Parameter dimension: width or length of the image output.
/// - Parameter resizeFramework: Technique for image resizing: UIKit / CoreImage / CoreGraphics / ImageIO / Accelerate.
/// - Returns: Resized image.
func resizeWithScaleAspectFitMode(to dimension: CGFloat, resizeFramework: ResizeFramework = .coreGraphics) -> UIImage? {
if max(size.width, size.height) <= dimension { return self }
var newSize: CGSize!
let aspectRatio = size.width/size.height
if aspectRatio > 1 {
// Landscape image
newSize = CGSize(width: dimension, height: dimension / aspectRatio)
} else {
// Portrait image
newSize = CGSize(width: dimension * aspectRatio, height: dimension)
}
return resize(to: newSize, with: resizeFramework)
}
/// Resize image from given size.
///
/// - Parameter newSize: Size of the image output.
/// - Parameter resizeFramework: Technique for image resizing: UIKit / CoreImage / CoreGraphics / ImageIO / Accelerate.
/// - Returns: Resized image.
public func resize(to newSize: CGSize, with resizeFramework: ResizeFramework = .coreGraphics) -> UIImage? {
switch resizeFramework {
case .uikit: return resizeWithUIKit(to: newSize)
case .coreGraphics: return resizeWithCoreGraphics(to: newSize)
case .coreImage: return resizeWithCoreImage(to: newSize)
case .imageIO: return resizeWithImageIO(to: newSize)
case .accelerate: return resizeWithAccelerate(to: newSize)
}
}
// MARK: - UIKit
/// Resize image from given size.
///
/// - Parameter newSize: Size of the image output.
/// - Returns: Resized image.
private func resizeWithUIKit(to newSize: CGSize) -> UIImage? {
UIGraphicsBeginImageContextWithOptions(newSize, true, 1.0)
self.draw(in: CGRect(Origin: .zero, size: newSize))
defer { UIGraphicsEndImageContext() }
return UIGraphicsGetImageFromCurrentImageContext()
}
// MARK: - CoreImage
/// Resize CI image from given size.
///
/// - Parameter newSize: Size of the image output.
/// - Returns: Resized image.
// https://developer.Apple.com/library/archive/documentation/GraphicsImaging/Reference/CoreImageFilterReference/index.html
private func resizeWithCoreImage(to newSize: CGSize) -> UIImage? {
guard let cgImage = cgImage, let filter = CIFilter(name: "CILanczosScaleTransform") else { return nil }
let ciImage = CIImage(cgImage: cgImage)
let scale = (Double)(newSize.width) / (Double)(ciImage.extent.size.width)
filter.setValue(ciImage, forKey: kCIInputImageKey)
filter.setValue(NSNumber(value:scale), forKey: kCIInputScaleKey)
filter.setValue(1.0, forKey: kCIInputAspectRatioKey)
guard let outputImage = filter.value(forKey: kCIOutputImageKey) as? CIImage else { return nil }
let context = CIContext(options: [.useSoftwareRenderer: false])
guard let resultCGImage = context.createCGImage(outputImage, from: outputImage.extent) else { return nil }
return UIImage(cgImage: resultCGImage)
}
// MARK: - CoreGraphics
/// Resize image from given size.
///
/// - Parameter newSize: Size of the image output.
/// - Returns: Resized image.
private func resizeWithCoreGraphics(to newSize: CGSize) -> UIImage? {
guard let cgImage = cgImage, let colorSpace = cgImage.colorSpace else { return nil }
let width = Int(newSize.width)
let height = Int(newSize.height)
let bitsPerComponent = cgImage.bitsPerComponent
let bytesPerRow = cgImage.bytesPerRow
let bitmapInfo = cgImage.bitmapInfo
guard let context = CGContext(data: nil, width: width, height: height,
bitsPerComponent: bitsPerComponent,
bytesPerRow: bytesPerRow, space: colorSpace,
bitmapInfo: bitmapInfo.rawValue) else { return nil }
context.interpolationQuality = .high
let rect = CGRect(Origin: CGPoint.zero, size: newSize)
context.draw(cgImage, in: rect)
return context.makeImage().flatMap { UIImage(cgImage: $0) }
}
// MARK: - ImageIO
/// Resize image from given size.
///
/// - Parameter newSize: Size of the image output.
/// - Returns: Resized image.
private func resizeWithImageIO(to newSize: CGSize) -> UIImage? {
var resultImage = self
guard let data = jpegData(compressionQuality: 1.0) else { return resultImage }
let imageCFData = NSData(data: data) as CFData
let options = [
kCGImageSourceCreateThumbnailWithTransform: true,
kCGImageSourceCreateThumbnailFromImageAlways: true,
kCGImageSourceThumbnailMaxPixelSize: max(newSize.width, newSize.height)
] as CFDictionary
guard let source = CGImageSourceCreateWithData(imageCFData, nil),
let imageReference = CGImageSourceCreateThumbnailAtIndex(source, 0, options) else { return resultImage }
resultImage = UIImage(cgImage: imageReference)
return resultImage
}
// MARK: - Accelerate
/// Resize image from given size.
///
/// - Parameter newSize: Size of the image output.
/// - Returns: Resized image.
private func resizeWithAccelerate(to newSize: CGSize) -> UIImage? {
var resultImage = self
guard let cgImage = cgImage, let colorSpace = cgImage.colorSpace else { return nil }
// create a source buffer
var format = vImage_CGImageFormat(bitsPerComponent: numericCast(cgImage.bitsPerComponent),
bitsPerPixel: numericCast(cgImage.bitsPerPixel),
colorSpace: Unmanaged.passUnretained(colorSpace),
bitmapInfo: cgImage.bitmapInfo,
version: 0,
decode: nil,
renderingIntent: .absoluteColorimetric)
var sourceBuffer = vImage_Buffer()
defer {
sourceBuffer.data.deallocate()
}
var error = vImageBuffer_InitWithCGImage(&sourceBuffer, &format, nil, cgImage, numericCast(kvImageNoFlags))
guard error == kvImageNoError else { return resultImage }
// create a destination buffer
let destWidth = Int(newSize.width)
let destHeight = Int(newSize.height)
let bytesPerPixel = cgImage.bitsPerPixel
let destBytesPerRow = destWidth * bytesPerPixel
let destData = UnsafeMutablePointer<UInt8>.allocate(capacity: destHeight * destBytesPerRow)
defer {
destData.deallocate()
}
var destBuffer = vImage_Buffer(data: destData, height: vImagePixelCount(destHeight), width: vImagePixelCount(destWidth), rowBytes: destBytesPerRow)
// scale the image
error = vImageScale_ARGB8888(&sourceBuffer, &destBuffer, nil, numericCast(kvImageHighQualityResampling))
guard error == kvImageNoError else { return resultImage }
// create a CGImage from vImage_Buffer
let destCGImage = vImageCreateCGImageFromBuffer(&destBuffer, &format, nil, nil, numericCast(kvImageNoFlags), &error)?.takeRetainedValue()
guard error == kvImageNoError else { return resultImage }
// create a UIImage
if let scaledImage = destCGImage.flatMap({ UIImage(cgImage: $0) }) {
resultImage = scaledImage
}
return resultImage
}
}
Usage
Obtenir la taille de l'image
import UIKit
// https://stackoverflow.com/a/55765409/4488252
extension UIImage {
func getFileSizeInfo(allowedUnits: ByteCountFormatter.Units = .useMB,
countStyle: ByteCountFormatter.CountStyle = .memory,
compressionQuality: CGFloat = 1.0) -> String? {
// https://developer.Apple.com/documentation/foundation/bytecountformatter
let formatter = ByteCountFormatter()
formatter.allowedUnits = allowedUnits
formatter.countStyle = countStyle
return getSizeInfo(formatter: formatter, compressionQuality: compressionQuality)
}
func getSizeInfo(formatter: ByteCountFormatter, compressionQuality: CGFloat = 1.0) -> String? {
guard let imageData = jpegData(compressionQuality: compressionQuality) else { return nil }
return formatter.string(fromByteCount: Int64(imageData.count))
}
}
Fonction de test
private func test() {
guard let img = UIImage(named: "img") else { return }
printInfo(of: img, title: "original image |")
let dimension: CGFloat = 2000
var framework: UIImage.ResizeFramework = .accelerate
var startTime = Date()
if let img = img.resizeWithScaleAspectFitMode(to: dimension, resizeFramework: framework) {
printInfo(of: img, title: "resized image |", with: framework, startedTime: startTime)
}
framework = .coreGraphics
startTime = Date()
if let img = img.resizeWithScaleAspectFitMode(to: dimension, resizeFramework: framework) {
printInfo(of: img, title: "resized image |", with: framework, startedTime: startTime)
}
framework = .coreImage
startTime = Date()
if let img = img.resizeWithScaleAspectFitMode(to: dimension, resizeFramework: framework) {
printInfo(of: img, title: "resized image |", with: framework, startedTime: startTime)
}
framework = .imageIO
startTime = Date()
if let img = img.resizeWithScaleAspectFitMode(to: dimension, resizeFramework: framework) {
printInfo(of: img, title: "resized image |", with: framework, startedTime: startTime)
}
framework = .uikit
startTime = Date()
if let img = img.resizeWithScaleAspectFitMode(to: dimension, resizeFramework: framework) {
printInfo(of: img, title: "resized image |", with: framework, startedTime: startTime)
}
}
private func printInfo(of image: UIImage, title: String, with resizeFramework: UIImage.ResizeFramework? = nil, startedTime: Date? = nil) {
var description = "\(title) \(image.size)"
if let startedTime = startedTime { description += ", execution time: \(Date().timeIntervalSince(startedTime))" }
if let fileSize = image.getFileSizeInfo(compressionQuality: 0.9) { description += ", size: \(fileSize)" }
if let resizeFramework = resizeFramework { description += ", framework: \(resizeFramework)" }
print(description)
}
Sortie
original image | (5790.0, 8687.0), size: 17.1 MB
resized image | (1333.0, 2000.0), execution time: 0.8192930221557617, size: 1.1 MB, framework: accelerate
resized image | (1333.0, 2000.0), execution time: 0.44696998596191406, size: 1 MB, framework: coreGraphics
resized image | (1334.0, 2000.0), execution time: 54.172922015190125, size: 1.1 MB, framework: coreImage
resized image | (1333.0, 2000.0), execution time: 1.8765920400619507, size: 1.1 MB, framework: imageIO
resized image | (1334.0, 2000.0), execution time: 0.4638739824295044, size: 1 MB, framework: uikit
Swift 4 Solution-
tilisez cette fonction
func image(with image: UIImage, scaledTo newSize: CGSize) -> UIImage {
UIGraphicsBeginImageContextWithOptions(newSize, false, 1.0)
image.draw(in: CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height))
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
drawingImageView.image = newImage
return newImage ?? UIImage()
}
appelant une fonction: -
image(with: predictionImage, scaledTo: CGSize(width: 28.0, height: 28.0)
ici 28.0 est la taille de pixel que vous souhaitez définir
appel de la méthode resizeimage
let image1 = resizeimage(image: myimage.image!, withSize: CGSize(width:200, height: 200))
méthode pour redimensionner l'image
func resizeimage(image:UIImage,withSize:CGSize) -> UIImage {
var actualHeight:CGFloat = image.size.height
var actualWidth:CGFloat = image.size.width
let maxHeight:CGFloat = withSize.height
let maxWidth:CGFloat = withSize.width
var imgRatio:CGFloat = actualWidth/actualHeight
let maxRatio:CGFloat = maxWidth/maxHeight
let compressionQuality = 0.5
if (actualHeight>maxHeight||actualWidth>maxWidth) {
if (imgRatio<maxRatio){
//adjust width according to maxHeight
imgRatio = maxHeight/actualHeight
actualWidth = imgRatio * actualWidth
actualHeight = maxHeight
}else if(imgRatio>maxRatio){
// adjust height according to maxWidth
imgRatio = maxWidth/actualWidth
actualHeight = imgRatio * actualHeight
actualWidth = maxWidth
}else{
actualHeight = maxHeight
actualWidth = maxWidth
}
}
let rec:CGRect = CGRect(x:0.0,y:0.0,width:actualWidth,height:actualHeight)
UIGraphicsBeginImageContext(rec.size)
image.draw(in: rec)
let image:UIImage = UIGraphicsGetImageFromCurrentImageContext()!
let imageData = UIImageJPEGRepresentation(image, CGFloat(compressionQuality))
UIGraphicsEndImageContext()
let resizedimage = UIImage(data: imageData!)
return resizedimage!
}
Ici vous avez deux fonctions simples de l'extension UIImage:
func scaledWithMaxWidthOrHeightValue(value: CGFloat) -> UIImage? {
let width = self.size.width
let height = self.size.height
let ratio = width/height
var newWidth = value
var newHeight = value
if ratio > 1 {
newWidth = width * (newHeight/height)
} else {
newHeight = height * (newWidth/width)
}
UIGraphicsBeginImageContextWithOptions(CGSize(width: newWidth, height: newHeight), false, 0)
draw(in: CGRect(x: 0, y: 0, width: newWidth, height: newHeight))
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image
}
func scaled(withScale scale: CGFloat) -> UIImage? {
let size = CGSize(width: self.size.width * scale, height: self.size.height * scale)
UIGraphicsBeginImageContextWithOptions(size, false, 0)
draw(in: CGRect(x: 0, y: 0, width: size.width, height: size.height))
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return image
}
Vous pouvez l’utiliser pour une image en forme sur Swift;
extension UIImage {
func resizedImage(newSize: CGSize) -> UIImage {
// Guard newSize is different
guard self.size != newSize else { return self }
UIGraphicsBeginImageContextWithOptions(newSize, false, 0.0);
self.draw(in: CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height))
let newImage: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
UIGraphicsEndImageContext()
return newImage
}
func resizedImageWithinRect(rectSize: CGSize) -> UIImage {
let widthFactor = size.width / rectSize.width
let heightFactor = size.height / rectSize.height
var resizeFactor = widthFactor
if size.height > size.width {
resizeFactor = heightFactor
}
let newSize = CGSize(width: size.width/resizeFactor, height: size.height/resizeFactor)
let resized = resizedImage(newSize: newSize)
return resized
}
}
Usage;
let resizedImage = image.resizedImageWithinRect(rectSize: CGSize(width: 1900, height: 1900))
Voici une méthode générale (en Swift 5) pour la réduction de la taille d'une image en fonction de sa taille. L'image résultante peut avoir le même rapport d'aspect que l'original ou la taille de la cible avec l'image originale centrée. Si l'image est plus petite que la taille cible, elle n'est pas redimensionnée.
extension UIImage {
func scaledDown(into size:CGSize, centered:Bool = false) -> UIImage {
var (targetWidth, targetHeight) = (self.size.width, self.size.height)
var (scaleW, scaleH) = (1 as CGFloat, 1 as CGFloat)
if targetWidth > size.width {
scaleW = size.width/targetWidth
}
if targetHeight > size.height {
scaleH = size.height/targetHeight
}
let scale = min(scaleW,scaleH)
targetWidth *= scale; targetHeight *= scale
let sz = CGSize(width:targetWidth, height:targetHeight)
if !centered {
return UIGraphicsImageRenderer(size:sz).image { _ in
self.draw(in:CGRect(Origin:.zero, size:sz))
}
}
let x = (size.width - targetWidth)/2
let y = (size.height - targetHeight)/2
let Origin = CGPoint(x:x,y:y)
return UIGraphicsImageRenderer(size:size).image { _ in
self.draw(in:CGRect(Origin:origin, size:sz))
}
}
}
Exemple: réduire l’image à 1024 et moins
func resizeImage (image: UIImage) -> UIImage {
if image.size.height >= 1024 && image.size.width >= 1024 {
UIGraphicsBeginImageContext(CGSize(width:1024, height:1024))
image.draw(in: CGRect(x:0, y:0, width:1024, height:1024))
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}
else if image.size.height >= 1024 && image.size.width < 1024
{
UIGraphicsBeginImageContext(CGSize(width:image.size.width, height:1024))
image.draw(in: CGRect(x:0, y:0, width:image.size.width, height:1024))
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}
else if image.size.width >= 1024 && image.size.height < 1024
{
UIGraphicsBeginImageContext(CGSize(width:1024, height:image.size.height))
image.draw(in: CGRect(x:0, y:0, width:1024, height:image.size.height))
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}
else
{
return image
}
}