[英]UIImage resizing scale
我有這樣的圖像:
我想將此圖像調整為特定寬度:假設 200px也應該計算高度。 (因此圖像應保持其寬高比例)
這是我到目前為止所得到的:
extension UIImage {
func resize(newSize1: CGSize) -> UIImage {
let size = self.size
let widthRatio = newSize1.width / size.width
let heightRatio = newSize1.height / size.height
var newSize2: CGSize
if(widthRatio > heightRatio) {
newSize2 = CGSize(width: size.width * heightRatio, height: size.height * heightRatio)
} else {
newSize2 = CGSize(width: size.width * widthRatio, height: size.height * widthRatio)
}
let rect = CGRect(x: 0, y: 0, width: newSize2.width, height: newSize2.height)
UIGraphicsBeginImageContextWithOptions(newSize2, false, 1.0)
self.draw(in: rect)
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage2!
}
}
但是 function 采用CGSize
大小參數(寬度和高度),但我只想獲得采用寬度參數的 function。
如何編輯我的代碼來解決我的問題?
任何幫助將不勝感激:)
注意:UIImage 應該獲得更小的分辨率(更少像素),而不是圖像視圖本身!
您可以根據圖像的寬度和縱橫比計算所需的高度。 高度參數也可以相同。 這是UIImage
擴展的示例。
extension UIImage {
func resize(width: CGFloat) -> UIImage {
let height = (width/self.size.width)*self.size.height
return self.resize(size: CGSize(width: width, height: height))
}
func resize(height: CGFloat) -> UIImage {
let width = (height/self.size.height)*self.size.width
return self.resize(size: CGSize(width: width, height: height))
}
func resize(size: CGSize) -> UIImage {
let widthRatio = size.width/self.size.width
let heightRatio = size.height/self.size.height
var updateSize = size
if(widthRatio > heightRatio) {
updateSize = CGSize(width:self.size.width*heightRatio, height:self.size.height*heightRatio)
} else if heightRatio > widthRatio {
updateSize = CGSize(width:self.size.width*widthRatio, height:self.size.height*widthRatio)
}
UIGraphicsBeginImageContextWithOptions(updateSize, false, UIScreen.main.scale)
self.draw(in: CGRect(origin: .zero, size: updateSize))
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}
}
對於Swift 4和Swift 3,請使用以下UIImage
擴展來調整圖像大小。 它是根據給定寬度計算的高度。
extension UIImage {
func resized(toWidth width: CGFloat) -> UIImage? {
let canvasSize = CGSize(width: width, height: CGFloat(ceil(width/size.width * size.height)))
UIGraphicsBeginImageContextWithOptions(canvasSize, false, scale)
defer { UIGraphicsEndImageContext() }
draw(in: CGRect(origin: .zero, size: canvasSize))
return UIGraphicsGetImageFromCurrentImageContext()
}
}
基於@deoKasuhal 的解決方案,我開發了以下方法來縮放圖像,以便更大的尺寸(寬度或高度)不超過由參數“base”定義的定義的最大尺寸。 示例:如果原始大小為 width = 4000 和 height = 3000 並且參數“base”設置為 200,則返回的圖像大小為 200 x 150(如果高度大於寬度,反之亦然):
extension UIImage {
func resize(toBase base: CGFloat) -> UIImage {
guard base > 0 else {
return self
}
let widthRatio = base / max(self.size.width, 1)
let heightRatio = base / max(self.size.height, 1)
var updateSize = CGSize()
if (widthRatio > heightRatio) {
updateSize = CGSize(width:self.size.width * heightRatio, height:self.size.height * heightRatio)
} else {
updateSize = CGSize(width:self.size.width * widthRatio, height:self.size.height * widthRatio)
}
UIGraphicsBeginImageContextWithOptions(updateSize, false, UIScreen.main.scale)
self.draw(in: CGRect(origin: .zero, size: updateSize))
if let newImage = UIGraphicsGetImageFromCurrentImageContext() {
UIGraphicsEndImageContext()
return newImage
} else {
UIGraphicsEndImageContext()
return self
}
}
}
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