swift image resize
iOS Swift: Resize image to 200x200pt/px – Stack Overflow
iphone – The simplest way to resize an UIImage? – Stack Overflow
iPhone & iPad Application Development Help World: Image Resize in swift ios8
Snip2Code – Resize Image in iOS Swift
代码：
//: Playground – noun: a place where people can play import UIKit extension UIImage { func resize(newSize:CGSize) -> UIImage { // here both true and false seems both work to resize // let hasAlpha = false let hasAlpha = true let scale:CGFloat = 0.0 //system will auto get the real factor UIGraphicsBeginImageContextWithOptions(newSize, !hasAlpha, scale) self.drawInRect(CGRect(origin: CGPointZero, size: newSize)) let resizedImage:UIImage = UIGraphicsGetImageFromCurrentImageContext() UIGraphicsEndImageContext() return resizedImage } func resizeToWidth(newWidth:CGFloat) -> UIImage { let scale = newWidth / self.size.width print("scale=\(scale)") let newHeight = self.size.height * scale print("newHeight=\(newHeight)") let newSize = CGSize(width: newWidth, height: newHeight) return self.resize(newSize) } func resizeToHeight(newHeight:CGFloat) -> UIImage { let scale = newHeight / self.size.width print("scale=\(scale)") let newWidth = self.size.height * scale print("newWidth=\(newWidth)") let newSize = CGSize(width: newWidth, height: newHeight) return self.resize(newSize) } } let originImage = [#Image(imageLiteral: "mergedGroupHeaderImage_82x82.png")#] let resized41 = originImage.resize(CGSize(width: 41, height: 41)) let resized30 = originImage.resizeToWidth(30) let resized50 = originImage.resizeToHeight(60) |
效果：
另外，附上之前的代码，共是：
extension UIImage { // func resize(scale:CGFloat)-> UIImage { // let imageView = UIImageView(frame: CGRect(origin: CGPoint(x: 0, y: 0), size: CGSize(width: size.width*scale, height: size.height*scale))) // imageView.contentMode = UIViewContentMode.ScaleAspectFit // imageView.image = self // UIGraphicsBeginImageContext(imageView.bounds.size) // imageView.layer.renderInContext(UIGraphicsGetCurrentContext()!) // let result = UIGraphicsGetImageFromCurrentImageContext() // UIGraphicsEndImageContext() // return result // } // func resizeToWidth(width:CGFloat)-> UIImage { // let imageView = UIImageView(frame: CGRect(origin: CGPoint(x: 0, y: 0), size: CGSize(width: width, height: CGFloat(ceil(width/size.width * size.height))))) // imageView.contentMode = UIViewContentMode.ScaleAspectFit // imageView.image = self // UIGraphicsBeginImageContext(imageView.bounds.size) // imageView.layer.renderInContext(UIGraphicsGetCurrentContext()!) // let result = UIGraphicsGetImageFromCurrentImageContext() // UIGraphicsEndImageContext() // return result // } func resize(newSize:CGSize) -> UIImage { // here both true and false seems both work to resize // let hasAlpha = false let hasAlpha = true let scale:CGFloat = 0.0 //system will auto get the real factor UIGraphicsBeginImageContextWithOptions(newSize, !hasAlpha, scale) self.drawInRect(CGRect(origin: CGPointZero, size: newSize)) let resizedImage:UIImage = UIGraphicsGetImageFromCurrentImageContext() UIGraphicsEndImageContext() return resizedImage } func resizeToWidth(newWidth:CGFloat) -> UIImage { let scale = newWidth / self.size.width print("scale=\(scale)") let newHeight = self.size.height * scale print("newHeight=\(newHeight)") let newSize = CGSize(width: newWidth, height: newHeight) return self.resize(newSize) } func resizeToHeight(newHeight:CGFloat) -> UIImage { let scale = newHeight / self.size.width print("scale=\(scale)") let newWidth = self.size.height * scale print("newWidth=\(newWidth)") let newSize = CGSize(width: newWidth, height: newHeight) return self.resize(newSize) } } |
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