在我的iPhone应用程序中,我用相机拍了一张照片,然后我想把它调整为290*390像素。我用这个方法来调整图像的大小:
UIImage *newImage = [image _imageScaledToSize:CGSizeMake(290, 390)
interpolationQuality:1];
它工作得很好,但它是一个没有记录的功能,所以我不能再在iPhone OS4上使用它了。
所以…调整UIImage大小最简单的方法是什么?
下面是iwasrob对上述类别的修改。它保持原始图像的纵横比,而不是扭曲它。
- (UIImage*)scaleToSizeKeepAspect:(CGSize)size {
UIGraphicsBeginImageContext(size);
CGFloat ws = size.width/self.size.width;
CGFloat hs = size.height/self.size.height;
if (ws > hs) {
ws = hs/ws;
hs = 1.0;
} else {
hs = ws/hs;
ws = 1.0;
}
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextTranslateCTM(context, 0.0, size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextDrawImage(context, CGRectMake(size.width/2-(size.width*ws)/2,
size.height/2-(size.height*hs)/2, size.width*ws,
size.height*hs), self.CGImage);
UIImage* scaledImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return scaledImage;
}
快速解决方案的拉伸填充,方面填补和方面适合
extension UIImage {
enum ContentMode {
case contentFill
case contentAspectFill
case contentAspectFit
}
func resize(withSize size: CGSize, contentMode: ContentMode = .contentAspectFill) -> UIImage? {
let aspectWidth = size.width / self.size.width
let aspectHeight = size.height / self.size.height
switch contentMode {
case .contentFill:
return resize(withSize: size)
case .contentAspectFit:
let aspectRatio = min(aspectWidth, aspectHeight)
return resize(withSize: CGSize(width: self.size.width * aspectRatio, height: self.size.height * aspectRatio))
case .contentAspectFill:
let aspectRatio = max(aspectWidth, aspectHeight)
return resize(withSize: CGSize(width: self.size.width * aspectRatio, height: self.size.height * aspectRatio))
}
}
private func resize(withSize size: CGSize) -> UIImage? {
UIGraphicsBeginImageContextWithOptions(size, false, self.scale)
defer { UIGraphicsEndImageContext() }
draw(in: CGRect(x: 0.0, y: 0.0, width: size.width, height: size.height))
return UIGraphicsGetImageFromCurrentImageContext()
}
}
要使用,您可以执行以下操作:
let image = UIImage(named: "image.png")!
let newImage = image.resize(withSize: CGSize(width: 200, height: 150), contentMode: .contentAspectFill)
感谢abdullahselek最初的解决方案。
Swift 3.0带有故障安全选项(在错误的情况下返回原始图像):
func resize(image: UIImage, toSize size: CGSize) -> UIImage{
UIGraphicsBeginImageContextWithOptions(size,false,1.0)
image.draw(in: CGRect(x: 0, y: 0, width: size.width, height: size.height))
if let resizedImage = UIGraphicsGetImageFromCurrentImageContext() {
UIGraphicsEndImageContext()
return resizedImage
}
UIGraphicsEndImageContext()
return image
}