调整图像大小而不会损失质量

问题描述：

我正在使用以下功能来调整图片的宽度和宽度；高度，但我注意到它会破坏图像质量.

I'm using the functions below to resize my images width & height but I noticed that it ruins the image quality.

class func imageWithSize(image: UIImage,size: CGSize)->UIImage{
    if UIScreen.mainScreen().respondsToSelector("scale"){
        UIGraphicsBeginImageContextWithOptions(size,false,UIScreen.mainScreen().scale);
    }
    else
    {
        UIGraphicsBeginImageContext(size);
    }

    image.drawInRect(CGRectMake(0, 0, size.width, size.height));
    var newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return newImage;
}

class func resizeImageWithAspect(image: UIImage,scaledToMaxWidth width:CGFloat,maxHeight height :CGFloat)->UIImage
{


    let scaleFactor =  width / height;


    let newSize = CGSizeMake(width, height);

    return imageWithSize(image, size: newSize);
}

还有另一种方法来调整图像大小而又不影响画质吗?或者如何在下面修复我的功能，以免在调整大小后不会破坏图像质量?

Is there another way to resize images without ruining the quality? Or how can I fix my functions below so it doesn't ruin the image quality after resizing?

答

下面是我的代码.对于平方图像，它确实可以很好地工作，并且没有任何质量损失！

Here is my code in swift. For squared images, it works really well and without any loss of quality!

extension UIImage {

    func resize(targetSize: CGSize) -> UIImage {
        return UIGraphicsImageRenderer(size:targetSize).image { _ in
            self.draw(in: CGRect(origin: .zero, size: targetSize))
        }
    }

}

调整图像大小而不会损失质量

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