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);
}
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?
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))
}
}
}
Here is my Objective-C
code. It's work for me.
+ (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize isAspectRation:(BOOL)aspect {
if (!image) {
return nil;
}
//UIGraphicsBeginImageContext(newSize);
// In next line, pass 0.0 to use the current device's pixel scaling factor (and thus account for Retina resolution).
// Pass 1.0 to force exact pixel size.
CGFloat originRatio = image.size.width / image.size.height;
CGFloat newRatio = newSize.width / newSize.height;
CGSize sz;
if (!aspect) {
sz = newSize;
}else {
if (originRatio < newRatio) {
sz.height = newSize.height;
sz.width = newSize.height * originRatio;
}else {
sz.width = newSize.width;
sz.height = newSize.width / originRatio;
}
}
CGFloat scale = 1.0;
// if([[UIScreen mainScreen]respondsToSelector:@selector(scale)]) {
// CGFloat tmp = [[UIScreen mainScreen]scale];
// if (tmp > 1.5) {
// scale = 2.0;
// }
// }
sz.width /= scale;
sz.height /= scale;
UIGraphicsBeginImageContextWithOptions(sz, NO, scale);
[image drawInRect:CGRectMake(0, 0, sz.width, sz.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
I saw your code in Swift
. I just convert my Objective-C
to Swift
without test. Can you try it and let's me know. Thanks!
struct CommonUtils {
static func imageWithImage(image: UIImage, scaleToSize newSize: CGSize, isAspectRation aspect: Bool) -> UIImage{
let originRatio = image.size.width / image.size.height;//CGFloat
let newRatio = newSize.width / newSize.height;
var sz: CGSize = CGSizeZero
if (!aspect) {
sz = newSize
}else {
if (originRatio < newRatio) {
sz.height = newSize.height
sz.width = newSize.height * originRatio
}else {
sz.width = newSize.width
sz.height = newSize.width / originRatio
}
}
let scale: CGFloat = 1.0
sz.width /= scale
sz.height /= scale
UIGraphicsBeginImageContextWithOptions(sz, false, scale)
image.drawInRect(CGRectMake(0, 0, sz.width, sz.height))
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage
}
}
func image(image:UIImage,imageSize:CGSize)->UIImage
{
UIGraphicsBeginImageContextWithOptions(imageSize, false, 0.0)
[image .drawInRect(CGRectMake(0, 3, imageSize.width, imageSize.height))]
let newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext()
return newImage;
}
I just created this useful UIImage extension with swift 5. You can use it to resize your UIImages without losing quality.
I added a couple of methods in order to be able to resize an image to a width or a height keeping the aspect ratio.
extension UIImage {
func resize(targetSize: CGSize) -> UIImage {
return UIGraphicsImageRenderer(size:targetSize).image { _ in
self.draw(in: CGRect(origin: .zero, size: targetSize))
}
}
func resize(scaledToWidth desiredWidth: CGFloat) -> UIImage {
let oldWidth = size.width
let scaleFactor = desiredWidth / oldWidth
let newHeight = size.height * scaleFactor
let newWidth = oldWidth * scaleFactor
let newSize = CGSize(width: newWidth, height: newHeight)
return resize(targetSize: newSize)
}
func resize(scaledToHeight desiredHeight: CGFloat) -> UIImage {
let scaleFactor = desiredHeight / size.height
let newWidth = size.width * scaleFactor
let newSize = CGSize(width: newWidth, height: desiredHeight)
return resize(targetSize: newSize)
}
}
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