Resize UIImage by keeping Aspect ratio and width - iphone

Question

I seen in many posts for resizing the image by keeping aspect ratio. These functions uses the fixed points(Width and Height) for RECT while resizing. But in my project, I need to resize the view based on the Width alone, Height should be taken automatically based on the aspect ratio.
anyone help me to achieve this.

Answer 1

The method of Srikar works very well, if you know both height and width of your new Size.
If you for example know only the width you want to scale to and don't care about the height you first have to calculate the scale factor of the height.
+(UIImage*)imageWithImage: (UIImage*) sourceImage scaledToWidth: (float) i_width
{
float oldWidth = sourceImage.size.width;
float scaleFactor = i_width / oldWidth;
float newHeight = sourceImage.size.height * scaleFactor;
float newWidth = oldWidth * scaleFactor;
UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight));
[sourceImage drawInRect:CGRectMake(0, 0, newWidth, newHeight)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}

Answer 2

If you don't happen to know if the image will be portrait or landscape (e.g user takes pic with camera), I created another method that takes max width and height parameters.
Lets say you have a UIImage *myLargeImage which is a 4:3 ratio.
UIImage *myResizedImage = [ImageUtilities imageWithImage:myLargeImage
scaledToMaxWidth:1024
maxHeight:1024];
The resized UIImage will be 1024x768 if landscape; 768x1024 if portrait. This method will also generate higher res images for retina display.
+ (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)size {
if ([[UIScreen mainScreen] respondsToSelector:#selector(scale)]) {
UIGraphicsBeginImageContextWithOptions(size, NO, [[UIScreen mainScreen] scale]);
} else {
UIGraphicsBeginImageContext(size);
}
[image drawInRect:CGRectMake(0, 0, size.width, size.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
+ (UIImage *)imageWithImage:(UIImage *)image scaledToMaxWidth:(CGFloat)width maxHeight:(CGFloat)height {
CGFloat oldWidth = image.size.width;
CGFloat oldHeight = image.size.height;
CGFloat scaleFactor = (oldWidth > oldHeight) ? width / oldWidth : height / oldHeight;
CGFloat newHeight = oldHeight * scaleFactor;
CGFloat newWidth = oldWidth * scaleFactor;
CGSize newSize = CGSizeMake(newWidth, newHeight);
return [ImageUtilities imageWithImage:image scaledToSize:newSize];
}

Answer 3

Best answer Maverick 1st's correctly translated to Swift (working with latest swift 3):
func imageWithImage (sourceImage:UIImage, scaledToWidth: CGFloat) -> UIImage {
let oldWidth = sourceImage.size.width
let scaleFactor = scaledToWidth / oldWidth
let newHeight = sourceImage.size.height * scaleFactor
let newWidth = oldWidth * scaleFactor
UIGraphicsBeginImageContext(CGSize(width:newWidth, height:newHeight))
sourceImage.draw(in: CGRect(x:0, y:0, width:newWidth, height:newHeight))
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage!
}

Answer 4

thanks #Maverick1st the algorithm, I implemented it to Swift, in my case height is the input parameter
class func resizeImage(image: UIImage, newHeight: CGFloat) -> UIImage {
let scale = newHeight / image.size.height
let newWidth = image.size.width * scale
UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight))
image.drawInRect(CGRectMake(0, 0, newWidth, newHeight))
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage
}

Answer 5

This method is a category on UIImage. Does scale to fit in few lines of code using AVFoundation.
Don't forget to import #import <AVFoundation/AVFoundation.h>.
#implementation UIImage (Helper)
- (UIImage *)imageScaledToFitToSize:(CGSize)size
{
CGRect scaledRect = AVMakeRectWithAspectRatioInsideRect(self.size, CGRectMake(0, 0, size.width, size.height));
UIGraphicsBeginImageContextWithOptions(size, NO, 0);
[self drawInRect:scaledRect];
UIImage *scaledImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return scaledImage;
}
#end

Answer 6

Swift 5 version of aspect-fit-to-height, based on answer by #János
Uses the modern UIGraphicsImageRenderer API, so a valid UIImage is guaranteed to return.
extension UIImage
{
/// Given a required height, returns a (rasterised) copy
/// of the image, aspect-fitted to that height.
func aspectFittedToHeight(_ newHeight: CGFloat) -> UIImage
{
let scale = newHeight / self.size.height
let newWidth = self.size.width * scale
let newSize = CGSize(width: newWidth, height: newHeight)
let renderer = UIGraphicsImageRenderer(size: newSize)
return renderer.image { _ in
self.draw(in: CGRect(origin: .zero, size: newSize))
}
}
}
You can use this in conjunction with a (vector-based) PDF image asset, to preserve quality at any render size.

Answer 7

The simplest way is to set the frame of your UIImageView and set the contentMode to one of the resizing options.
The code goes like this - This can be used as an utility method -
+ (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize
{
UIGraphicsBeginImageContext(newSize);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}

Answer 8

Just import AVFoundation and use AVMakeRectWithAspectRatioInsideRect(CGRectCurrentSize, CGRectMake(0, 0, YOUR_WIDTH, CGFLOAT_MAX)

Answer 9

Well, we have few good answers here for resizing image, but I just modify as per my need. hope this help someone like me.
My Requirement was
If image width is more than 1920, resize it with 1920 width and maintaining height with original aspect ratio.
If image height is more than 1080, resize it with 1080 height and maintaining width with original aspect ratio.
if (originalImage.size.width > 1920)
{
CGSize newSize;
newSize.width = 1920;
newSize.height = (1920 * originalImage.size.height) / originalImage.size.width;
originalImage = [ProfileEditExperienceViewController imageWithImage:originalImage scaledToSize:newSize];
}
if (originalImage.size.height > 1080)
{
CGSize newSize;
newSize.width = (1080 * originalImage.size.width) / originalImage.size.height;
newSize.height = 1080;
originalImage = [ProfileEditExperienceViewController imageWithImage:originalImage scaledToSize:newSize];
}
+ (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)newSize
{
UIGraphicsBeginImageContext(newSize);
[image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}
Thanks to #Srikar Appal , for resizing I have used his method.
You may like to check this as well for resize calculation.

Answer 10

Programmatically:
imageView.contentMode = UIViewContentModeScaleAspectFit;
Storyboard:

Answer 11

If somebody needs this solution in Swift 5:
private func resizeImage(image: UIImage, newHeight: CGFloat) -> UIImage {
let scale = newHeight / image.size.height
let newWidth = image.size.width * scale
UIGraphicsBeginImageContext(CGSize(width:newWidth, height:newHeight))
image.draw(in:CGRect(x:0, y:0, width:newWidth, height:newHeight))
let newImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage
}

Answer 12

To improve on Ryan's answer:
+ (UIImage *)imageWithImage:(UIImage *)image scaledToSize:(CGSize)size {
CGFloat oldWidth = image.size.width;
CGFloat oldHeight = image.size.height;
//You may need to take some retina adjustments into consideration here
CGFloat scaleFactor = (oldWidth > oldHeight) ? width / oldWidth : height / oldHeight;
return [UIImage imageWithCGImage:image.CGImage scale:scaleFactor orientation:UIImageOrientationUp];
}

Answer 13

Ryan's Solution #Ryan
in swift code
use:
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;
}
//Summon this function VVV
func resizeImageWithAspect(image: UIImage,scaledToMaxWidth width:CGFloat,maxHeight height :CGFloat)->UIImage
{
let oldWidth = image.size.width;
let oldHeight = image.size.height;
let scaleFactor = (oldWidth > oldHeight) ? width / oldWidth : height / oldHeight;
let newHeight = oldHeight * scaleFactor;
let newWidth = oldWidth * scaleFactor;
let newSize = CGSizeMake(newWidth, newHeight);
return imageWithSize(image, size: newSize);
}

Answer 14

extension UIImage {
/// Returns a image that fills in newSize
func resizedImage(newSize: CGSize) -> UIImage? {
guard size != newSize else { return self }
let hasAlpha = false
let scale: CGFloat = 0.0
UIGraphicsBeginImageContextWithOptions(newSize, !hasAlpha, scale)
draw(in: CGRect(x: 0, y: 0, width: newSize.width, height: newSize.height))
let newImage: UIImage? = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return newImage
}
/// Returns a resized image that fits in rectSize, keeping it's aspect ratio
/// Note that the new image size is not rectSize, but within it.
func resizedImageWithinRect(rectSize: CGSize) -> UIImage? {
let widthFactor = size.width / rectSize.width
let heightFactor = size.height / rectSize.height
var resizeFactor = widthFactor
if size.height > size.width {
resizeFactor = heightFactor
}
let newSize = CGSize(width: size.width / resizeFactor, height: size.height / resizeFactor)
let resized = resizedImage(newSize: newSize)
return resized
}
}
When scale is set to 0.0, the scale factor of the main screen is used, which for Retina displays is 2.0 or higher (3.0 on the iPhone 6 Plus).

Answer 15

In Swift 3 there are some changes.
Here is an extension to UIImage:
public extension UIImage {
public func resize(height: CGFloat) -> UIImage? {
let scale = height / self.size.height
let width = self.size.width * scale
UIGraphicsBeginImageContext(CGSize(width: width, height: height))
self.draw(in: CGRect(x:0, y:0, width:width, height:height))
let resultImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
return resultImage
}
}

Answer 16

Calculates the best height of the image for available width.
import Foundation
public extension UIImage {
public func height(forWidth width: CGFloat) -> CGFloat {
let boundingRect = CGRect(
x: 0,
y: 0,
width: width,
height: CGFloat(MAXFLOAT)
)
let rect = AVMakeRect(
aspectRatio: size,
insideRect: boundingRect
)
return rect.size.height
}
}

Answer 17

Zeeshan Tufail and Womble answers in Swift 5 with small improvements.
Here we have extension with 2 functions to scale image to maxLength of any dimension and jpeg compression.
extension UIImage {
func aspectFittedToMaxLengthData(maxLength: CGFloat, compressionQuality: CGFloat) -> Data {
let scale = maxLength / max(self.size.height, self.size.width)
let format = UIGraphicsImageRendererFormat()
format.scale = scale
let renderer = UIGraphicsImageRenderer(size: self.size, format: format)
return renderer.jpegData(withCompressionQuality: compressionQuality) { context in
self.draw(in: CGRect(origin: .zero, size: self.size))
}
}
func aspectFittedToMaxLengthImage(maxLength: CGFloat, compressionQuality: CGFloat) -> UIImage? {
let newImageData = aspectFittedToMaxLengthData(maxLength: maxLength, compressionQuality: compressionQuality)
return UIImage(data: newImageData)
}
}

Answer 18

This one was perfect for me. Keeps aspect ratio and takes a maxLength. Width or Height will not be more than maxLength
-(UIImage*)imageWithImage: (UIImage*) sourceImage maxLength: (float) maxLength
{
CGFloat scaleFactor = maxLength / MAX(sourceImage.size.width, sourceImage.size.height);
float newHeight = sourceImage.size.height * scaleFactor;
float newWidth = sourceImage.size.width * scaleFactor;
UIGraphicsBeginImageContext(CGSizeMake(newWidth, newHeight));
[sourceImage drawInRect:CGRectMake(0, 0, newWidth, newHeight)];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return newImage;
}

Answer 19

I have solved it in a much simpler way
UIImage *placeholder = [UIImage imageNamed:#"OriginalImage.png"];
self.yourImageview.image = [UIImage imageWithCGImage:[placeholder CGImage] scale:(placeholder.scale * 1.5)
orientation:(placeholder.imageOrientation)];
multiplier of the scale will define the scalling of the image,more the multiplier smaller the image. so You can check what fits your screen.
Or you can also get the multiplire by dividing imagewidth/screenwidth.