UIImage rounded corners

Question

I try to get rounded corners on a UIImage, what I read so far, the easiest way is to use a mask images. For this I used code from TheElements iPhone Example and some image resize code I found. My problem is that resizedImage is always nil and I don't find the error...

- (UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize
{
    CGSize imageSize = [self size];
    float width = imageSize.width;
    float height = imageSize.height;

    // scaleFactor will be the fraction that we'll
    // use to adjust the size. For example, if we shrink
    // an image by half, scaleFactor will be 0.5. the
    // scaledWidth and scaledHeight will be the original,
    // multiplied by the scaleFactor.
    //
    // IMPORTANT: the "targetHeight" is the size of the space
    // we're drawing into. The "scaledHeight" is the height that
    // the image actually is drawn at, once we take into
    // account the ideal of maintaining proportions

    float scaleFactor = 0.0; 
    float scaledWidth = targetSize.width;
    float scaledHeight = targetSize.height;

    CGPoint thumbnailPoint = CGPointMake(0,0);

    // since not all images are square, we want to scale
    // proportionately. To do this, we find the longest
    // edge and use that as a guide.

    if ( CGSizeEqualToSize(imageSize, targetSize) == NO )
    { 
        // use the longeset edge as a guide. if the
        // image is wider than tall, we'll figure out
        // the scale factor by dividing it by the
        // intended width. Otherwise, we'll use the
        // height.

        float widthFactor = targetSize.width / width;
        float heightFactor = targetSize.height / height;

        if ( widthFactor < heightFactor )
            scaleFactor = widthFactor;
        else
            scaleFactor = heightFactor;

        // ex: 500 * 0.5 = 250 (newWidth)

        scaledWidth = width * scaleFactor;
        scaledHeight = height * scaleFactor;

        // center the thumbnail in the frame. if
        // wider than tall, we need to adjust the
        // vertical drawing point (y axis)

        if ( widthFactor < heightFactor )
            thumbnailPoint.y = (targetSize.height - scaledHeight) * 0.5;

        else if ( widthFactor > heightFactor )
            thumbnailPoint.x = (targetSize.width - scaledWidth) * 0.5;
    }


    CGContextRef mainViewContentContext;
    CGColorSpaceRef colorSpace;

    colorSpace = CGColorSpaceCreateDeviceRGB();

    // create a bitmap graphics context the size of the image
    mainViewContentContext = CGBitmapContextCreate (NULL, targetSize.width, targetSize.height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast);

    // free the rgb colorspace
    CGColorSpaceRelease(colorSpace);    

    if (mainViewContentContext==NULL)
        return NULL;

    //CGContextSetFillColorWithColor(mainViewContentContext, [[UIColor whiteColor] CGColor]);
    //CGContextFillRect(mainViewContentContext, CGRectMake(0, 0, targetSize.width, targetSize.height));

    CGContextDrawImage(mainViewContentContext, CGRectMake(thumbnailPoint.x, thumbnailPoint.y, scaledWidth, scaledHeight), self.CGImage);

    // Create CGImageRef of the main view bitmap content, and then
    // release that bitmap context
    CGImageRef mainViewContentBitmapContext = CGBitmapContextCreateImage(mainViewContentContext);
    CGContextRelease(mainViewContentContext);

    CGImageRef maskImage = [[UIImage imageNamed:@"Mask.png"] CGImage];

    CGImageRef resizedImage = CGImageCreateWithMask(mainViewContentBitmapContext, maskImage);
    CGImageRelease(mainViewContentBitmapContext);

    // convert the finished resized image to a UIImage 
    UIImage *theImage = [UIImage imageWithCGImage:resizedImage];

    // image is retained by the property setting above, so we can 
    // release the original
    CGImageRelease(resizedImage);

    // return the image
    return theImage;
}

Biotype

Any swift code? – Limnetic

Answer 1

The problem was the use of CGImageCreateWithMask which returned an all black image. The solution I found was to use CGContextClipToMask instead:

CGContextRef mainViewContentContext;
CGColorSpaceRef colorSpace;

colorSpace = CGColorSpaceCreateDeviceRGB();

// create a bitmap graphics context the size of the image
mainViewContentContext = CGBitmapContextCreate (NULL, targetSize.width, targetSize.height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast);

// free the rgb colorspace
CGColorSpaceRelease(colorSpace);    

if (mainViewContentContext==NULL)
    return NULL;

CGImageRef maskImage = [[UIImage imageNamed:@"mask.png"] CGImage];
CGContextClipToMask(mainViewContentContext, CGRectMake(0, 0, targetSize.width, targetSize.height), maskImage);
CGContextDrawImage(mainViewContentContext, CGRectMake(thumbnailPoint.x, thumbnailPoint.y, scaledWidth, scaledHeight), self.CGImage);


// Create CGImageRef of the main view bitmap content, and then
// release that bitmap context
CGImageRef mainViewContentBitmapContext = CGBitmapContextCreateImage(mainViewContentContext);
CGContextRelease(mainViewContentContext);

// convert the finished resized image to a UIImage 
UIImage *theImage = [UIImage imageWithCGImage:mainViewContentBitmapContext];
// image is retained by the property setting above, so we can 
// release the original
CGImageRelease(mainViewContentBitmapContext);

// return the image
return theImage;

Biotype

Answer 2

If you are using a UIImageView to display the image you can simply do the following:

imageView.layer.cornerRadius = 5.0;
imageView.layer.masksToBounds = YES;

And to add a border:

imageView.layer.borderColor = [UIColor lightGrayColor].CGColor;
imageView.layer.borderWidth = 1.0;

I believe that you'll have to import <QuartzCore/QuartzCore.h> and link against it for the above code to work.

Creatural

Import and link against what? – Selfrespect

sorry #import <QuartzCore/QuartzCore.h> – Creatural

turns out it was there, but didn't display because of the less than/greater than. – Creatural

Nice! Works great when the image is set UIViewModeContentModeScaleAspectFill – Manning

Super easy, but decreases scrolling performance of UITableView is custom cell has an UIImageView... I go with CG! :) – Amethist

for UITableviewCell ... just overlay a png with a hole on the center... that will do – Kitti

@Amethist did you Profile your app and find out the CG has a noticeable performance over this method? Because I am using this for my UITableView and mine updates the cells in realtime so there is that overload too. Let me know if you did that test. thanks – Blas

Answer 3

How about these lines...

// Get your image somehow
UIImage *image = [UIImage imageNamed:@"image.jpg"];

// Begin a new image that will be the new image with the rounded corners 
// (here with the size of an UIImageView)
UIGraphicsBeginImageContextWithOptions(imageView.bounds.size, NO, 1.0);

// Add a clip before drawing anything, in the shape of an rounded rect
[[UIBezierPath bezierPathWithRoundedRect:imageView.bounds 
                            cornerRadius:10.0] addClip];
// Draw your image
[image drawInRect:imageView.bounds];

// Get the image, here setting the UIImageView image
imageView.image = UIGraphicsGetImageFromCurrentImageContext();

// Lets forget about that we were drawing
UIGraphicsEndImageContext();

Trattoria

Answer 4

I created an UIImage-extension in swift, based on @epatel's great answer:

extension UIImage{
    var roundedImage: UIImage {
        let rect = CGRect(origin:CGPoint(x: 0, y: 0), size: self.size)
        UIGraphicsBeginImageContextWithOptions(self.size, false, 1)
        defer { 
            // End context after returning to avoid memory leak
            UIGraphicsEndImageContext() 
        }
       
        UIBezierPath(
            roundedRect: rect,
            cornerRadius: self.size.height
            ).addClip()
        self.drawInRect(rect)
        return UIGraphicsGetImageFromCurrentImageContext()
    }
}

Tested in a storyboard:

Seidule

Great.. I would like to make a small change regarding the scaling of rounded image. If you use the code as it is it will affect image resolution. So I made a small change in the code as given; let window = UIApplication.sharedApplication().windows[0]; UIGraphicsBeginImageContextWithOptions(self.size, false, window.screen.scale) – Hartnett

Shouldn't the cornerRadius be self.size.height / 2? – Spelter

@IulianOnofrei that makes perfect sense to me :) – Differentiable

I have been searching for something like this forever. The only issue now is that, since I use it in an animated (by tvOS) UIImageView, I get a dark background outside the corners, but only when focused (which scales the image). Not sure from where it comes out, I checked both Storyboard and code. – Szczecin

@AugustinePA according to the docs, you can just pass 0 in the scale option and the system will get current scale for you. – Cinerarium

@ W1nged D0om - Thanks. – Hartnett

Warning!!! It will cause a memory leak! You have to End the Context before "return" Instead of Line 21 (return UIGraphicsGetImageFromCurrentImageContext.......) let img = UIGraphicsGetImageFromCurrentImageContext()! UIGraphicsEndImageContext() return img – Cinelli

@YuraBuyaroff I've edited the answer to fix the memory leak. – Suspense

Answer 5

Extending Besi's excellent answer, with correct scale, in Swift 4:

extension UIImage {

    public func rounded(radius: CGFloat) -> UIImage {
        let rect = CGRect(origin: .zero, size: size)
        UIGraphicsBeginImageContextWithOptions(size, false, 0)
        UIBezierPath(roundedRect: rect, cornerRadius: radius).addClip()
        draw(in: rect)
        return UIGraphicsGetImageFromCurrentImageContext()!
    }

}

Newspaperwoman

Answer 6

You aren't actually doing anything other than scaling there. What you need to do is to "mask" the corners of the image by clipping it with a CGPath. For instance -

 - (void)drawRect:(CGRect)rect {
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextBeginTransparencyLayerWithRect(context, self.frame, NULL);
    CGContextSetRGBFillColor(context, 1.0, 1.0, 1.0, 1.0);  
    CGFloat roundRadius = (radius) ? radius : 12.0;
    CGFloat minx = CGRectGetMinX(self.frame), midx = CGRectGetMidX(self.frame), maxx = CGRectGetMaxX(self.frame);
    CGFloat miny = CGRectGetMinY(self.frame), midy = CGRectGetMidY(self.frame), maxy = CGRectGetMaxY(self.frame);

    // draw the arcs, handle paths
    CGContextMoveToPoint(context, minx, midy);
    CGContextAddArcToPoint(context, minx, miny, midx, miny, roundRadius);
    CGContextAddArcToPoint(context, maxx, miny, maxx, midy, roundRadius);
    CGContextAddArcToPoint(context, maxx, maxy, midx, maxy, roundRadius);
    CGContextAddArcToPoint(context, minx, maxy, minx, midy, roundRadius);
    CGContextClosePath(context);
    CGContextDrawPath(context, kCGPathFill);
    CGContextEndTransparencyLayer(context);
}

I suggest checking out the Quartz 2D programming guide or some other samples.

Threephase

the first part of my code is scaling, but the second part try to mask the image with CGImageCreateWithMask. The problem is CGImageCreateWithMask returns null and I don't know why... – Biotype

Answer 7

static void addRoundedRectToPath(CGContextRef context, CGRect rect, float ovalWidth, float ovalHeight)
{
  float fw, fh;
  if (ovalWidth == 0 || ovalHeight == 0) {
    CGContextAddRect(context, rect);
    return;
  }
  CGContextSaveGState(context);
  CGContextTranslateCTM (context, CGRectGetMinX(rect), CGRectGetMinY(rect));
  CGContextScaleCTM (context, ovalWidth, ovalHeight);
  fw = CGRectGetWidth (rect) / ovalWidth;
  fh = CGRectGetHeight (rect) / ovalHeight;
  CGContextMoveToPoint(context, fw, fh/2);
  CGContextAddArcToPoint(context, fw, fh, fw/2, fh, 1);
  CGContextAddArcToPoint(context, 0, fh, 0, fh/2, 1);
  CGContextAddArcToPoint(context, 0, 0, fw/2, 0, 1);
  CGContextAddArcToPoint(context, fw, 0, fw, fh/2, 1);
  CGContextClosePath(context);
  CGContextRestoreGState(context);
}

+ (UIImage *)imageWithRoundCorner:(UIImage*)img andCornerSize:(CGSize)size
{
    UIImage * newImage = nil;

    if( nil != img)
    {
       @autoreleasepool {
        int w = img.size.width;
        int h = img.size.height;

        CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
        CGContextRef context = CGBitmapContextCreate(NULL, w, h, 8, 4 * w, colorSpace, kCGImageAlphaPremultipliedFirst);

        CGContextBeginPath(context);
        CGRect rect = CGRectMake(0, 0, img.size.width, img.size.height);
        addRoundedRectToPath(context, rect, size.width, size.height);
        CGContextClosePath(context);
        CGContextClip(context);

        CGContextDrawImage(context, CGRectMake(0, 0, w, h), img.CGImage);

        CGImageRef imageMasked = CGBitmapContextCreateImage(context);
        CGContextRelease(context);
        CGColorSpaceRelease(colorSpace);
        [img release];

        newImage = [[UIImage imageWithCGImage:imageMasked] retain];
        CGImageRelease(imageMasked);

       }
    }

  return newImage;
}

Gariepy

Answer 8

I think this could be very related: In iOS 11 there is a very elgant way of rounding each single corner of a (Image)View.

let imageView = UIImageView(image: UIImage(named: "myImage"))    
imageView.layer.maskedCorners = [.layerMinXMinYCorner, .layerMaxXMinYCorner]
imageView.layer.cornerRadius = 10.0

Viewable

Answer 9

I liked the answer of @samwize, however it caused me nasty memory leaks when used with collectionView. To fix it I found that UIGraphicsEndImageContext() was missing

extension UIImage {
    /**
     Rounds corners of UIImage
     - Parameter proportion: Proportion to minimum paramter (width or height)
                             in order to have the same look of corner radius independetly
                             from aspect ratio and actual size
     */
    func roundCorners(proportion: CGFloat) -> UIImage {
        let minValue = min(self.size.width, self.size.height)
        let radius = minValue/proportion
        
        let rect = CGRect(origin: CGPoint(x: 0, y: 0), size: self.size)
        UIGraphicsBeginImageContextWithOptions(self.size, false, 1)
        UIBezierPath(roundedRect: rect, cornerRadius: radius).addClip()
        self.draw(in: rect)
        let image = UIGraphicsGetImageFromCurrentImageContext() ?? self
        UIGraphicsEndImageContext()
        return image
    }
}

Feel free to just pass the radius instead of proportion. proportion is used because I have collectionView scroll and images have different sizes, therefore when using constant radius it actually looks different in terms of proprtions (example: two images, one is 1000x1000 and another 2000x2000, corner radius of 30 will look different on each one of them)

So if you do image.roundCorners(proportion: 20) all the pictures look like the have the same corner radius.

This answer is also an updated version.

Gribble

Answer 10

The reason it worked with clipping, not with masking, seems to be the color space.

Apple Documentation's below.

mask A mask. If the mask is an image, it must be in the DeviceGray color space, must not have an alpha component, and may not itself be masked by an image mask or a masking color. If the mask is not the same size as the image specified by the image parameter, then Quartz scales the mask to fit the image.

Darr

Answer 11

Hi guys try this code,

+ (UIImage *)roundedRectImageFromImage:(UIImage *)image withRadious:(CGFloat)radious {

if(radious == 0.0f)
    return image;

if( image != nil) {

    CGFloat imageWidth = image.size.width;
    CGFloat imageHeight = image.size.height;

    CGRect rect = CGRectMake(0.0f, 0.0f, imageWidth, imageHeight);
    UIWindow *window = [[[UIApplication sharedApplication] windows] objectAtIndex:0];
    const CGFloat scale = window.screen.scale;
    UIGraphicsBeginImageContextWithOptions(rect.size, NO, scale);

    CGContextRef context = UIGraphicsGetCurrentContext();

    CGContextBeginPath(context);
    CGContextSaveGState(context);
    CGContextTranslateCTM (context, CGRectGetMinX(rect), CGRectGetMinY(rect));
    CGContextScaleCTM (context, radious, radious);

    CGFloat rectWidth = CGRectGetWidth (rect)/radious;
    CGFloat rectHeight = CGRectGetHeight (rect)/radious;

    CGContextMoveToPoint(context, rectWidth, rectHeight/2.0f);
    CGContextAddArcToPoint(context, rectWidth, rectHeight, rectWidth/2.0f, rectHeight, radious);
    CGContextAddArcToPoint(context, 0.0f, rectHeight, 0.0f, rectHeight/2.0f, radious);
    CGContextAddArcToPoint(context, 0.0f, 0.0f, rectWidth/2.0f, 0.0f, radious);
    CGContextAddArcToPoint(context, rectWidth, 0.0f, rectWidth, rectHeight/2.0f, radious);
    CGContextRestoreGState(context);
    CGContextClosePath(context);
    CGContextClip(context);

    [image drawInRect:CGRectMake(0.0f, 0.0f, imageWidth, imageHeight)];

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return newImage;
}

return nil;
}

Cheers !!!

Hartnett

Answer 12

It's very easy to create a rounded image when you make use of the image dimension.

cell.messageImage.layer.cornerRadius = image.size.width / 2
cell.messageImage.layer.masksToBounds = true

Germiston

Should be the frame size – Tourer

Answer 13

Found out the best and simple way of doing it is as follows (no answer did that):

UIImageView *imageView;

imageView.layer.cornerRadius = imageView.frame.size.width/2.0f;
imageView.layer.masksToBounds = TRUE;

Pretty simple and done this right.

Tourer

Answer 14

See here... IMO unless you absolutely need to do it in code, just overlay an image on top.

Something along the lines of...

- (void)drawRect:(CGRect)rect 
{
    // Drawing code
    [backgroundImage drawInRect:rect];
    [buttonOverlay drawInRect:rect];    
}

Abdulabdulla

I try to avoid doing it in code by using CGImageCreateWithMask, but it always returns null. – Biotype

I mean literally draw another UIImage from a resource over top of it to round the corner. See the edit... – Abdulabdulla

Answer 15

For Creating a Round Corner image we can use quartzcore.

First How to add QuartzCore framework?

Click  project -Targets
    ->project
       ->BuildPhase
           ->Link Binary with Libraries
             ->Then click + symbol finally select from list and add it

or else

Click  project -Targets
    ->Targets
      ->general
        ->Linked Frameworks and Libraries
          ->Then click + symbol finally select from list and add the QuartzCore framework

Now import

#import <QuartzCore/QuartzCore.h> 

in your ViewController

Then in viewDidLoad method

self.yourImageView.layer.cornerRadius = 5.0;
self.yourImageView.layer.borderWidth = 1.0f;
self.yourImageView.layer.borderColor = [UIColor blackColor].CGColor;
self.yourImageView.layer.masksToBounds = YES;

Augie

I edited my answer please check it now.Don't down vote. – Augie

Answer 16

I was struggling to round the corners of a UIImage box in my storyboard. I had a IBOutlet for my UIImage called image. After reading a bunch of posts on here, I simply added 3 lines and that worked perfectly.

import UIKit

Then in viewDidLoad:

image.layer.cornerRadius = 20.0

image.layer.masksToBounds = true

This is for iOS 11.1 in Xcode 9.

Asyllabic