UIImage+Resize

// UIImage+Resize.h

// Created by Trevor Harmon on 8/5/09.

// Free for personal or commercial use, with or without modification.

// No warranty is expressed or implied.

// Extends the UIImage class to support resizing/cropping

@interface UIImage (Resize)

- (UIImage *)croppedImage:(CGRect)bounds;

- (UIImage *)thumbnailImage:(NSInteger)thumbnailSize

          transparentBorder:(NSUInteger)borderSize

               cornerRadius:(NSUInteger)cornerRadius

       interpolationQuality:(CGInterpolationQuality)quality;

- (UIImage *)resizedImage:(CGSize)newSize

     interpolationQuality:(CGInterpolationQuality)quality;

- (UIImage *)resizedImageWithContentMode:(UIViewContentMode)contentMode

                                  bounds:(CGSize)bounds

                    interpolationQuality:(CGInterpolationQuality)quality;

- (UIImage *)resizedImage:(CGSize)newSize

                transform:(CGAffineTransform)transform

           drawTransposed:(BOOL)transpose

     interpolationQuality:(CGInterpolationQuality)quality;

- (CGAffineTransform)transformForOrientation:(CGSize)newSize;

@end

// UIImage+Resize.m

// Created by Trevor Harmon on 8/5/09.

// Free for personal or commercial use, with or without modification.

// No warranty is expressed or implied.

#import"UIImage+Resize.h"

#import"UIImage+RoundedCorner.h"

#import"UIImage+Alpha.h"

@implementation UIImage (Resize)

// Returns a copy of this image that is cropped to the given bounds.

// The bounds will be adjusted using CGRectIntegral.

// This method ignores the image's imageOrientation setting.

- (UIImage *)croppedImage:(CGRect)bounds {

    CGImageRef imageRef = CGImageCreateWithImageInRect([self CGImage], bounds);

    UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];

    CGImageRelease(imageRef);

    return croppedImage;

}

// Returns a copy of this image that is squared to the thumbnail size.

// If transparentBorder is non-zero, a transparent border of the given size will be added around the edges of the thumbnail. (Adding a transparent border of at least one pixel in size has the side-effect of antialiasing the edges of the image when rotating it using Core Animation.)

- (UIImage *)thumbnailImage:(NSInteger)thumbnailSize

          transparentBorder:(NSUInteger)borderSize

               cornerRadius:(NSUInteger)cornerRadius

       interpolationQuality:(CGInterpolationQuality)quality {

    UIImage *resizedImage = [self resizedImageWithContentMode:UIViewContentModeScaleAspectFill

                                                       bounds:CGSizeMake(thumbnailSize, thumbnailSize)

                                         interpolationQuality:quality];

    

   // Crop out any part of the image that's larger than the thumbnail size

   // The cropped rect must be centered on the resized image

   // Round the origin points so that the size isn't altered when CGRectIntegral is later invoked

    CGRect cropRect = CGRectMake(round((resizedImage.size.width - thumbnailSize) /2),

                                 round((resizedImage.size.height - thumbnailSize) /2),

                                 thumbnailSize,

                                 thumbnailSize);

    UIImage *croppedImage = [resizedImage croppedImage:cropRect];

    

    UIImage *transparentBorderImage = borderSize ? [croppedImage transparentBorderImage:borderSize] : croppedImage;

    

    return [transparentBorderImage roundedCornerImage:cornerRadius borderSize:borderSize];

}

// Returns a rescaled copy of the image, taking into account its orientation

// The image will be scaled disproportionately if necessary to fit the bounds specified by the parameter

- (UIImage *)resizedImage:(CGSize)newSize interpolationQuality:(CGInterpolationQuality)quality {

    BOOL drawTransposed;

    CGAffineTransform transform = CGAffineTransformIdentity;

    

   // In iOS 5 the image is already correctly rotated. See Eran Sandler's

   // addition here: http://eran.sandler.co.il/2011/11/07/uiimage-in-ios-5-orientation-and-resize/

    

    if ( [[[UIDevice currentDevice] systemVersion] floatValue] >= 5.0 ) 

    {

        drawTransposed =NO;  

    } 

    else 

    {    

        switch ( self.imageOrientation ) 

        {

            case UIImageOrientationLeft:

            case UIImageOrientationLeftMirrored:

            case UIImageOrientationRight:

            case UIImageOrientationRightMirrored:

                drawTransposed =YES;

                break;

            default:

                drawTransposed =NO;

        }

        

        transform = [self transformForOrientation:newSize];

    } 

    

    return [self resizedImage:newSize transform:transform drawTransposed:drawTransposed interpolationQuality:quality];

}

// Resizes the image according to the given content mode, taking into account the image's orientation

- (UIImage *)resizedImageWithContentMode:(UIViewContentMode)contentMode

                                  bounds:(CGSize)bounds

                    interpolationQuality:(CGInterpolationQuality)quality {

    CGFloat horizontalRatio = bounds.width /self.size.width;

    CGFloat verticalRatio = bounds.height /self.size.height;

    CGFloat ratio;

    

    switch (contentMode) {

        case UIViewContentModeScaleAspectFill:

            ratio = MAX(horizontalRatio, verticalRatio);

            break;

            

        case UIViewContentModeScaleAspectFit:

            ratio = MIN(horizontalRatio, verticalRatio);

            break;

            

        default:

            [NSException raise:NSInvalidArgumentException format:@"Unsupported content mode: %d", contentMode];

    }

    

    CGSize newSize = CGSizeMake(self.size.width * ratio,self.size.height * ratio);

    

    return [self resizedImage:newSize interpolationQuality:quality];

}

#pragma mark -

#pragma mark Private helper methods

// Returns a copy of the image that has been transformed using the given affine transform and scaled to the new size

// The new image's orientation will be UIImageOrientationUp, regardless of the current image's orientation

// If the new size is not integral, it will be rounded up

- (UIImage *)resizedImage:(CGSize)newSize

                transform:(CGAffineTransform)transform

           drawTransposed:(BOOL)transpose

     interpolationQuality:(CGInterpolationQuality)quality {

    CGRect newRect = CGRectIntegral(CGRectMake(0,0, newSize.width, newSize.height));

    CGRect transposedRect = CGRectMake(0,0, newRect.size.height, newRect.size.width);

    CGImageRef imageRef =self.CGImage;

    

   // Fix for a colorspace / transparency issue that affects some types of 

   // images. See here: http://vocaro.com/trevor/blog/2009/10/12/resize-a-uiimage-the-right-way/comment-page-2/#comment-39951

        

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    CGContextRef bitmap =CGBitmapContextCreate(NULL,

                                               newRect.size.width,

                                               newRect.size.height,

                                              8,

                                              0,

                                               colorSpace,

                                               kCGImageAlphaPremultipliedLast );

    CGColorSpaceRelease(colorSpace);

   // Rotate and/or flip the image if required by its orientation

    CGContextConcatCTM(bitmap, transform);

    

   // Set the quality level to use when rescaling

    CGContextSetInterpolationQuality(bitmap, quality);

    

   // Draw into the context; this scales the image

    CGContextDrawImage(bitmap, transpose ? transposedRect : newRect, imageRef);

    

   // Get the resized image from the context and a UIImage

    CGImageRef newImageRef = CGBitmapContextCreateImage(bitmap);

    UIImage *newImage = [UIImage imageWithCGImage:newImageRef];

    

   // Clean up

    CGContextRelease(bitmap);

    CGImageRelease(newImageRef);

    

    return newImage;

}

// Returns an affine transform that takes into account the image orientation when drawing a scaled image

- (CGAffineTransform)transformForOrientation:(CGSize)newSize {

    CGAffineTransform transform = CGAffineTransformIdentity;

    

    switch (self.imageOrientation) {

        case UIImageOrientationDown:           // EXIF = 3

        case UIImageOrientationDownMirrored:   // EXIF = 4

            transform = CGAffineTransformTranslate(transform, newSize.width, newSize.height);

            transform = CGAffineTransformRotate(transform, M_PI);

            break;

            

        case UIImageOrientationLeft:           // EXIF = 6

        case UIImageOrientationLeftMirrored:   // EXIF = 5

            transform = CGAffineTransformTranslate(transform, newSize.width,0);

            transform = CGAffineTransformRotate(transform, M_PI_2);

            break;

            

        case UIImageOrientationRight:          // EXIF = 8

        case UIImageOrientationRightMirrored:  // EXIF = 7

            transform = CGAffineTransformTranslate(transform,0, newSize.height);

            transform = CGAffineTransformRotate(transform, -M_PI_2);

            break;

        default:

            break;

    }

    

    switch (self.imageOrientation) {

        case UIImageOrientationUpMirrored:     // EXIF = 2

        case UIImageOrientationDownMirrored:   // EXIF = 4

            transform = CGAffineTransformTranslate(transform, newSize.width,0);

            transform = CGAffineTransformScale(transform, -1,1);

            break;

            

        case UIImageOrientationLeftMirrored:   // EXIF = 5

        case UIImageOrientationRightMirrored:  // EXIF = 7

            transform = CGAffineTransformTranslate(transform, newSize.height,0);

            transform = CGAffineTransformScale(transform, -1,1);

            break;

        default:

            break;

    }

    

    return transform;

}

@end