Created
December 4, 2013 04:36
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UIImage category for resizing and rotating methods. Made by http://www.catamount.com/forums/viewtopic.php?f=21&t=967
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#import <UIKit/UIKit.h> | |
@interface UIImage (Transform) | |
- (UIImage *)imageAtRect:(CGRect)rect; | |
- (UIImage *)imageByScalingProportionallyToMinimumSize:(CGSize)targetSize; | |
- (UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize; | |
- (UIImage *)imageByScalingToSize:(CGSize)targetSize; | |
- (UIImage *)imageRotatedByRadians:(CGFloat)radians; | |
- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees; | |
@end |
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#import "UIImage+Transform.h" | |
CGFloat DegreesToRadians(CGFloat degrees) {return degrees * M_PI / 180;}; | |
CGFloat RadiansToDegrees(CGFloat radians) {return radians * 180/M_PI;}; | |
@implementation UIImage (Transform) | |
-(UIImage *)imageAtRect:(CGRect)rect | |
{ | |
CGImageRef imageRef = CGImageCreateWithImageInRect([self CGImage], rect); | |
UIImage* subImage = [UIImage imageWithCGImage: imageRef]; | |
CGImageRelease(imageRef); | |
return subImage; | |
} | |
- (UIImage *)imageByScalingProportionallyToMinimumSize:(CGSize)targetSize { | |
UIImage *sourceImage = self; | |
UIImage *newImage = nil; | |
CGSize imageSize = sourceImage.size; | |
CGFloat width = imageSize.width; | |
CGFloat height = imageSize.height; | |
CGFloat targetWidth = targetSize.width; | |
CGFloat targetHeight = targetSize.height; | |
CGFloat scaleFactor = 0.0; | |
CGFloat scaledWidth = targetWidth; | |
CGFloat scaledHeight = targetHeight; | |
CGPoint thumbnailPoint = CGPointMake(0.0,0.0); | |
if (CGSizeEqualToSize(imageSize, targetSize) == NO) { | |
CGFloat widthFactor = targetWidth / width; | |
CGFloat heightFactor = targetHeight / height; | |
if (widthFactor > heightFactor) | |
scaleFactor = widthFactor; | |
else | |
scaleFactor = heightFactor; | |
scaledWidth = width * scaleFactor; | |
scaledHeight = height * scaleFactor; | |
// center the image | |
if (widthFactor > heightFactor) { | |
thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5; | |
} else if (widthFactor < heightFactor) { | |
thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5; | |
} | |
} | |
// this is actually the interesting part: | |
UIGraphicsBeginImageContext(targetSize); | |
CGRect thumbnailRect = CGRectZero; | |
thumbnailRect.origin = thumbnailPoint; | |
thumbnailRect.size.width = scaledWidth; | |
thumbnailRect.size.height = scaledHeight; | |
[sourceImage drawInRect:thumbnailRect]; | |
newImage = UIGraphicsGetImageFromCurrentImageContext(); | |
UIGraphicsEndImageContext(); | |
if(newImage == nil) NSLog(@"could not scale image"); | |
return newImage ; | |
} | |
- (UIImage *)imageByScalingProportionallyToSize:(CGSize)targetSize { | |
UIImage *sourceImage = self; | |
UIImage *newImage = nil; | |
CGSize imageSize = sourceImage.size; | |
CGFloat width = imageSize.width; | |
CGFloat height = imageSize.height; | |
CGFloat targetWidth = targetSize.width; | |
CGFloat targetHeight = targetSize.height; | |
CGFloat scaleFactor = 0.0; | |
CGFloat scaledWidth = targetWidth; | |
CGFloat scaledHeight = targetHeight; | |
CGPoint thumbnailPoint = CGPointMake(0.0,0.0); | |
if (CGSizeEqualToSize(imageSize, targetSize) == NO) { | |
CGFloat widthFactor = targetWidth / width; | |
CGFloat heightFactor = targetHeight / height; | |
if (widthFactor < heightFactor) | |
scaleFactor = widthFactor; | |
else | |
scaleFactor = heightFactor; | |
scaledWidth = width * scaleFactor; | |
scaledHeight = height * scaleFactor; | |
// center the image | |
if (widthFactor < heightFactor) { | |
thumbnailPoint.y = (targetHeight - scaledHeight) * 0.5; | |
} else if (widthFactor > heightFactor) { | |
thumbnailPoint.x = (targetWidth - scaledWidth) * 0.5; | |
} | |
} | |
// this is actually the interesting part: | |
UIGraphicsBeginImageContext(targetSize); | |
CGRect thumbnailRect = CGRectZero; | |
thumbnailRect.origin = thumbnailPoint; | |
thumbnailRect.size.width = scaledWidth; | |
thumbnailRect.size.height = scaledHeight; | |
[sourceImage drawInRect:thumbnailRect]; | |
newImage = UIGraphicsGetImageFromCurrentImageContext(); | |
UIGraphicsEndImageContext(); | |
if(newImage == nil) NSLog(@"could not scale image"); | |
return newImage ; | |
} | |
- (UIImage *)imageByScalingToSize:(CGSize)targetSize { | |
UIImage *sourceImage = self; | |
UIImage *newImage = nil; | |
// CGSize imageSize = sourceImage.size; | |
// CGFloat width = imageSize.width; | |
// CGFloat height = imageSize.height; | |
CGFloat targetWidth = targetSize.width; | |
CGFloat targetHeight = targetSize.height; | |
// CGFloat scaleFactor = 0.0; | |
CGFloat scaledWidth = targetWidth; | |
CGFloat scaledHeight = targetHeight; | |
CGPoint thumbnailPoint = CGPointMake(0.0,0.0); | |
// this is actually the interesting part: | |
UIGraphicsBeginImageContext(targetSize); | |
CGRect thumbnailRect = CGRectZero; | |
thumbnailRect.origin = thumbnailPoint; | |
thumbnailRect.size.width = scaledWidth; | |
thumbnailRect.size.height = scaledHeight; | |
[sourceImage drawInRect:thumbnailRect]; | |
newImage = UIGraphicsGetImageFromCurrentImageContext(); | |
UIGraphicsEndImageContext(); | |
if(newImage == nil) NSLog(@"could not scale image"); | |
return newImage ; | |
} | |
- (UIImage *)imageRotatedByRadians:(CGFloat)radians | |
{ | |
return [self imageRotatedByDegrees:RadiansToDegrees(radians)]; | |
} | |
- (UIImage *)imageRotatedByDegrees:(CGFloat)degrees | |
{ | |
// calculate the size of the rotated view's containing box for our drawing space | |
UIView *rotatedViewBox = [[UIView alloc] initWithFrame:CGRectMake(0,0,self.size.width, self.size.height)]; | |
CGAffineTransform t = CGAffineTransformMakeRotation(DegreesToRadians(degrees)); | |
rotatedViewBox.transform = t; | |
CGSize rotatedSize = rotatedViewBox.frame.size; | |
// Create the bitmap context | |
UIGraphicsBeginImageContext(rotatedSize); | |
CGContextRef bitmap = UIGraphicsGetCurrentContext(); | |
// Move the origin to the middle of the image so we will rotate and scale around the center. | |
CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2); | |
// // Rotate the image context | |
CGContextRotateCTM(bitmap, DegreesToRadians(degrees)); | |
// Now, draw the rotated/scaled image into the context | |
CGContextScaleCTM(bitmap, 1.0, -1.0); | |
CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2, self.size.width, self.size.height), [self CGImage]); | |
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext(); | |
UIGraphicsEndImageContext(); | |
return newImage; | |
} | |
@end |
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