#import <Cocoa/Cocoa.h>
 
@interface NSImage (Transform)
 
 
/*!
 @brief    Rotates an image around its center by a given
 angle in degrees and returns the new image.
 
 @details  The width and height of the returned image are,
 respectively, the height and width of the receiver.
 
 I have not yet tested this with a non-square image.
 
authors: Jerry Krinock and Steve Christensen
 */
- (NSImage*)imageRotatedByDegrees:(CGFloat)degrees ;
 
@end
 
#import "NSImage+Transform.h"
 
@implementation NSImage (Transform)
 
 
- (NSImage*)imageRotatedByDegrees:(CGFloat)degrees {
 
	// calculate the bounds for the rotated image
    NSRect imageBounds = {NSZeroPoint, [self size]};
 
	NSBezierPath* boundsPath = [NSBezierPath bezierPathWithRect:imageBounds];
 
    NSAffineTransform* transform = [NSAffineTransform transform];
 
    [transform rotateByDegrees:degrees];
    [boundsPath transformUsingAffineTransform:transform];
 
    NSRect rotatedBounds = {NSZeroPoint, [boundsPath bounds].size};
 
	NSImage* rotatedImage = [[NSImage alloc] initWithSize:rotatedBounds.size];
 
    // center the image within the rotated bounds
 
	imageBounds.origin.x = NSMidX(rotatedBounds) - (NSWidth (imageBounds) / 2); imageBounds.origin.y = NSMidY(rotatedBounds) - (NSHeight (imageBounds) / 2);
 
    // set up the rotation transform
    transform = [NSAffineTransform transform];
 
	[transform translateXBy:+(NSWidth(rotatedBounds) / 2) yBy:+ (NSHeight(rotatedBounds) / 2)];
 
    [transform rotateByDegrees:degrees];
 
	[transform translateXBy:-(NSWidth(rotatedBounds) / 2) yBy:- (NSHeight(rotatedBounds) / 2)];
 
    // draw the original image, rotated, into the new image
    [rotatedImage lockFocus];
    [transform concat];
 
	[self drawInRect:imageBounds fromRect:NSZeroRect operation:NSCompositeCopy fraction:1.0] ;
 
    [rotatedImage unlockFocus];
 
    return [rotatedImage autorelease];	
 
}
@end