- (UIImage *) rotate: (UIImage *) image { double angle = 20; CGSize s = {image.size.width, image.size.height}; UIGraphicsBeginImageContext(s); CGContextRef ctx = UIGraphicsGetCurrentContext(); CGContextTranslateCTM(ctx, 0,image.size.height); CGContextScaleCTM(ctx, 1.0, -1.0); CGContextRotateCTM(ctx, 2*M_PI*angle/360); CGContextDrawImage(ctx,CGRectMake(0,0,image.size.width, image.size.height),image.CGImage); UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return newImage; }
#pragma mark - #pragma mark Rotate Image - (UIImage *)scaleAndRotateImage:(UIImage *)image { CGImageRef imgRef = image.CGImage; CGFloat width = CGImageGetWidth(imgRef); CGFloat height = CGImageGetHeight(imgRef); CGAffineTransform transform = CGAffineTransformIdentity; CGRect bounds = CGRectMake(0, 0, width, height); CGFloat boundHeight; boundHeight = bounds.size.height; bounds.size.height = bounds.size.width; bounds.size.width = boundHeight; transform = CGAffineTransformMakeScale(-1.0, 1.0); transform = CGAffineTransformRotate(transform, M_PI / 2.0); //use angle/360 *MPI UIGraphicsBeginImageContext(bounds.size); CGContextRef context = UIGraphicsGetCurrentContext(); CGContextConcatCTM(context, transform); CGContextDrawImage(context, CGRectMake(0, 0, width, height), imgRef); UIImage *imageCopy = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return imageCopy; }
- (UIImage *)rotate:(UIImage *)image radians:(float)rads { float newSide = MAX([image size].width, [image size].height); CGSize size = CGSizeMake(newSide, newSide); UIGraphicsBeginImageContext(size); CGContextRef ctx = UIGraphicsGetCurrentContext(); CGContextTranslateCTM(ctx, newSide/2, newSide/2); CGContextRotateCTM(ctx, rads); CGContextDrawImage(UIGraphicsGetCurrentContext(),CGRectMake(-[image size].width/2,-[image size].height/2,size.width, size.height),image.CGImage); //CGContextTranslateCTM(ctx, [image size].width/2, [image size].height/2); UIImage *i = UIGraphicsGetImageFromCurrentImageContext(); UIGraphicsEndImageContext(); return i; }
转帖:http://stackoverflow.com/questions/5102474/rotate-uiimage-custom-degree