I have a UIImageView with an image in it. I have rotated the image prior to display by setting the transform property of the UIImageView to CGAffineTransformMakeRotation(angle) where angle is the angle in radians.

I want to be able to create another UIImage that corresponds to the rotated version that I can see in my view.

I am almost there, by rotating the image context I get a rotated image:

- (UIImage *) rotatedImageFromImageView: (UIImageView *) imageView{    UIImage *rotatedImage;    // Get image width, height of the bounding rectangle    CGRect boundingRect = [self getBoundingRectAfterRotation: imageView.bounds byAngle:angle];    // Create a graphics context the size of the bounding rectangle    UIGraphicsBeginImageContext(boundingRect.size);    CGContextRef context = UIGraphicsGetCurrentContext();    // Rotate and translate the context    CGAffineTransform ourTransform = CGAffineTransformIdentity;    ourTransform = CGAffineTransformConcat(ourTransform, CGAffineTransformMakeRotation(angle));    CGContextConcatCTM(context, ourTransform);    // Draw the image into the context    CGContextDrawImage(context, CGRectMake(0, 0, imageView.image.size.width, imageView.image.size.height), imageView.image.CGImage);    // Get an image from the context    rotatedImage = [UIImage imageWithCGImage: CGBitmapContextCreateImage(context)];    // Clean up    UIGraphicsEndImageContext();    return rotatedImage; }

However the image is not rotated about its centre. I have tried all kinds of transforms concatenated with my rotate to get it to rotate around the centre but to no avail. Am I missing a trick? Is this even possible since I am rotating the context not the image?

Getting desperate to make this work now, so any help would be appreciated.

Dave

EDIT: I've been asked several times for my boundingRect code, so here it is:

- (CGRect) getBoundingRectAfterRotation: (CGRect) rectangle byAngle: (CGFloat) angleOfRotation {    // Calculate the width and height of the bounding rectangle using basic trig    CGFloat newWidth = rectangle.size.width * fabs(cosf(angleOfRotation)) + rectangle.size.height * fabs(sinf(angleOfRotation));    CGFloat newHeight = rectangle.size.height * fabs(cosf(angleOfRotation)) + rectangle.size.width * fabs(sinf(angleOfRotation));    // Calculate the position of the origin    CGFloat newX = rectangle.origin.x + ((rectangle.size.width - newWidth) / 2);    CGFloat newY = rectangle.origin.y + ((rectangle.size.height - newHeight) / 2);    // Return the rectangle    return CGRectMake(newX, newY, newWidth, newHeight);}

• this should do it <br/>stackoverflow.com/questions/1315251/…

  zapping

  – zapping

  2010-05-24 09:39:36 +00:00

  CommentedMay 24, 2010 at 9:39
• What is thisgetBoundingRectAfterRotation function?

  bmdhacks

  – bmdhacks

  2011-11-12 04:37:30 +00:00

  CommentedNov 12, 2011 at 4:37
• Hi @bmdhacks the getBoundingRectAfterRotation is a method I have created, so you wont find it in any of the Cocoa-Touch classes. It takes a rect and an angle as arguments and returns a new CGRect that would encompass the original rect if it were rotated by the given angle.

  Magic Bullet Dave

  – Magic Bullet Dave

  2011-11-13 22:30:38 +00:00

  CommentedNov 13, 2011 at 22:30
• Hi @bmdhacks due to popular demand have added the method in an edit to my original question.

  Magic Bullet Dave

  – Magic Bullet Dave

  2011-11-22 12:19:18 +00:00

  CommentedNov 22, 2011 at 12:19

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