View Full Version : Resizing UIImage?

May 25, 2011, 07:02 AM
I have a UIImage set by a UIImagePickerController, but the image needs to be exactly 115x115. How would I detect if the image is square, and if it is, scale it up or down to 115x115, and if it isn't square, crop it to get a square (but include most of the image), then scale it down to 115x115? I've been looking around online, and I can't find much.

May 25, 2011, 07:20 AM
When I was looking for it, google was full of it, that's 2 weeks ago.
This is my code

- (void) imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
// Access the uncropped image from info dictionary
UIImage* image = (UIImage* ) [info objectForKey:@"UIImagePickerControllerOriginalImage"];
imageFromCamera = [image copy];

// Save image
UIImageWriteToSavedPhotosAlbum(imageFromCamera, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);
[picker release];

CGSize size = CGSizeMake(340, 480);
UIGraphicsBeginImageContext(size);// a CGSize that has the size you want
[imageFromCamera drawInRect:CGRectMake(0,0,size.width,size.height)];
//image is the original UIImage
UIImage* newImage = UIGraphicsGetImageFromCurrentImageContext();

imageData = UIImageJPEGRepresentation(newImage, 0.5);
imageDataTotal = [imageData copy];

UIImage *imageFromCamera;
NSData *imageData;
NSData *imageDataTotal;

I got no time to explain, but i'm sure u can handle it.

May 25, 2011, 07:25 PM
To check of the size of the returned UIImage, use its size property. From that you can do any calculation to create a Rect that will be used to return a square representation.

I haven't used the image picker controller much, but you may want to try the following to get back a square of your image. I'll leave it to you read the documentation and integrate as needed. Combined with jnoxx's post, this should get the result you're looking for. You do this before the drawInRect: method.

I believe jnoxx's code assumes it is being run on the main thread, as UIGraphicsBeginImageContext suggest that to me.

- (void) imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
UIImage* image = (UIImage* ) [info objectForKey:@"UIImagePickerControllerOriginalImage"];

// Calculate a new rect for the pixels of interest. Assuming a 960x720 image from an iPod touch camera.
// The horizontal middle pixels.
CGRect sqrRect = CGRectMake(120,0,720,720);

// A retained pointer because the word Create in this function indicates that. We'll release below.
CGImageRef squareCGImage = CGImageCreateWithImageInRect( image.CGImage, sqrRect);

// An auto released UIImage via class method, so no need to release.
// Can skip the need for a UIImage if you use CGContextDrawImage().
UIImage* squareUIImage = [UIImage imageWithCGImage: squareCGImage];

// Release after assignment to UIImage or use in CGContextDrawImage(), and last use.