Crop Area of UIImage with subview rect

Question

This is my dilemma. I built a QR Scanner and need to crop out the top left colored portion of the QR Code into it's own image for further processing.

The blue bounding box is a subview of self.view, and the red bounding box is a subview of the blue bounding box. Im using AVCaptureStillImageOutput to generate the image; code below..

    [_imageOutput captureStillImageAsynchronouslyFromConnection:videoConnection completionHandler: ^(CMSampleBufferRef imageSampleBuffer, NSError *error) {

     NSData *jpegData = [AVCaptureStillImageOutput jpegStillImageNSDataRepresentation:imageSampleBuffer];
     UIImage *takenImage = [UIImage imageWithData:jpegData];

     //crop and process takenImage
     // tried utilizing convertRect:toView: and crop result is completely wrong.
     CGRect redFrame = [_colorBox convertRect:_colorBox.bounds toView:self.view];
 }];

Id really appreciate any assistance with this as I've been at it for days, and am at my wits end. Thanks!

@TejaNandamuri Desired rect being that of the red bordered bounding box. How would I go about that?..I know how to turn the UIView into an image as a screenshot..but the rest..? — skram, Mar 20 '16 at 23:41
http://stackoverflow.com/questions/2214957/how-do-i-take-a-screen-shot-of-a-uiview @skram — Teja Nandamuri, Mar 21 '16 at 13:02

score 0 · Answer 1 · edited Mar 20 '16 at 23:06

0

CGSize screenS = supperFrame.size;

CGFloat delX = image.size.width / screenS.width;
CGFloat delY = image.size.height / screenS.height;

CGRect sourceRect = CGRectMake(frame.origin.x * delX, frame.origin.y * delY, frame.size.width * delX, frame.size.height * delY);
CGImageRef imageRef = CGImageCreateWithImageInRect(image.CGImage, sourceRect);


UIImage *cropImage = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
return cropImage;

edited Mar 20 '16 at 23:06

Misa Lazovic

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answered Mar 20 '16 at 22:55

Khoren Asatryan

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Can you apply your solution to my example code? I tried implementing it and don't get the desired results. Thanks! @khoren-asatryan – skram Mar 20 '16 at 23:10

score 0 · Answer 2 · edited Mar 22 '16 at 10:26

- (UIImage *)imageAtFrameImage:(UIImage *)image creopFrame:(CGRect)creopFrame supperFrame:(CGRect)supperFrame {

    CGSize screenS = supperFrame.size;

    CGFloat delX = image.size.width / screenS.width;
    CGFloat delY = image.size.height / screenS.height;

    CGRect sourceRect = CGRectMake(creopFrame.origin.x * delX, creopFrame.origin.y * delY, creopFrame.size.width * delX, creopFrame.size.height * delY);
    CGImageRef imageRef = CGImageCreateWithImageInRect(image.CGImage, sourceRect);


    UIImage *cropImage = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);
    return cropImage;
}

creopFrame your cub frame, supperFrame your image view Frame, — Khoren Asatryan, Mar 21 '16 at 07:42

Crop Area of UIImage with subview rect

2 Answers2