CODEWITHSUNDEEP
objective-cipaduiviewios6screenshot
Alex Stone
Alex Stone

Reputation: 47348

iPhone iOS how to take a screenshot programmatically with rotation?

I know how to take a regular rectangular screenshots of the iPhone/iPad screen (code below). However, I'm looking for a way to get a screenshot that is rotated by an arbitrary number of degrees

How can I take a screenshot of UIView using a rectangle that is rotated arbitrarily?

    //this is the rotation of the rectangle
        NSNumber* savedRotation = [NSNumber numberWithFloat: 0.35]; //radians, get the real number from a gesture recognizer

        //create a screenshot
        CGSize screenshotSize;

//screenshot size has to be adjusted for the rotation, or multiplied by the square root of 2
        if( UIDeviceOrientationIsLandscape([[UIApplication sharedApplication]statusBarOrientation]))
        {
            screenshotSize  =  CGSizeMake(1024,768);
        }else
        {
            screenshotSize  =  CGSizeMake(768, 1024);

        }

        if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)])
            UIGraphicsBeginImageContextWithOptions(screenshotSize, NO, [UIScreen mainScreen].scale);


        else
            UIGraphicsBeginImageContext(screenshotSize);

        CGContextRef context = UIGraphicsGetCurrentContext();
        CGContextSaveGState(context);

    //this does the proper rotation, but there's some kind of extra translation required to make it capture what's under the rectangle
        CGContextRotateCTM(context, -savedRotation.floatValue);
        [self.view.layer renderInContext:UIGraphicsGetCurrentContext()];


        UIImage *screenshot = UIGraphicsGetImageFromCurrentImageContext();

        CGContextRestoreGState(context);

Here's the result of the code above, it seems to partially work, but requires some extra translation of the CTM to perfectly match the capture rectangle. Additionally, I need to change the bounds of the context to be wider ( probably 1024 * sqrt(2) width and height) to allow for any rotation without clipping.

enter image description here

Upvotes: 4

Views: 1133

Answers (1)

Priest
Priest

Reputation: 242

Here's the code required to crop an image based on a simple rectangle.

I'm not sure how you're tracking your rectangle's rotation, but it should be pretty straight forward from there to apply this solution;

// Create rectangle from middle of current image
CGRect croprect = CGRectMake(image.size.width / 4, image.size.height / 4 ,
(image.size.width / 2), (image.size.height / 2));

// Draw new image in current graphics context
CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], croprect);

// Create new cropped UIImage
UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];

CGImageRelease(imageRef);

Hope it helps.

Upvotes: 1

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