Saving 2 UIImages to one while saving rotation, resize info and its quality

I want to save 2 UIImages that are moved, resized and rotated by user. The problem is i dont want to use such function as any ‘printscreen one’, because it makes both images to lose a lot from their quality (resolution).

Atm i use something like this:

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  • UIGraphicsBeginImageContext(image1.size);
    [image1 drawInRect:CGRectMake(0, 0, image1.size.width, image1.size.height)];
    [image2 drawInRect:CGRectMake(0, 0, image1.size.width, image1.size.height)];
    UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    

    However ofc it just adds two images, their rotation, resizing and moving isn’t operated here. Can anybody help with considering these 3 aspects in coding? Any help is appreciated!

    My biggest thanks in advance 🙂

    EDIT: images can be rotated and zoomed by user (handling touch events)!

    2 Solutions Collect From Internet About “Saving 2 UIImages to one while saving rotation, resize info and its quality”

    You have to set the transform of the context to match your imageView’s transform before you start drawing into it.

    i.e.,

    CGAffineTransform transform = CGAffineTransformIdentity;
    transform = CGAffineTransformTranslate(transform, boundingRect.size.width/2, boundingRect.size.height/2);
    transform = CGAffineTransformRotate(transform, angle);
    transform = CGAffineTransformScale(transform, 1.0, -1.0);
    
    CGContextConcatCTM(context, transform);
    
    // Draw the image into the context
    CGContextDrawImage(context, CGRectMake(-imageView.image.size.width/2, -imageView.image.size.height/2, imageView.image.size.width, imageView.image.size.height), imageView.image.CGImage);
    
    // Get an image from the context
    rotatedImage = [UIImage imageWithCGImage: CGBitmapContextCreateImage(context)];
    

    and check out Creating a UIImage from a rotated UIImageView.

    EDIT: if you don’t know the angle of rotation of the image you can get the transform from the layer property of the UIImageView:

    UIGraphicsBeginImageContext(rotatedImageView.image.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGAffineTransform transform = rotatedImageView.transform;
    transform = CGAffineTransformScale(transform, 1.0, -1.0);
    CGContextConcatCTM(context, transform);
    
    // Draw the image into the context
    CGContextDrawImage(context, CGRectMake(0, 0, rotatedImageView.image.size.width, rotatedImageView.image.size.height), rotatedImageView.image.CGImage);
    
    // Get an image from the context
    UIImage *newRotatedImage = [UIImage imageWithCGImage: CGBitmapContextCreateImage(context)];
    
    UIGraphicsEndImageContext();
    

    You will have to play about with the transform matrix to centre the image in the context and you will also have to calculate a bounding rectangle for the rotated image or it will be cropped at the corners (i.e., rotatedImageView.image.size is not big enough to encompass a rotated version of itself).

    Try this:

    UIImage *temp = [[UIImage alloc] initWithCGImage:image1 scale:1.0 orientation: yourOrientation];
    [temp drawInRect:CGRectMake(0, 0, image1.size.width, image1.size.height)];
    

    Similarly for image2. Rotation and resizing are handled by orientation and scale respectively. yourOrientation is a UIImageOrientation enum variable and can have a value from 0-7(check this apple documentation on different UIImageOrientation values). Hope it helps…

    EDIT: To handle rotations, just write the desired orientation for the rotation you require. You can rotate 90 deg left/right or flip vertically/horizontally. For eg, in the apple documentation, UIImageOrientationUp is 0, UIImageOrientationDown is 1 and so on. Check out my github repo for an example.