Question

I’am doing an app something like this: You load a photo and you put images over it, like balloons, etc..

When I try to merge one of this over images with only resize it works fine. Like 10px more than it should be but no problem.

The problem comes when you rotate the image [UIImageView] it appears much bigger that the image its, I try allot of things and nothing. I leave the code. I hope someone could help.

Note: The image size its inside UIImageView, then multiplied it by the scale of the main image

- (UIImage *)mergeImage:(UIImageView *)mainImage withImageView:(UIImageView *)imageView {

    UIImage *temp = imageView.image;
    UIImage *tempMain = mainImage.image;

    CGFloat mainScale = [self imageViewScaleFactor:mainImage];
    CGFloat tempScale = 1/mainScale;
    NSLog(@"%f", tempScale);

    //Rotate UIIMAGE
    UIGraphicsBeginImageContext(temp.size);
    CGContextRef ctx = UIGraphicsGetCurrentContext();
    CGAffineTransform transform = CGAffineTransformIdentity;
    transform = CGAffineTransformTranslate(transform, temp.size.width/2, temp.size.height/2);    
    CGFloat angle = atan2(imageView.transform.b, imageView.transform.a);    
    transform = CGAffineTransformRotate(transform, angle);
    transform = CGAffineTransformScale(transform, 1.0, -1.0);
    CGContextConcatCTM(ctx, transform);
    // Draw the image into the context
    CGContextDrawImage(ctx, CGRectMake(-temp.size.width/2, -temp.size.height/2, temp.size.width, temp.size.height), temp.CGImage);
    // Get an image from the context
    temp = [UIImage imageWithCGImage: CGBitmapContextCreateImage(ctx)];


    NSLog(@"%f %f %f", mainScale, mainImage.frame.size.width, mainImage.frame.size.height);

    UIGraphicsBeginImageContextWithOptions(tempMain.size, NO, 1.0f);

    //Get imageView size & position 
    NSLog(@"%f %f %f %f", imageView.frame.origin.x, imageView.frame.origin.y, imageView.frame.size.width, imageView.frame.size.height);

    CGFloat offsetX = 0;
    CGFloat offsetY = -44;

    if (tempMain.size.height > tempMain.size.width) {
        offsetX = ((tempMain.size.width * mainScale) - 320)/2;
    }else{
        offsetY = ((tempMain.size.height * mainScale) - 416)/2;
        offsetY -= 44;
    }

    CGFloat imageViewX = (imageView.frame.origin.x + offsetX) * tempScale;
    CGFloat imageViewY = (imageView.frame.origin.y + offsetY) * tempScale;
    CGFloat imageViewW = imageView.frame.size.width * tempScale;
    CGFloat imageViewH = imageView.frame.size.height * tempScale;


    CGRect tempRect = CGRectMake(imageViewX, imageViewY, imageViewW, imageViewH);


    [tempMain drawAtPoint:CGPointZero];
    [temp drawInRect:tempRect];

    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    return newImage;
}

Thanks

Answer 1

This is the solution that works for me

Merging a previosly rotated by gesture UIImageView with another one. WYS is not WYG

I just take a photo to the main screen and then crop it to the size of the photo, its faster, and clean. and the resolution it ok if the apps runs in retina in a normal device isn’t too good. And you need to prepare that code to work in retina & non-retina