crop a zoomed image in ImageView inside scrollView

Question

I already do Lot of efforts from my Side. finally I need help. thanks

Goal : 1) How I fit imageView inside ScrollView

2) How I crop a zoomed Image in inside scro

Answer 1

I had a similar problem recently, I got the solution using the relative idea ( Xa,b = Xa,c - Xb,c )

-(IBAction)crop:(id)sender{

        // F = frame
        // i = image
        // iv = imageview
        // sv = self.view
        // of = offset

        //Frame Image in imageView coordinates
        CGRect Fi_iv = [self frameForImage:self.image inImageViewAspectFit:self.imageView];

        //Frame ImageView in self.view coordinates
        CGRect Fiv_sv = self.imageView.frame;

        //Frame Image in self.view coordinates
        CGRect Fi_sv = CGRectMake(Fi_iv.origin.x + Fiv_sv.origin.x
                                  ,Fi_iv.origin.y + Fiv_sv.origin.y,
                                  Fi_iv.size.width, Fi_iv.size.height);
        //ScrollView offset
        CGPoint offset = self.scrollView.contentOffset;

        //Frame Image in offset coordinates
        CGRect Fi_of = CGRectMake(Fi_sv.origin.x - offset.x,
                                        Fi_sv.origin.y - offset.y,
                                        Fi_sv.size.width,
                                        Fi_sv.size.height);

        CGFloat scale = self.imageView.image.size.width/Fi_of.size.width;

        //the crop frame in image offset coordinates
        CGRect Fcrop_iof = CGRectMake((self.cropView.frame.origin.x - Fi_of.origin.x)*scale,
                                      (self.cropView.frame.origin.y - Fi_of.origin.y)*scale,
                                      self.cropView.frame.size.width*scale,
                                      self.cropView.frame.size.height*scale);

        UIImage *image = [self image:self.imageView.image cropRect:Fcrop_iof];
        // Use this crop image...

You can crop the image using:

//Use this code to crop when you have the right frame
-(UIImage*)image:(UIImage *)image cropRect:(CGRect)frame
{
    // Create a new UIImage
    CGImageRef imageRef = CGImageCreateWithImageInRect(image.CGImage, frame);
    UIImage *croppedImage = [UIImage imageWithCGImage:imageRef];
    CGImageRelease(imageRef);

    return croppedImage;
}

Since you are using the ImageView in Aspect Fit, you need to calculate the image frame inside the imageView

-(CGRect)frameForImage:(UIImage*)image inImageViewAspectFit:(UIImageView*)imageView
{
    float imageRatio = image.size.width / image.size.height;

    float viewRatio = imageView.frame.size.width / imageView.frame.size.height;

    if(imageRatio < viewRatio)
    {
        float scale = imageView.frame.size.height / image.size.height;

        float width = scale * image.size.width;

        float topLeftX = (imageView.frame.size.width - width) * 0.5;

        return CGRectMake(topLeftX, 0, width, imageView.frame.size.height);
    }
    else
    {
        float scale = imageView.frame.size.width / image.size.width;

        float height = scale * image.size.height;

        float topLeftY = (imageView.frame.size.height - height) * 0.5;

        return CGRectMake(0, topLeftY, imageView.frame.size.width, height);
    }
}

I hope this code can work for you as it worked for me.

Best,

Rafael.