Deep Zoom - Zooming and centering image to fill the Deep Zoom screen

One of the readers (see comments here) wanted to zoom and center an image from the collection in such a way that it would fill the screen. Here is the code snippet that will fulfill this requirement. I haven't applied this to an example yet, but I will, if there is enough interest.

public void ZoomFullAndCenterImage(int subImageIndex)
{
    Rect subImageRect = GetSubImageRect(subImageIndex);
    Rect imageRectElement = msiLogicalToElementRect(GetSubImageRect(subImageIndex));
    
    // Calculate the zoom factor such that the image will fill up the entire screen
    double zoomFactor = (msi.Width / imageRectElement.Width) < (msi.Height / imageRectElement.Height) ? 
                                        msi.Width / imageRectElement.Width : msi.Height / imageRectElement.Height;
    
    // Center the image
    DisplaySubImageCentered(subImageIndex);
    // Use the mid point of the image to zoom from
    msi.ZoomAboutLogicalPoint(zoomFactor, (subImageRect.Left+subImageRect.Right)/2, (subImageRect.Top+subImageRect.Bottom)/2);
}