The image was smallish and not very legible on my 4K monitor, so it is not easy to tell what it is you are trying to display. It's a problem I have with many of the images posted here.

My understanding of item delegates is that they are displayed within the rectangle bounds of the table cell. What you are showing in the center of your screenshot seems to be sized and positioned independently of any particular cell. If you do use a delegate, maybe you can play with paint(), sizeHint(), and clipping to achieve what you want.