Adding custom background gradient to gridBackground

I am trying to add custom gradient to chart grid background, something like this:


I have done this by putting my view behind the chart view. I have printed _viewPortHandler.contentRect, and from there i positioned my view. Now, while this works, it is not most ideal solution. I would like to somehow at runtime have option to get gridview size, but since _viewPortHandler is internal, I see no option to do this.

Is there some better way to achieve this?