Draw link into port

I have a port that is image based and has a transparent part around the edges. My link draws up the edges of the port. I want the link to be able to draw into the port so it looks connected. How do I do this?

We don’t have any way of computing the edge of an image. GoPort does have overridables
GetFromLinkPoint and GetToLinkPoint to define the from and to points if you have enough
information to do that.