[Closed] Impossible cycle computer function?

Maybe I'm looking for the wrong function, maybe I don't really need it?

For navigation I would like:

My Speed - most computers have this.
Stopwatch - Again most have.

I can combine these to find a round about distance traveled.

I will combine this with looking at a map and features, but I thought a cycle computer would have a distance button, so when I knew I was at a point I would reset the distance counter and then could use that as reference, so if I knew the next turning should be 1km away - when the computer hit 1km I would keep an eye out.

So far all the computers I've looked at have a trip distance (I assume the whole trip) and a total distance (as in lifetime of computer?)

Would I basically just do lots of little trips, or is there another function?

Does anyone know a cycle computer with this function or have experience using one as a navigation aid?

Thanks for all the help!!

Jay