Question

I have an arbitrary tree structure of nodes. I want to draw this tree to provide users a visual representation. I need to recurse over the tree and for each node add a graphic item to a list, and then just draw the list of items once tree recursion has finished. The recursion and drawing of items is of course trivial – what’s a bit more complicated is how to position the graphic nodes so they do not overlap with other branches.

I’m using Android but that is not important – I’m looking for an approach, possibly an algorithm that can maintain a picture of 2D space as it passes over the tree so it just allocates the most appropriate coordinates for each node as it makes the pass.

Any ideas?

Update

This is the article with the best and most complete algorithm.

Answer 1

I would try the Walker algorithm. Here’s an academic paper on the algorithm. If you want code to look at, look at the NodeLinkTreeLayout in Prefuse. Prefuse is open source so there shouldn’t be any problems adapting the code to your situation as long as you follow the terms of the license.