I updated the user interface of the Rocs graph layout plugin. Now, each layout algorithm corresponds to a tab. See below the tab for the Radial Tree Layout.
Using the same algorithm, the graph layout plugin can draw rooted trees and free trees (trees without a root). The next two figures show the same tree represented as a free tree and as a rooted tree, respectively.
The root vertex can be selected by the user or determined automatically. Currently, a center of the tree is used for automatic root selection. The user can also control the distance between nodes by changing the node separation. Tomorrow I will finish the tests and add some code to check if the graph being laid out is a tree.
Note: I decided to change the title of my GSoC posts to reflect the fact that I am not being able to follow a weekly schedule.