Tutorial Exercise 2.2: Horizontal Fine-Tuning
Now we will modify the automatically calculated graph layout with the mouse. This kind of direct manipulation is called fine-tuning. To do this, select some graph node with the mouse. Then move the mouse slowly to the left and to the right by still holding down the left mouse button. This is called dragging. Be careful not to drag the node up or downwards to the next or previous level. This will cause a vertical fine tuning which is discussed in the next exercise. By moving the mouse to the left and to the right, you can see how the position of the node is changed. Move the node towards its left or right neighbour node at the same level. When you have reached the minimal distance, the neighbour node is moved as well in the same direction, and so on.
We will now manually change the order of nodes at a level. Select menu Options/Layout Algorithm to open the layout algorithm dialog. Under "Manual Layout" you can find three radio buttons to set the constraints of the horizontal fine tuning. The current setting is "Preserve Node Order" to move a touched neighbour node as well. This is what we have just seen before. Now select button "Modify Node Order" and press the ok push button afterwards. Move some node again towards its left or right neighbour node. This time, when you have reached the minimal distance, both nodes will exchange their positions. This operation allows you to change the order of nodes at a level, for example to eliminate obvious edge crossings by hand which have been left by the graph layout algorithm.
You might have noticed that by selecting the "Modify Node Order" constraint, the last group of buttons on the icon bar has been modified, too. For more comfort, the last three radio buttons on the icon bar can also be used to set the fine tuning constraints.
Buttons of the icon bar to control fine tuning
So select the last button (the one with STOP) of the base window's icon bar to set the "Fixed Neighbour Nodes" constraint. By moving some node, you can see that this setting protects the position of the left and right neighbour node when they are touched by a dragged node.
End of Exercise 2.2. Go back to the Section 2 Overview.
