Automatic Layout

Automatic layout places your actors and routes your edges automatically to arrive at a pleasing diagram without the hassle of having to move actors around yourself. To invoke automatic layout, click Graph → Automatic Layout, or simply press Control+T (on Windows) or Command+T (on a Mac).

Automatic layout is brought to you by the KIELER project, developed by the Real-time and Embedded Systems Group at the University of Kiel. To find out more, go to http://informatik.uni-kiel.de/rtsys/kieler/.

Configuring Automatic Layout

While the defaults should work well in most cases, there are some options you can configure to influence the results of automatic layout. To configure automatic layout, click Graph → Configure Layout.

• Include decorations: When switched on, objects not connected to anything (and thus probably not being part of the main graph) will be laid out as well. When switched off, those objects are left where they currently are. This is switched on by default.
• Object spacing: Determines the amount of space left between objects in the diagram. Turn up if you find objects to be too close to one another. The default is 10.
• Aspect ratio: Influences the aspect ratio of the layout, that is, how narrow or wide it is going to be. This is only taken into account if include decorations is switched on. Choose a wider aspect ratio for layouts intended to be viewed on a computer screen, and a narrower aspect ratio for layouts intended to be printed. The default value is somewhat to the wide side.
• Interaction mode: Determines how the current layout of a diagram influences the computation of the automatic layout. None computes the automatic layout without regarding the current layout. Cycles takes the current layout into account when determining where to break cycles in the graph. This effectively determines which of the links in a cycle will point leftwards instead of rightwards. Columns tries to place actors below one another that are currently placed that way too. Full also takes the vertical order of such actors into account. The default setting is None.

Expert Options

The configuration dialog by default does not show all available options. To show them all, open the configuration dialog, click Preferences, switch on expert mode, and click OK. You should now see more options than before.

• Use old algorithm: If switched on, the old algorithm originally built into Ptolemy is used to do the automatic layout. This is a good way to obfuscate your diagrams. This is switched off by default.
• Route edges: If switched on, the layout algorithm will compute a routing for the edges instead of relying on the interactive Manhattan edge routing algorithm. Edges will revert back to the interactive edge routing once one of their incident objects is moved. Switching this option off may degrade layout quality. This is switched on by default.
• Minimize edge bends: If switched on, the layout algorithm will try to straighten edges as much as possible, which will almost always increase the height of the diagram. If switched off, the layout algorithm will try to minimize the height at the expense of less straight edges. This is switched on by default.