Automatically arranging objects with the Diagram Layout inspector
Use this inspector to automatically lay out shapes based on the logical relationships established by the connection lines between them.
Select the Automatic layout checkbox to make OmniGraffle lay out the objects on the canvas whenever the connections between them change.
Four layout type buttons indicate the four methods OmniGraffle can use to lay out the diagram. The hierarchical layout creates layers of equally-ranked objects, extending in one direction. The force-directed layout grows in semi-random directions from the center, rather than in one particular direction from the edge. The circular layout tries to arrange sibling shapes in a circle around their parent. The radial layout tries to arrange sibling shapes in arcs around their parent.
When you use a hierarchical layout: The Direction buttons change where the top level objects start, and which way to layer the lower level objects from there.
The Rank Separation field controls how far away each level of objects should be from the next.
The Object Separation field controls how far away each object should be from other objects on the same level.
Use the Selected Object Rank buttons to assign a hierarchical rank to the selected objects. Default lets OmniGraffle decide the rank based on connections, Minimum puts the objects at the top of the hierarchy, Maximum puts the objects at the bottom of the hierarchy, and Same makes sure that the objects end up on the same level. These assignments don't change the directions of connection lines, so you can always select all of your objects and choose Default to return them to normal.
When you use other layout methods: Connection lines can stretch and compress, but you can adjust their average length by dragging the Line Length slider.
In a force-directed layout, you can select individual lines and then click the Custom length checkbox to adjust them separately from the rest of the lines.
The Shape Repulsion slider determines how strongly the shapes try to avoid coming near one another. If the line length and shape repulsion are small enough, shapes can be made to overlap.