Features of Views Graph Layout

The Graph Layout package of Views provides several ready-to-use layout algorithms. In addition, new layout algorithms can be developed using the generic layout framework of the Graph Layout package.

The Graph Layout package provides the following ready-to-use layout algorithms:

The Graph Layout package provides the following features for using the layout algorithms. (Note that some of these features are not supported by all the algorithms provided with Views.)

  • Capability to fit the layout into a manager view or a user-defined rectangle

  • Capability to take into account the size of the nodes when performing the layout to avoid overlapping nodes

  • Capability to perform the layout using only the nodes and links that are on user-defined layers of the graph

  • Capability to perform the layout only on those parts of the graph that meet user-defined conditions

  • Capability to use non-Views graphers

  • Layout reports providing information concerning the behavior of the layout algorithm

  • Layout-event listeners that can receive and report information during the graph layout

  • A generic framework for customizing the layout algorithms. The following generic parameters are defined. (Note that not all the layout algorithms provided with Views support all these parameters. Whether a generic parameter is supported depends on the particular layout algorithm.)

    • Allowed Time

      This parameter allows the layout algorithm to stop computation when a user-defined time specification is exceeded.

    • Animation

      This parameter allows the layout algorithm to redraw the graph after each iteration or step.

    • Preserve Fixed Nodes

      This parameter allows the layout algorithm to preserve the location of selected nodes. Certain nodes can be specified as fixed and will not be moved when the layout is performed. The layout algorithm can “pin” specified nodes in place.

    • Preserve Fixed Links

      This parameter allows the layout algorithm to preserve the shape of selected links. Certain links can be specified as fixed and will not be reshaped when the layout is performed. The layout algorithm can “pin” specified links in place.

    • Filtering

      The layout algorithms are able to perform the layout using only the nodes and links that are on user-defined layers of the grapher (see Filtering by Layers ) or to exclude nodes and links on an individual basis (see Filtering by Graphic Objects ).

    • Layout Region

      This parameter allows the layout algorithm to control the size of the graph drawing.

    • Random Generator Seed Value

      This parameter allows the layout algorithm to use randomly-generated numbers that can be initialized with a user-defined seed value. These seed values are then used during layout computations to produce different layouts of the graph.

    • Use Default Parameters

      This parameter allows the layout algorithm to return to using default parameter settings after the default settings have been modified.