ilog.views.graphlayout

Interface IlvLayoutProvider

All Known Implementing Classes:

IlvDefaultLayoutProvider, IlvRecursiveLayoutProvider

public interface IlvLayoutProvider

An interface used to specify the layout instance to be used for laying out a given graph.

This interface is mainly useful when laying out nested graphs, that is, graphs containing nodes that are other graphs.

The following code is an example of the implementation of the method getGraphLayout(ilog.views.graphlayout.IlvGraphModel) . In this example, the criteria used for choosing the layout instance is the value of a property stored in advance in the graph model:

 public IlvGraphLayout getGraphLayout(IlvGraphModel graphModel)
 {
   Object prop = graphModel.getProperty("layout type");
   // if none, return null (no layout needed for this graph)
   if (!(prop instanceof String))
     return null;
 
   IlvGraphLayout layout = null;
   String name = (String)prop;
 
   if (name.equals("tree"))
     layout = new IlvTreeLayout();
   else if (name.equals("flow");
     layout = new IlvHierarchicalLayout();
   else
     throw new RuntimeException("unsupported layout choice: " + name);

   layout.attach(graphModel);
 
   return layout;
 }
 

Of course, many other criteria can be used.

Note that in many cases, it is simpler either to use the subclass IlvDefaultLayoutProvider as is, or to subclass it, instead of directly implementing this interface.

Since:

JViews 5.0

See Also:

IlvDefaultLayoutProvider, IlvGraphLayout.performLayout(), IlvGraphModel.performLayout(IlvLayoutProvider, boolean, boolean, boolean)

Method Summary

Modifier and Type	Method and Description
IlvGraphLayout	getGraphLayout(IlvGraphModel graphModel) Returns the layout instance to be used for laying out graphModel.

Method Detail

getGraphLayout

IlvGraphLayout getGraphLayout(IlvGraphModel graphModel)

Returns the layout instance to be used for laying out graphModel. The layout instance that is returned must be attached to graphModel via the method IlvGraphLayout.attach(IlvGraphModel) .

Note that this method must return a different layout instance for each subgraph. The same layout instance should not be returned for two different subgraphs of the same graph. Also, the layout instance returned for a subgraph should not be the same as the one returned for the topmost graph.

This method is called during the recursive layout of a nested graph using the methods IlvGraphLayout.PerformLayout(ilog.views.graphlayout.IlvGraphModel, ilog.views.graphlayout.IlvLayoutProvider, boolean, boolean, boolean) and IlvGraphModel.performLayout(IlvLayoutProvider, boolean, boolean, boolean). If the method returns null, this means that no layout is needed for graphModel.

Parameters:

graphModel - The graph model (eventually the graph model that encapsulates the topmost grapher).

Returns:

The layout instance to be used for graphModel, or null if no layout is need for graphModel.

See Also:

IlvGraphLayout.attach(IlvGraphModel), IlvGraphLayout.attach(ilog.views.IlvGrapher)