Additional information for expert users

Interface parameters

Some layout classes allow an interface as input parameter. For instance, the method setNodeBoxInterface sets an IlvNodeBoxInterface (see IlvLinkLayout, IlvShortLinkLayout, and so on). If an application uses a node box class that implements the node box interface, this can only be stored to an .ivl file if the node box class also implements the IlvPersistentObject interface. Otherwise, the node box class is not saved to the .ivl file.

Compatibility issues

An .ivl file that contains layout properties can be loaded only when the package ilog.views.graphlayout and its subpackages are available.

Defining your own type of layout

If you develop your own layout algorithms by subclassing IlvGraphLayout and want to save the layout parameters of your own layout algorithm in .ivl files, you should subclass IlvGraphLayoutGrapherProperty, IlvGraphLayoutNodeProperty, and IlvGraphLayoutLinkProperty, see Defining your own type of layout. You can find example code by referring to these classes in the Java™ API Reference Manual. You should also override the following methods of IlvGraphLayout to return your subclasses:

protected IlvGraphLayoutGrapherProperty createLayoutGrapherProperty(
    String name, boolean withDefaults)
{
    return new MyOwnLayoutGrapherProperty(name, this, withDefaults);
}
protected IlvGraphLayoutNodeProperty createLayoutNodeProperty(
    String name, IlvGraphic node, boolean withDefaults)
{
    return new MyOwnLayoutNodeProperty(name, this, node, withDefaults);
}
protected IlvGraphLayoutLinkProperty createLayoutLinkProperty(
    String name, IlvGraphic link, boolean withDefaults)
{
    return new MyOwnLayoutLinkProperty(name, this, link, withDefaults);
}

Further applications of layout properties

The layout properties can be serialized. If you prefer to use the standard serialization mechanism of Java instead of .ivl files, it is recommended to use the layout properties as well because it guarantees that only the parameters are serialized and not any temporary data that may exist in the layout instance.

The following code shows an easy way to copy the parameter setting from layout1 to layout2 :

IlvGrapherAdapter adapter1 = (IlvGrapherAdapter)layout1.getGraphModel();
IlvGrapherAdapter adapter2 = (IlvGrapherAdapter)layout2.getGraphModel();
adapter1.saveParametersToNamedProperties(layout1, true);
adapter2.loadParametersFromNamedProperties(layout2);

The following code shows an easy way to undo temporary changes of layout parameters:

IlvGrapherAdapter adapter = (IlvGrapherAdapter)layout.getGraphModel();
adapter.saveParametersToNamedProperties(layout, true);
... change layout parameters
... work with changed parameters
// restore the layout parameters as they were before 
adapter.loadParametersFromNamedProperties(layout);