ilog.views.graphlayout

Class IlvGraphLayout

java.lang.Object

ilog.views.graphlayout.IlvGraphLayout

Direct Known Subclasses:

ilog.views.graphlayout.basic.IlvBasicLinkStyleLayout, IlvBusLayout, IlvGridLayout, IlvHierarchicalLayout, IlvLinkLayout, IlvLongLinkLayout, IlvShortLinkLayout, IlvSpringEmbedderLayout, IlvTreeLayout

public abstract class IlvGraphLayout
extends java.lang.Object

The base class of the Graph Layout algorithms.

JViews provides special support for applications that need to display graphs (also called networks) of nodes and links. Using the IlvGrapher class, any graphic object can be defined to behave like a node and can be connected to other nodes with links, which themselves can have many different forms. Used in conjunction with layout algorithms, this feature is often used to create network topologies for telecommunications networks and system management applications.

The usage of the Graph Layout algorithms is not restricted to applications using an IlvGrapher to store and display the graph. You can use external graph data source structures. This is achieved through the generic graph model (see IlvGraphModel). This abstract class defines the API that is necessary to allow the graph layout algorithms to work. To use an external graph, all you need to do is to implement an adapter that connects the graph with the generic graph model. For details, see the class IlvGraphModel.

The class IlvGraphLayout is abstract and cannot be used directly. You must use one of its concrete subclasses.

You can also create your own subclasses to implement other layout algorithms. Note that, in order to be applied on any graph, the layout algorithms must be written using the API of IlvGraphModel instead of the API of IlvGrapher.

The class contains layout parameters or options that can be useful for different layout algorithms. The implementation of the #layout(boolean) method is solely responsible for whether or not the current settings of the parameters are taken into account.

Note that all layout parameters that are specific to nodes or links, such as the "fixed" attribute (see #setFixed(Object, boolean), #isFixed(Object)), can be accessed only while the graph that contains the nodes or links is attached to the layout instance. Also, if the attached graph model is an IlvGrapherAdapter, layout parameters that are specific to nodes or links must be set after specifying filtering rules (see IlvGrapherAdapter.addLayer(ilog.views.IlvManagerLayer), IlvGrapherAdapter.setFilter(ilog.views.graphlayout.IlvLayoutGraphicFilter)).

If the documentation does not indicate a different coordinate space, all dimensional parameters are expressed in the same coordinate space as the position and dimension of the nodes and the link points. In particular, when laying out an IlvGrapher, the dimensional parameters are expressed by default in the coordinate space of the manager, not in the coordinate space of the view (IlvManagerView). However, optionally, the coordinate space of the view can be used. For details, see #setCoordinatesMode.

If you want to perform the layout on a subset of the nodes and links of and IlvGrapher, you can use a filter (see the class IlvLayoutGraphicFilter and the method IlvGrapherAdapter.setFilter(ilog.views.graphlayout.IlvLayoutGraphicFilter), or the method IlvGrapherAdapter.addLayer(ilog.views.IlvManagerLayer)). The filter allows the layout algorithm to determine, for each node and link of a graph, if it must be taken into account or can be ignored.

If you want to perform the layout recursively over a nested graph (for instance, an IlvGrapher contained in another IlvGrapher), you can use the method #performLayout(boolean, boolean, boolean) and pass true for the traverse argument. Alternatively, you can use the method #PerformLayout(IlvGraphModel, IlvLayoutProvider, boolean, boolean, boolean).

To learn more about the layout algorithms and the corresponding IlvGraphLayout subclasses, read the sections of the Reference Manual describing those classes and the JViews Graph Layout User's Manual.

Note that when implementing a subclass of IlvGraphLayout, the initialization of all instance variables of the subclass needs to be done in the overridden implementation of the method #init(). This is to prevent execution of methods of the subclasses before the initialization of the instance variables of the subclasses.

Note also that you must call the method #detach() when you no longer need the layout instance, otherwise some objects may not be garbage collected. This is necessary only if the layout instance is directly created by your code. Calling #detach() is not necessary if the layout instance is created internally by the JViews Graph Layout library, when using an IlvDefaultLayoutProvider for recursive layout.

CSS example:

This class cannot be instantiated because it is an abstract class.

See Also:

IlvBusLayout, IlvCircularLayout, IlvGridLayout, IlvHierarchicalLayout, IlvLinkLayout, IlvShortLinkLayout, IlvLongLinkLayout, IlvRandomLayout, IlvSpringEmbedderLayout, IlvTopologicalMeshLayout, IlvTreeLayout, IlvUniformLengthEdgesLayout

Method Summary

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait