ilog.views.graphlayout.labellayout

Class IlvLabelLayout

java.lang.Object

ilog.views.graphlayout.labellayout.IlvLabelLayout

Direct Known Subclasses:

IlvAnnealingLabelLayout

public abstract class IlvLabelLayout
extends java.lang.Object

The base class of the Label Layout algorithms.

A Label Layout algorithm has the task to place labels at graphic objects such that the labels are well readable. Labels should not overlap each other or overlap the graphic objects of the IlvManager . JViews provides special support for this task. Using the IlvManager class, any graphic object can be defined to behave like a label and can be automatically placed as a decoration close to any graphic obstacle object.

The Label Layout algorithms are not restricted to be used only with IlvManager. They can be used with any data structure. This is achieved an IlvLabelingModel. This abstract class defines the API that is necessary to allow the label layout algorithms to work. To use your own data structures, all you need to do is to implement an adapter (a bridge) that connects your graphic data with the generic labeling model. For details, see the class IlvLabelingModel.

The class IlvLabelLayout is abstract and cannot be used directly. You must use one of its subclasses provided in this package.

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

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.

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 labels and obstacles. In particular, when laying out an IlvManager , the dimensional parameters are expressed in manager coordinates, not in manager view coordinates. However, optionally, the coordinate space of the view can be used. For details, see #setCoordinatesMode(int).

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

Note that the initialization of all instance variables of the subclasses 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.

CSS example:

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

See Also:

IlvAnnealingLabelLayout

Method Summary

Methods inherited from class java.lang.Object

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