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y.base
Interface GraphListener

All Superinterfaces:
java.util.EventListener
All Known Implementing Classes:
Graph2DUndoManager, Selections.SelectionStateObserver

public interface GraphListener
extends java.util.EventListener

The listener interface for receiving graph events. A class that is interested in processing a graph event implements this interface. The object created with that class is then registered with a graph. When the graph structure changes, the listener object's onGraphEvent method is invoked.

The listener object's onGraphEvent method is also invoked on so-called PRE and POST events emitted by the graph. These events signal that a (possibly empty) sequence of graph events is about to be emitted (PRE event) or that the sequence is completed (POST event).

For example, if a node is about to be removed from a graph, then the following sequence of graph events can be observed:

  1. a PRE event
  2. a (possibly empty) sequence of edge removal events
  3. the actual node removal event
  4. a POST event
The POST event concludes the logically coherent sequence of structural graph changes that has been opened by the PRE event.

PRE and POST events must constitute a well-formed bracket-structure, e.g., ( ( () ) () ).

 

Method Summary
 void onGraphEvent(GraphEvent e)
          Invoked when the structure of the graph has changed.
 

Method Detail

onGraphEvent

void onGraphEvent(GraphEvent e)
Invoked when the structure of the graph has changed. The code written for this method performs the operations that need to occur when the graph changes.


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