How to change a NodeView to show a custom view for a node? I (MarcioSilva) have only a part of the answer. :-)

Here some discussions about my experiences with this and the problems I found. Feel free to add more information to this page.

I started my hack using as a base, the PetalNode from the MDNodes plugin. 

Then I started to make my modifications in the {{{drawNodeView()}}} method. I tried to use the {{{PPath}}} class, but I could not find a way to draw arcs of circles with it. Then I overrrided the {{{paint()}}} method from {{{PPath}}}, like this:
{{{#!java
PPath n = new PPath() {
    public void paint(PPaintContext aPaintContext) {

        Arc2D.Double arc = new Arc2D.Double();
        arc.setArcByCenter(0,0,40,0,300,Arc2D.PIE);
        Graphics2D g2 = aPaintContext.getGraphics();

        g2.setPaint(Color.red);
        g2.fill(arc);
    }
};
}}}

Then I had trouble selecting nodes that have the new shape. This was fixed with this modification in the {{{selected()}}} method:
{{{#!java
public void select() {
    selected = true;
    nodeView.setSelected(true); // added by mrsva
    drawSelected();
}
}}}

and with the use of {{{setPathToEllipse()}}} and {{{setBounds()}}} in the {{{drawNodeView()}}} method.

also the ''context menu'' doesn't work in the nodes with the changed shape. I tried to change:
{{{#!java
view.addContextMethod( "class phoebe.PNodeView",                      // <-- changed line
                       "csplugins.mrsva.metadata.MDMenus",
                       "getMetaDataMenu",
                        new Object[] { view } ,
                        CytoscapeInit.getClassLoader() );
}}}
to:
{{{#!java
view.addContextMethod( "class csplugins.mrsva.metadata.PieChartNode", // <-- changed line
                       "csplugins.mrsva.metadata.MDMenus",
                       "getMetaDataMenu",
                        new Object[] { view } ,
                        CytoscapeInit.getClassLoader() ); 
}}}
but this didn't helped.

Another problem, which affects the use of custom node views with the MetaNodes plugin, is that Cytoscape raises an exception when one tries to remove a node with the custom node view.

When I tried to remove such nodes (with custom view), I received the following exception:
{{{
 java.lang.ClassCastException
        at phoebe.PGraphView.removeNodeView(PGraphView.java:1166)
        at cytoscape.view.BasicGraphViewHandler.removeGraphViewNodes(BasicGraphViewHandler.java:388)
        at cytoscape.view.BasicGraphViewHandler.handleGraphPerspectiveEvent(BasicGraphViewHandler.java:76)
        at cytoscape.view.GraphViewController.graphPerspectiveChanged(GraphViewController.java:403)
        at fing.model.GraphPerspectiveChangeListenerChain.graphPerspectiveChanged(GraphPerspectiveChangeListenerChain.java:38)
        at fing.model.FGraphPerspective$GraphWeeder.hideNode(FGraphPerspective.java:1180)
        at fing.model.FGraphPerspective$GraphWeeder.access$300(FGraphPerspective.java:1133)
        at fing.model.FGraphPerspective.hideNode(FGraphPerspective.java:230)
        at metaNodeViewer.model.AbstractMetaNodeModeler.undoModel(AbstractMetaNodeModeler.java:600)
        at metaNodeViewer.MetaNodeUtils.uncollapseNodes(MetaNodeUtils.java:196)
        at metaNodeViewer.actions.UncollapseSelectedNodesAction.uncollapseSelectedNodes(UncollapseSelectedNodesAction.java:126)
        at metaNodeViewer.actions.UncollapseSelectedNodesAction.actionPerformed(UncollapseSelectedNodesAction.java:88)
        at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:1786)
        at javax.swing.AbstractButton$ForwardActionEvents.actionPerformed(AbstractButton.java:1839)
        at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:420)
        at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:258)
        at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:245)
        at java.awt.AWTEventMulticaster.mouseReleased(AWTEventMulticaster.java:231)
        at java.awt.Component.processMouseEvent(Component.java:5100)
        at java.awt.Component.processEvent(Component.java:4897)
        at java.awt.Container.processEvent(Container.java:1569)
        at java.awt.Component.dispatchEventImpl(Component.java:3615)
        at java.awt.Container.dispatchEventImpl(Container.java:1627)
        at java.awt.Component.dispatchEvent(Component.java:3477)
        at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:3483)
        at java.awt.LightweightDispatcher.processMouseEvent(Container.java:3198)
        at java.awt.LightweightDispatcher.dispatchEvent(Container.java:3128)
        at java.awt.Container.dispatchEventImpl(Container.java:1613)
        at java.awt.Window.dispatchEventImpl(Window.java:1606)
        at java.awt.Component.dispatchEvent(Component.java:3477)
        at java.awt.EventQueue.dispatchEvent(EventQueue.java:456)
        at java.awt.EventDispatchThread.pumpOneEventForHierarchy(EventDispatchThread.java:201)
        at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:151)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:145)
        at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:137)
        at java.awt.EventDispatchThread.run(EventDispatchThread.java:100)
}}}
I am not sure what that means, but looking at the method on the top of
the list ({{{phoebe.PGraphView.removeNodeView}}}) I found that there is a
cast to ({{{PNodeView}}}):
{{{
PNodeView node_view = ( PNodeView )getNodeView( node );
}}}
Shouldn't this be
{{{
NodeView node_view = ( NodeView )getNodeView( node );
}}}
as {{{NodeView}}} is the interface implemented by {{{PNodeView}}} (and by my
{{{PieChartNode}}})? Shouldn't we use the interface in such cases? 
If {{{PNodeView}}} is right here, how one can define other
node views and remove them?

Then, in the case that the correct cast is {{{NodeView}}}, {{{NodeView}}} should
have the interface for {{{removeFromParent()}}}. Here the complete code of
{{{phoebe.PGraphView.removeNodeView}}} to explain why:
{{{#!java
public NodeView removeNodeView ( int node ) {
    PNodeView node_view = ( PNodeView )getNodeView( node );
    try {
      node_view.removeFromParent();
    } catch ( Exception e ) {
      System.out.println( "GINY at PGraphView.removeNodeView(int): Parent was most likely null for: "+node);
      return null;
    }
    nodeViewMap.removeKey( perspective.getRootGraphNodeIndex( node_view.getGraphPerspectiveIndex() ) );
    ensureNodeSelectionCapacity();
    nodeSelectionList.setQuick( node_view.getGraphPerspectiveIndex(), 0 );
    return node_view;
  }
}}}
so, {{{node_view}}} should have the method {{{removeFromParent()}}}.

Here is the signature of my class (I didn't changed it from the
PetalNode class):
{{{#!java
public class PieChartNode extends PPath
                          implements NodeView,
                                     PropertyChangeListener {
}}}
and {{{PPath}}} extends {{{PNode}}}. 

Then I tried to modify {{{phoebe}}} and {{{NodeView}}} to test my theory. But when I
load the sources of {{{phoebe}}} some methods are not recognized well. For
example in the file {{{phoebe.PGraphView}}}, there is a call to
{{{edu.umd.cs.piccolo.PNode.firePropertyChange()}}} but seems to be a
difference in the signature of this method in {{{PGraphView}}} and in
'''Piccolo'''. My guess is that a different version of '''Piccolo''' was used in
the development of '''Phoebe''' and I got the version 1.1 of '''Piccolo'''
website. Which version of Piccolo was used in the development of
Phoebe?

Here the error I receive:
{{{
"The method firePropertyChange(int, String, Object, Object) in the type
  PNode is not applicable for the arguments (String, null, List)"
}}}
in this line:
{{{#!java
if ( firePiccoloEvents )
    firePropertyChange(PROPERTY_CHILDREN, null, getChildrenReference() ); 
}}}

Any ideas/discussion? Please, add your experience to this page.

MarcioSilva