Developing a DSL Graphical Notation - Eclipse Modeling Project: A Domain-Specific Language Toolkit - page 211

options functional. To begin, we add an inner class, PreferenceProperty
ChangeListener , that will detect a change in the appropriate property and
invoke the updateArchetypeColor() method. To initialize and register this
listener, we override the addNotationalListeners() method.

private PreferencePropertyChangeListener preferenceListener;

protected class PreferencePropertyChangeListener
implements IPropertyChangeListener {
public void propertyChange(PropertyChangeEvent event) {
if (event.getProperty().equals(
DiagramAppearancePreferencePage.PREF_MI_ARCHETYPE_COLOR)) {
updateArchetypeColor();

}

}

}

@Override
protected void addNotationalListeners() {
super .addNotationalListeners();
initPreferenceStoreListener();

}

protected void updateArchetypeColor() {
getFigure().setForegroundColor(getPreferenceColor());
getFigure().repaint();

}

private Color getPreferenceColor() {
IPreferenceStore preferenceStore = (IPreferenceStore)
getDiagramPreferencesHint().getPreferenceStore();
org.eclipse.swt.graphics.RGB archetypeColorPreference =
PreferenceConverter.getColor(preferenceStore,
DiagramAppearancePreferencePage.PREF_MI_ARCHETYPE_COLOR);
return new Color( null , archetypeColorPreference);

}

private void initPreferenceStoreListener() {
preferenceListener = new PreferencePropertyChangeListener();
IPreferenceStore preferenceStore = (IPreferenceStore)
getDiagramPreferencesHint().getPreferenceStore();
preferenceStore.addPropertyChangeListener(preferenceListener);

}

@Override
protected void setForegroundColor(Color color) {
super .setForegroundColor(getPreferenceColor());

}

The overridden setForegroundColor() method and the preference lis-
tener both obtain the appropriate color from the preference store, as shown in