PaletteTreeProvider.java

/*******************************************************************************
 * Copyright (c) 2000, 2005 IBM Corporation and others.
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     IBM Corporation - initial API and implementation
 *******************************************************************************/
package org.eclipse.gef.ui.palette.customize;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.Iterator;
import java.util.List;

import org.eclipse.jface.viewers.ITreeContentProvider;
import org.eclipse.jface.viewers.TreeViewer;
import org.eclipse.jface.viewers.Viewer;

import org.eclipse.gef.palette.PaletteContainer;
import org.eclipse.gef.palette.PaletteEntry;
import org.eclipse.gef.palette.PaletteRoot;

/**
 * This is the {@link org.eclipse.jface.viewers.IContentProvider} for the {@link
 * org.eclipse.jface.viewers.TreeViewer} used in {@link
 * org.eclipse.gef.ui.palette.customize.PaletteCustomizerDialog}.
 * 
 * @author Pratik Shah
 * @see org.eclipse.jface.viewer.TreeViewer
 * @see org.eclipse.gef.ui.palette.customize.PaletteCustomizerDialog
 */
class PaletteTreeProvider
	implements ITreeContentProvider
{

private TreeViewer viewer;
private PaletteRoot root;
private PropertyChangeListener modelListener = new PropertyChangeListener() {
	public void propertyChange(PropertyChangeEvent evt) {
		handlePropertyChanged(evt);
	}
};

/**
 * Constructor
 * 
 * @param treeviewer	The TreeViewer whose ContentProvider this PaletteTreeProvider is
 */
public PaletteTreeProvider(TreeViewer treeviewer) {
	this.viewer = treeviewer;
}

/**
 * Stops listening to the model
 * 
 * @see org.eclipse.jface.viewers.IContentProvider#dispose()
 */
public void dispose() {
	traverseModel(root, false);
}

/**
 * If the given element does not have any children, this method should return
 * <code>null</code>.  This fixes the problem where a "+" sign is incorrectly
 * placed next to an empty container in the tree.
 * 
 * @see org.eclipse.jface.viewers.ITreeContentProvider#getChildren(Object)
 */
public Object[] getChildren(Object parentElement) {
	if (parentElement instanceof PaletteContainer) {
		List children = ((PaletteContainer)parentElement).getChildren();
		if (!children.isEmpty()) {
			return children.toArray();
		}
	}
	return null;
}

/**
 * @see org.eclipse.jface.viewers.ITreeContentProvider#hasChildren(Object)
 */
public boolean hasChildren(Object element) {
	return getChildren(element) != null;
}


/**
 * This method should not return <code>null</code>.
 * 
 * @see org.eclipse.jface.viewers.IStructuredContentProvider#getElements(Object)
 */
public Object[] getElements(Object inputElement) {
	Object[] elements = getChildren(inputElement);
	if (elements == null) {
		elements = new Object[0];
	}
	return elements;
}

/**
 * @see org.eclipse.jface.viewers.ITreeContentProvider#getParent(Object)
 */
public Object getParent(Object element) {
	return ((PaletteEntry)element).getParent();
}

/**
 * This method is invoked whenever there is any change in the model.  It updates the
 * viewer with the changes that were made to the model.  Sub-classes may override this
 * method to change or extend its functionality.
 * 
 * @param evt	The {@link PropertyChangeEvent} that was fired from the model
 */
protected void handlePropertyChanged(PropertyChangeEvent evt) {
	PaletteEntry entry = ((PaletteEntry)evt.getSource());
	String property = evt.getPropertyName();
	if (property.equals(PaletteEntry.PROPERTY_LABEL)
	  || property.equals(PaletteEntry.PROPERTY_SMALL_ICON)) {
		viewer.update(entry, null);
	} else if (property.equals(PaletteEntry.PROPERTY_VISIBLE)) {
		viewer.refresh(entry);
	} else if (property.equals(PaletteContainer.PROPERTY_CHILDREN)) {
		viewer.refresh(entry);
		List oldChildren = (List)evt.getOldValue();
		for (Iterator iter = oldChildren.iterator(); iter.hasNext();) {
			PaletteEntry child = (PaletteEntry) iter.next();
			traverseModel(child, false);
		}
		traverseModel(entry, true);
	}
}

/**
 * @see org.eclipse.jface.viewers.IContentProvider#inputChanged(Viewer, Object, Object)
 */
public void inputChanged(Viewer viewer, Object oldInput, Object newInput) {
	if (root != null)
		traverseModel(root, false);
	if (newInput != null) {
		root = (PaletteRoot)newInput;
		traverseModel(root, true);
	}
}

private void traverseModel(PaletteEntry entry, boolean isHook) {
	if (isHook) {
		entry.addPropertyChangeListener(modelListener);
	} else {
		entry.removePropertyChangeListener(modelListener);
	}
		
	if (hasChildren(entry)) {
		Object[] children = getChildren(entry);
		for (int i = 0; i < children.length; i++) {
			traverseModel((PaletteEntry)children[i], isHook);
		}
	}
}

}