org.eclipse.mylar.zest.core.viewers.TreeRootViewer.java Source code

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Here is the source code for org.eclipse.mylar.zest.core.viewers.TreeRootViewer.java

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/*******************************************************************************
 * Copyright 2005, CHISEL Group, University of Victoria, Victoria, BC, Canada.
 * 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:
 *     The Chisel Group, University of Victoria
 *******************************************************************************/
package org.eclipse.mylar.zest.core.viewers;

import org.eclipse.jface.viewers.TreeViewer;
import org.eclipse.swt.SWT;
import org.eclipse.swt.widgets.Composite;
import org.eclipse.swt.widgets.Item;
import org.eclipse.swt.widgets.Tree;
import org.eclipse.swt.widgets.TreeItem;
import org.eclipse.swt.widgets.Widget;

/**
 * Extends the JFace {@linke TreeViewer} to automatically create a 
 * Root item from the given data {@link Item}.  All {@link TreeItem} objects
 * are then created under this item.
 * 
 * @author Chris Callendar
 */
public class TreeRootViewer extends TreeViewer {

    private Item dataItem = null;
    private TreeItem rootTreeItem = null;

    public TreeRootViewer(Composite parent, int style) {
        super(parent, style);
    }

    public void setRootDataItem(Item rootDataItem) {
        if (rootDataItem != null) {
            this.dataItem = rootDataItem;
        }
    }

    /**
     * Gets the root data Item.  
     * @see #setRootDataItem(Item)
     * @return Item or null if it hasn't been set
     */
    public Item getRootDataItem() {
        return dataItem;
    }

    /**
     * Creates a new item.  If the parent is the Tree and 
     * {@link #setRootDataItem(Item)} has been called then 
     * a root TreeItem will be created which all other TreeItems will go under.
     * @see org.eclipse.jface.viewers.TreeViewer#newItem(org.eclipse.swt.widgets.Widget, int, int)
     */
    protected Item newItem(Widget parent, int flags, int ix) {
        if (parent instanceof Tree) {
            Item rootItem = getRootDataItem();
            if (rootItem != null) {
                parent = createRootItem((Tree) parent, rootItem);
            }
        }
        return super.newItem(parent, flags, ix);
    }

    /**
     * Creates the root item with the Tree as its parent.
     * @param tree
     * @return the root TreeItem for convenience
     */
    private TreeItem createRootItem(Tree tree, Item rootItem) {
        if (rootItem == null)
            throw new IllegalArgumentException("Root item cannot be null");

        if ((rootTreeItem == null) || rootTreeItem.isDisposed()) {
            rootTreeItem = new TreeItem(tree, SWT.NULL, 0);
            rootTreeItem.setText(rootItem.getText());
            rootTreeItem.setImage(rootItem.getImage());
            rootTreeItem.setData(rootItem); // can't be null
            mapElement(dataItem, rootTreeItem);
        }
        return rootTreeItem;
    }

    /**
     * Tries to get the TreeItem associated with the given object.
     * @param data
     * @return TreeItem or null if not found.
     */
    public TreeItem getTreeItem(Object data) {
        TreeItem item = (TreeItem) findItem(data);
        return item;
    }

}