source: josm/src/org/openstreetmap/josm/gui/dialogs/CommandStackDialog.java@ 100

package org.openstreetmap.josm.gui.dialogs;

import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.event.KeyEvent;
import java.util.Collection;

import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JTree;
import javax.swing.tree.DefaultMutableTreeNode;
import javax.swing.tree.DefaultTreeCellRenderer;
import javax.swing.tree.DefaultTreeModel;

import org.openstreetmap.josm.Main;
import org.openstreetmap.josm.command.Command;
import org.openstreetmap.josm.gui.MapFrame;
import org.openstreetmap.josm.gui.MapView.LayerChangeListener;
import org.openstreetmap.josm.gui.layer.Layer;
import org.openstreetmap.josm.gui.layer.OsmDataLayer;
import org.openstreetmap.josm.gui.layer.OsmDataLayer.CommandQueueListener;

public class CommandStackDialog extends ToggleDialog implements CommandQueueListener {

        private DefaultTreeModel treeModel = new DefaultTreeModel(new DefaultMutableTreeNode());
    private JTree tree = new JTree(treeModel);

        public CommandStackDialog(final MapFrame mapFrame) {
                super("Command Stack", "commandstack", "Open a list of all commands (undo buffer).", KeyEvent.VK_C);
                setPreferredSize(new Dimension(320,100));
                mapFrame.mapView.addLayerChangeListener(new LayerChangeListener(){
                        public void activeLayerChange(Layer oldLayer, Layer newLayer) {}
                        public void layerAdded(Layer newLayer) {
                                if (newLayer instanceof OsmDataLayer)
                                        Main.main.editLayer().listenerCommands.add(CommandStackDialog.this);
                        }
                        public void layerRemoved(Layer oldLayer) {
                                if (oldLayer instanceof OsmDataLayer)
                                        Main.main.editLayer().listenerCommands.remove(CommandStackDialog.this);
                        }
                });
                if (mapFrame.mapView.editLayer != null)
                        mapFrame.mapView.editLayer.listenerCommands.add(this);
                        
                tree.setRootVisible(false);
                tree.setShowsRootHandles(true);
                tree.expandRow(0);
                tree.setCellRenderer(new DefaultTreeCellRenderer(){
                        @Override public Component getTreeCellRendererComponent(JTree tree, Object value, boolean sel, boolean expanded, boolean leaf, int row, boolean hasFocus) {
                                super.getTreeCellRendererComponent(tree, value, sel, expanded, leaf, row, hasFocus);
                                DefaultMutableTreeNode v = (DefaultMutableTreeNode)value;
                                if (v.getUserObject() instanceof JLabel) {
                                        JLabel l = (JLabel)v.getUserObject();
                                        setIcon(l.getIcon());
                                        setText(l.getText());
                                }
                                return this;
                        }
                });
                tree.setVisibleRowCount(8);
                add(new JScrollPane(tree), BorderLayout.CENTER);
        }

        @Override public void setVisible(boolean v) {
                if (v)
                        buildList();
                else if (tree != null)
                        treeModel.setRoot(new DefaultMutableTreeNode());
                super.setVisible(v);
        }

        private void buildList() {
                if (Main.map == null || Main.map.mapView == null || Main.map.mapView.editLayer == null)
                        return;
                Collection<Command> commands = Main.main.editLayer().commands;
                DefaultMutableTreeNode root = new DefaultMutableTreeNode();
                for (Command c : commands)
                        root.add(c.description());
                treeModel.setRoot(root);
                tree.scrollRowToVisible(treeModel.getChildCount(root)-1);
        }

        public void commandChanged(int queueSize, int redoSize) {
                if (!isVisible())
                        return;
        treeModel.setRoot(new DefaultMutableTreeNode());
                buildList();
    }
}