UndoSelectionAction.java

// License: GPL. For details, see LICENSE file.
package org.openstreetmap.josm.plugins.utilsplugin2.selection;

import static org.openstreetmap.josm.gui.help.HelpUtil.ht;
import static org.openstreetmap.josm.tools.I18n.tr;

import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.util.Collection;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Set;

import org.openstreetmap.josm.actions.JosmAction;
import org.openstreetmap.josm.data.osm.DataSet;
import org.openstreetmap.josm.data.osm.OsmPrimitive;
import org.openstreetmap.josm.tools.Shortcut;

/**
 * Use selection istory to restore previous selection
 */
public class UndoSelectionAction extends JosmAction {

    public UndoSelectionAction() {
        super(tr("Undo selection"), "undoselection",
                tr("Reselect last added object or selection form history"),
                Shortcut.registerShortcut("tools:undoselection", tr("Tool: {0}", "Undo selection"),
                        KeyEvent.VK_Z, Shortcut.CTRL_SHIFT), true);
        putValue("help", ht("/Action/UndoSelection"));
    }

    private int myAutomaticSelectionHash;
    private Collection<OsmPrimitive> lastSel;
    private int index;
    @Override
    public void actionPerformed(ActionEvent e) {
        DataSet ds = getLayerManager().getEditDataSet();
        if (ds != null) {
            LinkedList<Collection<? extends OsmPrimitive>> history = ds.getSelectionHistory();
            if (history == null || history.isEmpty()) return; // empty history
            int num = history.size();

            Collection<OsmPrimitive> selection = ds.getSelected();

            if (selection != null && selection.hashCode() != myAutomaticSelectionHash) {
                // manual selection or another pluging selection noticed
                index = history.indexOf(lastSel);
                // first is selected, next list is previous selection
            }
            int k = 0;
            Set<OsmPrimitive> newsel = new HashSet<>();
            do {
                if (index+1 < history.size()) index++; else index = 0;
                Collection<? extends OsmPrimitive> histsel = history.get(index);
                // remove deleted entities from selection
                newsel.clear();
                newsel.addAll(histsel);
                newsel.retainAll(ds.allNonDeletedPrimitives());
                if (!newsel.isEmpty()) break;
                k++;
            } while (k < num);

            ds.setSelected(newsel);
            lastSel = ds.getSelected();
            myAutomaticSelectionHash = lastSel.hashCode();
            // remember last automatic selection
        }
    }

    @Override
    protected void updateEnabledState() {
        setEnabled(getLayerManager().getEditDataSet() != null);
    }
}