001// License: GPL. For details, see LICENSE file.
002package org.openstreetmap.josm.actions;
003
004import static org.openstreetmap.josm.tools.I18n.tr;
005
006import java.awt.event.ActionEvent;
007import java.awt.event.KeyEvent;
008import java.util.Arrays;
009import java.util.Collection;
010import java.util.List;
011import java.util.Set;
012
013import org.openstreetmap.josm.Main;
014import org.openstreetmap.josm.actions.mapmode.DrawAction;
015import org.openstreetmap.josm.command.ChangeCommand;
016import org.openstreetmap.josm.command.SelectCommand;
017import org.openstreetmap.josm.command.SequenceCommand;
018import org.openstreetmap.josm.data.osm.Node;
019import org.openstreetmap.josm.data.osm.OsmPrimitive;
020import org.openstreetmap.josm.data.osm.Way;
021import org.openstreetmap.josm.gui.layer.OsmDataLayer;
022import org.openstreetmap.josm.tools.Shortcut;
023import org.openstreetmap.josm.tools.Utils;
024
025/**
026 * Follow line action - Makes easier to draw a line that shares points with another line
027 *
028 * Aimed at those who want to draw two or more lines related with
029 * each other, but carry different information (i.e. a river acts as boundary at
030 * some part of its course. It preferable to have a separated boundary line than to
031 * mix totally different kind of features in one single way).
032 *
033 * @author Germán Márquez Mejía
034 */
035public class FollowLineAction extends JosmAction {
036
037    /**
038     * Constructs a new {@code FollowLineAction}.
039     */
040    public FollowLineAction() {
041        super(
042                tr("Follow line"),
043                "followline",
044                tr("Continues drawing a line that shares nodes with another line."),
045                Shortcut.registerShortcut("tools:followline", tr(
046                "Tool: {0}", tr("Follow")),
047                KeyEvent.VK_F, Shortcut.DIRECT), true);
048    }
049
050    @Override
051    protected void updateEnabledState() {
052        updateEnabledStateOnCurrentSelection();
053    }
054
055    @Override
056    protected void updateEnabledState(Collection<? extends OsmPrimitive> selection) {
057        setEnabled(selection != null && !selection.isEmpty());
058    }
059
060    @Override
061    public void actionPerformed(ActionEvent evt) {
062        OsmDataLayer osmLayer = Main.getLayerManager().getEditLayer();
063        if (osmLayer == null)
064            return;
065        if (!(Main.map.mapMode instanceof DrawAction)) return; // We are not on draw mode
066
067        Collection<Node> selectedPoints = osmLayer.data.getSelectedNodes();
068        Collection<Way> selectedLines = osmLayer.data.getSelectedWays();
069        if ((selectedPoints.size() > 1) || (selectedLines.size() != 1)) // Unsuitable selection
070            return;
071
072        Node last = ((DrawAction) Main.map.mapMode).getCurrentBaseNode();
073        if (last == null)
074            return;
075        Way follower = selectedLines.iterator().next();
076        if (follower.isClosed())    /* Don't loop until OOM */
077            return;
078        Node prev = follower.getNode(1);
079        boolean reversed = true;
080        if (follower.lastNode().equals(last)) {
081            prev = follower.getNode(follower.getNodesCount() - 2);
082            reversed = false;
083        }
084        List<OsmPrimitive> referrers = last.getReferrers();
085        if (referrers.size() < 2) return; // There's nothing to follow
086
087        Node newPoint = null;
088        for (final Way toFollow : Utils.filteredCollection(referrers, Way.class)) {
089            if (toFollow.equals(follower)) {
090                continue;
091            }
092            Set<Node> points = toFollow.getNeighbours(last);
093            points.remove(prev);
094            if (points.isEmpty())     // No candidate -> consider next way
095                continue;
096            if (points.size() > 1)    // Ambiguous junction?
097                return;
098
099            // points contains exactly one element
100            Node newPointCandidate = points.iterator().next();
101
102            if ((newPoint != null) && (newPoint != newPointCandidate))
103                return;         // Ambiguous junction, force to select next
104
105            newPoint = newPointCandidate;
106        }
107        if (newPoint != null) {
108            Way newFollower = new Way(follower);
109            if (reversed) {
110                newFollower.addNode(0, newPoint);
111            } else {
112                newFollower.addNode(newPoint);
113            }
114            Main.main.undoRedo.add(new SequenceCommand(tr("Follow line"),
115                    new ChangeCommand(follower, newFollower),
116                    new SelectCommand(newFollower.isClosed() // see #10028 - unselect last node when closing a way
117                            ? Arrays.<OsmPrimitive>asList(newFollower)
118                            : Arrays.<OsmPrimitive>asList(newFollower, newPoint)
119                    ))
120            );
121            // "viewport following" mode for tracing long features
122            // from aerial imagery or GPS tracks.
123            if (Main.map.mapView.viewportFollowing) {
124                Main.map.mapView.smoothScrollTo(newPoint.getEastNorth());
125            }
126        }
127    }
128}