001// License: GPL. For details, see LICENSE file.
002package org.openstreetmap.josm.actions.mapmode;
003
004import static org.openstreetmap.josm.gui.help.HelpUtil.ht;
005import static org.openstreetmap.josm.tools.I18n.marktr;
006import static org.openstreetmap.josm.tools.I18n.tr;
007import static org.openstreetmap.josm.tools.I18n.trn;
008
009import java.awt.BasicStroke;
010import java.awt.Color;
011import java.awt.Cursor;
012import java.awt.Graphics2D;
013import java.awt.Point;
014import java.awt.event.ActionEvent;
015import java.awt.event.KeyEvent;
016import java.awt.event.MouseEvent;
017import java.util.ArrayList;
018import java.util.Collection;
019import java.util.Collections;
020import java.util.HashMap;
021import java.util.HashSet;
022import java.util.Iterator;
023import java.util.LinkedList;
024import java.util.List;
025import java.util.Map;
026import java.util.Set;
027
028import javax.swing.AbstractAction;
029import javax.swing.JCheckBoxMenuItem;
030import javax.swing.JMenuItem;
031import javax.swing.JOptionPane;
032import javax.swing.SwingUtilities;
033
034import org.openstreetmap.josm.actions.JosmAction;
035import org.openstreetmap.josm.command.AddCommand;
036import org.openstreetmap.josm.command.ChangeCommand;
037import org.openstreetmap.josm.command.Command;
038import org.openstreetmap.josm.command.SequenceCommand;
039import org.openstreetmap.josm.data.Bounds;
040import org.openstreetmap.josm.data.UndoRedoHandler;
041import org.openstreetmap.josm.data.coor.EastNorth;
042import org.openstreetmap.josm.data.osm.DataSelectionListener;
043import org.openstreetmap.josm.data.osm.DataSet;
044import org.openstreetmap.josm.data.osm.Node;
045import org.openstreetmap.josm.data.osm.OsmPrimitive;
046import org.openstreetmap.josm.data.osm.Way;
047import org.openstreetmap.josm.data.osm.WaySegment;
048import org.openstreetmap.josm.data.osm.event.SelectionEventManager;
049import org.openstreetmap.josm.data.osm.visitor.paint.ArrowPaintHelper;
050import org.openstreetmap.josm.data.osm.visitor.paint.PaintColors;
051import org.openstreetmap.josm.data.preferences.AbstractProperty;
052import org.openstreetmap.josm.data.preferences.BooleanProperty;
053import org.openstreetmap.josm.data.preferences.CachingProperty;
054import org.openstreetmap.josm.data.preferences.DoubleProperty;
055import org.openstreetmap.josm.data.preferences.NamedColorProperty;
056import org.openstreetmap.josm.data.preferences.StrokeProperty;
057import org.openstreetmap.josm.gui.MainApplication;
058import org.openstreetmap.josm.gui.MainMenu;
059import org.openstreetmap.josm.gui.MapFrame;
060import org.openstreetmap.josm.gui.MapView;
061import org.openstreetmap.josm.gui.MapViewState.MapViewPoint;
062import org.openstreetmap.josm.gui.NavigatableComponent;
063import org.openstreetmap.josm.gui.draw.MapPath2D;
064import org.openstreetmap.josm.gui.layer.Layer;
065import org.openstreetmap.josm.gui.layer.MapViewPaintable;
066import org.openstreetmap.josm.gui.layer.OsmDataLayer;
067import org.openstreetmap.josm.gui.util.KeyPressReleaseListener;
068import org.openstreetmap.josm.gui.util.ModifierExListener;
069import org.openstreetmap.josm.tools.Geometry;
070import org.openstreetmap.josm.tools.ImageProvider;
071import org.openstreetmap.josm.tools.Pair;
072import org.openstreetmap.josm.tools.Shortcut;
073import org.openstreetmap.josm.tools.Utils;
074
075/**
076 * Mapmode to add nodes, create and extend ways.
077 */
078public class DrawAction extends MapMode implements MapViewPaintable, DataSelectionListener, KeyPressReleaseListener, ModifierExListener {
079
080    /**
081     * If this property is set, the draw action moves the viewport when adding new points.
082     * @since 12182
083     */
084    public static final CachingProperty<Boolean> VIEWPORT_FOLLOWING = new BooleanProperty("draw.viewport.following", false).cached();
085
086    private static final Color ORANGE_TRANSPARENT = new Color(Color.ORANGE.getRed(), Color.ORANGE.getGreen(), Color.ORANGE.getBlue(), 128);
087
088    private static final ArrowPaintHelper START_WAY_INDICATOR = new ArrowPaintHelper(Utils.toRadians(90), 8);
089
090    static final CachingProperty<Boolean> USE_REPEATED_SHORTCUT
091            = new BooleanProperty("draw.anglesnap.toggleOnRepeatedA", true).cached();
092    static final CachingProperty<BasicStroke> RUBBER_LINE_STROKE
093            = new StrokeProperty("draw.stroke.helper-line", "3").cached();
094
095    static final CachingProperty<BasicStroke> HIGHLIGHT_STROKE
096            = new StrokeProperty("draw.anglesnap.stroke.highlight", "10").cached();
097    static final CachingProperty<BasicStroke> HELPER_STROKE
098            = new StrokeProperty("draw.anglesnap.stroke.helper", "1 4").cached();
099
100    static final CachingProperty<Double> SNAP_ANGLE_TOLERANCE
101            = new DoubleProperty("draw.anglesnap.tolerance", 5.0).cached();
102    static final CachingProperty<Boolean> DRAW_CONSTRUCTION_GEOMETRY
103            = new BooleanProperty("draw.anglesnap.drawConstructionGeometry", true).cached();
104    static final CachingProperty<Boolean> SHOW_PROJECTED_POINT
105            = new BooleanProperty("draw.anglesnap.drawProjectedPoint", true).cached();
106    static final CachingProperty<Boolean> SNAP_TO_PROJECTIONS
107            = new BooleanProperty("draw.anglesnap.projectionsnap", true).cached();
108
109    static final CachingProperty<Boolean> SHOW_ANGLE
110            = new BooleanProperty("draw.anglesnap.showAngle", true).cached();
111
112    static final CachingProperty<Color> SNAP_HELPER_COLOR
113            = new NamedColorProperty(marktr("draw angle snap"), Color.ORANGE).cached();
114
115    static final CachingProperty<Color> HIGHLIGHT_COLOR
116            = new NamedColorProperty(marktr("draw angle snap highlight"), ORANGE_TRANSPARENT).cached();
117
118    static final AbstractProperty<Color> RUBBER_LINE_COLOR
119            = PaintColors.SELECTED.getProperty().getChildColor(marktr("helper line"));
120
121    static final CachingProperty<Boolean> DRAW_HELPER_LINE
122            = new BooleanProperty("draw.helper-line", true).cached();
123    static final CachingProperty<Boolean> DRAW_TARGET_HIGHLIGHT
124            = new BooleanProperty("draw.target-highlight", true).cached();
125    static final CachingProperty<Double> SNAP_TO_INTERSECTION_THRESHOLD
126            = new DoubleProperty("edit.snap-intersection-threshold", 10).cached();
127
128    private final Cursor cursorJoinNode;
129    private final Cursor cursorJoinWay;
130
131    private transient Node lastUsedNode;
132    private double toleranceMultiplier;
133
134    private transient Node mouseOnExistingNode;
135    private transient Set<Way> mouseOnExistingWays = new HashSet<>();
136    // old highlights store which primitives are currently highlighted. This
137    // is true, even if target highlighting is disabled since the status bar
138    // derives its information from this list as well.
139    private transient Set<OsmPrimitive> oldHighlights = new HashSet<>();
140    // new highlights contains a list of primitives that should be highlighted
141    // but haven't been so far. The idea is to compare old and new and only
142    // repaint if there are changes.
143    private transient Set<OsmPrimitive> newHighlights = new HashSet<>();
144    private boolean wayIsFinished;
145    private Point mousePos;
146    private Point oldMousePos;
147
148    private transient Node currentBaseNode;
149    private transient Node previousNode;
150    private EastNorth currentMouseEastNorth;
151
152    private final transient DrawSnapHelper snapHelper = new DrawSnapHelper(this);
153
154    private final transient Shortcut backspaceShortcut;
155    private final BackSpaceAction backspaceAction;
156    private final transient Shortcut snappingShortcut;
157    private boolean ignoreNextKeyRelease;
158
159    private final SnapChangeAction snapChangeAction;
160    private final JCheckBoxMenuItem snapCheckboxMenuItem;
161    private static final BasicStroke BASIC_STROKE = new BasicStroke(1);
162
163    private Point rightClickPressPos;
164
165    /**
166     * Constructs a new {@code DrawAction}.
167     * @since 11713
168     */
169    public DrawAction() {
170        super(tr("Draw"), "node/autonode", tr("Draw nodes"),
171                Shortcut.registerShortcut("mapmode:draw", tr("Mode: {0}", tr("Draw")), KeyEvent.VK_A, Shortcut.DIRECT),
172                ImageProvider.getCursor("crosshair", null));
173
174        snappingShortcut = Shortcut.registerShortcut("mapmode:drawanglesnapping",
175                tr("Mode: Draw Angle snapping"), KeyEvent.CHAR_UNDEFINED, Shortcut.NONE);
176        snapChangeAction = new SnapChangeAction();
177        snapCheckboxMenuItem = addMenuItem();
178        snapHelper.setMenuCheckBox(snapCheckboxMenuItem);
179        backspaceShortcut = Shortcut.registerShortcut("mapmode:backspace",
180                tr("Backspace in Add mode"), KeyEvent.VK_BACK_SPACE, Shortcut.DIRECT);
181        backspaceAction = new BackSpaceAction();
182        cursorJoinNode = ImageProvider.getCursor("crosshair", "joinnode");
183        cursorJoinWay = ImageProvider.getCursor("crosshair", "joinway");
184
185        snapHelper.init();
186    }
187
188    private JCheckBoxMenuItem addMenuItem() {
189        int n = MainApplication.getMenu().editMenu.getItemCount();
190        for (int i = n-1; i > 0; i--) {
191            JMenuItem item = MainApplication.getMenu().editMenu.getItem(i);
192            if (item != null && item.getAction() != null && item.getAction() instanceof SnapChangeAction) {
193                MainApplication.getMenu().editMenu.remove(i);
194            }
195        }
196        return MainMenu.addWithCheckbox(MainApplication.getMenu().editMenu, snapChangeAction, MainMenu.WINDOW_MENU_GROUP.VOLATILE);
197    }
198
199    /**
200     * Checks if a map redraw is required and does so if needed. Also updates the status bar.
201     * @param e event, can be null
202     * @return true if a repaint is needed
203     */
204    private boolean redrawIfRequired(Object e) {
205        updateStatusLine();
206        // repaint required if the helper line is active.
207        boolean needsRepaint = DRAW_HELPER_LINE.get() && !wayIsFinished;
208        if (DRAW_TARGET_HIGHLIGHT.get()) {
209            // move newHighlights to oldHighlights; only update changed primitives
210            for (OsmPrimitive x : newHighlights) {
211                if (oldHighlights.contains(x)) {
212                    continue;
213                }
214                x.setHighlighted(true);
215                needsRepaint = true;
216            }
217            oldHighlights.removeAll(newHighlights);
218            for (OsmPrimitive x : oldHighlights) {
219                x.setHighlighted(false);
220                needsRepaint = true;
221            }
222        }
223        // required in order to print correct help text
224        oldHighlights = newHighlights;
225
226        if (!needsRepaint && !DRAW_TARGET_HIGHLIGHT.get())
227            return false;
228
229        // update selection to reflect which way being modified
230        OsmDataLayer editLayer = getLayerManager().getEditLayer();
231        Node baseNode = getCurrentBaseNode();
232        if (editLayer != null && baseNode != null && !editLayer.data.selectionEmpty()) {
233            DataSet currentDataSet = editLayer.getDataSet();
234            Way continueFrom = getWayForNode(baseNode);
235            if (alt && continueFrom != null && (!baseNode.isSelected() || continueFrom.isSelected())) {
236                addRemoveSelection(currentDataSet, baseNode, continueFrom);
237                needsRepaint = true;
238            } else if (!alt && continueFrom != null && !continueFrom.isSelected()) {
239                addSelection(currentDataSet, continueFrom);
240                needsRepaint = true;
241            }
242        }
243
244        if (!needsRepaint && e instanceof SelectionChangeEvent) {
245            SelectionChangeEvent event = (SelectionChangeEvent) e;
246            needsRepaint = !event.getOldSelection().isEmpty() && event.getSelection().isEmpty();
247        }
248
249        if (needsRepaint && editLayer != null) {
250            editLayer.invalidate();
251        }
252        return needsRepaint;
253    }
254
255    private static void addRemoveSelection(DataSet ds, OsmPrimitive toAdd, OsmPrimitive toRemove) {
256        ds.beginUpdate(); // to prevent the selection listener to screw around with the state
257        try {
258            addSelection(ds, toAdd);
259            clearSelection(ds, toRemove);
260        } finally {
261            ds.endUpdate();
262        }
263    }
264
265    private static void updatePreservedFlag(OsmPrimitive osm, boolean state) {
266        // Preserves selected primitives and selected way nodes
267        osm.setPreserved(state);
268        if (osm instanceof Way) {
269            for (Node n : ((Way) osm).getNodes()) {
270                n.setPreserved(state);
271            }
272        }
273    }
274
275    private static void setSelection(DataSet ds, Collection<OsmPrimitive> toSet) {
276        toSet.stream().forEach(x -> updatePreservedFlag(x, true));
277        ds.setSelected(toSet);
278    }
279
280    private static void setSelection(DataSet ds, OsmPrimitive toSet) {
281        updatePreservedFlag(toSet, true);
282        ds.setSelected(toSet);
283    }
284
285    private static void addSelection(DataSet ds, OsmPrimitive toAdd) {
286        updatePreservedFlag(toAdd, true);
287        ds.addSelected(toAdd);
288    }
289
290    private static void clearSelection(DataSet ds, OsmPrimitive toRemove) {
291        ds.clearSelection(toRemove);
292        updatePreservedFlag(toRemove, false);
293    }
294
295    @Override
296    public void enterMode() {
297        if (!isEnabled())
298            return;
299        super.enterMode();
300        readPreferences();
301
302        // determine if selection is suitable to continue drawing. If it
303        // isn't, set wayIsFinished to true to avoid superfluous repaints.
304        determineCurrentBaseNodeAndPreviousNode(getLayerManager().getEditDataSet().getSelected());
305        wayIsFinished = getCurrentBaseNode() == null;
306
307        toleranceMultiplier = 0.01 * NavigatableComponent.PROP_SNAP_DISTANCE.get();
308
309        snapHelper.init();
310        snapCheckboxMenuItem.getAction().setEnabled(true);
311
312        MapFrame map = MainApplication.getMap();
313        map.statusLine.getAnglePanel().addMouseListener(snapHelper.anglePopupListener);
314        MainApplication.registerActionShortcut(backspaceAction, backspaceShortcut);
315
316        map.mapView.addMouseListener(this);
317        map.mapView.addMouseMotionListener(this);
318        map.mapView.addTemporaryLayer(this);
319        SelectionEventManager.getInstance().addSelectionListenerForEdt(this);
320
321        map.keyDetector.addKeyListener(this);
322        map.keyDetector.addModifierExListener(this);
323        ignoreNextKeyRelease = true;
324    }
325
326    @Override
327    public void exitMode() {
328        super.exitMode();
329        MapFrame map = MainApplication.getMap();
330        map.mapView.removeMouseListener(this);
331        map.mapView.removeMouseMotionListener(this);
332        map.mapView.removeTemporaryLayer(this);
333        SelectionEventManager.getInstance().removeSelectionListener(this);
334        MainApplication.unregisterActionShortcut(backspaceAction, backspaceShortcut);
335        snapHelper.unsetFixedMode();
336        snapCheckboxMenuItem.getAction().setEnabled(false);
337
338        map.statusLine.getAnglePanel().removeMouseListener(snapHelper.anglePopupListener);
339        map.statusLine.activateAnglePanel(false);
340
341        DataSet ds = getLayerManager().getEditDataSet();
342        if (ds != null) {
343            ds.getSelected().stream().forEach(x -> updatePreservedFlag(x, false));
344        }
345
346        removeHighlighting(null);
347        map.keyDetector.removeKeyListener(this);
348        map.keyDetector.removeModifierExListener(this);
349    }
350
351    /**
352     * redraw to (possibly) get rid of helper line if selection changes.
353     */
354    @Override
355    public void modifiersExChanged(int modifiers) {
356        if (!MainApplication.isDisplayingMapView() || !MainApplication.getMap().mapView.isActiveLayerDrawable())
357            return;
358        updateKeyModifiersEx(modifiers);
359        computeHelperLine();
360        addHighlighting(null);
361    }
362
363    @Override
364    public void doKeyPressed(KeyEvent e) {
365        if (!snappingShortcut.isEvent(e) && !(USE_REPEATED_SHORTCUT.get() && getShortcut().isEvent(e)))
366            return;
367        snapHelper.setFixedMode();
368        computeHelperLine();
369        redrawIfRequired(e);
370    }
371
372    @Override
373    public void doKeyReleased(KeyEvent e) {
374        if (!snappingShortcut.isEvent(e) && !(USE_REPEATED_SHORTCUT.get() && getShortcut().isEvent(e)))
375            return;
376        if (ignoreNextKeyRelease) {
377            ignoreNextKeyRelease = false;
378            return;
379        }
380        snapHelper.unFixOrTurnOff();
381        computeHelperLine();
382        redrawIfRequired(e);
383    }
384
385    /**
386     * redraw to (possibly) get rid of helper line if selection changes.
387     */
388    @Override
389    public void selectionChanged(SelectionChangeEvent event) {
390        if (!MainApplication.getMap().mapView.isActiveLayerDrawable())
391            return;
392        if (event.getSelection().isEmpty())
393            finishDrawing();
394        // Make sure helper line is computed later (causes deadlock in selection event chain otherwise)
395        SwingUtilities.invokeLater(() -> {
396            event.getOldSelection().stream().forEach(x -> updatePreservedFlag(x, false));
397            event.getSelection().stream().forEach(x -> updatePreservedFlag(x, true));
398            if (MainApplication.getMap() != null) {
399                computeHelperLine();
400                addHighlighting(event);
401            }
402        });
403    }
404
405    private void tryAgain(MouseEvent e) {
406        getLayerManager().getEditDataSet().clearSelection();
407        mouseReleased(e);
408    }
409
410    /**
411     * This function should be called when the user wishes to finish his current draw action.
412     * If Potlatch Style is enabled, it will switch to select tool, otherwise simply disable
413     * the helper line until the user chooses to draw something else.
414     */
415    private void finishDrawing() {
416        lastUsedNode = null;
417        wayIsFinished = true;
418        MainApplication.getMap().selectSelectTool(true);
419        snapHelper.noSnapNow();
420
421        // Redraw to remove the helper line stub
422        computeHelperLine();
423        removeHighlighting(null);
424    }
425
426    @Override
427    public void mousePressed(MouseEvent e) {
428        if (e.getButton() == MouseEvent.BUTTON3) {
429            rightClickPressPos = e.getPoint();
430        }
431    }
432
433    /**
434     * If user clicked with the left button, add a node at the current mouse
435     * position.
436     *
437     * If in nodeway mode, insert the node into the way.
438     */
439    @Override
440    public void mouseReleased(MouseEvent e) {
441        if (e.getButton() == MouseEvent.BUTTON3) {
442            Point curMousePos = e.getPoint();
443            if (curMousePos.equals(rightClickPressPos)) {
444                tryToSetBaseSegmentForAngleSnap();
445            }
446            return;
447        }
448        if (e.getButton() != MouseEvent.BUTTON1)
449            return;
450        MapView mapView = MainApplication.getMap().mapView;
451        if (!mapView.isActiveLayerDrawable())
452            return;
453        // request focus in order to enable the expected keyboard shortcuts
454        //
455        mapView.requestFocus();
456
457        if (e.getClickCount() > 1 && mousePos != null && mousePos.equals(oldMousePos)) {
458            // A double click equals "user clicked last node again, finish way"
459            // Change draw tool only if mouse position is nearly the same, as
460            // otherwise fast clicks will count as a double click
461            finishDrawing();
462            return;
463        }
464        oldMousePos = mousePos;
465
466        // we copy ctrl/alt/shift from the event just in case our global
467        // keyDetector didn't make it through the security manager. Unclear
468        // if that can ever happen but better be safe.
469        updateKeyModifiers(e);
470        mousePos = e.getPoint();
471
472        DataSet ds = getLayerManager().getEditDataSet();
473        Collection<OsmPrimitive> selection = new ArrayList<>(ds.getSelected());
474
475        boolean newNode = false;
476        Node n = mapView.getNearestNode(mousePos, OsmPrimitive::isSelectable);
477        if (ctrl) {
478            Iterator<Way> it = ds.getSelectedWays().iterator();
479            if (it.hasNext()) {
480                // ctrl-click on node of selected way = reuse node despite of ctrl
481                if (!it.next().containsNode(n)) n = null;
482            } else {
483                n = null; // ctrl-click + no selected way = new node
484            }
485        }
486
487        if (n != null && !snapHelper.isActive()) {
488            // user clicked on node
489            if (selection.isEmpty() || wayIsFinished) {
490                // select the clicked node and do nothing else
491                // (this is just a convenience option so that people don't
492                // have to switch modes)
493
494                setSelection(ds, n);
495                // If we extend/continue an existing way, select it already now to make it obvious
496                Way continueFrom = getWayForNode(n);
497                if (continueFrom != null) {
498                    addSelection(ds, continueFrom);
499                }
500
501                // The user explicitly selected a node, so let him continue drawing
502                wayIsFinished = false;
503                return;
504            }
505        } else {
506            EastNorth newEN;
507            if (n != null) {
508                EastNorth foundPoint = n.getEastNorth();
509                // project found node to snapping line
510                newEN = snapHelper.getSnapPoint(foundPoint);
511                // do not add new node if there is some node within snapping distance
512                double tolerance = mapView.getDist100Pixel() * toleranceMultiplier;
513                if (foundPoint.distance(newEN) > tolerance) {
514                    n = new Node(newEN); // point != projected, so we create new node
515                    newNode = true;
516                }
517            } else { // n==null, no node found in clicked area
518                EastNorth mouseEN = mapView.getEastNorth(e.getX(), e.getY());
519                newEN = snapHelper.isSnapOn() ? snapHelper.getSnapPoint(mouseEN) : mouseEN;
520                n = new Node(newEN); //create node at clicked point
521                newNode = true;
522            }
523            snapHelper.unsetFixedMode();
524        }
525
526        Collection<Command> cmds = new LinkedList<>();
527        Collection<OsmPrimitive> newSelection = new LinkedList<>(ds.getSelected());
528        List<Way> reuseWays = new ArrayList<>();
529        List<Way> replacedWays = new ArrayList<>();
530
531        if (newNode) {
532            if (n.isOutSideWorld()) {
533                JOptionPane.showMessageDialog(
534                        MainApplication.getMainFrame(),
535                        tr("Cannot add a node outside of the world."),
536                        tr("Warning"),
537                        JOptionPane.WARNING_MESSAGE
538                        );
539                return;
540            }
541            cmds.add(new AddCommand(ds, n));
542
543            if (!ctrl) {
544                // Insert the node into all the nearby way segments
545                List<WaySegment> wss = mapView.getNearestWaySegments(
546                        mapView.getPoint(n), OsmPrimitive::isSelectable);
547                if (snapHelper.isActive()) {
548                    tryToMoveNodeOnIntersection(wss, n);
549                }
550                insertNodeIntoAllNearbySegments(wss, n, newSelection, cmds, replacedWays, reuseWays);
551            }
552        }
553        // now "n" is newly created or reused node that shoud be added to some way
554
555        // This part decides whether or not a "segment" (i.e. a connection) is made to an existing node.
556
557        // For a connection to be made, the user must either have a node selected (connection
558        // is made to that node), or he must have a way selected *and* one of the endpoints
559        // of that way must be the last used node (connection is made to last used node), or
560        // he must have a way and a node selected (connection is made to the selected node).
561
562        // If the above does not apply, the selection is cleared and a new try is started
563
564        boolean extendedWay = false;
565        boolean wayIsFinishedTemp = wayIsFinished;
566        wayIsFinished = false;
567
568        // don't draw lines if shift is held
569        if (!selection.isEmpty() && !shift) {
570            Node selectedNode = null;
571            Way selectedWay = null;
572
573            for (OsmPrimitive p : selection) {
574                if (p instanceof Node) {
575                    if (selectedNode != null) {
576                        // Too many nodes selected to do something useful
577                        tryAgain(e);
578                        return;
579                    }
580                    selectedNode = (Node) p;
581                } else if (p instanceof Way) {
582                    if (selectedWay != null) {
583                        // Too many ways selected to do something useful
584                        tryAgain(e);
585                        return;
586                    }
587                    selectedWay = (Way) p;
588                }
589            }
590
591            // the node from which we make a connection
592            Node n0 = findNodeToContinueFrom(selectedNode, selectedWay);
593            // We have a selection but it isn't suitable. Try again.
594            if (n0 == null) {
595                tryAgain(e);
596                return;
597            }
598            if (!wayIsFinishedTemp) {
599                if (isSelfContainedWay(selectedWay, n0, n))
600                    return;
601
602                // User clicked last node again, finish way
603                if (n0 == n) {
604                    finishDrawing();
605                    return;
606                }
607
608                // Ok we know now that we'll insert a line segment, but will it connect to an
609                // existing way or make a new way of its own? The "alt" modifier means that the
610                // user wants a new way.
611                Way way = alt ? null : (selectedWay != null ? selectedWay : getWayForNode(n0));
612                Way wayToSelect;
613
614                // Don't allow creation of self-overlapping ways
615                if (way != null) {
616                    int nodeCount = 0;
617                    for (Node p : way.getNodes()) {
618                        if (p.equals(n0)) {
619                            nodeCount++;
620                        }
621                    }
622                    if (nodeCount > 1) {
623                        way = null;
624                    }
625                }
626
627                if (way == null) {
628                    way = new Way();
629                    way.addNode(n0);
630                    cmds.add(new AddCommand(ds, way));
631                    wayToSelect = way;
632                } else {
633                    int i;
634                    if ((i = replacedWays.indexOf(way)) != -1) {
635                        way = reuseWays.get(i);
636                        wayToSelect = way;
637                    } else {
638                        wayToSelect = way;
639                        Way wnew = new Way(way);
640                        cmds.add(new ChangeCommand(way, wnew));
641                        way = wnew;
642                    }
643                }
644
645                // Connected to a node that's already in the way
646                if (way.containsNode(n)) {
647                    wayIsFinished = true;
648                    selection.clear();
649                }
650
651                // Add new node to way
652                if (way.getNode(way.getNodesCount() - 1) == n0) {
653                    way.addNode(n);
654                } else {
655                    way.addNode(0, n);
656                }
657
658                extendedWay = true;
659                newSelection.clear();
660                newSelection.add(wayToSelect);
661            }
662        }
663        if (!extendedWay && !newNode) {
664            return; // We didn't do anything.
665        }
666
667        String title = getTitle(newNode, n, newSelection, reuseWays, extendedWay);
668
669        Command c = new SequenceCommand(title, cmds);
670
671        UndoRedoHandler.getInstance().add(c);
672        if (!wayIsFinished) {
673            lastUsedNode = n;
674        }
675
676        setSelection(ds, newSelection);
677
678        // "viewport following" mode for tracing long features
679        // from aerial imagery or GPS tracks.
680        if (VIEWPORT_FOLLOWING.get()) {
681            mapView.smoothScrollTo(n.getEastNorth());
682        }
683        computeHelperLine();
684        removeHighlighting(e);
685    }
686
687    private static String getTitle(boolean newNode, Node n, Collection<OsmPrimitive> newSelection, List<Way> reuseWays,
688            boolean extendedWay) {
689        String title;
690        if (!extendedWay) {
691            if (reuseWays.isEmpty()) {
692                title = tr("Add node");
693            } else {
694                title = tr("Add node into way");
695                for (Way w : reuseWays) {
696                    newSelection.remove(w);
697                }
698            }
699            newSelection.clear();
700            newSelection.add(n);
701        } else if (!newNode) {
702            title = tr("Connect existing way to node");
703        } else if (reuseWays.isEmpty()) {
704            title = tr("Add a new node to an existing way");
705        } else {
706            title = tr("Add node into way and connect");
707        }
708        return title;
709    }
710
711    private void insertNodeIntoAllNearbySegments(List<WaySegment> wss, Node n, Collection<OsmPrimitive> newSelection,
712            Collection<Command> cmds, List<Way> replacedWays, List<Way> reuseWays) {
713        Map<Way, List<Integer>> insertPoints = new HashMap<>();
714        for (WaySegment ws : wss) {
715            List<Integer> is;
716            if (insertPoints.containsKey(ws.way)) {
717                is = insertPoints.get(ws.way);
718            } else {
719                is = new ArrayList<>();
720                insertPoints.put(ws.way, is);
721            }
722
723            is.add(ws.lowerIndex);
724        }
725
726        Set<Pair<Node, Node>> segSet = new HashSet<>();
727
728        for (Map.Entry<Way, List<Integer>> insertPoint : insertPoints.entrySet()) {
729            Way w = insertPoint.getKey();
730            List<Integer> is = insertPoint.getValue();
731
732            Way wnew = new Way(w);
733
734            pruneSuccsAndReverse(is);
735            for (int i : is) {
736                segSet.add(Pair.sort(new Pair<>(w.getNode(i), w.getNode(i+1))));
737                wnew.addNode(i + 1, n);
738            }
739
740            // If ALT is pressed, a new way should be created and that new way should get
741            // selected. This works every time unless the ways the nodes get inserted into
742            // are already selected. This is the case when creating a self-overlapping way
743            // but pressing ALT prevents this. Therefore we must de-select the way manually
744            // here so /only/ the new way will be selected after this method finishes.
745            if (alt) {
746                newSelection.add(insertPoint.getKey());
747            }
748
749            cmds.add(new ChangeCommand(insertPoint.getKey(), wnew));
750            replacedWays.add(insertPoint.getKey());
751            reuseWays.add(wnew);
752        }
753
754        adjustNode(segSet, n);
755    }
756
757    /**
758     * Prevent creation of ways that look like this: &lt;----&gt;
759     * This happens if users want to draw a no-exit-sideway from the main way like this:
760     * ^
761     * |&lt;----&gt;
762     * |
763     * The solution isn't ideal because the main way will end in the side way, which is bad for
764     * navigation software ("drive straight on") but at least easier to fix. Maybe users will fix
765     * it on their own, too. At least it's better than producing an error.
766     *
767     * @param selectedWay the way to check
768     * @param currentNode the current node (i.e. the one the connection will be made from)
769     * @param targetNode the target node (i.e. the one the connection will be made to)
770     * @return {@code true} if this would create a selfcontaining way, {@code false} otherwise.
771     */
772    private boolean isSelfContainedWay(Way selectedWay, Node currentNode, Node targetNode) {
773        if (selectedWay != null) {
774            int posn0 = selectedWay.getNodes().indexOf(currentNode);
775            // CHECKSTYLE.OFF: SingleSpaceSeparator
776            if ((posn0 != -1 && // n0 is part of way
777                (posn0 >= 1                            && targetNode.equals(selectedWay.getNode(posn0-1)))) || // previous node
778                (posn0 < selectedWay.getNodesCount()-1 && targetNode.equals(selectedWay.getNode(posn0+1)))) {  // next node
779                setSelection(getLayerManager().getEditDataSet(), targetNode);
780                lastUsedNode = targetNode;
781                return true;
782            }
783            // CHECKSTYLE.ON: SingleSpaceSeparator
784        }
785
786        return false;
787    }
788
789    /**
790     * Finds a node to continue drawing from. Decision is based upon given node and way.
791     * @param selectedNode Currently selected node, may be null
792     * @param selectedWay Currently selected way, may be null
793     * @return Node if a suitable node is found, null otherwise
794     */
795    private Node findNodeToContinueFrom(Node selectedNode, Way selectedWay) {
796        // No nodes or ways have been selected, this occurs when a relation
797        // has been selected or the selection is empty
798        if (selectedNode == null && selectedWay == null)
799            return null;
800
801        if (selectedNode == null) {
802            if (selectedWay.isFirstLastNode(lastUsedNode))
803                return lastUsedNode;
804
805            // We have a way selected, but no suitable node to continue from. Start anew.
806            return null;
807        }
808
809        if (selectedWay == null)
810            return selectedNode;
811
812        if (selectedWay.isFirstLastNode(selectedNode))
813            return selectedNode;
814
815        // We have a way and node selected, but it's not at the start/end of the way. Start anew.
816        return null;
817    }
818
819    @Override
820    public void mouseDragged(MouseEvent e) {
821        mouseMoved(e);
822    }
823
824    @Override
825    public void mouseMoved(MouseEvent e) {
826        if (!MainApplication.getMap().mapView.isActiveLayerDrawable())
827            return;
828
829        // we copy ctrl/alt/shift from the event just in case our global
830        // keyDetector didn't make it through the security manager. Unclear
831        // if that can ever happen but better be safe.
832        updateKeyModifiers(e);
833        mousePos = e.getPoint();
834        if (snapHelper.isSnapOn() && ctrl)
835            tryToSetBaseSegmentForAngleSnap();
836
837        computeHelperLine();
838        addHighlighting(e);
839    }
840
841    /**
842     * This method is used to detect segment under mouse and use it as reference for angle snapping
843     */
844    private void tryToSetBaseSegmentForAngleSnap() {
845        if (mousePos != null) {
846            WaySegment seg = MainApplication.getMap().mapView.getNearestWaySegment(mousePos, OsmPrimitive::isSelectable);
847            if (seg != null) {
848                snapHelper.setBaseSegment(seg);
849            }
850        }
851    }
852
853    /**
854     * This method prepares data required for painting the "helper line" from
855     * the last used position to the mouse cursor. It duplicates some code from
856     * mouseReleased() (FIXME).
857     */
858    private synchronized void computeHelperLine() {
859        if (mousePos == null) {
860            // Don't draw the line.
861            currentMouseEastNorth = null;
862            currentBaseNode = null;
863            return;
864        }
865
866        DataSet ds = getLayerManager().getEditDataSet();
867        Collection<OsmPrimitive> selection = ds != null ? ds.getSelected() : Collections.emptyList();
868
869        MapView mv = MainApplication.getMap().mapView;
870        Node currentMouseNode = null;
871        mouseOnExistingNode = null;
872        mouseOnExistingWays = new HashSet<>();
873
874        if (!ctrl && mousePos != null) {
875            currentMouseNode = mv.getNearestNode(mousePos, OsmPrimitive::isSelectable);
876        }
877
878        // We need this for highlighting and we'll only do so if we actually want to re-use
879        // *and* there is no node nearby (because nodes beat ways when re-using)
880        if (!ctrl && currentMouseNode == null) {
881            List<WaySegment> wss = mv.getNearestWaySegments(mousePos, OsmPrimitive::isSelectable);
882            for (WaySegment ws : wss) {
883                mouseOnExistingWays.add(ws.way);
884            }
885        }
886
887        if (currentMouseNode != null) {
888            // user clicked on node
889            if (selection.isEmpty()) return;
890            currentMouseEastNorth = currentMouseNode.getEastNorth();
891            mouseOnExistingNode = currentMouseNode;
892        } else {
893            // no node found in clicked area
894            currentMouseEastNorth = mv.getEastNorth(mousePos.x, mousePos.y);
895        }
896
897        determineCurrentBaseNodeAndPreviousNode(selection);
898        if (previousNode == null) {
899            snapHelper.noSnapNow();
900        }
901
902        if (getCurrentBaseNode() == null || getCurrentBaseNode() == currentMouseNode)
903            return; // Don't create zero length way segments.
904
905        showStatusInfo(-1, -1, -1, snapHelper.isSnapOn());
906
907        double curHdg = Utils.toDegrees(getCurrentBaseNode().getEastNorth()
908                .heading(currentMouseEastNorth));
909        double baseHdg = -1;
910        if (previousNode != null) {
911            EastNorth en = previousNode.getEastNorth();
912            if (en != null) {
913                baseHdg = Utils.toDegrees(en.heading(getCurrentBaseNode().getEastNorth()));
914            }
915        }
916
917        snapHelper.checkAngleSnapping(currentMouseEastNorth, baseHdg, curHdg);
918
919        // status bar was filled by snapHelper
920    }
921
922    static void showStatusInfo(double angle, double hdg, double distance, boolean activeFlag) {
923        MapFrame map = MainApplication.getMap();
924        map.statusLine.setAngle(angle);
925        map.statusLine.activateAnglePanel(activeFlag);
926        map.statusLine.setHeading(hdg);
927        map.statusLine.setDist(distance);
928    }
929
930    /**
931     * Helper function that sets fields currentBaseNode and previousNode
932     * @param selection
933     * uses also lastUsedNode field
934     */
935    private synchronized void determineCurrentBaseNodeAndPreviousNode(Collection<OsmPrimitive> selection) {
936        Node selectedNode = null;
937        Way selectedWay = null;
938        for (OsmPrimitive p : selection) {
939            if (p instanceof Node) {
940                if (selectedNode != null)
941                    return;
942                selectedNode = (Node) p;
943            } else if (p instanceof Way) {
944                if (selectedWay != null)
945                    return;
946                selectedWay = (Way) p;
947            }
948        }
949        // we are here, if not more than 1 way or node is selected,
950
951        // the node from which we make a connection
952        currentBaseNode = null;
953        previousNode = null;
954
955        // Try to find an open way to measure angle from it. The way is not to be continued!
956        // warning: may result in changes of currentBaseNode and previousNode
957        // please remove if bugs arise
958        if (selectedWay == null && selectedNode != null) {
959            for (OsmPrimitive p: selectedNode.getReferrers()) {
960                if (p.isUsable() && p instanceof Way && ((Way) p).isFirstLastNode(selectedNode)) {
961                    if (selectedWay != null) { // two uncontinued ways, nothing to take as reference
962                        selectedWay = null;
963                        break;
964                    } else {
965                        // set us ~continue this way (measure angle from it)
966                        selectedWay = (Way) p;
967                    }
968                }
969            }
970        }
971
972        if (selectedNode == null) {
973            if (selectedWay == null)
974                return;
975            continueWayFromNode(selectedWay, lastUsedNode);
976        } else if (selectedWay == null) {
977            currentBaseNode = selectedNode;
978        } else if (!selectedWay.isDeleted()) { // fix #7118
979            continueWayFromNode(selectedWay, selectedNode);
980        }
981    }
982
983    /**
984     * if one of the ends of {@code way} is given {@code node},
985     * then set currentBaseNode = node and previousNode = adjacent node of way
986     * @param way way to continue
987     * @param node starting node
988     */
989    private void continueWayFromNode(Way way, Node node) {
990        int n = way.getNodesCount();
991        if (node == way.firstNode()) {
992            currentBaseNode = node;
993            if (n > 1) previousNode = way.getNode(1);
994        } else if (node == way.lastNode()) {
995            currentBaseNode = node;
996            if (n > 1) previousNode = way.getNode(n-2);
997        }
998    }
999
1000    /**
1001     * Repaint on mouse exit so that the helper line goes away.
1002     */
1003    @Override
1004    public void mouseExited(MouseEvent e) {
1005        OsmDataLayer editLayer = MainApplication.getLayerManager().getEditLayer();
1006        if (editLayer == null)
1007            return;
1008        mousePos = e.getPoint();
1009        snapHelper.noSnapNow();
1010        boolean repaintIssued = removeHighlighting(e);
1011        // force repaint in case snapHelper needs one. If removeHighlighting
1012        // caused one already, don't do it again.
1013        if (!repaintIssued) {
1014            editLayer.invalidate();
1015        }
1016    }
1017
1018    /**
1019     * Replies the parent way of a node, if it is the end of exactly one usable way.
1020     * @param n node
1021     * @return If the node is the end of exactly one way, return this.
1022     *  <code>null</code> otherwise.
1023     */
1024    public static Way getWayForNode(Node n) {
1025        Way way = null;
1026        for (Way w : (Iterable<Way>) n.referrers(Way.class)::iterator) {
1027            if (!w.isUsable() || w.getNodesCount() < 1) {
1028                continue;
1029            }
1030            Node firstNode = w.firstNode();
1031            Node lastNode = w.lastNode();
1032            if ((firstNode == n || lastNode == n) && (firstNode != lastNode)) {
1033                if (way != null)
1034                    return null;
1035                way = w;
1036            }
1037        }
1038        return way;
1039    }
1040
1041    /**
1042     * Replies the current base node, after having checked it is still usable (see #11105).
1043     * @return the current base node (can be null). If not-null, it's guaranteed the node is usable
1044     */
1045    public synchronized Node getCurrentBaseNode() {
1046        if (currentBaseNode != null && (currentBaseNode.getDataSet() == null || !currentBaseNode.isUsable())) {
1047            currentBaseNode = null;
1048        }
1049        return currentBaseNode;
1050    }
1051
1052    private static void pruneSuccsAndReverse(List<Integer> is) {
1053        Set<Integer> is2 = new HashSet<>();
1054        for (int i : is) {
1055            if (!is2.contains(i - 1) && !is2.contains(i + 1)) {
1056                is2.add(i);
1057            }
1058        }
1059        is.clear();
1060        is.addAll(is2);
1061        Collections.sort(is);
1062        Collections.reverse(is);
1063    }
1064
1065    /**
1066     * Adjusts the position of a node to lie on a segment (or a segment intersection).
1067     *
1068     * If one or more than two segments are passed, the node is adjusted
1069     * to lie on the first segment that is passed.
1070     *
1071     * If two segments are passed, the node is adjusted to be at their intersection.
1072     *
1073     * No action is taken if no segments are passed.
1074     *
1075     * @param segs the segments to use as a reference when adjusting
1076     * @param n the node to adjust
1077     */
1078    private static void adjustNode(Collection<Pair<Node, Node>> segs, Node n) {
1079        switch (segs.size()) {
1080        case 0:
1081            return;
1082        case 2:
1083            adjustNodeTwoSegments(segs, n);
1084            break;
1085        default:
1086            adjustNodeDefault(segs, n);
1087        }
1088    }
1089
1090    private static void adjustNodeTwoSegments(Collection<Pair<Node, Node>> segs, Node n) {
1091        // This computes the intersection between the two segments and adjusts the node position.
1092        Iterator<Pair<Node, Node>> i = segs.iterator();
1093        Pair<Node, Node> seg = i.next();
1094        EastNorth pA = seg.a.getEastNorth();
1095        EastNorth pB = seg.b.getEastNorth();
1096        seg = i.next();
1097        EastNorth pC = seg.a.getEastNorth();
1098        EastNorth pD = seg.b.getEastNorth();
1099
1100        double u = det(pB.east() - pA.east(), pB.north() - pA.north(), pC.east() - pD.east(), pC.north() - pD.north());
1101
1102        // Check for parallel segments and do nothing if they are
1103        // In practice this will probably only happen when a way has been duplicated
1104
1105        if (u == 0)
1106            return;
1107
1108        // q is a number between 0 and 1
1109        // It is the point in the segment where the intersection occurs
1110        // if the segment is scaled to length 1
1111
1112        double q = det(pB.north() - pC.north(), pB.east() - pC.east(), pD.north() - pC.north(), pD.east() - pC.east()) / u;
1113        EastNorth intersection = new EastNorth(
1114                pB.east() + q * (pA.east() - pB.east()),
1115                pB.north() + q * (pA.north() - pB.north()));
1116
1117
1118        // only adjust to intersection if within snapToIntersectionThreshold pixel of mouse click; otherwise
1119        // fall through to default action.
1120        // (for semi-parallel lines, intersection might be miles away!)
1121        MapFrame map = MainApplication.getMap();
1122        if (map.mapView.getPoint2D(n).distance(map.mapView.getPoint2D(intersection)) < SNAP_TO_INTERSECTION_THRESHOLD.get()) {
1123            n.setEastNorth(intersection);
1124            return;
1125        }
1126
1127        adjustNodeDefault(segs, n);
1128    }
1129
1130    private static void adjustNodeDefault(Collection<Pair<Node, Node>> segs, Node n) {
1131        EastNorth p = n.getEastNorth();
1132        Pair<Node, Node> seg = segs.iterator().next();
1133        EastNorth pA = seg.a.getEastNorth();
1134        EastNorth pB = seg.b.getEastNorth();
1135        double a = p.distanceSq(pB);
1136        double b = p.distanceSq(pA);
1137        double c = pA.distanceSq(pB);
1138        double q = (a - b + c) / (2*c);
1139        n.setEastNorth(new EastNorth(pB.east() + q * (pA.east() - pB.east()), pB.north() + q * (pA.north() - pB.north())));
1140    }
1141
1142    // helper for adjustNode
1143    static double det(double a, double b, double c, double d) {
1144        return a * d - b * c;
1145    }
1146
1147    private void tryToMoveNodeOnIntersection(List<WaySegment> wss, Node n) {
1148        if (wss.isEmpty())
1149            return;
1150        WaySegment ws = wss.get(0);
1151        EastNorth p1 = ws.getFirstNode().getEastNorth();
1152        EastNorth p2 = ws.getSecondNode().getEastNorth();
1153        if (snapHelper.dir2 != null && getCurrentBaseNode() != null) {
1154            EastNorth xPoint = Geometry.getSegmentSegmentIntersection(p1, p2, snapHelper.dir2,
1155                    getCurrentBaseNode().getEastNorth());
1156            if (xPoint != null) {
1157                n.setEastNorth(xPoint);
1158            }
1159        }
1160    }
1161
1162    /**
1163     * Takes the data from computeHelperLine to determine which ways/nodes should be highlighted
1164     * (if feature enabled). Also sets the target cursor if appropriate. It adds the to-be-
1165     * highlighted primitives to newHighlights but does not actually highlight them. This work is
1166     * done in redrawIfRequired. This means, calling addHighlighting() without redrawIfRequired()
1167     * will leave the data in an inconsistent state.
1168     *
1169     * The status bar derives its information from oldHighlights, so in order to update the status
1170     * bar both addHighlighting() and repaintIfRequired() are needed, since former fills newHighlights
1171     * and latter processes them into oldHighlights.
1172     * @param event event, can be null
1173     */
1174    private void addHighlighting(Object event) {
1175        newHighlights = new HashSet<>();
1176        MapView mapView = MainApplication.getMap().mapView;
1177
1178        // if ctrl key is held ("no join"), don't highlight anything
1179        if (ctrl) {
1180            mapView.setNewCursor(cursor, this);
1181            redrawIfRequired(event);
1182            return;
1183        }
1184
1185        // This happens when nothing is selected, but we still want to highlight the "target node"
1186        DataSet ds = getLayerManager().getEditDataSet();
1187        if (mouseOnExistingNode == null && mousePos != null && ds != null && ds.selectionEmpty()) {
1188            mouseOnExistingNode = mapView.getNearestNode(mousePos, OsmPrimitive::isSelectable);
1189        }
1190
1191        if (mouseOnExistingNode != null) {
1192            mapView.setNewCursor(cursorJoinNode, this);
1193            newHighlights.add(mouseOnExistingNode);
1194            redrawIfRequired(event);
1195            return;
1196        }
1197
1198        // Insert the node into all the nearby way segments
1199        if (mouseOnExistingWays.isEmpty()) {
1200            mapView.setNewCursor(cursor, this);
1201            redrawIfRequired(event);
1202            return;
1203        }
1204
1205        mapView.setNewCursor(cursorJoinWay, this);
1206        newHighlights.addAll(mouseOnExistingWays);
1207        redrawIfRequired(event);
1208    }
1209
1210    /**
1211     * Removes target highlighting from primitives. Issues repaint if required.
1212     * @param event event, can be null
1213     * @return true if a repaint has been issued.
1214     */
1215    private boolean removeHighlighting(Object event) {
1216        newHighlights = new HashSet<>();
1217        return redrawIfRequired(event);
1218    }
1219
1220    @Override
1221    public synchronized void paint(Graphics2D g, MapView mv, Bounds box) {
1222        // sanity checks
1223        MapView mapView = MainApplication.getMap().mapView;
1224        if (mapView == null || mousePos == null
1225                // don't draw line if we don't know where from or where to
1226                || currentMouseEastNorth == null || getCurrentBaseNode() == null
1227                // don't draw line if mouse is outside window
1228                || !mapView.getState().getForView(mousePos.getX(), mousePos.getY()).isInView())
1229            return;
1230
1231        Graphics2D g2 = g;
1232        snapHelper.drawIfNeeded(g2, mv.getState());
1233        if (!DRAW_HELPER_LINE.get() || wayIsFinished || shift)
1234            return;
1235
1236        if (!snapHelper.isActive()) {
1237            g2.setColor(RUBBER_LINE_COLOR.get());
1238            g2.setStroke(RUBBER_LINE_STROKE.get());
1239            paintConstructionGeometry(mv, g2);
1240        } else if (DRAW_CONSTRUCTION_GEOMETRY.get()) {
1241            // else use color and stoke from  snapHelper.draw
1242            paintConstructionGeometry(mv, g2);
1243        }
1244    }
1245
1246    private void paintConstructionGeometry(MapView mv, Graphics2D g2) {
1247        MapPath2D b = new MapPath2D();
1248        MapViewPoint p1 = mv.getState().getPointFor(getCurrentBaseNode());
1249        MapViewPoint p2 = mv.getState().getPointFor(currentMouseEastNorth);
1250
1251        b.moveTo(p1);
1252        b.lineTo(p2);
1253
1254        // if alt key is held ("start new way"), draw a little perpendicular line
1255        if (alt) {
1256            START_WAY_INDICATOR.paintArrowAt(b, p1, p2);
1257        }
1258
1259        g2.draw(b);
1260        g2.setStroke(BASIC_STROKE);
1261    }
1262
1263    @Override
1264    public String getModeHelpText() {
1265        StringBuilder rv;
1266        /*
1267         *  No modifiers: all (Connect, Node Re-Use, Auto-Weld)
1268         *  CTRL: disables node re-use, auto-weld
1269         *  Shift: do not make connection
1270         *  ALT: make connection but start new way in doing so
1271         */
1272
1273        /*
1274         * Status line text generation is split into two parts to keep it maintainable.
1275         * First part looks at what will happen to the new node inserted on click and
1276         * the second part will look if a connection is made or not.
1277         *
1278         * Note that this help text is not absolutely accurate as it doesn't catch any special
1279         * cases (e.g. when preventing <---> ways). The only special that it catches is when
1280         * a way is about to be finished.
1281         *
1282         * First check what happens to the new node.
1283         */
1284
1285        // oldHighlights stores the current highlights. If this
1286        // list is empty we can assume that we won't do any joins
1287        if (ctrl || oldHighlights.isEmpty()) {
1288            rv = new StringBuilder(tr("Create new node."));
1289        } else {
1290            // oldHighlights may store a node or way, check if it's a node
1291            OsmPrimitive x = oldHighlights.iterator().next();
1292            if (x instanceof Node) {
1293                rv = new StringBuilder(tr("Select node under cursor."));
1294            } else {
1295                rv = new StringBuilder(trn("Insert new node into way.", "Insert new node into {0} ways.",
1296                        oldHighlights.size(), oldHighlights.size()));
1297            }
1298        }
1299
1300        /*
1301         * Check whether a connection will be made
1302         */
1303        if (!wayIsFinished && getCurrentBaseNode() != null) {
1304            if (alt) {
1305                rv.append(' ').append(tr("Start new way from last node."));
1306            } else {
1307                rv.append(' ').append(tr("Continue way from last node."));
1308            }
1309            if (snapHelper.isSnapOn()) {
1310                rv.append(' ').append(tr("Angle snapping active."));
1311            }
1312        }
1313
1314        Node n = mouseOnExistingNode;
1315        DataSet ds = getLayerManager().getEditDataSet();
1316        /*
1317         * Handle special case: Highlighted node == selected node => finish drawing
1318         */
1319        if (n != null && ds != null && ds.getSelectedNodes().contains(n)) {
1320            if (wayIsFinished) {
1321                rv = new StringBuilder(tr("Select node under cursor."));
1322            } else {
1323                rv = new StringBuilder(tr("Finish drawing."));
1324            }
1325        }
1326
1327        /*
1328         * Handle special case: Self-Overlapping or closing way
1329         */
1330        if (ds != null && !ds.getSelectedWays().isEmpty() && !wayIsFinished && !alt) {
1331            Way w = ds.getSelectedWays().iterator().next();
1332            for (Node m : w.getNodes()) {
1333                if (m.equals(mouseOnExistingNode) || mouseOnExistingWays.contains(w)) {
1334                    rv.append(' ').append(tr("Finish drawing."));
1335                    break;
1336                }
1337            }
1338        }
1339        return rv.toString();
1340    }
1341
1342    /**
1343     * Get selected primitives, while draw action is in progress.
1344     *
1345     * While drawing a way, technically the last node is selected.
1346     * This is inconvenient when the user tries to add/edit tags to the way.
1347     * For this case, this method returns the current way as selection,
1348     * to work around this issue.
1349     * Otherwise the normal selection of the current data layer is returned.
1350     * @return selected primitives, while draw action is in progress
1351     */
1352    public Collection<OsmPrimitive> getInProgressSelection() {
1353        DataSet ds = getLayerManager().getEditDataSet();
1354        if (ds == null) return Collections.emptyList();
1355        if (getCurrentBaseNode() != null && !ds.selectionEmpty()) {
1356            Way continueFrom = getWayForNode(getCurrentBaseNode());
1357            if (continueFrom != null)
1358                return Collections.<OsmPrimitive>singleton(continueFrom);
1359        }
1360        return ds.getSelected();
1361    }
1362
1363    @Override
1364    public boolean layerIsSupported(Layer l) {
1365        return isEditableDataLayer(l);
1366    }
1367
1368    @Override
1369    protected void updateEnabledState() {
1370        setEnabled(getLayerManager().getEditLayer() != null);
1371    }
1372
1373    @Override
1374    public void destroy() {
1375        super.destroy();
1376        finishDrawing();
1377        snapChangeAction.destroy();
1378    }
1379
1380    /**
1381     * Undo the last command. Binded by default to backspace key.
1382     */
1383    public class BackSpaceAction extends AbstractAction {
1384
1385        @Override
1386        public void actionPerformed(ActionEvent e) {
1387            UndoRedoHandler.getInstance().undo();
1388            Command lastCmd = UndoRedoHandler.getInstance().getLastCommand();
1389            if (lastCmd == null) return;
1390            Node n = null;
1391            for (OsmPrimitive p: lastCmd.getParticipatingPrimitives()) {
1392                if (p instanceof Node) {
1393                    if (n == null) {
1394                        n = (Node) p; // found one node
1395                        wayIsFinished = false;
1396                    } else {
1397                        // if more than 1 node were affected by previous command,
1398                        // we have no way to continue, so we forget about found node
1399                        n = null;
1400                        break;
1401                    }
1402                }
1403            }
1404            // select last added node - maybe we will continue drawing from it
1405            if (n != null) {
1406                addSelection(getLayerManager().getEditDataSet(), n);
1407            }
1408        }
1409    }
1410
1411    private class SnapChangeAction extends JosmAction {
1412        /**
1413         * Constructs a new {@code SnapChangeAction}.
1414         */
1415        SnapChangeAction() {
1416            super(tr("Angle snapping"), /* ICON() */ "anglesnap",
1417                    tr("Switch angle snapping mode while drawing"), null, false);
1418            setHelpId(ht("/Action/Draw/AngleSnap"));
1419        }
1420
1421        @Override
1422        public void actionPerformed(ActionEvent e) {
1423            if (snapHelper != null) {
1424                snapHelper.toggleSnapping();
1425            }
1426        }
1427
1428        @Override
1429        protected void updateEnabledState() {
1430            MapFrame map = MainApplication.getMap();
1431            setEnabled(map != null && map.mapMode instanceof DrawAction);
1432        }
1433    }
1434}