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.JOptionPane;
031import javax.swing.SwingUtilities;
032
033import org.openstreetmap.josm.actions.JosmAction;
034import org.openstreetmap.josm.command.AddCommand;
035import org.openstreetmap.josm.command.ChangeNodesCommand;
036import org.openstreetmap.josm.command.Command;
037import org.openstreetmap.josm.command.SequenceCommand;
038import org.openstreetmap.josm.data.Bounds;
039import org.openstreetmap.josm.data.UndoRedoHandler;
040import org.openstreetmap.josm.data.coor.EastNorth;
041import org.openstreetmap.josm.data.osm.DataSelectionListener;
042import org.openstreetmap.josm.data.osm.DataSet;
043import org.openstreetmap.josm.data.osm.Node;
044import org.openstreetmap.josm.data.osm.OsmPrimitive;
045import org.openstreetmap.josm.data.osm.Way;
046import org.openstreetmap.josm.data.osm.WaySegment;
047import org.openstreetmap.josm.data.osm.event.SelectionEventManager;
048import org.openstreetmap.josm.data.osm.visitor.paint.ArrowPaintHelper;
049import org.openstreetmap.josm.data.osm.visitor.paint.PaintColors;
050import org.openstreetmap.josm.data.preferences.AbstractProperty;
051import org.openstreetmap.josm.data.preferences.BooleanProperty;
052import org.openstreetmap.josm.data.preferences.CachingProperty;
053import org.openstreetmap.josm.data.preferences.DoubleProperty;
054import org.openstreetmap.josm.data.preferences.NamedColorProperty;
055import org.openstreetmap.josm.data.preferences.StrokeProperty;
056import org.openstreetmap.josm.gui.MainApplication;
057import org.openstreetmap.josm.gui.MainMenu;
058import org.openstreetmap.josm.gui.MapFrame;
059import org.openstreetmap.josm.gui.MapView;
060import org.openstreetmap.josm.gui.MapViewState.MapViewPoint;
061import org.openstreetmap.josm.gui.NavigatableComponent;
062import org.openstreetmap.josm.gui.draw.MapPath2D;
063import org.openstreetmap.josm.gui.layer.Layer;
064import org.openstreetmap.josm.gui.layer.MapViewPaintable;
065import org.openstreetmap.josm.gui.layer.OsmDataLayer;
066import org.openstreetmap.josm.gui.util.KeyPressReleaseListener;
067import org.openstreetmap.josm.gui.util.ModifierExListener;
068import org.openstreetmap.josm.tools.Geometry;
069import org.openstreetmap.josm.tools.ImageProvider;
070import org.openstreetmap.josm.tools.Pair;
071import org.openstreetmap.josm.tools.Shortcut;
072import org.openstreetmap.josm.tools.Utils;
073
074/**
075 * Mapmode to add nodes, create and extend ways.
076 */
077public class DrawAction extends MapMode implements MapViewPaintable, DataSelectionListener, KeyPressReleaseListener, ModifierExListener {
078
079    /**
080     * If this property is set, the draw action moves the viewport when adding new points.
081     * @since 12182
082     */
083    public static final CachingProperty<Boolean> VIEWPORT_FOLLOWING = new BooleanProperty("draw.viewport.following", false).cached();
084
085    private static final Color ORANGE_TRANSPARENT = new Color(Color.ORANGE.getRed(), Color.ORANGE.getGreen(), Color.ORANGE.getBlue(), 128);
086
087    private static final ArrowPaintHelper START_WAY_INDICATOR = new ArrowPaintHelper(Utils.toRadians(90), 8);
088
089    static final CachingProperty<Boolean> USE_REPEATED_SHORTCUT
090            = new BooleanProperty("draw.anglesnap.toggleOnRepeatedA", true).cached();
091    static final CachingProperty<BasicStroke> RUBBER_LINE_STROKE
092            = new StrokeProperty("draw.stroke.helper-line", "3").cached();
093
094    static final CachingProperty<BasicStroke> HIGHLIGHT_STROKE
095            = new StrokeProperty("draw.anglesnap.stroke.highlight", "10").cached();
096    static final CachingProperty<BasicStroke> HELPER_STROKE
097            = new StrokeProperty("draw.anglesnap.stroke.helper", "1 4").cached();
098
099    static final CachingProperty<Double> SNAP_ANGLE_TOLERANCE
100            = new DoubleProperty("draw.anglesnap.tolerance", 5.0).cached();
101    static final CachingProperty<Boolean> DRAW_CONSTRUCTION_GEOMETRY
102            = new BooleanProperty("draw.anglesnap.drawConstructionGeometry", true).cached();
103    static final CachingProperty<Boolean> SHOW_PROJECTED_POINT
104            = new BooleanProperty("draw.anglesnap.drawProjectedPoint", true).cached();
105    static final CachingProperty<Boolean> SNAP_TO_PROJECTIONS
106            = new BooleanProperty("draw.anglesnap.projectionsnap", true).cached();
107
108    static final CachingProperty<Boolean> SHOW_ANGLE
109            = new BooleanProperty("draw.anglesnap.showAngle", true).cached();
110
111    static final CachingProperty<Color> SNAP_HELPER_COLOR
112            = new NamedColorProperty(marktr("draw angle snap"), Color.ORANGE).cached();
113
114    static final CachingProperty<Color> HIGHLIGHT_COLOR
115            = new NamedColorProperty(marktr("draw angle snap highlight"), ORANGE_TRANSPARENT).cached();
116
117    static final AbstractProperty<Color> RUBBER_LINE_COLOR
118            = PaintColors.SELECTED.getProperty().getChildColor(marktr("helper line"));
119
120    static final CachingProperty<Boolean> DRAW_HELPER_LINE
121            = new BooleanProperty("draw.helper-line", true).cached();
122    static final CachingProperty<Boolean> DRAW_TARGET_HIGHLIGHT
123            = new BooleanProperty("draw.target-highlight", true).cached();
124    static final CachingProperty<Double> SNAP_TO_INTERSECTION_THRESHOLD
125            = new DoubleProperty("edit.snap-intersection-threshold", 10).cached();
126
127    private final Cursor cursorJoinNode;
128    private final Cursor cursorJoinWay;
129
130    private transient Node lastUsedNode;
131    private double toleranceMultiplier;
132
133    private transient Node mouseOnExistingNode;
134    private transient Set<Way> mouseOnExistingWays = new HashSet<>();
135    // old highlights store which primitives are currently highlighted. This
136    // is true, even if target highlighting is disabled since the status bar
137    // derives its information from this list as well.
138    private transient Set<OsmPrimitive> oldHighlights = new HashSet<>();
139    // new highlights contains a list of primitives that should be highlighted
140    // but haven't been so far. The idea is to compare old and new and only
141    // repaint if there are changes.
142    private transient Set<OsmPrimitive> newHighlights = new HashSet<>();
143    private boolean wayIsFinished;
144    private Point mousePos;
145    private Point oldMousePos;
146
147    private transient Node currentBaseNode;
148    private transient Node previousNode;
149    private EastNorth currentMouseEastNorth;
150
151    private final transient DrawSnapHelper snapHelper = new DrawSnapHelper(this);
152
153    private final transient Shortcut backspaceShortcut;
154    private final BackSpaceAction backspaceAction;
155    private final transient Shortcut snappingShortcut;
156    private boolean ignoreNextKeyRelease;
157
158    private final SnapChangeAction snapChangeAction;
159    private final JCheckBoxMenuItem snapCheckboxMenuItem;
160    private static final BasicStroke BASIC_STROKE = new BasicStroke(1);
161
162    private Point rightClickPressPos;
163
164    /**
165     * Constructs a new {@code DrawAction}.
166     * @since 11713
167     */
168    public DrawAction() {
169        super(tr("Draw"), "node/autonode", tr("Draw nodes"),
170                Shortcut.registerShortcut("mapmode:draw", tr("Mode: {0}", tr("Draw")), KeyEvent.VK_A, Shortcut.DIRECT),
171                ImageProvider.getCursor("crosshair", null));
172
173        snappingShortcut = Shortcut.registerShortcut("mapmode:drawanglesnapping",
174                tr("Edit: {0}", tr("Draw Angle snapping")), KeyEvent.CHAR_UNDEFINED, Shortcut.NONE);
175        snapChangeAction = new SnapChangeAction();
176        snapCheckboxMenuItem = addMenuItem();
177        snapHelper.setMenuCheckBox(snapCheckboxMenuItem);
178        backspaceShortcut = Shortcut.registerShortcut("mapmode:backspace",
179                tr("Backspace in Add mode"), KeyEvent.VK_BACK_SPACE, Shortcut.DIRECT);
180        backspaceAction = new BackSpaceAction();
181        cursorJoinNode = ImageProvider.getCursor("crosshair", "joinnode");
182        cursorJoinWay = ImageProvider.getCursor("crosshair", "joinway");
183
184        snapHelper.init();
185    }
186
187    private JCheckBoxMenuItem addMenuItem() {
188        int n = MainApplication.getMenu().editMenu.getItemCount();
189        return MainMenu.addWithCheckbox(MainApplication.getMenu().editMenu, snapChangeAction, n >= 5 ? n-5 : -1, false);
190    }
191
192    /**
193     * Checks if a map redraw is required and does so if needed. Also updates the status bar.
194     * @param e event, can be null
195     * @return true if a repaint is needed
196     */
197    private boolean redrawIfRequired(Object e) {
198        updateStatusLine();
199        // repaint required if the helper line is active.
200        boolean needsRepaint = DRAW_HELPER_LINE.get() && !wayIsFinished;
201        if (DRAW_TARGET_HIGHLIGHT.get()) {
202            // move newHighlights to oldHighlights; only update changed primitives
203            for (OsmPrimitive x : newHighlights) {
204                if (oldHighlights.contains(x)) {
205                    continue;
206                }
207                x.setHighlighted(true);
208                needsRepaint = true;
209            }
210            oldHighlights.removeAll(newHighlights);
211            for (OsmPrimitive x : oldHighlights) {
212                x.setHighlighted(false);
213                needsRepaint = true;
214            }
215        }
216        // required in order to print correct help text
217        oldHighlights = newHighlights;
218
219        if (!needsRepaint && !DRAW_TARGET_HIGHLIGHT.get())
220            return false;
221
222        // update selection to reflect which way being modified
223        OsmDataLayer editLayer = getLayerManager().getEditLayer();
224        Node baseNode = getCurrentBaseNode();
225        if (editLayer != null && baseNode != null && !editLayer.data.selectionEmpty()) {
226            DataSet currentDataSet = editLayer.getDataSet();
227            Way continueFrom = getWayForNode(baseNode);
228            if (alt && continueFrom != null && (!baseNode.isSelected() || continueFrom.isSelected())) {
229                addRemoveSelection(currentDataSet, baseNode, continueFrom);
230                needsRepaint = true;
231            } else if (!alt && continueFrom != null && !continueFrom.isSelected()) {
232                addSelection(currentDataSet, continueFrom);
233                needsRepaint = true;
234            }
235        }
236
237        if (!needsRepaint && e instanceof SelectionChangeEvent) {
238            SelectionChangeEvent event = (SelectionChangeEvent) e;
239            needsRepaint = !event.getOldSelection().isEmpty() && event.getSelection().isEmpty();
240        }
241
242        if (needsRepaint && editLayer != null) {
243            editLayer.invalidate();
244        }
245        return needsRepaint;
246    }
247
248    private static void addRemoveSelection(DataSet ds, OsmPrimitive toAdd, OsmPrimitive toRemove) {
249        ds.update(() -> { // to prevent the selection listener to screw around with the state
250            addSelection(ds, toAdd);
251            clearSelection(ds, toRemove);
252        });
253    }
254
255    private static void updatePreservedFlag(OsmPrimitive osm, boolean state) {
256        // Preserves selected primitives and selected way nodes
257        osm.setPreserved(state);
258        if (osm instanceof Way) {
259            for (Node n : ((Way) osm).getNodes()) {
260                n.setPreserved(state);
261            }
262        }
263    }
264
265    private static void setSelection(DataSet ds, Collection<OsmPrimitive> toSet) {
266        toSet.forEach(x -> updatePreservedFlag(x, true));
267        ds.setSelected(toSet);
268    }
269
270    private static void setSelection(DataSet ds, OsmPrimitive toSet) {
271        updatePreservedFlag(toSet, true);
272        ds.setSelected(toSet);
273    }
274
275    private static void addSelection(DataSet ds, OsmPrimitive toAdd) {
276        updatePreservedFlag(toAdd, true);
277        ds.addSelected(toAdd);
278    }
279
280    private static void clearSelection(DataSet ds, OsmPrimitive toRemove) {
281        ds.clearSelection(toRemove);
282        updatePreservedFlag(toRemove, false);
283    }
284
285    @Override
286    public void enterMode() {
287        if (!isEnabled())
288            return;
289        super.enterMode();
290        readPreferences();
291
292        // determine if selection is suitable to continue drawing. If it
293        // isn't, set wayIsFinished to true to avoid superfluous repaints.
294        determineCurrentBaseNodeAndPreviousNode(getLayerManager().getEditDataSet().getSelected());
295        wayIsFinished = getCurrentBaseNode() == null;
296
297        toleranceMultiplier = 0.01 * NavigatableComponent.PROP_SNAP_DISTANCE.get();
298
299        snapHelper.init();
300        snapCheckboxMenuItem.getAction().setEnabled(true);
301
302        MapFrame map = MainApplication.getMap();
303        map.statusLine.getAnglePanel().addMouseListener(snapHelper.anglePopupListener);
304        MainApplication.registerActionShortcut(backspaceAction, backspaceShortcut);
305
306        map.mapView.addMouseListener(this);
307        map.mapView.addMouseMotionListener(this);
308        map.mapView.addTemporaryLayer(this);
309        SelectionEventManager.getInstance().addSelectionListenerForEdt(this);
310
311        map.keyDetector.addKeyListener(this);
312        map.keyDetector.addModifierExListener(this);
313        ignoreNextKeyRelease = true;
314    }
315
316    @Override
317    public void exitMode() {
318        super.exitMode();
319
320        MapFrame map = MainApplication.getMap();
321        map.mapView.removeMouseListener(this);
322        map.mapView.removeMouseMotionListener(this);
323        map.mapView.removeTemporaryLayer(this);
324        SelectionEventManager.getInstance().removeSelectionListener(this);
325        MainApplication.unregisterActionShortcut(backspaceAction, backspaceShortcut);
326        snapHelper.unsetFixedMode();
327        snapCheckboxMenuItem.getAction().setEnabled(false);
328
329        map.statusLine.getAnglePanel().removeMouseListener(snapHelper.anglePopupListener);
330        map.statusLine.activateAnglePanel(false);
331
332        DataSet ds = getLayerManager().getEditDataSet();
333        if (ds != null) {
334            ds.getSelected().forEach(x -> updatePreservedFlag(x, false));
335            map.statusLine.setDist(ds.getSelectedWays());
336        }
337
338        removeHighlighting(null);
339        map.keyDetector.removeKeyListener(this);
340        map.keyDetector.removeModifierExListener(this);
341        lastUsedNode = null;
342    }
343
344    /**
345     * redraw to (possibly) get rid of helper line if selection changes.
346     */
347    @Override
348    public void modifiersExChanged(int modifiers) {
349        if (!MainApplication.isDisplayingMapView() || !MainApplication.getMap().mapView.isActiveLayerDrawable())
350            return;
351        updateKeyModifiersEx(modifiers);
352        computeHelperLine();
353        addHighlighting(null);
354    }
355
356    @Override
357    public void doKeyPressed(KeyEvent e) {
358        if (!snappingShortcut.isEvent(e) && !(USE_REPEATED_SHORTCUT.get() && getShortcut().isEvent(e)))
359            return;
360        snapHelper.setFixedMode();
361        computeHelperLine();
362        redrawIfRequired(e);
363    }
364
365    @Override
366    public void doKeyReleased(KeyEvent e) {
367        if (!snappingShortcut.isEvent(e) && !(USE_REPEATED_SHORTCUT.get() && getShortcut().isEvent(e)))
368            return;
369        if (ignoreNextKeyRelease) {
370            ignoreNextKeyRelease = false;
371            return;
372        }
373        snapHelper.unFixOrTurnOff();
374        computeHelperLine();
375        redrawIfRequired(e);
376    }
377
378    /**
379     * redraw to (possibly) get rid of helper line if selection changes.
380     */
381    @Override
382    public void selectionChanged(SelectionChangeEvent event) {
383        if (!MainApplication.getMap().mapView.isActiveLayerDrawable())
384            return;
385        if (event.getSelection().isEmpty())
386            finishDrawing();
387        // Make sure helper line is computed later (causes deadlock in selection event chain otherwise)
388        SwingUtilities.invokeLater(() -> {
389            event.getOldSelection().forEach(x -> updatePreservedFlag(x, false));
390            event.getSelection().forEach(x -> updatePreservedFlag(x, true));
391            if (MainApplication.getMap() != null) {
392                computeHelperLine();
393                addHighlighting(event);
394            }
395        });
396    }
397
398    private void tryAgain(MouseEvent e) {
399        getLayerManager().getEditDataSet().clearSelection();
400        mouseReleased(e);
401    }
402
403    /**
404     * This function should be called when the user wishes to finish his current draw action.
405     * If Potlatch Style is enabled, it will switch to select tool, otherwise simply disable
406     * the helper line until the user chooses to draw something else.
407     */
408    private void finishDrawing() {
409        lastUsedNode = null;
410        wayIsFinished = true;
411        MainApplication.getMap().selectSelectTool(true);
412        snapHelper.noSnapNow();
413
414        // Redraw to remove the helper line stub
415        computeHelperLine();
416        removeHighlighting(null);
417    }
418
419    @Override
420    public void mousePressed(MouseEvent e) {
421        if (e.getButton() == MouseEvent.BUTTON3) {
422            rightClickPressPos = e.getPoint();
423        }
424    }
425
426    /**
427     * If user clicked with the left button, add a node at the current mouse
428     * position.
429     *
430     * If in nodeway mode, insert the node into the way.
431     */
432    @Override
433    public void mouseReleased(MouseEvent e) {
434        if (e.getButton() == MouseEvent.BUTTON3) {
435            Point curMousePos = e.getPoint();
436            if (curMousePos.equals(rightClickPressPos)) {
437                tryToSetBaseSegmentForAngleSnap();
438            }
439            return;
440        }
441        if (e.getButton() != MouseEvent.BUTTON1)
442            return;
443        MapView mapView = MainApplication.getMap().mapView;
444        if (!mapView.isActiveLayerDrawable())
445            return;
446        // request focus in order to enable the expected keyboard shortcuts
447        //
448        mapView.requestFocus();
449
450        if (e.getClickCount() > 1 && mousePos != null && mousePos.equals(oldMousePos)) {
451            // A double click equals "user clicked last node again, finish way"
452            // Change draw tool only if mouse position is nearly the same, as
453            // otherwise fast clicks will count as a double click
454            finishDrawing();
455            return;
456        }
457        oldMousePos = mousePos;
458
459        // we copy ctrl/alt/shift from the event just in case our global
460        // keyDetector didn't make it through the security manager. Unclear
461        // if that can ever happen but better be safe.
462        updateKeyModifiers(e);
463        mousePos = e.getPoint();
464
465        DataSet ds = getLayerManager().getEditDataSet();
466        Collection<OsmPrimitive> selection = new ArrayList<>(ds.getSelected());
467
468        boolean newNode = false;
469        Node n = mapView.getNearestNode(mousePos, OsmPrimitive::isSelectable);
470        if (ctrl) {
471            Iterator<Way> it = ds.getSelectedWays().iterator();
472            if (it.hasNext()) {
473                // ctrl-click on node of selected way = reuse node despite of ctrl
474                if (!it.next().containsNode(n)) n = null;
475            } else {
476                n = null; // ctrl-click + no selected way = new node
477            }
478        }
479
480        if (n != null && !snapHelper.isActive()) {
481            // user clicked on node
482            if (selection.isEmpty() || wayIsFinished) {
483                // select the clicked node and do nothing else
484                // (this is just a convenience option so that people don't
485                // have to switch modes)
486
487                setSelection(ds, n);
488                // If we extend/continue an existing way, select it already now to make it obvious
489                Way continueFrom = getWayForNode(n);
490                if (continueFrom != null) {
491                    addSelection(ds, continueFrom);
492                }
493
494                // The user explicitly selected a node, so let him continue drawing
495                wayIsFinished = false;
496                return;
497            }
498        } else {
499            EastNorth newEN;
500            if (n != null) {
501                EastNorth foundPoint = n.getEastNorth();
502                // project found node to snapping line
503                newEN = snapHelper.getSnapPoint(foundPoint);
504                // do not add new node if there is some node within snapping distance
505                double tolerance = mapView.getDist100Pixel() * toleranceMultiplier;
506                if (foundPoint.distance(newEN) > tolerance) {
507                    n = new Node(newEN); // point != projected, so we create new node
508                    newNode = true;
509                }
510            } else { // n==null, no node found in clicked area
511                EastNorth mouseEN = mapView.getEastNorth(e.getX(), e.getY());
512                newEN = snapHelper.isSnapOn() ? snapHelper.getSnapPoint(mouseEN) : mouseEN;
513                n = new Node(newEN); //create node at clicked point
514                newNode = true;
515            }
516            snapHelper.unsetFixedMode();
517        }
518
519        Collection<Command> cmds = new LinkedList<>();
520        Collection<OsmPrimitive> newSelection = new LinkedList<>(ds.getSelected());
521        Map<Way, List<Node>> reuseWays = new HashMap<>();
522
523        if (newNode) {
524            if (n.isOutSideWorld()) {
525                JOptionPane.showMessageDialog(
526                        MainApplication.getMainFrame(),
527                        tr("Cannot add a node outside of the world."),
528                        tr("Warning"),
529                        JOptionPane.WARNING_MESSAGE
530                        );
531                return;
532            }
533            cmds.add(new AddCommand(ds, n));
534
535            if (!ctrl) {
536                // Insert the node into all the nearby way segments
537                List<WaySegment> wss = mapView.getNearestWaySegments(
538                        mapView.getPoint(n), OsmPrimitive::isSelectable);
539                if (snapHelper.isActive()) {
540                    tryToMoveNodeOnIntersection(wss, n);
541                }
542                insertNodeIntoAllNearbySegments(wss, n, newSelection, cmds, reuseWays);
543            }
544        }
545        // now "n" is newly created or reused node that shoud be added to some way
546
547        // This part decides whether or not a "segment" (i.e. a connection) is made to an existing node.
548
549        // For a connection to be made, the user must either have a node selected (connection
550        // is made to that node), or he must have a way selected *and* one of the endpoints
551        // of that way must be the last used node (connection is made to last used node), or
552        // he must have a way and a node selected (connection is made to the selected node).
553
554        // If the above does not apply, the selection is cleared and a new try is started
555
556        boolean extendedWay = false;
557        boolean wayIsFinishedTemp = wayIsFinished;
558        wayIsFinished = false;
559
560        // don't draw lines if shift is held
561        if (!selection.isEmpty() && !shift) {
562            Node selectedNode = null;
563            Way selectedWay = null;
564
565            for (OsmPrimitive p : selection) {
566                if (p instanceof Node) {
567                    if (selectedNode != null) {
568                        // Too many nodes selected to do something useful
569                        tryAgain(e);
570                        return;
571                    }
572                    selectedNode = (Node) p;
573                } else if (p instanceof Way) {
574                    if (selectedWay != null) {
575                        // Too many ways selected to do something useful
576                        tryAgain(e);
577                        return;
578                    }
579                    selectedWay = (Way) p;
580                }
581            }
582
583            // the node from which we make a connection
584            Node n0 = findNodeToContinueFrom(selectedNode, selectedWay);
585            // We have a selection but it isn't suitable. Try again.
586            if (n0 == null) {
587                tryAgain(e);
588                return;
589            }
590            if (!wayIsFinishedTemp) {
591                if (isSelfContainedWay(selectedWay, n0, n))
592                    return;
593
594                // User clicked last node again, finish way
595                if (n0 == n) {
596                    finishDrawing();
597                    return;
598                }
599
600                // Ok we know now that we'll insert a line segment, but will it connect to an
601                // existing way or make a new way of its own? The "alt" modifier means that the
602                // user wants a new way.
603                Way way = alt ? null : (selectedWay != null ? selectedWay : getWayForNode(n0));
604
605                // Don't allow creation of self-overlapping ways
606                if (way != null) {
607                    long nodeCount = way.getNodes().stream().filter(p -> p.equals(n0)).count();
608                    if (nodeCount > 1) {
609                        way = null;
610                    }
611                }
612
613                if (way == null) {
614                    way = new Way();
615                    way.addNode(n0);
616                    way.addNode(n);
617                    cmds.add(new AddCommand(ds, way));
618                } else {
619                    List<Node> modNodes = reuseWays.get(way);
620                    boolean reuse = (modNodes != null);
621                    if (modNodes == null) {
622                        modNodes = way.getNodes();
623                    }
624                    // Connected to a node that's already in the way
625                    if (modNodes.contains(n)) {
626                        wayIsFinished = true;
627                        selection.clear();
628                    }
629                    if (modNodes.get(modNodes.size() - 1) == n0)
630                        modNodes.add(n);
631                    else
632                        modNodes.add(0, n);
633                    if (!reuse) {
634                        cmds.add(new ChangeNodesCommand(way, modNodes));
635                    }
636                }
637
638                extendedWay = true;
639                newSelection.clear();
640                newSelection.add(way);
641            }
642        }
643        if (!extendedWay && !newNode) {
644            return; // We didn't do anything.
645        }
646
647        String title = getTitle(newNode, n, newSelection, reuseWays, extendedWay);
648
649        Command c = new SequenceCommand(title, cmds);
650
651        UndoRedoHandler.getInstance().add(c);
652        if (!wayIsFinished) {
653            lastUsedNode = n;
654        }
655
656        setSelection(ds, newSelection);
657
658        // "viewport following" mode for tracing long features
659        // from aerial imagery or GPS tracks.
660        if (VIEWPORT_FOLLOWING.get()) {
661            mapView.smoothScrollTo(n.getEastNorth());
662        }
663        computeHelperLine();
664        removeHighlighting(e);
665    }
666
667    private static String getTitle(boolean newNode, Node n, Collection<OsmPrimitive> newSelection, Map<Way, List<Node>> reuseWays,
668            boolean extendedWay) {
669        String title;
670        if (!extendedWay) {
671            if (reuseWays.isEmpty()) {
672                title = tr("Add node");
673            } else {
674                title = tr("Add node into way");
675                for (Way w : reuseWays.keySet()) {
676                    newSelection.remove(w);
677                }
678            }
679            newSelection.clear();
680            newSelection.add(n);
681        } else if (!newNode) {
682            title = tr("Connect existing way to node");
683        } else if (reuseWays.isEmpty()) {
684            title = tr("Add a new node to an existing way");
685        } else {
686            title = tr("Add node into way and connect");
687        }
688        return title;
689    }
690
691    private void insertNodeIntoAllNearbySegments(List<WaySegment> wss, Node n, Collection<OsmPrimitive> newSelection,
692            Collection<Command> cmds, Map<Way, List<Node>> reuseWays) {
693        Map<Way, List<Integer>> insertPoints = new HashMap<>();
694        for (WaySegment ws : wss) {
695            List<Integer> is;
696            if (insertPoints.containsKey(ws.getWay())) {
697                is = insertPoints.get(ws.getWay());
698            } else {
699                is = new ArrayList<>();
700                insertPoints.put(ws.getWay(), is);
701            }
702
703            is.add(ws.getLowerIndex());
704        }
705
706        Set<Pair<Node, Node>> segSet = new HashSet<>();
707
708        for (Map.Entry<Way, List<Integer>> insertPoint : insertPoints.entrySet()) {
709            Way w = insertPoint.getKey();
710            List<Integer> is = insertPoint.getValue();
711
712            List<Node> modNodes = w.getNodes();
713            pruneSuccsAndReverse(is);
714            for (int i : is) {
715                segSet.add(Pair.sort(new Pair<>(w.getNode(i), w.getNode(i+1))));
716                modNodes.add(i + 1, n);
717            }
718
719            // If ALT is pressed, a new way should be created and that new way should get
720            // selected. This works every time unless the ways the nodes get inserted into
721            // are already selected. This is the case when creating a self-overlapping way
722            // but pressing ALT prevents this. Therefore we must de-select the way manually
723            // here so /only/ the new way will be selected after this method finishes.
724            if (alt) {
725                newSelection.add(insertPoint.getKey());
726            }
727
728            cmds.add(new ChangeNodesCommand(insertPoint.getKey(), modNodes));
729            reuseWays.put(w, modNodes);
730        }
731
732        adjustNode(segSet, n);
733    }
734
735    /**
736     * Prevent creation of ways that look like this: &lt;----&gt;
737     * This happens if users want to draw a no-exit-sideway from the main way like this:
738     * ^
739     * |&lt;----&gt;
740     * |
741     * The solution isn't ideal because the main way will end in the side way, which is bad for
742     * navigation software ("drive straight on") but at least easier to fix. Maybe users will fix
743     * it on their own, too. At least it's better than producing an error.
744     *
745     * @param selectedWay the way to check
746     * @param currentNode the current node (i.e. the one the connection will be made from)
747     * @param targetNode the target node (i.e. the one the connection will be made to)
748     * @return {@code true} if this would create a selfcontaining way, {@code false} otherwise.
749     */
750    private boolean isSelfContainedWay(Way selectedWay, Node currentNode, Node targetNode) {
751        if (selectedWay != null) {
752            int posn0 = selectedWay.getNodes().indexOf(currentNode);
753            // CHECKSTYLE.OFF: SingleSpaceSeparator
754            if ((posn0 != -1 && // n0 is part of way
755                (posn0 >= 1                            && targetNode.equals(selectedWay.getNode(posn0-1)))) || // previous node
756                (posn0 < selectedWay.getNodesCount()-1 && targetNode.equals(selectedWay.getNode(posn0+1)))) {  // next node
757                setSelection(getLayerManager().getEditDataSet(), targetNode);
758                lastUsedNode = targetNode;
759                return true;
760            }
761            // CHECKSTYLE.ON: SingleSpaceSeparator
762        }
763
764        return false;
765    }
766
767    /**
768     * Finds a node to continue drawing from. Decision is based upon given node and way.
769     * @param selectedNode Currently selected node, may be null
770     * @param selectedWay Currently selected way, may be null
771     * @return Node if a suitable node is found, null otherwise
772     */
773    private Node findNodeToContinueFrom(Node selectedNode, Way selectedWay) {
774        // No nodes or ways have been selected, this occurs when a relation
775        // has been selected or the selection is empty
776        if (selectedNode == null && selectedWay == null)
777            return null;
778
779        if (selectedNode == null) {
780            if (selectedWay.isFirstLastNode(lastUsedNode))
781                return lastUsedNode;
782
783            // We have a way selected, but no suitable node to continue from. Start anew.
784            return null;
785        }
786
787        if (selectedWay == null)
788            return selectedNode;
789
790        if (selectedWay.isFirstLastNode(selectedNode))
791            return selectedNode;
792
793        // We have a way and node selected, but it's not at the start/end of the way. Start anew.
794        return null;
795    }
796
797    @Override
798    public void mouseDragged(MouseEvent e) {
799        mouseMoved(e);
800    }
801
802    @Override
803    public void mouseMoved(MouseEvent e) {
804        if (!MainApplication.getMap().mapView.isActiveLayerDrawable())
805            return;
806
807        // we copy ctrl/alt/shift from the event just in case our global
808        // keyDetector didn't make it through the security manager. Unclear
809        // if that can ever happen but better be safe.
810        updateKeyModifiers(e);
811        mousePos = e.getPoint();
812        if (snapHelper.isSnapOn() && ctrl)
813            tryToSetBaseSegmentForAngleSnap();
814
815        computeHelperLine();
816        addHighlighting(e);
817    }
818
819    /**
820     * This method is used to detect segment under mouse and use it as reference for angle snapping
821     */
822    private void tryToSetBaseSegmentForAngleSnap() {
823        if (mousePos != null) {
824            WaySegment seg = MainApplication.getMap().mapView.getNearestWaySegment(mousePos, OsmPrimitive::isSelectable);
825            if (seg != null) {
826                snapHelper.setBaseSegment(seg);
827            }
828        }
829    }
830
831    /**
832     * This method prepares data required for painting the "helper line" from
833     * the last used position to the mouse cursor. It duplicates some code from
834     * mouseReleased() (FIXME).
835     */
836    private synchronized void computeHelperLine() {
837        if (mousePos == null) {
838            // Don't draw the line.
839            currentMouseEastNorth = null;
840            currentBaseNode = null;
841            return;
842        }
843
844        DataSet ds = getLayerManager().getEditDataSet();
845        Collection<OsmPrimitive> selection = ds != null ? ds.getSelected() : Collections.emptyList();
846
847        MapView mv = MainApplication.getMap().mapView;
848        Node currentMouseNode = null;
849        mouseOnExistingNode = null;
850        mouseOnExistingWays = new HashSet<>();
851
852        if (!ctrl && mousePos != null) {
853            currentMouseNode = mv.getNearestNode(mousePos, OsmPrimitive::isSelectable);
854        }
855
856        // We need this for highlighting and we'll only do so if we actually want to re-use
857        // *and* there is no node nearby (because nodes beat ways when re-using)
858        if (!ctrl && currentMouseNode == null) {
859            List<WaySegment> wss = mv.getNearestWaySegments(mousePos, OsmPrimitive::isSelectable);
860            for (WaySegment ws : wss) {
861                mouseOnExistingWays.add(ws.getWay());
862            }
863        }
864
865        if (currentMouseNode != null) {
866            // user clicked on node
867            if (selection.isEmpty()) return;
868            currentMouseEastNorth = currentMouseNode.getEastNorth();
869            mouseOnExistingNode = currentMouseNode;
870        } else {
871            // no node found in clicked area
872            currentMouseEastNorth = mv.getEastNorth(mousePos.x, mousePos.y);
873        }
874
875        determineCurrentBaseNodeAndPreviousNode(selection);
876        if (previousNode == null) {
877            snapHelper.noSnapNow();
878        }
879
880        if (getCurrentBaseNode() == null || getCurrentBaseNode() == currentMouseNode)
881            return; // Don't create zero length way segments.
882
883        showStatusInfo(Double.NaN, -1, -1, snapHelper.isSnapOn());
884
885        double curHdg = Utils.toDegrees(getCurrentBaseNode().getEastNorth()
886                .heading(currentMouseEastNorth));
887        double baseHdg = -1;
888        if (previousNode != null) {
889            EastNorth en = previousNode.getEastNorth();
890            if (en != null) {
891                baseHdg = Utils.toDegrees(en.heading(getCurrentBaseNode().getEastNorth()));
892            }
893        }
894
895        snapHelper.checkAngleSnapping(currentMouseEastNorth, baseHdg, curHdg);
896
897        // status bar was filled by snapHelper
898    }
899
900    static void showStatusInfo(double angle, double hdg, double distance, boolean activeFlag) {
901        MapFrame map = MainApplication.getMap();
902        map.statusLine.setAngleNaN(angle);
903        map.statusLine.activateAnglePanel(activeFlag);
904        map.statusLine.setHeading(hdg);
905        map.statusLine.setDist(distance);
906    }
907
908    /**
909     * Helper function that sets fields currentBaseNode and previousNode
910     * @param selection
911     * uses also lastUsedNode field
912     */
913    private synchronized void determineCurrentBaseNodeAndPreviousNode(Collection<OsmPrimitive> selection) {
914        Node selectedNode = null;
915        Way selectedWay = null;
916        for (OsmPrimitive p : selection) {
917            if (p instanceof Node) {
918                if (selectedNode != null)
919                    return;
920                selectedNode = (Node) p;
921            } else if (p instanceof Way) {
922                if (selectedWay != null)
923                    return;
924                selectedWay = (Way) p;
925            }
926        }
927        // we are here, if not more than 1 way or node is selected,
928
929        // the node from which we make a connection
930        currentBaseNode = null;
931        previousNode = null;
932
933        // Try to find an open way to measure angle from it. The way is not to be continued!
934        // warning: may result in changes of currentBaseNode and previousNode
935        // please remove if bugs arise
936        if (selectedWay == null && selectedNode != null) {
937            for (OsmPrimitive p: selectedNode.getReferrers()) {
938                if (p.isUsable() && p instanceof Way && ((Way) p).isFirstLastNode(selectedNode)) {
939                    if (selectedWay != null) { // two uncontinued ways, nothing to take as reference
940                        selectedWay = null;
941                        break;
942                    } else {
943                        // set us ~continue this way (measure angle from it)
944                        selectedWay = (Way) p;
945                    }
946                }
947            }
948        }
949
950        if (selectedNode == null) {
951            if (selectedWay == null)
952                return;
953            continueWayFromNode(selectedWay, lastUsedNode);
954        } else if (selectedWay == null) {
955            currentBaseNode = selectedNode;
956        } else if (!selectedWay.isDeleted()) { // fix #7118
957            continueWayFromNode(selectedWay, selectedNode);
958        }
959    }
960
961    /**
962     * if one of the ends of {@code way} is given {@code node},
963     * then set currentBaseNode = node and previousNode = adjacent node of way
964     * @param way way to continue
965     * @param node starting node
966     */
967    private void continueWayFromNode(Way way, Node node) {
968        int n = way.getNodesCount();
969        if (node == way.firstNode()) {
970            currentBaseNode = node;
971            if (n > 1) previousNode = way.getNode(1);
972        } else if (node == way.lastNode()) {
973            currentBaseNode = node;
974            if (n > 1) previousNode = way.getNode(n-2);
975        }
976    }
977
978    /**
979     * Repaint on mouse exit so that the helper line goes away.
980     */
981    @Override
982    public void mouseExited(MouseEvent e) {
983        OsmDataLayer editLayer = MainApplication.getLayerManager().getEditLayer();
984        if (editLayer == null)
985            return;
986        mousePos = e.getPoint();
987        snapHelper.noSnapNow();
988        boolean repaintIssued = removeHighlighting(e);
989        // force repaint in case snapHelper needs one. If removeHighlighting
990        // caused one already, don't do it again.
991        if (!repaintIssued) {
992            editLayer.invalidate();
993        }
994    }
995
996    /**
997     * Replies the parent way of a node, if it is the end of exactly one usable way.
998     * @param n node
999     * @return If the node is the end of exactly one way, return this.
1000     *  <code>null</code> otherwise.
1001     */
1002    public static Way getWayForNode(Node n) {
1003        Way way = null;
1004        for (Way w : (Iterable<Way>) n.referrers(Way.class)::iterator) {
1005            if (!w.isUsable() || w.getNodesCount() < 1) {
1006                continue;
1007            }
1008            Node firstNode = w.firstNode();
1009            Node lastNode = w.lastNode();
1010            if ((firstNode == n || lastNode == n) && (firstNode != lastNode)) {
1011                if (way != null)
1012                    return null;
1013                way = w;
1014            }
1015        }
1016        return way;
1017    }
1018
1019    /**
1020     * Replies the current base node, after having checked it is still usable (see #11105).
1021     * @return the current base node (can be null). If not-null, it's guaranteed the node is usable
1022     */
1023    public synchronized Node getCurrentBaseNode() {
1024        if (currentBaseNode != null && (currentBaseNode.getDataSet() == null || !currentBaseNode.isUsable())) {
1025            currentBaseNode = null;
1026        }
1027        return currentBaseNode;
1028    }
1029
1030    private static void pruneSuccsAndReverse(List<Integer> is) {
1031        Set<Integer> is2 = new HashSet<>();
1032        for (int i : is) {
1033            if (!is2.contains(i - 1) && !is2.contains(i + 1)) {
1034                is2.add(i);
1035            }
1036        }
1037        is.clear();
1038        is.addAll(is2);
1039        Collections.sort(is);
1040        Collections.reverse(is);
1041    }
1042
1043    /**
1044     * Adjusts the position of a node to lie on a segment (or a segment intersection).
1045     *
1046     * If one or more than two segments are passed, the node is adjusted
1047     * to lie on the first segment that is passed.
1048     *
1049     * If two segments are passed, the node is adjusted to be at their intersection.
1050     *
1051     * No action is taken if no segments are passed.
1052     *
1053     * @param segs the segments to use as a reference when adjusting
1054     * @param n the node to adjust
1055     */
1056    private static void adjustNode(Collection<Pair<Node, Node>> segs, Node n) {
1057        switch (segs.size()) {
1058        case 0:
1059            return;
1060        case 2:
1061            adjustNodeTwoSegments(segs, n);
1062            break;
1063        default:
1064            adjustNodeDefault(segs, n);
1065        }
1066    }
1067
1068    private static void adjustNodeTwoSegments(Collection<Pair<Node, Node>> segs, Node n) {
1069        // This computes the intersection between the two segments and adjusts the node position.
1070        Iterator<Pair<Node, Node>> i = segs.iterator();
1071        Pair<Node, Node> seg = i.next();
1072        EastNorth pA = seg.a.getEastNorth();
1073        EastNorth pB = seg.b.getEastNorth();
1074        seg = i.next();
1075        EastNorth pC = seg.a.getEastNorth();
1076        EastNorth pD = seg.b.getEastNorth();
1077
1078        double u = det(pB.east() - pA.east(), pB.north() - pA.north(), pC.east() - pD.east(), pC.north() - pD.north());
1079
1080        // Check for parallel segments and do nothing if they are
1081        // In practice this will probably only happen when a way has been duplicated
1082
1083        if (u == 0)
1084            return;
1085
1086        // q is a number between 0 and 1
1087        // It is the point in the segment where the intersection occurs
1088        // if the segment is scaled to length 1
1089
1090        double q = det(pB.north() - pC.north(), pB.east() - pC.east(), pD.north() - pC.north(), pD.east() - pC.east()) / u;
1091        EastNorth intersection = new EastNorth(
1092                pB.east() + q * (pA.east() - pB.east()),
1093                pB.north() + q * (pA.north() - pB.north()));
1094
1095
1096        // only adjust to intersection if within snapToIntersectionThreshold pixel of mouse click; otherwise
1097        // fall through to default action.
1098        // (for semi-parallel lines, intersection might be miles away!)
1099        MapFrame map = MainApplication.getMap();
1100        if (map.mapView.getPoint2D(n).distance(map.mapView.getPoint2D(intersection)) < SNAP_TO_INTERSECTION_THRESHOLD.get()) {
1101            n.setEastNorth(intersection);
1102            return;
1103        }
1104
1105        adjustNodeDefault(segs, n);
1106    }
1107
1108    private static void adjustNodeDefault(Collection<Pair<Node, Node>> segs, Node n) {
1109        EastNorth p = n.getEastNorth();
1110        Pair<Node, Node> seg = segs.iterator().next();
1111        EastNorth pA = seg.a.getEastNorth();
1112        EastNorth pB = seg.b.getEastNorth();
1113        double a = p.distanceSq(pB);
1114        double b = p.distanceSq(pA);
1115        double c = pA.distanceSq(pB);
1116        double q = (a - b + c) / (2*c);
1117        n.setEastNorth(new EastNorth(pB.east() + q * (pA.east() - pB.east()), pB.north() + q * (pA.north() - pB.north())));
1118    }
1119
1120    // helper for adjustNode
1121    static double det(double a, double b, double c, double d) {
1122        return a * d - b * c;
1123    }
1124
1125    private void tryToMoveNodeOnIntersection(List<WaySegment> wss, Node n) {
1126        if (wss.isEmpty())
1127            return;
1128        WaySegment ws = wss.get(0);
1129        EastNorth p1 = ws.getFirstNode().getEastNorth();
1130        EastNorth p2 = ws.getSecondNode().getEastNorth();
1131        if (snapHelper.dir2 != null && getCurrentBaseNode() != null) {
1132            EastNorth xPoint = Geometry.getSegmentSegmentIntersection(p1, p2, snapHelper.dir2,
1133                    getCurrentBaseNode().getEastNorth());
1134            if (xPoint != null) {
1135                n.setEastNorth(xPoint);
1136            }
1137        }
1138    }
1139
1140    /**
1141     * Takes the data from computeHelperLine to determine which ways/nodes should be highlighted
1142     * (if feature enabled). Also sets the target cursor if appropriate. It adds the to-be-
1143     * highlighted primitives to newHighlights but does not actually highlight them. This work is
1144     * done in redrawIfRequired. This means, calling addHighlighting() without redrawIfRequired()
1145     * will leave the data in an inconsistent state.
1146     *
1147     * The status bar derives its information from oldHighlights, so in order to update the status
1148     * bar both addHighlighting() and repaintIfRequired() are needed, since former fills newHighlights
1149     * and latter processes them into oldHighlights.
1150     * @param event event, can be null
1151     */
1152    private void addHighlighting(Object event) {
1153        newHighlights = new HashSet<>();
1154        MapView mapView = MainApplication.getMap().mapView;
1155
1156        // if ctrl key is held ("no join"), don't highlight anything
1157        if (ctrl) {
1158            mapView.setNewCursor(cursor, this);
1159            redrawIfRequired(event);
1160            return;
1161        }
1162
1163        // This happens when nothing is selected, but we still want to highlight the "target node"
1164        DataSet ds = getLayerManager().getEditDataSet();
1165        if (mouseOnExistingNode == null && mousePos != null && ds != null && ds.selectionEmpty()) {
1166            mouseOnExistingNode = mapView.getNearestNode(mousePos, OsmPrimitive::isSelectable);
1167        }
1168
1169        if (mouseOnExistingNode != null) {
1170            mapView.setNewCursor(cursorJoinNode, this);
1171            newHighlights.add(mouseOnExistingNode);
1172            redrawIfRequired(event);
1173            return;
1174        }
1175
1176        // Insert the node into all the nearby way segments
1177        if (mouseOnExistingWays.isEmpty()) {
1178            mapView.setNewCursor(cursor, this);
1179            redrawIfRequired(event);
1180            return;
1181        }
1182
1183        mapView.setNewCursor(cursorJoinWay, this);
1184        newHighlights.addAll(mouseOnExistingWays);
1185        redrawIfRequired(event);
1186    }
1187
1188    /**
1189     * Removes target highlighting from primitives. Issues repaint if required.
1190     * @param event event, can be null
1191     * @return true if a repaint has been issued.
1192     */
1193    private boolean removeHighlighting(Object event) {
1194        newHighlights = new HashSet<>();
1195        return redrawIfRequired(event);
1196    }
1197
1198    @Override
1199    public synchronized void paint(Graphics2D g, MapView mv, Bounds box) {
1200        // sanity checks
1201        MapView mapView = MainApplication.getMap().mapView;
1202        if (mapView == null || mousePos == null
1203                // don't draw line if we don't know where from or where to
1204                || currentMouseEastNorth == null || getCurrentBaseNode() == null
1205                // don't draw line if mouse is outside window
1206                || !mapView.getState().getForView(mousePos.getX(), mousePos.getY()).isInView())
1207            return;
1208
1209        Graphics2D g2 = g;
1210        snapHelper.drawIfNeeded(g2, mv.getState());
1211        if (!DRAW_HELPER_LINE.get() || wayIsFinished || shift)
1212            return;
1213
1214        if (!snapHelper.isActive()) {
1215            g2.setColor(RUBBER_LINE_COLOR.get());
1216            g2.setStroke(RUBBER_LINE_STROKE.get());
1217            paintConstructionGeometry(mv, g2);
1218        } else if (DRAW_CONSTRUCTION_GEOMETRY.get()) {
1219            // else use color and stoke from  snapHelper.draw
1220            paintConstructionGeometry(mv, g2);
1221        }
1222    }
1223
1224    private void paintConstructionGeometry(MapView mv, Graphics2D g2) {
1225        MapPath2D b = new MapPath2D();
1226        MapViewPoint p1 = mv.getState().getPointFor(getCurrentBaseNode());
1227        MapViewPoint p2 = mv.getState().getPointFor(currentMouseEastNorth);
1228
1229        b.moveTo(p1);
1230        b.lineTo(p2);
1231
1232        // if alt key is held ("start new way"), draw a little perpendicular line
1233        if (alt) {
1234            START_WAY_INDICATOR.paintArrowAt(b, p1, p2);
1235        }
1236
1237        g2.draw(b);
1238        g2.setStroke(BASIC_STROKE);
1239    }
1240
1241    @Override
1242    public String getModeHelpText() {
1243        StringBuilder rv;
1244        /*
1245         *  No modifiers: all (Connect, Node Re-Use, Auto-Weld)
1246         *  CTRL: disables node re-use, auto-weld
1247         *  Shift: do not make connection
1248         *  ALT: make connection but start new way in doing so
1249         */
1250
1251        /*
1252         * Status line text generation is split into two parts to keep it maintainable.
1253         * First part looks at what will happen to the new node inserted on click and
1254         * the second part will look if a connection is made or not.
1255         *
1256         * Note that this help text is not absolutely accurate as it doesn't catch any special
1257         * cases (e.g. when preventing <---> ways). The only special that it catches is when
1258         * a way is about to be finished.
1259         *
1260         * First check what happens to the new node.
1261         */
1262
1263        // oldHighlights stores the current highlights. If this
1264        // list is empty we can assume that we won't do any joins
1265        if (ctrl || oldHighlights.isEmpty()) {
1266            rv = new StringBuilder(tr("Create new node."));
1267        } else {
1268            // oldHighlights may store a node or way, check if it's a node
1269            OsmPrimitive x = oldHighlights.iterator().next();
1270            if (x instanceof Node) {
1271                rv = new StringBuilder(tr("Select node under cursor."));
1272            } else {
1273                rv = new StringBuilder(trn("Insert new node into way.", "Insert new node into {0} ways.",
1274                        oldHighlights.size(), oldHighlights.size()));
1275            }
1276        }
1277
1278        /*
1279         * Check whether a connection will be made
1280         */
1281        if (!wayIsFinished && getCurrentBaseNode() != null) {
1282            if (alt) {
1283                rv.append(' ').append(tr("Start new way from last node."));
1284            } else {
1285                rv.append(' ').append(tr("Continue way from last node."));
1286            }
1287            if (snapHelper.isSnapOn()) {
1288                rv.append(' ').append(tr("Angle snapping active."));
1289            }
1290        }
1291
1292        Node n = mouseOnExistingNode;
1293        DataSet ds = getLayerManager().getEditDataSet();
1294        /*
1295         * Handle special case: Highlighted node == selected node => finish drawing
1296         */
1297        if (n != null && ds != null && ds.getSelectedNodes().contains(n)) {
1298            if (wayIsFinished) {
1299                rv = new StringBuilder(tr("Select node under cursor."));
1300            } else {
1301                rv = new StringBuilder(tr("Finish drawing."));
1302            }
1303        }
1304
1305        /*
1306         * Handle special case: Self-Overlapping or closing way
1307         */
1308        if (ds != null && !ds.getSelectedWays().isEmpty() && !wayIsFinished && !alt) {
1309            Way w = ds.getSelectedWays().iterator().next();
1310            if (w.getNodes().stream().anyMatch(m -> m.equals(mouseOnExistingNode) || mouseOnExistingWays.contains(w))) {
1311                rv.append(' ').append(tr("Finish drawing."));
1312            }
1313        }
1314        return rv.toString();
1315    }
1316
1317    /**
1318     * Get selected primitives, while draw action is in progress.
1319     *
1320     * While drawing a way, technically the last node is selected.
1321     * This is inconvenient when the user tries to add/edit tags to the way.
1322     * For this case, this method returns the current way as selection,
1323     * to work around this issue.
1324     * Otherwise the normal selection of the current data layer is returned.
1325     * @return selected primitives, while draw action is in progress
1326     */
1327    public Collection<OsmPrimitive> getInProgressSelection() {
1328        DataSet ds = getLayerManager().getEditDataSet();
1329        if (ds == null) return Collections.emptyList();
1330        if (getCurrentBaseNode() != null && !ds.selectionEmpty()) {
1331            Way continueFrom = getWayForNode(getCurrentBaseNode());
1332            if (continueFrom != null)
1333                return Collections.<OsmPrimitive>singleton(continueFrom);
1334        }
1335        return ds.getSelected();
1336    }
1337
1338    @Override
1339    public boolean layerIsSupported(Layer l) {
1340        return isEditableDataLayer(l);
1341    }
1342
1343    @Override
1344    protected void updateEnabledState() {
1345        setEnabled(getLayerManager().getEditLayer() != null);
1346    }
1347
1348    @Override
1349    public void destroy() {
1350        super.destroy();
1351        finishDrawing();
1352        MainApplication.getMenu().editMenu.remove(snapCheckboxMenuItem);
1353        snapChangeAction.destroy();
1354    }
1355
1356    /**
1357     * Undo the last command. Binded by default to backspace key.
1358     */
1359    public class BackSpaceAction extends AbstractAction {
1360
1361        @Override
1362        public void actionPerformed(ActionEvent e) {
1363            UndoRedoHandler.getInstance().undo();
1364            Command lastCmd = UndoRedoHandler.getInstance().getLastCommand();
1365            if (lastCmd == null) return;
1366            Node n = null;
1367            for (OsmPrimitive p: lastCmd.getParticipatingPrimitives()) {
1368                if (p instanceof Node) {
1369                    if (n == null) {
1370                        n = (Node) p; // found one node
1371                        wayIsFinished = false;
1372                    } else {
1373                        // if more than 1 node were affected by previous command,
1374                        // we have no way to continue, so we forget about found node
1375                        n = null;
1376                        break;
1377                    }
1378                }
1379            }
1380            // select last added node - maybe we will continue drawing from it
1381            if (n != null) {
1382                addSelection(getLayerManager().getEditDataSet(), n);
1383            }
1384        }
1385    }
1386
1387    private class SnapChangeAction extends JosmAction {
1388        /**
1389         * Constructs a new {@code SnapChangeAction}.
1390         */
1391        SnapChangeAction() {
1392            super(tr("Angle snapping"), /* ICON() */ "anglesnap",
1393                    tr("Switch angle snapping mode while drawing"), null, false);
1394            setHelpId(ht("/Action/Draw/AngleSnap"));
1395        }
1396
1397        @Override
1398        public void actionPerformed(ActionEvent e) {
1399            if (snapHelper != null) {
1400                snapHelper.toggleSnapping();
1401            }
1402        }
1403
1404        @Override
1405        protected void updateEnabledState() {
1406            MapFrame map = MainApplication.getMap();
1407            setEnabled(map != null && map.mapMode instanceof DrawAction);
1408        }
1409    }
1410}