001/* KIELER Bend Points with Manhattan Geometry Link.
002
003 Copyright (c) 1998-2016 The Regents of the University of California.
004 All rights reserved.
005 Permission is hereby granted, without written agreement and without
006 license or royalty fees, to use, copy, modify, and distribute this
007 software and its documentation for any purpose, provided that the above
008 copyright notice and the following two paragraphs appear in all copies
009 of this software.
010
011 IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO ANY PARTY
012 FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
013 ARISING OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF
014 THE UNIVERSITY OF CALIFORNIA HAS BEEN ADVISED OF THE POSSIBILITY OF
015 SUCH DAMAGE.
016
017 THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY WARRANTIES,
018 INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
019 MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE SOFTWARE
020 PROVIDED HEREUNDER IS ON AN "AS IS" BASIS, AND THE UNIVERSITY OF
021 CALIFORNIA HAS NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES,
022 ENHANCEMENTS, OR MODIFICATIONS.
023
024 PT_COPYRIGHT_VERSION_2
025 COPYRIGHTENDKEY
026
027 */
028package ptolemy.vergil.actor;
029
030import java.awt.geom.GeneralPath;
031import java.awt.geom.Point2D;
032import java.util.List;
033
034import diva.canvas.Site;
035import ptolemy.kernel.Relation;
036import ptolemy.vergil.actor.LayoutHint.LayoutHintItem;
037import ptolemy.vergil.kernel.Link;
038
039///////////////////////////////////////////////////////////////////
040////KielerLayoutConnector
041
042/**
043 * An extension to LinkManhattanRouter supporting bend points for routing links
044 * provided by the corresponding relation. These bend points can be set by any
045 * mechanism, e.g. the KIELER dataflow layout. The latter is currently used by
046 * the automatic layout mechanism that simply adds such bend point layout hints
047 * to relations.
048 *
049 * @author Christian Motika
050 * @see ptolemy.vergil.modal.KielerLayoutArcConnector
051 * @since Ptolemy II 10.0
052 * @Pt.ProposedRating Red (cmot)
053 */
054
055public class KielerLayoutConnector extends LinkManhattanConnector {
056
057    ///////////////////////////////////////////////////////////////////
058    ////                         public methods                    ////
059
060    /**
061     * Construct a new connector with the given tail and head for the specified
062     * link. The head and tail sites may be representative sites for multiport,
063     * in which case they are not necessarily the ones returned by getHeadSite()
064     * or getTailSite(). Those methods will return new sites as needed to ensure
065     * that each each connection is to its own site.
066     *
067     * @param tail The tail site.
068     * @param head The head site.
069     * @param link The link.
070     */
071    public KielerLayoutConnector(Site tail, Site head, Link link) {
072        super(tail, head, link);
073    }
074
075    /**
076     * Tell the connector to route itself between the current positions of the
077     * head and tail sites. If bend points are available, draw the line with
078     * these instead. Delete bend point information if modification detected
079     * (i.e., movement of one or the other end of a link).
080     */
081    @Override
082    public void route() {
083        // Parse the bend points if existing.
084        List<Point2D> bendPointList = null;
085        Object object = this.getUserObject();
086        Link link = null;
087        Relation relation = null;
088        LayoutHintItem layoutHintItem = null;
089        boolean considerBendPoints = false;
090        if (object instanceof Link) {
091            link = (Link) object;
092            relation = link.getRelation();
093            // relation may be null if a new link is currently dragged from some port
094            if (relation != null) {
095                LayoutHint layoutHint = (LayoutHint) relation
096                        .getAttribute("_layoutHint");
097                if (layoutHint != null) {
098                    layoutHintItem = layoutHint
099                            .getLayoutHintItem(link.getHead(), link.getTail());
100                    if (layoutHintItem != null) {
101                        // Bend points are always considered while a layout operation is
102                        // in progress to keep them from being removed. This is not quite
103                        // thread-safe, but should work since no more than one MomlChangeRequest
104                        // is executed at a given time, and those are the only things that
105                        // could trigger a problem with this code.
106                        considerBendPoints = _layoutInProgress
107                                || layoutHintItem.revalidate();
108                        if (considerBendPoints) {
109                            bendPointList = layoutHintItem.getBendPointList();
110                        } else {
111                            layoutHint.removeLayoutHintItem(layoutHintItem);
112                        }
113                    }
114                }
115            }
116        }
117
118        if (considerBendPoints) {
119            repaint();
120
121            GeneralPath path = new GeneralPath();
122
123            // we need the "real" start and end points, i.e. the anchor points on the sites
124            Point2D[] startEnd = KielerLayoutUtil.getHeadTailPoints(this,
125                    bendPointList);
126            double startX = startEnd[0].getX();
127            double startY = startEnd[0].getY();
128            double previousX = startX;
129            double previousY = startY;
130            double endX = startEnd[1].getX();
131            double endY = startEnd[1].getY();
132
133            // Start drawing the line.
134            // Under Java 1.5, we only have moveTo(float, float).
135            path.moveTo((float) startX, (float) startY);
136
137            // Add the start point and end point to the bendPointList in
138            // order to get the curveTo-effect working.
139            bendPointList.add(0, new Point2D.Double(startX, startY));
140            bendPointList.add(new Point2D.Double(endX, endY));
141
142            for (int i = 1; i <= bendPointList.size() - 1; i++) {
143                int i1 = i;
144                int i0 = i - 1;
145                // Coverity points out that i0 can never be less than 0.
146                //if (i0 < 0) {
147                //    i0 = 0;
148                //}
149                if (i0 > bendPointList.size() - 1) {
150                    i0 = bendPointList.size() - 1;
151                }
152
153                // Consider triplets of coordinates.
154                double x0 = previousX;
155                double y0 = previousY;
156                double x1 = bendPointList.get(i0).getX();
157                double y1 = bendPointList.get(i0).getY();
158
159                double x2 = bendPointList.get(i1).getX();
160                double y2 = bendPointList.get(i1).getY();
161
162                // Calculate midpoints.
163                x2 = (x1 + x2) / 2;
164                y2 = (y1 + y2) / 2;
165
166                // First make sure that the radius is not
167                // bigger than half one of the arms of the triplets
168                double d0 = Math
169                        .sqrt((x1 - x0) * (x1 - x0) + (y1 - y0) * (y1 - y0));
170                double d1 = Math
171                        .sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
172                double r = Math.min(_bendRadius, d0);
173                r = Math.min(r, d1);
174
175                // The degenerate case of a direct line.
176                if (d0 == 0.0 || d1 == 0.0) {
177                    path.lineTo((float) x1, (float) y1);
178                } else {
179                    // Next calculate the intermediate points
180                    // that define the bend.
181                    double intX0 = x1 + r / d0 * (x0 - x1);
182                    double intY0 = y1 + r / d0 * (y0 - y1);
183                    double intX1 = x1 + r / d1 * (x2 - x1);
184                    double intY1 = y1 + r / d1 * (y2 - y1);
185
186                    // Next draw the line from the previous
187                    // coord to the intermediate coord, and
188                    // curve around the corner.
189                    path.lineTo((float) intX0, (float) intY0);
190                    path.curveTo((float) x1, (float) y1, (float) x1, (float) y1,
191                            (float) intX1, (float) intY1);
192                    previousX = x2;
193                    previousY = y2;
194                }
195            }
196
197            // Finally close the last segment with a line.
198            // Under Java 1.5, we only have moveTo(float, float).
199            path.lineTo((float) endX, (float) endY);
200
201            // Now set the shape.
202            setShape(path);
203
204            // Move the label.
205            int count = bendPointList.size();
206            // Pick a location for the label in the middle of the connector.
207            Point2D point1 = bendPointList.get(count / 2 - 1);
208            Point2D point2 = bendPointList.get(count / 2);
209            _labelLocation = new Point2D.Double(
210                    (point1.getX() + point2.getX()) / 2,
211                    (point1.getY() + point2.getY()) / 2);
212            repositionLabel();
213
214            repaint();
215        } else {
216            // In this case we have no bend point annotations available so
217            // we use the normal draw functionality.
218            super.route();
219        }
220    }
221
222    /**
223     * Notifies layout connections that a layout is in progress, which stops them
224     * from deciding to remove layout hints from relations. Without this mechanism,
225     * it can happen that layout hints get removed seemingly at random. This is
226     * caused by layout connectors thinking that one actor in a relation is moved
227     * during the application of the layout results. This in turn triggers the
228     * corresponding layout hint to be viewed as being invalid, and consequently to
229     * be removed.
230     * <p>
231     * A call to this method with the parameter value {@code true} must always be
232     * followed by a call with the parameter value {@code false}.</p>
233     * <p>
234     * <b>Note:</b> This mechanism is not thread-safe! However, since the problem
235     * only occurs while a layout result is being applied through a
236     * {@code MoMLChangeRequest} (of which only one is ever being executed at a
237     * given time), this shouldn't be a problem.</p>
238     *
239     * @param inProgress {@code true} if a layout result is currently being applied.
240     */
241    public static void setLayoutInProgress(boolean inProgress) {
242        _layoutInProgress = inProgress;
243    }
244
245    ///////////////////////////////////////////////////////////////////
246    ////                         private variables                 ////
247
248    /**
249     * The radius for filleting the corners of the connector.
250     */
251    private double _bendRadius = 10;
252
253    /**
254     * Whether automatic layout is currently in progress. If so, no layout hints
255     * are removed.
256     */
257    private static boolean _layoutInProgress = false;
258
259}