001/**
002 * Copyright (c) 2011, The University of Southampton and the individual contributors.
003 * All rights reserved.
004 *
005 * Redistribution and use in source and binary forms, with or without modification,
006 * are permitted provided that the following conditions are met:
007 *
008 *   *  Redistributions of source code must retain the above copyright notice,
009 *      this list of conditions and the following disclaimer.
010 *
011 *   *  Redistributions in binary form must reproduce the above copyright notice,
012 *      this list of conditions and the following disclaimer in the documentation
013 *      and/or other materials provided with the distribution.
014 *
015 *   *  Neither the name of the University of Southampton nor the names of its
016 *      contributors may be used to endorse or promote products derived from this
017 *      software without specific prior written permission.
018 *
019 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
020 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
021 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
022 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
023 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
024 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
025 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
026 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
027 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
028 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
029 */
030package org.openimaj.demos.touchtable;
031
032import java.util.ArrayList;
033import java.util.Collection;
034import java.util.List;
035
036import org.openimaj.math.geometry.line.Line2d;
037import org.openimaj.math.geometry.point.Point2dImpl;
038import org.openimaj.math.geometry.shape.Circle;
039
040public class ReallyBasicTouchTracker {
041        private static final long TIME_TO_DIE = 500;
042        private long currentId = 0; 
043        private List<Touch> lastPoints = new ArrayList<Touch>();
044        private double threshold;
045        
046        public ReallyBasicTouchTracker(double threshold) {
047                this.threshold = threshold;
048        }
049        
050        public List<Touch> trackPoints(Collection<Touch> pts) {
051                List<Touch> newPoints = new ArrayList<Touch>(pts.size());
052                for (Touch pt : pts) {
053                        Touch matched = matchPoint(pt);
054                        
055                        if (matched == null) {
056                                newPoints.add(new Touch(pt, currentId++, null));
057                        } else {
058                                
059                                lastPoints.remove(matched);
060                                
061                                Point2dImpl mv = new Point2dImpl(pt.calculateCentroid());
062                                mv.x -= matched.getX();
063                                mv.y -= matched.getY();
064                                
065                                newPoints.add(new Touch(pt, matched.touchID, mv));
066                        }
067                }
068                for (Touch touch : lastPoints) {
069                        if(System.currentTimeMillis() - touch.createdTime < TIME_TO_DIE){
070                                newPoints.add(touch);
071                        }
072                }
073                lastPoints = newPoints;
074                
075                return lastPoints;
076        }
077
078        private Touch matchPoint(Circle query) {
079                double minDist = Double.MAX_VALUE;
080                Touch best = null;
081                
082                for (Touch pt : lastPoints) {
083                        double dist = Line2d.distance(query.calculateCentroid(), pt.calculateCentroid());
084                        
085                        if (dist < minDist) {
086                                minDist = dist;
087                                best = pt;
088                        }
089                }
090                
091                if (minDist > threshold) 
092                        return null;
093                if(System.currentTimeMillis() - best.createdTime > TIME_TO_DIE){
094                        best=null;
095                }
096                return best;
097        }
098}