/**
 * Copyright (c) 2011, The University of Southampton and the individual contributors.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 *   *  Redistributions of source code must retain the above copyright notice,
 *      this list of conditions and the following disclaimer.
 *
 *   *  Redistributions in binary form must reproduce the above copyright notice,
 *      this list of conditions and the following disclaimer in the documentation
 *      and/or other materials provided with the distribution.
 *
 *   *  Neither the name of the University of Southampton nor the names of its
 *      contributors may be used to endorse or promote products derived from this
 *      software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR
 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */
package org.openimaj.video.processing.tracking;

import java.util.ArrayList;
import java.util.List;

import org.openimaj.image.FImage;
import org.openimaj.math.geometry.shape.Rectangle;
import org.openimaj.video.tracking.klt.FeatureList;
import org.openimaj.video.tracking.klt.KLTTracker;
import org.openimaj.video.tracking.klt.TrackingContext;

/**
 *      A tracker that will track one rectangular region using the KLTTracker.
 * 
 *  @author David Dupplaw (dpd@ecs.soton.ac.uk)
 *      
 *      @created 13 Oct 2011
 */
public class BasicObjectTracker implements ObjectTracker<Rectangle,FImage>
{               
        /** The tracking context for the KLTTracker */
        private TrackingContext trackingContext = new TrackingContext();
        
        /** The feature list used for the tracking */
        private FeatureList featureList = null;
        
        /** The number of features found during the initialisation stage of the tracking */
        private int featuresFound = -1;
        
        /** The tracker used to track the faces */
        private KLTTracker tracker = null;

        /** The accuracy to use when tracking, between 0 and 1 */
        private double accuracy = 0.5;

        /** The previous frame */
        private FImage previousFrame;
        
        /**
         *      Default constructor that will use 50 features and an accuracy of 0.5.
         */
        public BasicObjectTracker()
    {
                this( 50, 0.5 );
    }
        
        /**
         *      Default constructor that takes the number of features to be used.
         *      Will use an accuracy of 0.5.
         * 
         *      @param nFeatures The number of features to use.
         */
        public BasicObjectTracker( int nFeatures )
        {
                this( nFeatures, 0.5 );
        }
        
        /**
         *      Constructor that takes the accuracy to use for tracking. Will use 50
         *      features.
         * 
         *      @param accuracy The accuracy to use.
         */
        public BasicObjectTracker( double accuracy )
        {
                this( 50, accuracy );
        }
        
        /**
         *      Constructor that takes the number of features to use and the accuracy
         *      for tracking.
         * 
         *      @param nFeatures The number of features to use.
         *      @param accuracy The accuracy to use
         */
        public BasicObjectTracker( int nFeatures, double accuracy )
        {
                this.featureList = new FeatureList( nFeatures );
                this.accuracy  = accuracy;
                tracker = new KLTTracker( trackingContext, featureList );
        }
        
        /**
         *      Reset this tracker using the given image
         *      @return TRUE if the tracking continued ok; FALSE otherwise
         */
        @Override
        public List<Rectangle> trackObject( FImage img )
        {
                List<Rectangle> trackedObjects = new ArrayList<Rectangle>();
                
                tracker.trackFeatures( previousFrame, img );
                
                // If we're losing features left-right and centre then we say
                // we've lost the object we're tracking
                if( featureList.countRemainingFeatures() <= featuresFound * accuracy )
                        return trackedObjects;
                
                trackedObjects.add( featureList.getBounds() );
                
                previousFrame = img;
                
                return trackedObjects;
        }

        /**
         *      Initialise this tracker with a particular area on a particular
         *      image.
         * 
         *  @param bounds The area to track
         *  @param img The image
         */
        @Override
        public List<Rectangle> initialiseTracking( Rectangle bounds, FImage img )
    {
                List<Rectangle> initialObjects = new ArrayList<Rectangle>();
                
                // Set the tracking area to be the face found
                trackingContext.setTargetArea( bounds );
                
                // Select the good features from the area
                tracker.selectGoodFeatures( img );

                // Remember how many features we found, so that if we
                // start to lose them, we can re-initialise the tracking
                featuresFound = featureList.countRemainingFeatures();

                // Add the initial bounds as the found object
                initialObjects.add( bounds );
                
                previousFrame = img;
        
        return initialObjects;
    }
        
        /**
         *      Returns the list of features that the tracker has been tracking.
         *      @return the {@link FeatureList}
         */
        public FeatureList getFeatureList()
        {
                return featureList;
        }
}