PenStrokeListener.java

package edu.stanford.hci.r3.pen.streaming.listeners;

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

import edu.stanford.hci.r3.pen.PenSample;
import edu.stanford.hci.r3.pen.ink.InkStroke;
import edu.stanford.hci.r3.util.DebugUtils;

public abstract class PenStrokeListener implements PenListener {

        private List<PenSample> currentStroke;

        public void penDown(PenSample sample) {
                // start a new stroke, which is just a list of PenSamples
                currentStroke = new ArrayList<PenSample>();
                currentStroke.add(sample);
                DebugUtils.println(sample);
        }

        public abstract void penStroke(InkStroke stroke);

        /*
         * (non-Javadoc)
         * 
         * @see edu.stanford.hci.r3.pen.streaming.listeners.PenListener#penUp(edu.stanford.hci.r3.pen.PenSample)
         */
        public void penUp(PenSample sample) {
                if (currentStroke == null) {
                        return;
                }
                
                // end the stroke... Since the up sample is the same as the last sample, do not add it
                final List<PenSample> stroke = currentStroke;

                // this line will be useful if we decide to spawn a new thread to notify the
                // PenStrokeListener
                currentStroke = null;

                // notify the PenStrokeListener
                penStroke(new InkStroke(stroke));
        }

        public void sample(PenSample sample) {
                currentStroke.add(sample);
                DebugUtils.println(sample);
        }
}

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