ClickHandler.java

package edu.stanford.hci.r3.events.handlers;

import edu.stanford.hci.r3.events.EventHandler;
import edu.stanford.hci.r3.events.PenEvent;

public abstract class ClickHandler extends EventHandler {

        private class ClickNotifier implements Runnable {

                private boolean doNotNotify;

                private PenEvent event;

                public ClickNotifier(PenEvent myEvent) {
                        event = myEvent;
                }

                public void run() {
                        try {
                                Thread.sleep(MILLIS_TO_DELAY);
                        } catch (InterruptedException e) {
                                e.printStackTrace();
                        }
                        if (doNotNotify) {
                                // someone told us to cancel
                                return;
                        }
                        released(event);
                        clicked(event);
                        lastClickTime = event.getTimestamp();
                        penDownHappened = false;
                }

                public void setDoNotNotify(boolean b) {
                        doNotNotify = b;
                }
        }

        private static final long MILLIS_TO_DELAY = 30;

        protected int clickCount = 1;

        private boolean filterJitteryPenEvents = true;

        private ClickNotifier lastClickNotifier;

        private long lastClickTime = 0;

        private PenEvent lastEvent;

        private long lastPenUpTime;

        protected int maxMillisBetweenMultipleClicks = 300; // 300 ms for a double-click

        private boolean penDownHappened = false;

        public abstract void clicked(PenEvent e);

        public void handleEvent(PenEvent event) {
                if (event.isTypePenDown()) {
                        long currPenDownTime = System.currentTimeMillis();
                        long diff = currPenDownTime - lastPenUpTime;
                        if (diff > MILLIS_TO_DELAY) {
                                // long enough... so a new pen down!
                                pressed(event);
                                penDownHappened = true;
                        } else {
                                // just filter this out
                                // cancel the notifier
                                if (lastClickNotifier != null) {
                                        lastClickNotifier.setDoNotNotify(true);
                                        lastClickNotifier = null;
                                }
                        }
                } else if (event.isTypePenUp()) {

                        lastPenUpTime = System.currentTimeMillis();

                        // really, this should always be true
                        if (penDownHappened) {
                                if (event.getTimestamp() - lastClickTime <= maxMillisBetweenMultipleClicks) {
                                        clickCount++;
                                } else {
                                        clickCount = 1; // reset the click count
                                }

                                if (filterJitteryPenEvents) {
                                        lastClickNotifier = new ClickNotifier(lastEvent);
                                        new Thread(lastClickNotifier).start();
                                } else {
                                        released(lastEvent);
                                        clicked(lastEvent);
                                        lastClickTime = event.getTimestamp();
                                        penDownHappened = false;
                                }
                        }
                }
                lastEvent = event;

                // do not consume the event (event has a consumed property that we do not set here)
        }

        public abstract void pressed(PenEvent e);

        public abstract void released(PenEvent e);

        public String toString() {
                return "ClickHandler";
        }
}

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