/*
* Copyright 2012 Daniel Kurka
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package com.googlecode.mgwt.dom.client.recognizer;
import com.google.gwt.core.client.GWT;
import com.google.gwt.dom.client.Element;
import com.google.gwt.dom.client.Touch;
import com.google.gwt.event.dom.client.TouchCancelEvent;
import com.google.gwt.event.dom.client.TouchEndEvent;
import com.google.gwt.event.dom.client.TouchMoveEvent;
import com.google.gwt.event.dom.client.TouchStartEvent;
import com.google.gwt.event.shared.HasHandlers;
import com.googlecode.mgwt.dom.client.event.tap.TapEvent;
import com.googlecode.mgwt.dom.client.event.touch.TouchHandler;
/**
* A recognizer that recognizes Tap events
*
* A Tap is the mobile equivalent of a click
*
* @author Daniel Kurka
*/
public class TapRecognizer implements TouchHandler {
public static final int DEFAULT_DISTANCE = 15;
private final int distance;
private boolean touchCanceled;
private boolean hasMoved;
private int start_x;
private int start_y;
private Element targetElement;
private final HasHandlers source;
private EventPropagator eventPropagator;
private static EventPropagator DEFAULT_EVENT_PROPAGATOR;
public TapRecognizer(HasHandlers source) {
this(source, DEFAULT_DISTANCE);
}
public TapRecognizer(HasHandlers source, int distance) {
if (source == null)
throw new IllegalArgumentException("source can not be null");
if (distance < 0)
throw new IllegalArgumentException("distance has to be greater than zero");
this.source = source;
this.distance = distance;
}
@Override
public void onTouchStart(TouchStartEvent event) {
touchCanceled = false;
hasMoved = false;
if(event.getNativeEvent() != null){
targetElement = event.getNativeEvent().getEventTarget().<Element>cast();
}else {
targetElement = null;
}
start_x = event.getTouches().get(0).getPageX();
start_y = event.getTouches().get(0).getPageY();
}
@Override
public void onTouchMove(TouchMoveEvent event) {
Touch touch = event.getTouches().get(0);
if (Math.abs(touch.getPageX() - start_x) > distance || Math.abs(touch.getPageY() - start_y) > distance) {
hasMoved = true;
}
}
@Override
public void onTouchEnd(TouchEndEvent event) {
if (!hasMoved && !touchCanceled) {
TapEvent tapEvent = new TapEvent(source, targetElement, start_x, start_y);
getEventPropagator().fireEvent(source, tapEvent);
}
}
@Override
public void onTouchCancel(TouchCancelEvent event) {
touchCanceled = true;
}
public int getDistance() {
return distance;
}
protected EventPropagator getEventPropagator() {
if (eventPropagator == null) {
if (DEFAULT_EVENT_PROPAGATOR == null) {
DEFAULT_EVENT_PROPAGATOR = GWT.create(EventPropagator.class);
}
eventPropagator = DEFAULT_EVENT_PROPAGATOR;
}
return eventPropagator;
}
public Element getTargetElement() {
return targetElement;
}
}