de.swm.commons.mobile.client.utils.GhostClickPreventer Maven / Gradle / Ivy
/*
* Copyright 2011 SWM Services GmbH.
*
* 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 de.swm.commons.mobile.client.utils;
import com.google.gwt.user.client.Event;
import com.google.gwt.user.client.Timer;
import de.swm.commons.mobile.client.event.DragControllerMobile;
import java.util.ArrayList;
import java.util.List;
/**
* Helper class to prevent 'ghost clicks' (extra click events that occur when a touch end event is converted to a click event).
* Used in {code}DragControllerMobile{code}.
*
* See https://developers.google.com/mobile/articles/fast_buttons?hl=fi-FI
*
* @see DragControllerMobile
*/
public class GhostClickPreventer {
private static final int GHOST_CLICK_DELAY_MILLIS = 2500;
private static final int GHOST_CLICK_RADIUS = 25;
final List clickedPoints = new ArrayList();
public void rememberGhostClick(Point point) {
clickedPoints.add(point);
Timer timer = new Timer() {
@Override
public void run() {
Point removedP = clickedPoints.remove(0);
}
};
timer.schedule(GHOST_CLICK_DELAY_MILLIS);
}
public boolean preventGhostClick(Event event, Point point) {
for (Point clickedPoint : clickedPoints) {
if ( (Math.abs(clickedPoint.xPos() - point.xPos()) < GHOST_CLICK_RADIUS) &&
(Math.abs(clickedPoint.yPos() - point.yPos()) < GHOST_CLICK_RADIUS) ) {
event.stopPropagation();
event.preventDefault();
return true;
}
}
return false;
}
}