ch.sebastienzurfluh.swissmuseum.core.client.view.eventbushooks.ScrollToPanelOnEvent.java Source code

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Here is the source code for ch.sebastienzurfluh.swissmuseum.core.client.view.eventbushooks.ScrollToPanelOnEvent.java

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/*
 * Copyright 2012-2013 Sebastien Zurfluh
 * 
 * This file is part of "Parcours".
 * 
 * "Parcours" is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 * 
 * "Parcours" is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 *  You should have received a copy of the GNU General Public License
 *  along with "Parcours".  If not, see <http://www.gnu.org/licenses/>.
 */

package ch.sebastienzurfluh.swissmuseum.core.client.view.eventbushooks;

import com.google.gwt.animation.client.Animation;
import com.google.gwt.user.client.Window;
import com.google.gwt.user.client.ui.Panel;

import ch.sebastienzurfluh.swissmuseum.core.client.control.eventbus.AbstractEvent;
import ch.sebastienzurfluh.swissmuseum.core.client.control.eventbus.EventBus;
import ch.sebastienzurfluh.swissmuseum.core.client.control.eventbus.EventBusListener;
import ch.sebastienzurfluh.swissmuseum.core.client.control.eventbus.AbstractEvent.EventType;

/**
 * This class listens to the page changes in order to scroll
 * automatically to the right position on load.
 *
 *
 * @author Sebastien Zurfluh
 *
 */
public class ScrollToPanelOnEvent extends Animation implements EventBusListener {
    private Panel panel;
    private EventType eventType;

    private ScrollToPanelOnEvent(EventBus eventBus, Panel panel, EventType eventType) {
        this.panel = panel;
        this.eventType = eventType;

        eventBus.addListener(this);
    }

    @Override
    public EventType getEventType() {
        return eventType;
    }

    @Override
    public void notify(AbstractEvent e) {
        origin = Window.getScrollTop();
        destination = panel.getElement().getAbsoluteTop();

        run(400);
    }

    public static ScrollToPanelOnEvent addRule(EventBus eventBus, Panel panel, EventType eventType) {
        return new ScrollToPanelOnEvent(eventBus, panel, eventType);
    }

    private int destination = 0;
    private int origin = 0;

    @Override
    protected void onUpdate(double progress) {
        Window.scrollTo(0, (int) (origin + (destination - origin) * progress));
    }

}