content: // ===============================================================================
  // Authors: AFRL/RQQD
  // Organization: Air Force Research Laboratory, Aerospace Systems Directorate, Power and Control Division
  // 
  // Copyright (c) 2017 Government of the United State of America, as represented by
  // the Secretary of the Air Force.  No copyright is claimed in the United States under
  // Title 17, U.S. Code.  All Other Rights Reserved.
  // ===============================================================================
  
  /*
   * GRAL: GRAphing Library for Java(R)
   *
   * (C) Copyright 2009-2013 Erich Seifert <dev[at]erichseifert.de>,
   * Michael Seifert <mseifert[at]error-reports.org>
   *
   * This file is part of GRAL.
   *
   * GRAL is free software: you can redistribute it and/or modify
   * it under the terms of the GNU Lesser General Public License as published by
   * the Free Software Foundation, either version 3 of the License, or
   * (at your option) any later version.
   *
   * GRAL 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 Lesser General Public License for more details.
   *
   * You should have received a copy of the GNU Lesser General Public License
   * along with GRAL.  If not, see <http://www.gnu.org/licenses/>.
   */
  package de.erichseifert.gral.navigation;
  
  /**
   * Data class that describes a navigational event, like zooming or panning.
   *
   * @param <T> Data type of the value that has been changed.
   */
  public class NavigationEvent<T> {
  	/** Object that has caused the change. */
  	private final Navigator source;
  	/** Value before the change. */
  	private final T valueOld;
  	/** Value after the change. */
  	private final T valueNew;
  
  	/**
  	 * Initializes a new instance.
  	 * @param source Navigator object that has caused the change.
  	 * @param valueOld Value before the change
  	 * @param valueNew Value after the change.
  	 */
  	public NavigationEvent(Navigator source, T valueOld, T valueNew) {
  		this.source = source;
  		this.valueOld = valueOld;
  		this.valueNew = valueNew;
  	}
  
  	/**
  	 * Returns the navigator that has caused the change.
  	 * @return Navigator object that has caused the change.
  	 */
  	public Navigator getSource() {
  		return source;
  	}
  
  	/**
  	 * Returns the value before the change.
  	 * @return Value before the change.
  	 */
  	public T getValueOld() {
  		return valueOld;
  	}
  
  	/**
  	 * Returns the value after the change.
  	 * @return Value after the change.
  	 */
  	public T getValueNew() {
  		return valueNew;
  	}
  }
  