/* ===========================================================

 * JFreeChart : a free chart library for the Java(tm) platform

 * ===========================================================

 *

 * (C) Copyright 2000-2004, by Object Refinery Limited and Contributors.

 *

 * Project Info:  http://www.jfree.org/jfreechart/index.html

 *

 * This library 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 2.1 of the License, or (at your option) any later version.

 *

 * This library 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 this

 * library; if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330,

 * Boston, MA 02111-1307, USA.

 *

 * [Java is a trademark or registered trademark of Sun Microsystems, Inc. 

 * in the United States and other countries.]

 *

 * ---------------------------

 * StandardTickUnitSource.java

 * ---------------------------

 * (C) Copyright 2003, 2004, by Object Refinery Limited.

 *

 * Original Author:  David Gilbert (for Object Refinery Limited);

 * Contributor(s):   -;

 *

 * $Id: StandardTickUnitSource.java,v 1.1 2004/08/31 14:30:24 mungady Exp $

 *

 * Changes

 * -------

 * 23-Sep-2003 : Version 1 (DG);

 *

 */



package org.jfree.chart.axis;



import java.text.DecimalFormat;



/**

 * A source that can used by the {@link NumberAxis} class to obtain a

 * suitable {@link TickUnit}.

 *

 */

public class StandardTickUnitSource implements TickUnitSource {



    /** Constant for log(10.0). */

    private static final double LOG_10_VALUE = Math.log(10.0);

    

    /**

     * Returns a tick unit that is larger than the supplied unit.

     *

     * @param unit   the unit.

     *

     * @return A tick unit that is larger than the supplied unit.

     */

    public TickUnit getLargerTickUnit(TickUnit unit) {

        double x = unit.getSize();

        double log = Math.log(x) / LOG_10_VALUE;

        double higher = Math.ceil(log);

        return new NumberTickUnit(Math.pow(10, higher), new DecimalFormat("0.0E0"));

    }



    /**

     * Returns the tick unit in the collection that is greater than or equal

     * to (in size) the specified unit.

     *

     * @param unit  the unit.

     *

     * @return A unit from the collection.

     */

    public TickUnit getCeilingTickUnit(TickUnit unit) {

        return getLargerTickUnit(unit);

    }



    /**

     * Returns the tick unit in the collection that is greater than or equal

     * to the specified size.

     *

     * @param size  the size.

     *

     * @return A unit from the collection.

     */

    public TickUnit getCeilingTickUnit(double size) {

        double log = Math.log(size) / LOG_10_VALUE;

        double higher = Math.ceil(log);

        return new NumberTickUnit(Math.pow(10, higher), new DecimalFormat("0.0E0"));

    }

    

}

