compassformat.java

来自「JfreeChart 常用图表例子」· Java 代码 · 共 128 行

/* ===========================================================
 * JFreeChart : a free chart library for the Java(tm) platform
 * ===========================================================
 *
 * (C) Copyright 2000-2005, 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.]
 *
 * ------------------
 * CompassFormat.java
 * ------------------
 * (C) Copyright 2003, 2004, by Sylvain Vieujot and Contributors.
 *
 * Original Author:  Sylvain Vieujot;
 * Contributor(s):   David Gilbert (for Object Refinery Limited);
 *
 * $Id: CompassFormat.java,v 1.3 2005/03/16 12:09:18 mungady Exp $
 *
 * Changes
 * -------
 * 18-Feb-2004 : Version 1 contributed by Sylvain Vieujot (DG);
 *
 */

package org.jfree.chart.axis;

import java.text.FieldPosition;
import java.text.NumberFormat;
import java.text.ParsePosition;

/**
 * A formatter that displays numbers as directions.
 */
public class CompassFormat extends NumberFormat {
    
    /** North. */
    private static final String N = "N";
    
    /** East. */
    private static final String E = "E";
    
    /** South. */
    private static final String S = "S";
    
    /** West. */
    private static final String W = "W";
    
    /** The directions. */
    public static final String[] DIRECTIONS = {
        N, N + N + E, N + E, E + N + E, E, E + S + E, S + E, S + S + E, S,
        S + S + W, S + W, W + S + W, W, W + N + W, N + W, N + N + W, N
    };
    
    /**
     * Creates a new formatter.
     */
    public CompassFormat() {
        super();
    }
    
    /**
     * Returns a string representing the direction.
     * 
     * @param direction  the direction.
     * 
     * @return A string.
     */
    public String getDirectionCode(double direction) {
        
        direction = direction % 360;
        if (direction < 0.0) {
            direction = direction + 360.0;
        }
        int index = ((int) Math.floor(direction / 11.25) + 1) / 2; 
        return DIRECTIONS[index];
        
    }

    /* (non-Javadoc)
     * @see java.text.NumberFormat#format(double, java.lang.StringBuffer, 
     *      java.text.FieldPosition)
     */
    public StringBuffer format(double number, StringBuffer toAppendTo, 
                               FieldPosition pos) {
        return toAppendTo.append(getDirectionCode(number));
    }

    /* (non-Javadoc)
     * @see java.text.NumberFormat#format(long, java.lang.StringBuffer, 
     *      java.text.FieldPosition)
     */
    public StringBuffer format(long number, StringBuffer toAppendTo, 
                               FieldPosition pos) {
        return toAppendTo.append(getDirectionCode(number));
    }

    /**
     * This method returns <code>null</code> for all inputs.  This class cannot
     * be used for parsing.
     * 
     * @param source  the source string.
     * @param parsePosition  the parse position.
     * 
     * @return <code>null</code>.
     */
    public Number parse(String source, ParsePosition parsePosition) {
        return null;
    }
    
}