www.pudn.com > jfreechart-0.9.12.zip > CrosshairInfo.java

/* ====================================== 
 * JFreeChart : a free Java chart library 
 * ====================================== 
 * 
 * Project Info:  http://www.jfree.org/jfreechart/index.html 
 * Project Lead:  David Gilbert (david.gilbert@object-refinery.com); 
 * 
 * (C) Copyright 2000-2003, by Object Refinery Limited and Contributors. 
 * 
 * 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. 
 * 
 * ------------------ 
 * CrosshairInfo.java 
 * ------------------ 
 * (C) Copyright 2002, 2003, by Object Refinery Limited. 
 * 
 * Original Author:  David Gilbert (for Object Refinery Limited); 
 * Contributor(s):   -; 
 * 
 * $Id: CrosshairInfo.java,v 1.3 2003/08/07 15:13:05 mungady Exp $ 
 * 
 * Changes 
 * ------- 
 * 24-Jan-2002 : Version 1 (DG); 
 * 05-Mar-2002 : Added Javadoc comments (DG); 
 * 26-Sep-2002 : Fixed errors reported by Checkstyle (DG); 
 * 
 */ 
 
package org.jfree.chart; 
 
/** 
 * Maintains information about crosshairs on a plot. 
 * 
 * @author David Gilbert 
 */ 
public class CrosshairInfo { 
 
    /** The x-value for the anchor point. */ 
    private double anchorX; 
 
    /** The y-value for the anchor point. */ 
    private double anchorY; 
 
    /** The x-value for the crosshair point. */ 
    private double crosshairX; 
 
    /** The y-value for the crosshair point. */ 
    private double crosshairY; 
 
    /** The smallest distance so far between the anchor point and a data point. */ 
    private double distance; 
 
    /** 
     * Default constructor. 
     */ 
    public CrosshairInfo() { 
    } 
 
    /** 
     * Sets the distance. 
     * 
     * @param distance  the distance. 
     */ 
    public void setCrosshairDistance(double distance) { 
        this.distance = distance; 
    } 
 
    /** 
     * Evaluates a data point and if it is the closest to the anchor point it 
     * becomes the new crosshair point. 
     * 
 
     * To understand this method, you need to know the context in which it will 
     * be called.  An instance of this class is passed to an XYItemRenderer as 
     * each data point is plotted.  As the point is plotted, it is passed to 
     * this method to see if it should be the new crosshair point. 
     * 
     * @param candidateX  x position of candidate for the new crosshair point. 
     * @param candidateY  y position of candidate for the new crosshair point. 
     */ 
    public void updateCrosshairPoint(double candidateX, double candidateY) { 
 
        double d = (candidateX - anchorX) * (candidateX - anchorX) 
                 + (candidateY - anchorY) * (candidateY - anchorY); 
 
        if (d < distance) { 
            crosshairX = candidateX; 
            crosshairY = candidateY; 
            distance = d; 
        } 
 
    } 
 
    /** 
     * Evaluates an x-value and if it is the closest to the anchor point it 
     * becomes the new crosshair point. 
     * 
 
     * Used in cases where only the x-axis is numerical. 
     * 
     * @param candidateX  x position of the candidate for the new crosshair point. 
     */ 
    public void updateCrosshairX(double candidateX) { 
 
        double d = Math.abs(candidateX - anchorX); 
        if (d < distance) { 
            crosshairX = candidateX; 
            distance = d; 
        } 
 
    } 
 
    /** 
     * Evaluates a y-value and if it is the closest to the anchor point it 
     * becomes the new crosshair point. 
     * 
 
     * Used in cases where only the y-axis is numerical. 
     * 
     * @param candidateY  y position of the candidate for the new crosshair point. 
     */ 
    public void updateCrosshairY(double candidateY) { 
 
        double d = Math.abs(candidateY - anchorY); 
        if (d < distance) { 
            crosshairY = candidateY; 
            distance = d; 
        } 
 
    } 
 
    /** 
     * Set the x-value for the anchor point. 
     * 
     * @param x  the x position. 
     */ 
    public void setAnchorX(double x) { 
        this.anchorX = x; 
        this.crosshairX = x; 
    } 
 
    /** 
     * Set the y-value for the anchor point. 
     * 
     * @param y  the y position. 
     */ 
    public void setAnchorY(double y) { 
        this.anchorY = y; 
        this.crosshairY = y; 
    } 
 
    /** 
     * Get the x-value for the crosshair point. 
     * 
     * @return the x position of the crosshair point. 
     */ 
    public double getCrosshairX() { 
        return this.crosshairX; 
    } 
 
    /** 
     * Get the y-value for the crosshair point. 
     * 
     * @return the y position of the crosshair point. 
     */ 
    public double getCrosshairY() { 
        return this.crosshairY; 
    } 
 
}