funpanel.java

java设计模式源码

package app.decorator.brightness;

/*
 * Copyright (c) 2001, 2005. Steven J. Metsker.
 * 
 * Steve Metsker makes no representations or warranties about
 * the fitness of this software for any particular purpose, 
 * including the implied warranty of merchantability.
 *
 * Please use this software as you wish with the sole
 * restriction that you may not claim that you wrote it.
 */

import java.awt.*;
import javax.swing.*;
import com.oozinoz.function.*;

/**
 * Plots a curve given parametric functions x and y that are parameterized on
 * time t, where t goes 0 to 1 during the life of the curve.
 * 
 * @author Steven J. Metsker
 */
public class FunPanel extends JPanel {
    protected Function fx = new T();

    protected Function fy = new T();

    protected int nPoint;

    protected int[] xArray;

    protected double xMax = 1;

    protected double xMin = 0;

    protected int[] yArray;

    protected double yMax = 1;

    protected double yMin = 0;

    public FunPanel() {
        this(101);
    }
    
    public FunPanel(int nPoint) {
        this.nPoint = nPoint;
        xArray = new int[nPoint];
        yArray = new int[nPoint];
    }
    
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        double h = getHeight() - 1;
        double w = getWidth() - 1;
        for (int i = 0; i < nPoint; i++) {
            double t = ((double) i) / (nPoint - 1);
            xArray[i] = (int) (w * (fx.f(t) - xMin) / (xMax - xMin));
            yArray[i] = (int) (h - h * (fy.f(t) - yMin) / (yMax - yMin));
        }
        g.setColor(Color.black);
        g.drawPolyline(xArray, yArray, nPoint);
    }

    /**
     * Establish the functions to plot.
     * 
     * @param fx
     *            the x function
     * @param fy
     *            the y function
     */
    public void setXY(Function fx, Function fy) {
        this.fx = fx;
        this.fy = fy;
        calculateExtrema();
        repaint();
    }

    protected void calculateExtrema() {
        for (int i = 0; i < nPoint; i++) {
            double t = ((double) i) / (nPoint - 1);
            double dx = fx.f(t);
            double dy = fy.f(t);
            
            if (i == 0 || dx > xMax)
                xMax = dx;
            if (i == 0 || dx < xMin)
                xMin = dx;
            if (i == 0 || dy > yMax)
                yMax = dy;
            if (i == 0 || dy < yMin)
                yMin = dy;
        }
    }
}