ch8_e8_18.java

来自「清华的Java程序」· Java 代码 · 共 54 行

import java.awt.*; 
import javax.swing.*;
import javax.swing.event.*;

public class ch8_e8_18 extends JApplet implements ChangeListener
{
    JButton myButton = new JButton("My True Color");
    JSlider redSlider = new JSlider(JSlider.HORIZONTAL,0,255,204);
    JSlider greenSlider = new JSlider(JSlider.HORIZONTAL,0,255,204);
    JSlider blueSlider = new JSlider(JSlider.HORIZONTAL,0,255,204);
    int value=0;
    
    public void init()
    {
        Panel p = new Panel();
        p.setLayout(new GridLayout(3,1));
        p.add(redSlider);
        p.add(greenSlider);
        p.add(blueSlider);
        redSlider.addChangeListener(this);
        greenSlider.addChangeListener(this);
        blueSlider.addChangeListener(this);
        
        getContentPane().add("East",myButton);
        getContentPane().add("Center",p);
    }
        
    public void stateChanged(ChangeEvent ae)
    {
        Color oldColor = myButton.getBackground();
        
        if(ae.getSource() == redSlider)
        {
            value = redSlider.getValue();
            myButton.setBackground(new Color(value,
                oldColor.getGreen(),oldColor.getBlue()));
            //System.out.println(value+ "," +oldColor.getGreen() +"," +oldColor.getBlue());
        }
        else if(ae.getSource() == greenSlider)
        {
            value = greenSlider.getValue();
            myButton.setBackground(new Color(oldColor.getRed(),
                value,oldColor.getBlue()));
        }
        else if(ae.getSource() == blueSlider)
        {
            value = blueSlider.getValue();
            myButton.setBackground(new Color(oldColor.getRed(),
                oldColor.getGreen(),value));
        }
    }
}