getting values from change listener

[Steven Coddington]

I am a beginner and just learning to use swing widgets. I want to make a color maker to see what various rgb combos look like. I want three sliders, with values from 0-255, get the values, and re-color a region so I can see the effect. I have the sliders working, but don't know how to get the value from the change listener to the panel drawer. Here is what I have so far.

Any help is greatly appreciated. Thanks.


/*
* SliderTest.java
*/

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.awt.Container;
import java.awt.BorderLayout;
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JSlider;
import javax.swing.event.*;

public class SliderTest extends JFrame{
// Declare class variables
JFrame frame;
JLabel label;

// Creates a new instance of SliderTest
public static void main(String[] args) {
SliderTest gui = new SliderTest();
gui.go();
}

// Build a gui
public void go() {
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

JButton colorButton = new JButton("Change Circle");

// Add three sliders to the a container

Container sliderContainer = getContentPane();
sliderContainer.setLayout(new GridLayout(3,1));

JSlider redSlider = new JSlider(0,0,255,127);
JSlider greenSlider = new JSlider(0,0,255,127);
JSlider blueSlider = new JSlider(0,0,255,127);

redSlider.addChangeListener(new RedChangeListener());

sliderContainer.add(redSlider);
sliderContainer.add(greenSlider);
sliderContainer.add(blueSlider);

MyDrawPanel drawPanel= new MyDrawPanel();

frame.getContentPane().add(BorderLayout.SOUTH, colorButton);
frame.getContentPane().add(BorderLayout.CENTER, drawPanel);
frame.getContentPane().add(BorderLayout.NORTH, sliderContainer);

frame.setSize(800,700);
frame.setVisible(true);
}

// An inner class for the slider event
class RedChangeListener implements ChangeListener {
public void stateChanged(ChangeEvent e){
JSlider redSource = (JSlider)e.getSource();
if (!redSource.getValueIsAdjusting()) {
redValue = (int)redSource.getValue();
System.out.println (redValue);
}
}
}

// Make the Draw Panel an inner class
class MyDrawPanel extends JPanel {
public void paintComponent(Graphics g) {

int redValue = 127; /* This is where I would like to put the value from the slider.
int greenValue = 127;
int blueValue = 127;
Color newColor = new Color(redValue, greenValue, blueValue);

//erase old oval by repainting rectangle
g.fillRect(0, 0, this.getWidth(), this.getHeight());

g.setColor(newColor);
g.fillOval(70, 70, 100, 100);
}
public void stateChanged(javax.swing.event.ChangeEvent changeEvent) {
}

}
}

[Michael Dunn]

maybe something like this

import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import javax.swing.event.*;
import javax.swing.plaf.basic.BasicSliderUI;
 
class SliderTest extends JFrame implements ChangeListener
{
  MyDrawPanel drawPanel= new MyDrawPanel();
  JSlider redSlider = new JSlider(0,255,0);
  JSlider greenSlider = new JSlider(0,255,0);
  JSlider blueSlider = new JSlider(0,255,0);
  public SliderTest()
  {
    setDefaultCloseOperation(EXIT_ON_CLOSE);
    setLocation(200,100);
    MyBasicSliderUI redUI = new MyBasicSliderUI(redSlider,Color.RED);
    redSlider.setUI(redUI);
    redSlider.addChangeListener(this);
    redSlider.setMajorTickSpacing(10);
    redSlider.setMinorTickSpacing(5);
    redSlider.setPaintTicks(true);
    redSlider.setPaintLabels(true);
    MyBasicSliderUI greenUI = new MyBasicSliderUI(greenSlider,Color.GREEN);
    greenSlider.setUI(greenUI);
    greenSlider.addChangeListener(this);
    greenSlider.setMajorTickSpacing(10);
    greenSlider.setMinorTickSpacing(5);
    greenSlider.setPaintTicks(true);
    greenSlider.setPaintLabels(true);
    MyBasicSliderUI blueUI = new MyBasicSliderUI(blueSlider,Color.BLUE);
    blueSlider.setUI(blueUI);
    blueSlider.addChangeListener(this);
    blueSlider.setMajorTickSpacing(10);
    blueSlider.setMinorTickSpacing(5);
    blueSlider.setPaintTicks(true);
    blueSlider.setPaintLabels(true);
    JPanel sliderContainer = new JPanel(new GridLayout(3,1));
    sliderContainer.add(redSlider);
    sliderContainer.add(greenSlider);
    sliderContainer.add(blueSlider);
    getContentPane().add(sliderContainer,BorderLayout.NORTH);
    getContentPane().add(drawPanel,BorderLayout.CENTER);
    pack();
  }
  public void stateChanged(ChangeEvent ce)
  {
    drawPanel.redValue = redSlider.getValue();
    drawPanel.greenValue = greenSlider.getValue();
    drawPanel.blueValue = blueSlider.getValue();
    getContentPane().repaint();
  }
  class MyDrawPanel extends JPanel
  {
    int redValue, greenValue,blueValue;
    public MyDrawPanel()
    {
      setPreferredSize(new Dimension(600,400));
    }
    public void paintComponent(Graphics g)
    {
      Color newColor = new Color(redValue, greenValue, blueValue);
      g.setColor(newColor);
      g.fillOval(200, 100, 200, 200);
    }
  }
  class MyBasicSliderUI extends BasicSliderUI
  {
    Color color;
    public MyBasicSliderUI(JSlider js, Color c)
    {
      super(js);
      color = c;
    }
    public void paintThumb(Graphics g)
    {
      Rectangle thumb = thumbRect;
      g.setColor(color);
      g.fillRect(thumb.x, thumb.y, 7,15);
    }
  }
  public static void main(String[] args){new SliderTest().setVisible(true);}
}