JColorChooser dialog with the custom GrayScalePanel picker tab. : Color Chooser « Swing JFC « Java

JColorChooser dialog with the custom GrayScalePanel picker tab.

JColorChooser dialog with the custom GrayScalePanel picker tab.
Java Swing, 2nd Edition
By Marc Loy, Robert Eckstein, Dave Wood, James Elliott, Brian Cole
ISBN: 0-596-00408-7
Publisher: O'Reilly 
// ColorPicker2.java
//A quick test of the JColorChooser dialog. This one installs the custom
//GrayScalePanel picker tab.

import java.awt.Color;
import java.awt.Container;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.Icon;
import javax.swing.JButton;
import javax.swing.JColorChooser;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.JTextField;
import javax.swing.SwingConstants;
import javax.swing.colorchooser.AbstractColorChooserPanel;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;

public class ColorPicker2 extends JFrame {

  Color c;

  public ColorPicker2() {
    super("JColorChooser Test Frame");
    setSize(200, 100);

    final JButton go = new JButton("Show JColorChoser");
    final Container contentPane = getContentPane();
    go.addActionListener(new ActionListener() {
      final JColorChooser chooser = new JColorChooser();

      boolean first = true;

      public void actionPerformed(ActionEvent e) {
        if (first) {
          first = false;
          GrayScalePanel gsp = new GrayScalePanel();
        JDialog dialog = JColorChooser.createDialog(ColorPicker2.this,
            "Demo 2", true, chooser, new ActionListener() {
              public void actionPerformed(ActionEvent e) {
                c = chooser.getColor();
            }, null);

  public static void main(String args[]) {
    ColorPicker2 cp2 = new ColorPicker2();

//A simple implementation of the AbstractColorChooserPanel class. This class
//provides a slider and a textfield for picking out a shade of gray.

class GrayScalePanel extends AbstractColorChooserPanel implements
    ChangeListener, ActionListener {

  JSlider scale;

  JTextField percentField;

  // Set up our list of grays. We'll assume we have all 256 possible shades,
  // and we'll do it when the class is loaded.
  static Color[] grays = new Color[256];
  static {
    for (int i = 0; i < 256; i++) {
      grays[i] = new Color(i, i, i);

  public GrayScalePanel() {
    setLayout(new GridLayout(0, 1));

    // create the slider and attach us as a listener
    scale = new JSlider(JSlider.HORIZONTAL, 0, 255, 128);

    // Set up our display for the chooser
    add(new JLabel("Pick your shade of gray:", JLabel.CENTER));
    JPanel jp = new JPanel();
    jp.add(new JLabel("Black"));
    jp.add(new JLabel("White"));

    JPanel jp2 = new JPanel();
    percentField = new JTextField(3);
    jp2.add(new JLabel("%"));

  // We did this work in the constructor so we can skip it here.
  protected void buildChooser() {

  // Make sure the slider is in sync with the other panels.
  public void updateChooser() {
    Color c = getColorSelectionModel().getSelectedColor();

  protected int toGray(Color c) {
    int r = c.getRed();
    int g = c.getGreen();
    int b = c.getBlue();
    // Grab the luminance the same way GIMP does...
    return (int) Math.round(0.3 * r + 0.59 * g + 0.11 * b);

  // Pick a name for our tab in the chooser
  public String getDisplayName() {
    return "Gray Scale";

  // No need for an icon.
  public Icon getSmallDisplayIcon() {
    return null;

  public Icon getLargeDisplayIcon() {
    return null;

  // And lastly, update the selection model as our slider changes.
  public void stateChanged(ChangeEvent ce) {
        + (100 - (int) Math.round(scale.getValue() / 2.55)));

  public void actionPerformed(ActionEvent ae) {
    int val = 100 - Integer.parseInt(ae.getActionCommand());
    getColorSelectionModel().setSelectedColor(grays[(int) (val * 2.55)]);


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