CODE: A simple desktop color sampler and JColorChooser Panel based on it.

Question

// ColorSamplerColorChooserPanel.java
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Font;
import javax.swing.Icon;
import javax.swing.JColorChooser;
import javax.swing.JFrame;
import javax.swing.UIManager;
import javax.swing.colorchooser.AbstractColorChooserPanel;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
* A simple ColorChooserPanel for JColorChooser based on ColorSampler.
* @author Sandip V. Chitale
* @version 1.0
* @see ColorSampler
public class ColorSamplerColorChooserPanel
     extends AbstractColorChooserPanel
     implements ChangeListener
     private boolean isAdjusting = false;
     private ColorSampler colorSampler;
     public ColorSamplerColorChooserPanel() {
          colorSampler = new ColorSampler();
          colorSampler.addChangeListener(this);
     public void stateChanged(ChangeEvent ce) {
          getColorSelectionModel().
          setSelectedColor(colorSampler.getSelectedColor());
     // Implementation of AbstractColorChooserPanel
     * Return display name.
     * @return a <code>String</code> value
     public String getDisplayName() {
          return "Color Sampler";
     * Update the chooser.
     public void updateChooser() {
if (!isAdjusting) {
isAdjusting = true;
               colorSampler.
               showColor(getColorSelectionModel().getSelectedColor(), false);
isAdjusting = false;
     * Build the chooser panel.
     public void buildChooser() {
          setLayout(new BorderLayout());
          add(colorSampler, BorderLayout.NORTH);
     * Return small icon.
     * @return an <code>Icon</code> value
     public Icon getSmallDisplayIcon() {
          return null;
     * Return large icon.
     * @return an <code>Icon</code> value
     public Icon getLargeDisplayIcon() {
          return null;
     * Return font.
     * @return a <code>Font</code> value
     public Font getFont() {
          return null;
     * <code>ColorSampler</code> test.
     * @param args a <code>String[]</code> value
     public static void main(String[] args) {
          try {
               UIManager.
               setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
          } catch (Exception e) {
          final JFrame frame = new JFrame("Color Sampler Color Chooser");
          JColorChooser colorChooser = new JColorChooser();
          colorChooser.addChooserPanel(new ColorSamplerColorChooserPanel());
          frame.setContentPane(colorChooser);
          frame.pack();
          frame.setVisible(true);
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// ColorSampler.java
import java.awt.AWTException;
import java.awt.Color;
import java.awt.Cursor;
import java.awt.Font;
import java.awt.Point;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.datatransfer.StringSelection;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;
import javax.swing.BorderFactory;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.BoxLayout;
import javax.swing.event.ChangeEvent;
import javax.swing.event.EventListenerList;
import javax.swing.event.ChangeListener;
* A simple desktop color sampler. Drag mouse from the color sample
* label and release mouse anywhere on desktop to sample color at that
* point. The hex string for the color is also copied to the system
* clipboard.
* Note: Uses java.awt.Robot.
* @author Sandip V. Chitale
* @version 1.0
public class ColorSampler extends JPanel {
     private JLabel sampleColorLabel;
     private JLabel colorLabel;
     private JTextField colorValueField;
     private Robot robot;
     * Creates a new <code>ColorSampler</code> instance.
     public ColorSampler() {
          setLayout(new BoxLayout(this, BoxLayout.X_AXIS));
          setBorder(BorderFactory.createEtchedBorder());
          Font font = new Font("Monospaced", Font.PLAIN, 11);
          sampleColorLabel = //new JLabel(new ImageIcon(getClass().getResource("ColorSampler.gif")), JLabel.CENTER);
          new JLabel(" + ", JLabel.CENTER);
          sampleColorLabel.setBorder(BorderFactory.createEtchedBorder());
          sampleColorLabel
          .setToolTipText("<html>Drag mouse to sample the color.<br>" +
                              "Release to set color and save hex value in clipboard.");
          add(sampleColorLabel);
          colorValueField = new JTextField(9);
          colorValueField.setFont(font);
          colorValueField.setEditable(false);
          colorValueField.setBorder(BorderFactory.createLoweredBevelBorder());
          add(colorValueField);
          colorLabel = new JLabel(" ");
          colorLabel.setFont(font);
          colorLabel.setOpaque(true);
          colorLabel.setBorder(BorderFactory.createEtchedBorder());
          add(colorLabel);
          showColor(colorLabel.getBackground(), false);
          try {
               robot = new Robot();
          } catch (AWTException e) {
               System.err.println(e);
          sampleColorLabel.addMouseListener(
               new MouseAdapter() {
                    public void mousePressed(MouseEvent me) {
                         SwingUtilities.getWindowAncestor(ColorSampler.this)
                         .setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
                    public void mouseReleased(MouseEvent me) {
                         Point p = me.getPoint();
                         SwingUtilities.convertPointToScreen(p, me.getComponent());
                         sampleColorAtPoint(p, false);
                         SwingUtilities.getWindowAncestor(ColorSampler.this)
                         .setCursor(Cursor.getDefaultCursor());                         
          sampleColorLabel.addMouseMotionListener(
               new MouseMotionAdapter() {
                    public void mouseDragged(MouseEvent me) {
                         Point p = me.getPoint();
                         SwingUtilities.convertPointToScreen(p, me.getComponent());
                         sampleColorAtPoint(p, true);
                         SwingUtilities.getWindowAncestor(ColorSampler.this)
                         .setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
     public Color getSelectedColor() {
          return colorLabel.getBackground();
     public void setSelectedColor(Color color) {
          if (color.equals(getSelectedColor())) {
               return;
          showColor(color, false);
     public String getSelectedColorString() {
          return getHexStringOfColor(getSelectedColor());
     public void sampleColorAtPoint(Point p, boolean temporary) {
          showColor(robot.getPixelColor(p.x, p.y), temporary);
     void showColor(Color color, boolean temporary) {
          colorLabel.setBackground(color);
          colorValueField.setText(getHexStringOfColor(color));
          colorValueField.selectAll();
          if (!temporary) {
               Toolkit.getDefaultToolkit().getSystemClipboard().setContents(
                    new StringSelection(getHexStringOfColor(color)),null);
               fireStateChanged();
     private String getHexStringOfColor(Color c) {
          int r = c.getRed();
          int g = c.getGreen();
          int b = c.getBlue();
          String rh = Integer.toHexString(r);
          if(rh.length() < 2) {
               rh = "0" + rh;
          String gh = Integer.toHexString(g);
          if(gh.length() < 2) {
               gh = "0" + gh;
          String bh = Integer.toHexString(b);
          if(bh.length() < 2) {
               bh = "0" + bh;
          return ("#"+rh+gh+bh).toUpperCase();
* Only one <code>ChangeEvent</code> is needed per model instance
* since the event's only (read-only) state is the source property.
* The source of events generated here is always "this".
protected transient ChangeEvent changeEvent = null;
protected EventListenerList listenerList = new EventListenerList();
* Adds a <code>ChangeListener</code> to the model.
* @param l the <code>ChangeListener</code> to be added
public void addChangeListener(ChangeListener l) {
          listenerList.add(ChangeListener.class, l);
* Removes a <code>ChangeListener</code> from the model.
* @param l the <code>ChangeListener</code> to be removed
public void removeChangeListener(ChangeListener l) {
          listenerList.remove(ChangeListener.class, l);
* Returns an array of all the <code>ChangeListener</code>s added
* to this <code>DefaultColorSelectionModel</code> with
* <code>addChangeListener</code>.
* @return all of the <code>ChangeListener</code>s added, or an empty
* array if no listeners have been added
* @since 1.4
public ChangeListener[] getChangeListeners() {
return (ChangeListener[])listenerList.getListeners(
               ChangeListener.class);
* Runs each <code>ChangeListener</code>'s
* <code>stateChanged</code> method.
* <!-- @see #setRangeProperties //bad link-->
* @see EventListenerList
protected void fireStateChanged()
Object[] listeners = listenerList.getListenerList();
for (int i = listeners.length - 2; i >= 0; i -=2 ) {
if (listeners[i] == ChangeListener.class) {
if (changeEvent == null) {
changeEvent = new ChangeEvent(this);
((ChangeListener)listeners[i+1]).stateChanged(changeEvent);
     * <code>ColorSampler</code> test.
     * @param args a <code>String[]</code> value
     public static void main(String[] args) {
          final JFrame frame = new JFrame("Desktop Color Sampler");
          frame.setContentPane(new ColorSampler
          frame.pack();
          frame.setVisible(true);
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}

Answer 1

Hi vg007, what version LabVIEW are you using? I found an example in the NI Example Finder  (LabVIEW 2014) that might be helpful to accomplish what you are trying to do. In LabVIEW navigate to Help >> Find Examples.
In the Example Finder under the 'Browse' tab go to:
Analysis, Signal Processing and Mathematics >> Signal Processing >> Edge Detection with 2D Convolution.vi
Robert S.
Applications Engineer
National Instruments
Attachments:
Edge Detection with 2D Convolution.vi ‏238 KB