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Description:
This program is to view the color palette in applet. Using the JSlider menu three JSlider objects are created for red, green and blue. The initial values for each color are set to 128.You choose your own values. GraphicsPanel class is also declared to display the palette. When you move the pointer on the JSlider of each color, the corresponding color is displayed on the Graphics panel. Based on the pointer in each JSlider the corresponding RGB Integer value and hash code values of each color is displayed. ChangeListener interface will get the position of each JSlider.
Displaying color Palette Using Java Applet:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
////////////////////////////////////////////////////////////////// ColorDisplay
class ColorDisplay extends JFrame {
JSlider redBar; // Slider for adjusting red from 0-255
JSlider grnBar;
JSlider bluBar;
int red = 128; // initial red color value
int green = 128;
int blue = 128;
GraphicsPanel palette; // an area to display the color
JTextField txtField; // shows the Java source equivalent
//================================================ constructor
public ColorDisplay() {
palette = new GraphicsPanel();
// Create a textfield for displaying the values
txtField = new JTextField();
txtField.setFont(new Font("Monospaced", Font.PLAIN, 12));
txtField.setText("Color(" + red + ", " + green + ", " + blue +
") or " + "Color(0x" +
Integer.toHexString(blue + 256 * (green + 256 * red)) + ")");
txtField.setEditable(false);
// Create one object that will listen to all sliders
ChangeListener al = new ColorListener();
redBar = new JSlider(JSlider.VERTICAL, 0, 255, red);
redBar.addChangeListener(al);
redBar.setBackground(Color.red);
grnBar = new JSlider(JSlider.VERTICAL, 0, 255, green);
grnBar.addChangeListener(al);
grnBar.setBackground(Color.green);
bluBar = new JSlider(JSlider.VERTICAL, 0, 255, blue);
bluBar.addChangeListener(al);
bluBar.setBackground(Color.blue);
//=== Put the color palette and textfield in a box
Box paletteText = Box.createVerticalBox();
paletteText.add(palette);
paletteText.add(txtField);
//=== put the 3 sliders in a gridlayout panel
JPanel colorControls = new JPanel();
colorControls.setLayout(new GridLayout(1, 3));
colorControls.add(redBar);
colorControls.add(grnBar);
colorControls.add(bluBar);
//=== Now let's build the content pane
Container content = this.getContentPane();
content.setLayout(new BoxLayout(content, BoxLayout.X_AXIS));
content.add(paletteText);
content.add(colorControls);
this.setTitle("ColorDisplay");
this.pack();
}//end constructor
class GraphicsPanel extends JPanel {
public GraphicsPanel() {
this.setPreferredSize(new Dimension(300, 300));
this.setBackground(Color.white);
this.setForeground(Color.black);
}//end constructor
public void paintComponent(Graphics g) {
super.paintComponent(g); // paint background, border
g.setColor(new Color(red, green, blue)); // Set the color
g.fillRect(0, 0, this.getWidth(), this.getHeight()); // Color everything
}//endmethod paintComponent
}//endclass GraphicsPanel
class ColorListener implements ChangeListener {
public void stateChanged(ChangeEvent ae) {
red = redBar.getValue();
green = grnBar.getValue();
blue = bluBar.getValue();
txtField.setText("Color(" + red + ", " + green + ", " + blue +
") or " + "Color(0x" + Integer.toHexString(blue +
256 * (green + 256 * red)) + ")");
palette.repaint();
}//endmethod stateChanged
}//endclass ColorListener
//================================================================= main
public static void main(String[] args) {
JFrame window = new ColorDisplay();
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setVisible(true);
}//end main
}//end class ColorDisplay
Sample ScreenShot:
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