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Is it possible to write paint on screen program in java/swing?

I'm writing paint on screen program using Java Swing. It working on ubuntu linux. But windows shows black screen instead of transparent panel. I included similar example code. What is wrong in my code?
import javax.swing.*;
import java.awt.*;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
public class Example {
public static final Color COLOR_TRANSPARENT = new Color(0,0,0,0);
public Example() {
Canvas drawArea = new Canvas();
drawArea.setBackground(COLOR_TRANSPARENT);
drawArea.setOpaque(true);
JWindow drawingFrame = new JWindow();
drawingFrame.setBackground(COLOR_TRANSPARENT);
drawingFrame.setContentPane(drawArea);
drawingFrame.pack();
drawingFrame.setSize(640, 460);
drawingFrame.setVisible(true);
drawingFrame.setLocationRelativeTo(null);
drawingFrame.setAlwaysOnTop(true);
}
public static void main(String[] args){
SwingUtilities.invokeLater(Example::new);
}
class Canvas extends JPanel{
private Image image;
private Graphics2D g2;
public Canvas() {
super();
addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
int x = e.getX();
int y = e.getY();
g2.setPaint(Color.RED);
g2.fillOval(x-10, y-10, 20, 20);
repaint(x-10, y-10, 20, 20);
}
});
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (image == null){
image = createImage(getWidth(), getHeight());
g2 = (Graphics2D) image.getGraphics();
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.setBackground(COLOR_TRANSPARENT);
clear();
}
Graphics2D g2 = (Graphics2D) g;
g2.drawImage(image, 0,0, null);
}
public void clear(){
System.out.println("clearing canvas ");
g2.setComposite(AlphaComposite.Clear);
g2.setBackground(COLOR_TRANSPARENT);
g2.setColor(COLOR_TRANSPARENT);
g2.fillRect(0, 0, getWidth(), getHeight());
g2.clearRect(0, 0, getWidth(), getHeight());
g2.setPaint(Color.RED);
g2.setComposite(AlphaComposite.SrcOver);
repaint();
}
}
}
Here is screenshot what I wanted.
Example code updated. Now code should work without any other additional code.

For windows I made a couple of changes:
image = createImage(getWidth(), getHeight());
image = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_ARGB);
I used a BufferedImage to you can set the alpha values of the image to be transparent.
//public static final Color COLOR_TRANSPARENT = new Color(0,0,0,0);
public static final Color COLOR_TRANSPARENT = new Color(0,0,0,1);
I made the alpha value non-zero, because a value of zero means the Java application won't receive the MouseEvent because it is passed to the application under the window.

How to add imagepanel in jpanel inside Jframe?

I'm trying to add an imagepanel which extends JPanel to another JPanel. Which is not working well for me. The paint function of image panel don't get invoked inside Jpanel but works fine in JFrame. Any ideas or help will be appreciated.
import javax.swing.*;
import java.awt.*;
import java.awt.geom.RoundRectangle2D;
import java.awt.image.BufferedImage;
class ImagePanel extends JPanel
{
int g_h=10,g_w=10;
int width=50,height=50;
int cornerradius;
Image castle;
Dimension size;
protected int x1,y1;
Color c1=new Color(255, 0, 0);
Rectangle rec;
boolean b=false;
boolean imboo=false;
boolean roundb= false;
Graphics g= this.getGraphics();
protected int strokeSize = 1;
protected Color shadowColor = Color.BLACK;
boolean shadowed = false;
public ImagePanel()
{
//super();
setOpaque(false);
setLayout(null);
System.out.println("it executed");
}
public ImagePanel(int x, int y)
{
setSize(x, y);
}
public void setSize(int x,int y){
width=x;
height=y;
}
public int getheight(){
return height;
}
public int getwidth(){
return width;
}
public void setImagePanelBounds(
int x, int y, int width, int height){
x1=x;
y1=y;
this.width= width;
this.height= height;
System.out.println("6it executed");
}
public void setroundcorners(boolean b, int i){
roundb=b;
cornerradius=i;
System.out.println("5it executed");
}
public void setImage(String s){
imboo=true;
size = new Dimension();
castle = new ImageIcon(s).getImage();
size.width = castle.getWidth(null);
size.height = castle.getHeight(null);
setPreferredSize(size);
System.out.println("4it executed");
}
public void paint(Graphics gh){
System.out.println("it executed p");
{int x=this.getWidth();
int j=20,a=20;
Graphics2D g2= (Graphics2D)gh.create();
{
g2.setColor(Color.WHITE);
g2.setComposite(AlphaComposite.Src);
g2.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.setComposite(AlphaComposite.SrcAtop);
rec= new Rectangle(x1, y1, width, height);
//Start of If-else
if(roundb){
g2.setClip(new RoundRectangle2D.Float(
(int)rec.getX(),(int)rec.getY(),
(int)rec.getWidth(),(int)rec.getHeight(),
cornerradius, cornerradius));
System.out.println("it executed");
}
// End of If-Else
// Image condition Starts
if (imboo){
g2.drawImage(castle, (int)rec.getX(),
(int)rec.getY(), (int)rec.getWidth(),
(int)rec.getHeight(), null);
//g.drawImage(castle, (int)rec.getX(),(int)rec.getY(), null);
}
// Image condition Ends
g2.setColor(Color.BLUE);
}
}
}
public static void main(String[]args)
{
ImagePanel t1=new ImagePanel();
JPanel jp1= new JPanel();
jp1.add(t1);
jp1.setLayout(null);
jp1.setBounds(0, 0, 600, 600);
JFrame jf1= new JFrame("Testing");
t1.setImage("icons/1.png");
//t1.setImage("1.jpg");
t1.setLayout(null);
t1.setroundcorners(true, 10);
//t1.setShadow(true);
t1.add(new JLabel("niak"));
//t1.setShadowDimensions(18, 18, 305, 305, 12);
t1.setImagePanelBounds(20, 20, 100, 100);
// jf1.add(t1);
jf1.setSize(600, 600);
jf1.setDefaultCloseOperation(jf1.EXIT_ON_CLOSE);
jf1.setVisible(true);
//jf1.revalidate();
jf1.setLayout(null);
}
}

Let's start with...
Don't use getGraphics. This is not how to perform custom painting. getGraphics may return null and is, at best, a snapshot, which will be discard when the next paint cycle occurs.
JPanel already has getWidth, getHeight and setSize methods, you should never have a need to overridden them. Instead, you should override getPreferredSize and return a size hint back that the parent layout manager can use.
If you create a Graphics context, you should dispose of it. In your paint method, you use gh.create, this is consuming resources and under some systems, until the Graphics context is disposed, it may not actually paint anything.
Don't override paint, instead use paintComponent
DO NOT modify the clip rectangle. Seriously, this is going to cause you more issues then you can imagine.
Don't use null layout managers without EXTREMELY good reason.
JPanel has a setBounds method, while, under normal circumstances, you shouldn't need to use it, since you've thrown away the layout manager, you should use it.
Basically, you've discard all the inner workings of the JPanel that enable the paint system to know that it should actually paint your panel
Updated with example
As an example...
Instead of using the clip, I use a masking technique, and mask the shape I want over the source image. I also buffer the result, which should make it more memory conservative as well as render faster
import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Insets;
import java.awt.RenderingHints;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;
public class ImagePaneExample {
public static void main(String[] args) {
new ImagePaneExample();
}
public ImagePaneExample() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
try {
BufferedImage img = ImageIO.read(new File("C:\\hold\\thumbnails\\2005-09-29-3957.jpeg"));
ImagePane imgPane = new ImagePane();
imgPane.setImage(img);
imgPane.setRounded(true);
imgPane.setBorder(new EmptyBorder(20, 20, 20, 20));
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(imgPane);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (Exception exp) {
exp.printStackTrace();
}
}
});
}
public class ImagePane extends JPanel {
private BufferedImage img;
private BufferedImage renderImg;
private boolean rounded;
public ImagePane() {
}
public void setRounded(boolean value) {
if (value != rounded) {
rounded = value;
renderImg = null;
firePropertyChange("rounded", !rounded, rounded);
repaint();
}
}
public boolean isRounded() {
return rounded;
}
public void setImage(BufferedImage value) {
if (value != img) {
BufferedImage old = img;
img = value;
renderImg = null;
firePropertyChange("image", old, img);
repaint();
}
}
public BufferedImage getImage() {
return img;
}
#Override
public Dimension getPreferredSize() {
Dimension size = img == null ? new Dimension(200, 200) : new Dimension(img.getWidth(), img.getHeight());
Insets insets = getInsets();
size.width += (insets.left + insets.right);
size.height += (insets.top + insets.bottom);
return size;
}
protected void applyQualityRenderHints(Graphics2D g2d) {
g2d.setRenderingHint(RenderingHints.KEY_ALPHA_INTERPOLATION, RenderingHints.VALUE_ALPHA_INTERPOLATION_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.setRenderingHint(RenderingHints.KEY_COLOR_RENDERING, RenderingHints.VALUE_COLOR_RENDER_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
g2d.setRenderingHint(RenderingHints.KEY_FRACTIONALMETRICS, RenderingHints.VALUE_FRACTIONALMETRICS_ON);
g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g2d.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
g2d.setRenderingHint(RenderingHints.KEY_STROKE_CONTROL, RenderingHints.VALUE_STROKE_PURE);
}
protected BufferedImage getImageToRender() {
if (renderImg == null) {
BufferedImage source = getImage();
if (source != null) {
if (isRounded()) {
BufferedImage mask = new BufferedImage(source.getWidth(), source.getHeight(), BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = mask.createGraphics();
applyQualityRenderHints(g2d);
g2d.setBackground(new Color(255, 255, 255, 0));
g2d.clearRect(0, 0, mask.getWidth(), mask.getHeight());
g2d.setBackground(new Color(255, 255, 255, 255));
g2d.fillRoundRect(0, 0, mask.getWidth(), mask.getHeight(), 40, 40);
g2d.dispose();
BufferedImage comp = new BufferedImage(source.getWidth(), source.getHeight(), BufferedImage.TYPE_INT_ARGB);
g2d = comp.createGraphics();
applyQualityRenderHints(g2d);
g2d.setBackground(new Color(255, 255, 255, 0));
g2d.clearRect(0, 0, source.getWidth(), source.getHeight());
g2d.drawImage(source, 0, 0, this);
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.DST_IN));
g2d.drawImage(mask, 0, 0, this);
g2d.dispose();
renderImg = comp;
} else {
renderImg = source;
}
}
}
return renderImg;
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
BufferedImage img = getImageToRender();
System.out.println(img);
if (img != null) {
Insets insets = getInsets();
Graphics2D g2d = (Graphics2D) g.create();
int width = getWidth();
int height = getHeight();
int x = ((width - img.getWidth()) / 2);
int y = ((height - img.getHeight()) / 2);
g2d.drawImage(img, x, y, this);
g2d.dispose();
}
}
}
}
I'd recommend some more reading through Creating a UI with Swing, in particular the section on layout managers, as well as Performing Custom Painting and Painting in AWT and Swing

All you have to do is to set the Layout of your panel jp1 to BorderLayout and add the image panel t1 to BorderLayout.CENTER, like this:
JPanel jp1= new JPanel(new BorderLayout());
jp1.add(t1, BorderLayout.CENTER);

How to make the Panels on JLayeredPane transparent?

I have a JLayeredPane with 4 layers added to it. 1 base layer, which is opaque and three 'transparent' layers (setOpaque(false)).
The problem is that although the panels are drawn onto, with every refresh a gray color is shown. The same thing happens if there is no refresh happening. In other words, instead of showing whatever was drawn onto the base layer, a gray color is shown, I assume this is from one of the layers above.
Here is a SSCCE - I'm not sure if this is short enough but it shows my problem.
public class SSCCE extends JLayeredPane{
public static void main(String[] args){
JFrame frame = new JFrame();
frame.setSize(950, 600);
frame.add(new SSCCE());
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
// private fields
private boolean drawInitial = true;
private boolean drawn = false;
private JPanel overlay, base, iconPanel, middle;
private BufferedImage baseBuffer, midBuffer, overlayBuffer, iconBuffer;
private boolean updateInit = true;
private Rectangle2D stored = new Rectangle2D.Double(60, 60, 40, 100);
public SSCCE() {
setBorder(new LineBorder(Color.BLACK));
setDoubleBuffered(false);
setOpaque(true);
setSize(new Dimension(950, 600));
setPreferredSize(new Dimension(950, 600));
base = new JPanel();
base.setBackground(new Color(0,0,0,0));
base.setSize(new Dimension(getWidth(), getHeight()));
this.add(base, new Integer(0));
middle = new JPanel();
middle.setSize(new Dimension(getWidth(), getHeight()));
middle.setBackground(new Color(0,0,0,0));
middle.setOpaque(false);
this.add(middle, new Integer(1));
overlay = new JPanel();
overlay.setBackground(new Color(0,0,0,0));
overlay.setOpaque(false);
overlay.setSize(new Dimension(getWidth(), getHeight()));
this.add(overlay, new Integer(2));
iconPanel = new JPanel();
iconPanel.setBackground(new Color(0,0,0,0));
iconPanel.setSize(getWidth(), getHeight());
iconPanel.setOpaque(false);
this.add(iconPanel, new Integer(3));
}
public void update() {
if(updateInit){
checkBuffer();
updateInit = false;
}
drawInfoRect();
drawIcon();
highlightPath(stored);
}
public void render() {
if (drawInitial) {
Graphics2D baseGraphics = (Graphics2D) base.getGraphics();
baseGraphics.drawImage(baseBuffer, 0, 0, null);
}
setResistanceColor((Graphics2D)baseBuffer.getGraphics());
middle.getGraphics().drawImage(midBuffer, 0, 0, null);
iconPanel.getGraphics().drawImage(iconBuffer, 0, 0, null);
drawInfoRect();
base.getGraphics().drawImage(baseBuffer, 0, 0, null);
if (drawn) {
overlay.getGraphics().drawImage(overlayBuffer, 0, 0, null);
}
repaint();
}
// /**
// * draws the appropriate colour
// */
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
update();
render();
}
/**
* sets the appropriate colours according to the resistance
* #param g2
*/
private void setResistanceColor(Graphics2D g2) {
Rectangle2D sp = new Rectangle2D.Double(50,50, 50, 50);
g2.setColor(Color.GREEN);
g2.fill(sp);
g2.setColor(Color.BLACK);
}
/**
* checks if there already exists an image to buffer with
*/
private void checkBuffer() {
if (baseBuffer == null) {
baseBuffer = (new BufferedImage(this.getWidth(), this.getHeight(), BufferedImage.TYPE_INT_ARGB));
// background color
Graphics2D g2 = (Graphics2D) baseBuffer.getGraphics();
g2.setColor(Color.decode("#729fcf"));
Rectangle2D rect = new Rectangle2D.Double(0, 0, baseBuffer.getWidth(), baseBuffer.getHeight());
g2.fill(rect);
}
if (midBuffer == null) {
midBuffer = (new BufferedImage(this.getWidth(), this.getHeight(), BufferedImage.TYPE_INT_ARGB));
// background color
Graphics2D g2 = (Graphics2D) midBuffer.getGraphics();
g2.setColor(Color.RED);
Rectangle2D rect = new Rectangle2D.Double(0, 0, midBuffer.getWidth(), midBuffer.getHeight());
g2.fill(rect);
}
if (overlayBuffer == null) {
overlayBuffer = (new BufferedImage(this.getWidth(), this.getHeight(), BufferedImage.TYPE_INT_ARGB));
}
if (iconBuffer == null) {
iconBuffer = (new BufferedImage(this.getWidth(), this.getHeight(), BufferedImage.TYPE_INT_ARGB));
}
}
public void highlightPath(Shape enlighten) {
Area area = new Area();
area.add(new Area(enlighten));
// clearing image before drawing
Graphics2D midBufferG = (Graphics2D) midBuffer.getGraphics();
clearImage(midBufferG);
midBufferG.setColor(Color.white);
// adds a transparent overlay
midBufferG.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.50f));
midBufferG.fill(area);
}
public void drawIcon() {
Graphics2D iconG = (Graphics2D) iconBuffer.getGraphics();
clearImage(iconG);
}
public void drawInfoRect() {
Graphics2D graph = (Graphics2D) overlayBuffer.getGraphics();
Rectangle2D visible = getVisibleRect();
int boxX = (int) (visible.getX() + 50);
int boxY = (int) (visible.getY() + 450);
RoundRectangle2D rect = new RoundRectangle2D.Double(boxX, boxY, 200, 150, 25, 25);
graph.setColor(Color.decode("#729fcf").darker());
graph.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.4f));
graph.fill(rect);
graph.setColor(Color.BLACK);
drawn = true;
}
private void clearImage(Graphics2D graph){
graph.setComposite(AlphaComposite.Clear);
graph.fillRect(0, 0, overlayBuffer.getWidth(), overlayBuffer.getHeight());
graph.setComposite(AlphaComposite.SrcOver);
}
}
It might be some basic mistake I made. Thanks for your help!

One of the previously suggested answers actually solved my question, but for some reason they deleted their answer.
Setting the Background of my panels to setBackground(new
Color(0,0,0,0)); solved my problems.
According to the person that suggested this, the cause of that is the fact that JComponent may or may not draw transparent if not explicitly specified.
Thanks again!

Java 3 Color Gradient

I have a JPanel, and I would like to paint a gradient within it. I have the code below, but that only paints a 2 color gradient. I would like to add a 3rd but don't know how. What I want is to have the top left of the panel as white, top right red, and both bottom corners black. What would I have to do to achieve this, something that looks like this:
package pocketshop.util;
import java.awt.Color;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JPanel;
public class ColorPicker extends JPanel{
public ColorPicker(){
repaint();
}
#Override
public void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D g2d = (Graphics2D)g;
int w = getWidth();
int h = getHeight();
GradientPaint gp = new GradientPaint(
0, 0, Color.white,
0, h, Color.black);
g2d.setPaint(gp);
g2d.fillRect(0, 0, w, h);
}
}
Edit: Possible solution
I was able to come up with using 2 gradients one horizontal and one vertical, like this:
public void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D g2d = (Graphics2D)g;
int w = getWidth();
int h = getHeight();
// Vertical
GradientPaint gp = new GradientPaint(
0, 0, new Color(0,0,0,0),
0, h, Color.black);
// Horizontal
GradientPaint gp2 = new GradientPaint(
0, 0, Color.white,
w, 0, Color.red, true);
g2d.setPaint(gp2);
g2d.fillRect(0, 0, w, h);
g2d.setPaint(gp);
g2d.fillRect(0, 0, w, h);
}

Something like this?
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import javax.imageio.ImageIO;
import javax.swing.*;
public class ThreeWayGradient {
public static void main(String[] args) {
final BufferedImage image = new BufferedImage(
200, 200, BufferedImage.TYPE_INT_RGB);
Runnable r = new Runnable() {
#Override
public void run() {
Graphics2D g = image.createGraphics();
GradientPaint primary = new GradientPaint(
0f, 0f, Color.WHITE, 200f, 0f, Color.ORANGE);
GradientPaint shade = new GradientPaint(
0f, 0f, new Color(0, 0, 0, 0),
0f, 200f, new Color(0, 0, 0, 255));
g.setPaint(primary);
g.fillRect(0, 0, 200, 200);
g.setPaint(shade);
g.fillRect(0, 0, 200, 200);
JLabel l = new JLabel(new ImageIcon(image));
JOptionPane.showMessageDialog(null, l);
File f = new File(System.getProperty("user.home"),
"ThreeWayGradient.png");
try {
ImageIO.write(image, "png", f);
} catch (IOException ex) {
ex.printStackTrace();
}
}
};
SwingUtilities.invokeLater(r);
}
}
Making it into a factory method
..because it is prettier.
import java.awt.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
public class ThreeWayGradient {
public static BufferedImage getThreeWayGradient(
int size,
Color primaryLeft,
Color primaryRight,
Color shadeColor) {
BufferedImage image = new BufferedImage(
size, size, BufferedImage.TYPE_INT_RGB);
Graphics2D g = image.createGraphics();
GradientPaint primary = new GradientPaint(
0f, 0f, primaryLeft, size, 0f, primaryRight);
int rC = shadeColor.getRed();
int gC = shadeColor.getGreen();
int bC = shadeColor.getBlue();
GradientPaint shade = new GradientPaint(
0f, 0f, new Color(rC, gC, bC, 0),
0f, size, shadeColor);
g.setPaint(primary);
g.fillRect(0, 0, size, size);
g.setPaint(shade);
g.fillRect(0, 0, size, size);
g.dispose();
return image;
}
/**
* Presumed to have a layout that shows multiple components.
*/
public static void addGradient(
JPanel p, int s, Color pL, Color pR, Color sh) {
JLabel l = new JLabel(new ImageIcon(getThreeWayGradient(s, pL, pR, sh)));
p.add(l);
}
public static void main(String[] args) {
Runnable r = new Runnable() {
#Override
public void run() {
JPanel gui = new JPanel(new GridLayout(2,4,1,1));
addGradient(gui,100,Color.YELLOW,Color.RED,Color.GREEN);
addGradient(gui,100,Color.GREEN,Color.YELLOW,Color.RED);
addGradient(gui,100,Color.RED,Color.GREEN,Color.YELLOW);
addGradient(gui,100,Color.BLUE,Color.MAGENTA,Color.PINK);
addGradient(gui,100,Color.WHITE,Color.RED,Color.BLACK);
addGradient(gui,100,Color.RED,Color.GREEN,Color.BLACK);
addGradient(gui,100,Color.BLUE,Color.PINK,Color.BLACK);
addGradient(gui,100,Color.BLUE,Color.CYAN,Color.BLACK);
JOptionPane.showMessageDialog(null, gui);
}
};
SwingUtilities.invokeLater(r);
}
}

Take a look at LinearGradientPaint, it allows you to specify n number of colours and their weights.
Update 1
With a "small" change in requirements, it is debatable if either LinearGradientPaint over GradientPant will have any significant effect in performance.
I highly recommend that you take a look at Harmonic Code. This guy does some really interesting posts, and some on gradients. ;)
Update 2
Knew I'd seen something like it before Bilinear color interpolation.

Creating a custom button in Java with JButton

I am trying to create a button that has a custom shape (hexagon), but otherwise acts like a normal JButton would (that is, works with an ActionListener).
I have created a class that extends AbstractButton, but it doesn't seem to be sending events to the ActionListener when I click it. If I change the class to extend JButton it works perfectly, but it screws up the way the button is displayed. I'm assuming that there is a method that I need to override to get it to fire events, but I can't figure out what it is.

If you want to create a CustomButtonUI then you have to look
deepest to the BasicXxxUI.
overide List of Colors from JButton
Note there isn't paintComponent(). It's wrong, just use the paint() method,
Below is just a simple example if that is possible (for Metal JButton). Note just for Metal LaF, I'm so lazy and there isn't something about override paintText, paintIcon, paintFocus, paintBorder (for all funcionalities you have to check available methods from BasicButtonUI), and something I put to the ButtonModel, just for my enjoyment.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.AbstractBorder;
import javax.swing.border.Border;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.plaf.ComponentUI;
import javax.swing.plaf.metal.MetalButtonUI;
public class TextAreaInButton {
private JFrame frame = new JFrame("sssssssss");
private JButton tip1Null = new JButton(" test button ");
public TextAreaInButton() {
Border line, raisedbevel, loweredbevel, title, empty;
line = BorderFactory.createLineBorder(Color.black);
raisedbevel = BorderFactory.createRaisedBevelBorder();
loweredbevel = BorderFactory.createLoweredBevelBorder();
title = BorderFactory.createTitledBorder("");
empty = BorderFactory.createEmptyBorder(1, 1, 1, 1);
final Border compound;
Color crl = (Color.blue);
compound = BorderFactory.createCompoundBorder(empty, new OldRoundedBorderLine(crl));
Color crl1 = (Color.red);
final Border compound1;
compound1 = BorderFactory.createCompoundBorder(empty, new OldRoundedBorderLine(crl1));
Color crl2 = (Color.black);
final Border compound2;
compound2 = BorderFactory.createCompoundBorder(empty, new OldRoundedBorderLine(crl2));
tip1Null.setFont(new Font("Serif", Font.BOLD, 14));
tip1Null.setForeground(Color.darkGray);
tip1Null.setPreferredSize(new Dimension(50, 30));
tip1Null.addActionListener(new java.awt.event.ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
}
});
tip1Null.setBorderPainted(true);
tip1Null.setFocusPainted(false);
tip1Null.setBorder(compound);
tip1Null.setHorizontalTextPosition(SwingConstants.CENTER);
tip1Null.setVerticalTextPosition(SwingConstants.BOTTOM);
tip1Null.setUI(new ModifButtonUI());
tip1Null.getModel().addChangeListener(new ChangeListener() {
#Override
public void stateChanged(ChangeEvent e) {
ButtonModel model = (ButtonModel) e.getSource();
if (model.isRollover()) {
tip1Null.setBorder(compound1);
} else {
tip1Null.setBorder(compound);
}
if (model.isPressed()) {
tip1Null.setBorder(compound2);
}
}
});
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(tip1Null, BorderLayout.CENTER);
frame.setLocation(150, 150);
frame.setPreferredSize(new Dimension(310, 75));
frame.setLocationRelativeTo(null);
frame.pack();
frame.setVisible(true);
}
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
TextAreaInButton taib = new TextAreaInButton();
}
});
}
}
class OldRoundedBorderLine extends AbstractBorder {
private final static int MARGIN = 5;
private static final long serialVersionUID = 1L;
private Color color;
OldRoundedBorderLine(Color clr) {
color = clr;
}
public void setColor(Color clr) {
color = clr;
}
#Override
public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
((Graphics2D) g).setRenderingHint(
RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g.setColor(color);
g.drawRoundRect(x, y, width, height, MARGIN, MARGIN);
}
#Override
public Insets getBorderInsets(Component c) {
return new Insets(MARGIN, MARGIN, MARGIN, MARGIN);
}
#Override
public Insets getBorderInsets(Component c, Insets insets) {
insets.left = MARGIN;
insets.top = MARGIN;
insets.right = MARGIN;
insets.bottom = MARGIN;
return insets;
}
}
class ModifButtonUI extends MetalButtonUI {
private static final ModifButtonUI buttonUI = new ModifButtonUI();
ModifButtonUI() {
}
public static ComponentUI createUI(JComponent c) {
return new ModifButtonUI();
}
#Override
public void paint(Graphics g, JComponent c) {
final Color color1 = new Color(230, 255, 255, 0);
final Color color2 = new Color(255, 230, 255, 64);
final Color alphaColor = new Color(200, 200, 230, 64);
final Color color3 = new Color(
alphaColor.getRed(), alphaColor.getGreen(), alphaColor.getBlue(), 0);
final Color color4 = new Color(
alphaColor.getRed(), alphaColor.getGreen(), alphaColor.getBlue(), 64);
super.paint(g, c);
Graphics2D g2D = (Graphics2D) g;
GradientPaint gradient1 = new GradientPaint(
0.0F, (float) c.getHeight() / (float) 2, color1, 0.0F, 0.0F, color2);
Rectangle rec1 = new Rectangle(0, 0, c.getWidth(), c.getHeight() / 2);
g2D.setPaint(gradient1);
g2D.fill(rec1);
GradientPaint gradient2 = new GradientPaint(
0.0F, (float) c.getHeight() / (float) 2, color3, 0.0F, c.getHeight(), color4);
Rectangle rec2 = new Rectangle(0, c.getHeight() / 2, c.getWidth(), c.getHeight());
g2D.setPaint(gradient2);
g2D.fill(rec2);
}
#Override
public void paintButtonPressed(Graphics g, AbstractButton b) {
paintText(g, b, b.getBounds(), b.getText());
g.setColor(Color.red.brighter());
g.fillRect(0, 0, b.getSize().width, b.getSize().height);
}
public void paintBorder(Graphics g) {
}
#Override
protected void paintFocus(Graphics g, AbstractButton b,
Rectangle viewRect, Rectangle textRect, Rectangle iconRect) {
}
}

You will have to extend JButton class not AbstractButton. Try the following things and you will get idea.
The first move is to subclass JButton.
Then, in your subclass, start by redefining the paintComponent(Graphics) method. If you want any changes.
Then, override paintBorder(Graphics) to give it a shape of hexagon.

I know this question has been answered, but you might want to look at using the built-in methods, and using images to draw your button in different states.
Here is a bit of code I used to generate a custom button.
BufferedImage startButton = ImageIO.read(getClass().getResource("/icons/standard/buttons/start_backup.png"));
BufferedImage startButtonHover = ImageIO.read(getClass().getResource("/icons/standard/buttons/start_backup_hover.png"));
BufferedImage startButtonActive = ImageIO.read(getClass().getResource("/icons/standard/buttons/start_backup_active.png"));
JButton startBackupButton = new JButton(new ImageIcon(startButton));
startBackupButton.setRolloverIcon(new ImageIcon(startButtonHover));
startBackupButton.setPressedIcon(new ImageIcon(startButtonActive));
startBackupButton.setBorder(BorderFactory.createEmptyBorder());
startBackupButton.setContentAreaFilled(false);
startBackupButton.setFocusable(false);
You can then add an action listener to it as normal.

try a Jlabel and use an image for any shape!!
JLabel lbl = new JLabel("");
lbl.setIcon(new ImageIcon("shape.png"));
lbl.setBounds(548, 11, 66, 20);
contentPane.add(lbl);
lbl.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent arg0) {
System.exit(0);
}
});