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Background image for a jPanel not working

I am new to making GUIs so I decided to try the the windows builder for eclipse, and while great I do have some doubts. I have been searching but I cannot seen to find a good way to add a background image to my "menu". For example I tried this:
public Menu() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setBounds(50, 50, 300, 250); //Dimensiones
contentPane = new JPanel() { //Imagen de Fondo
public void paintComponent(Graphics g) {
Image img = Toolkit.getDefaultToolkit().getImage(
Menu.class.getResource("/imgs/rotom.jpg"));
g.drawImage(img, 0, 0, this.getWidth(), this.getHeight(), this);
}
};
And adding the following classes:
import java.awt.Graphics;
import java.awt.Image;
import java.awt.Toolkit;
But to no avail the window remains with its dull grey color, so far my code is just the standard one WindowsBuilder cooks for you plus 4 buttons but I doubt they're of importance here. Shouldn't the code I added override the paintComponent() method of the jPanel and draw the image in it?
The class for the menu is in a package within my project and the image is within a imgs package is within the same project as well.
Thanks a lot in advance.

A simple method, if you're not interested in resizing the background image or applying any effects is to use a JLabel...
BufferedImage bg = ImageIO.read(Menu.class.getResource("/imgs/rotom.jpg"));
JLabel label = new JLabel(new ImageIcon(bg));
setContentPane(label);
setLayout(...);
There are limitations to this approach (beyond scaling), in that the preferred size of the label will always be that of the image and never take into account it's content. This is both good and bad.
The other approach, which you seem to be using, is to use a specialised component
public class BackgroundPane extends JPanel {
private BufferedImage img;
public BackgroundPane(BufferedImage img) {
this.img = img;
}
#Override
public Dimension getPreferredSize() {
return img == null ? super.getPreferredSize() : new Dimension(img.getWidth(), img.getHeight());
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(img, 0, 0, this);
}
}
You should avoid trying to perform any task in the paintComponent method which may take time to complete as paintComponent may be called often and usually in quick succession....
Getting the image to scale when the component is resized is an entire question into of it self, for some ideas, you could take a look at...
Java: maintaining aspect ratio of JPanel background image
Java: JPanel background not scaling
Quality of Image after resize very low -- Java
Reading/Loading images
Oh, and, you should avoid extending directly from top level containers, like JFrame, they reduce the reusability for your components and lock you into a single container

Drawing a Component to BufferedImage causes display corruption

I am using the JScrollNavigator component described here, in order to provide a navigation window onto a large "canvas-like" CAD component I have embedded within a JScrollPane.
I have tried to adapt the JScrollNavigator to draw a thumbnail image of the canvas to provide some additional context to the user. However, the action of doing this causes the rendering of my application's main frame to become corrupted. Specifically, it is the action of calling paint(Graphics) on the viewport component (i.e. my main canvas), passing in the Graphics object created by the BufferedImage that causes subsequent display corruption; if I comment this line out everything works fine.
Below is the JScrollNavigator's overridden paintComponent method:
#Override
protected void paintComponent(Graphics g) {
Component view = jScrollPane.getViewport().getView();
BufferedImage img = new BufferedImage(view.getWidth(), view.getHeight(), BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = img.createGraphics();
// Paint JScrollPane view to off-screen image and then scale.
// It is this action that causes the display corruption!
view.paint(g2d);
g2d.drawImage(img, 0, 0, null);
Image scaled = img.getScaledInstance(getWidth(), getHeight(), 0);
super.paintComponent(g);
g.drawImage(scaled, 0, 0, null);
}
Does anyone have any suggestions as to the cause of the corruption? I would have thought that painting to an offscreen image should have no effect on existing paint operations.
EDIT
To provide some additional detail: The JScrollNavigator forms a sub-panel on the left-hand side of a JSplitPane. The JScrollPane associated with the navigator is on the right-hand side. The "corruption" causes the splitter to no longer be rendered and the scrollbars to not be visible (they appear white). If I resize the JFrame, the JMenu section also becomes white. If I attempt to use the navigator or interact with the scrollbars, they become visible, but the splitter remains white. It's as if the opaque settings of the various components has been affected by the rendering of the viewport view to an offscreen image.
Also, if I make the JScrollNavigator appear in a completely separate JDialog, everything works correctly.
EDIT 2
I can reproduce the problem consistently by doing the following:
Add a JMenuBar to the mFrame:
JMenuBar bar = new JMenuBar();
bar.add(new JMenu("File"));
mFrame.setJMenuBar(bar);
In the main() method of JScrollNavigator replace:
jsp.setViewportView(textArea);
... with:
jsp.setViewportView(new JPanel() {
{
setBackground(Color.GREEN);
setBorder(BorderFactory.createLineBorder(Color.BLACK, 5));
}
});
Ensure that the JScrollNavigator is embedded as a panel within mFrame, rather than appearing as a separate JDialog:
mFrame.add(jsp, BorderLayout.CENTER);
mFrame.add(nav, BorderLayout.NORTH);
Now when the application runs the JMenuBar is no longer visible; the act of painting the view (i.e. a green JPanel with thick black border) to the Graphics2D returned by BufferedImage.createGraphics() actually appears to be rendering it onscreen, possibly from the top-left corner of the JFrame, thus obscuring other components. This only seems to happen if a JPanel is used as the viewport view, and not another component such as JTextArea, JTable, etc.
EDIT 3
Looks like this person was having the same problem (no solution posted though): http://www.javaworld.com/community/node/2894/
EDIT 4
Here's the main and paintComponent methods that result in the reproducible error described in Edit 2:
public static void main(String[] args) {
JScrollPane jsp = new JScrollPane();
jsp.setViewportView(new JPanel() {
{
setBackground(Color.GREEN);
setBorder(BorderFactory.createLineBorder(Color.BLACK, 5));
}
});
JScrollNavigator nav = new JScrollNavigator();
nav.setJScrollPane(jsp);
JFrame mFrame = new JFrame();
JMenuBar bar = new JMenuBar();
bar.add(new JMenu("File"));
mFrame.setJMenuBar(bar);
mFrame.setTitle("JScrollNavigator Test");
mFrame.setSize(800, 600);
mFrame.setLayout(new GridLayout(1, 2));
mFrame.add(jsp);
mFrame.add(nav);
Dimension screenDim = Toolkit.getDefaultToolkit().getScreenSize();
mFrame.setLocation((screenDim.width - mFrame.getSize().width) / 2, (screenDim.height - mFrame.getSize().height) / 2);
mFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
mFrame.setVisible(true);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Component view = jScrollPane.getViewport().getView();
if (img == null) {
GraphicsConfiguration gfConf = GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice().getDefaultConfiguration();
img = new BufferedImage(view.getWidth(), view.getHeight(), BufferedImage.TYPE_INT_ARGB);
}
Graphics2D g2d = img.createGraphics();
view.paint(g2d);
Image scaled = img.getScaledInstance(getWidth(), getHeight(), 0);
g.drawImage(scaled, 0, 0, null);
}
EDIT 5
It seems like others are having trouble recreating the exact problem. I would ask people to run the code pasted here. When I first run this example I see the following:
Neither the JScrollNavigator or the JMenuBar have been painted; these frame areas are transparent.
After resizing I see the following:
The JMenuBar has still not been painted and it appears that the JPanel was at some point rendered at (0,0) (where the JMenuBar should be). The view.paint call within paintComponent is the direct cause of this.

Summary: The original JScrollNavigator uses the Swing opacity property to render a convenient green NavBox over a scaled thumbnail of the component in an adjacent JScrollPane. Because it extends JPanel, the (shared) UI delegate's use of opacity conflicts with that of the scrollable component. The images seen in edit 5 above typify the associated rendering artifact, also shown here. The solution is to let NavBox, JScrollNavigator and the scrollable component extend JComponent, as suggested in the second addendum below. Each component can then manage it's own properties individually.
I see no unusual rendering artifact with your code as posted on my platform, Mac OS X, Java 1.6. Sorry, I don't see any glaring portability violations.
A few probably irrelevant, but perhaps useful, observations.
Even if you use setSize(), appropriately in this case, you should still pack() the enclosing Window.
f.pack();
f.setSize(300, 200);
For convenience, add() forwards the component to the content pane.
f.add(nav, BorderLayout.WEST);
Prefer StringBuilder to StringBuffer.
Consider ComponentAdapter in place of ComponentListener.
Addendum: As suggested here, I got somewhat more flexible results using RenderingHints instead of getScaledInstance() as shown below. Adding a few icons makes it easier to see the disparate effect on images and text.
editPane.insertIcon(UIManager.getIcon("OptionPane.errorIcon"));
editPane.insertIcon(UIManager.getIcon("OptionPane.warningIcon"));
...
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Component view = jScrollPane.getViewport().getView();
BufferedImage img = new BufferedImage(view.getWidth(),
view.getHeight(), BufferedImage.TYPE_INT_ARGB);
Graphics2D off = img.createGraphics();
off.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
off.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BICUBIC);
view.paint(off);
Graphics2D on = (Graphics2D)g;
on.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
on.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BICUBIC);
on.drawImage(img, 0, 0, getWidth(), getHeight(), null);
}
Addendum secundum: It looks like the JPanel UI delegate is not cooperating. One workaround is to extend JComponent so that you can control opacity. It's only slightly more work to manage the backgroundColor. NavBox and JScrollNavigator are also candidates for a similar treatment.
jsp.setViewportView(new JComponent() {
{
setBackground(Color.red);
setBorder(BorderFactory.createLineBorder(Color.BLACK, 16));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(getBackground());
g.fillRect(0, 0, getWidth(), getHeight());
}
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
});

I am also not sure what you mean by corruption, but I noticed that the resampled image is much nicer if you specify Image.SCALE_SMOOTH as the rescaling hint:
Image scaled = img.getScaledInstance(getWidth(), getHeight(), Image.SCALE_SMOOTH);
Maybe this is what you are looking for...

I was able to reproduce your problem and get you the result your looking for. The problem is that the drawing of the image wasn't complete by the time you were repainting again, so only portions of the image were being painted. To fix this, add this field to your JScrollNavigator class (as a lock):
/** Lock to prevent trying to repaint too many times */
private boolean blockRepaint = false;
When we repaint the component, this lock will be activated. It won't be released until we have been able to successfully paint the panel - then another paint can be executed.
The paintComponent needs to be changed to abide by the lock and use a ImageObserver when painting your navigation panel.
#Override
protected void paintComponent(final Graphics g) {
super.paintComponent(g);
if(!blockRepaint){
final Component view = (Component)jScrollPane.getViewport().getView();
BufferedImage img = new BufferedImage(view.getWidth(), view.getHeight(), BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = img.createGraphics();
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
// Paint JScrollPane view to off-screen image and then scale.
// It is this action that causes the display corruption!
view.paint(g2d);
ImageObserver io = new ImageObserver() {
#Override
public boolean imageUpdate(Image img, int infoflags, int x, int y,int width, int height) {
boolean result = true;
g.drawImage(img, 0, 0, null);
if((infoflags & ImageObserver.FRAMEBITS) == ImageObserver.FRAMEBITS){
blockRepaint = false;
result = false;
}
return result;
}
};
Image scaled = img.getScaledInstance(getWidth(), getHeight(), 0);
blockRepaint = g.drawImage(scaled, 0, 0, io);
}
}

draw buffered image ontop of another buffered image

my goal is to draw some bufferedimage onto another. then all this stuff draw onto some other bufferedimage and so on. And finally draw this on top of a panel.
For now i'm trying to draw bufferedimage onto panel and nothing works. My bufferedimage looks completely white:
public class Main2 {
public static void main(String[] args) {
JFrame frame = new JFrame("asdf");
final JPanel panel = (JPanel) frame.getContentPane();
frame.setSize(500,500);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
panel.addMouseListener(new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
somepaint(panel);
}
});
}
private static void somepaint(JPanel panel) {
BufferedImage image = new BufferedImage(200,200,BufferedImage.TYPE_INT_ARGB);
image.getGraphics().setColor(Color.red);
image.getGraphics().fillRect(0, 0, 200, 200);
Graphics2D graphics = (Graphics2D) panel.getGraphics();
graphics.setColor(Color.magenta);
graphics.fillRect(0, 0, 500, 500);
graphics.drawImage(image, null, 0, 0); // draws white square instead of red one
}
}
thanks

Re:
private static void somepaint(JPanel panel) {
BufferedImage image = new BufferedImage(200,200,BufferedImage.TYPE_INT_ARGB);
image.getGraphics().setColor(Color.red);
image.getGraphics().fillRect(0, 0, 200, 200);
Graphics2D graphics = (Graphics2D) panel.getGraphics();
This is not how you draw inside of a JPanel or JComponent.
Don't call getGraphics() on a component as the Graphics object returned will be short-lived, and anything drawn with it will not persist. Instead do your JPanel's drawing inside of its paintComponent(Graphics G) method override. You will need to create a class that extends JPanel in order to override paintComponent(...).
Most importantly, to see how to do Swing graphics correctly, don't guess. You'll want to read the Swing Graphics Tutorials first as it will require you to toss out some incorrect assumptions (I know that this is what I had to do to get it right).

You need to rectify your parameters in the drawImage() call. Change this:
graphics.drawImage(image, null, 0, 0);
to
graphics.drawImage(image, 0, 0,null);
Check the Java docs for more details.

JOptionPane background Image

How to set background Image of JOptionPane? I want to show a different image on background of an JOptionPane.

You could extend the JOptionPane class and override the paint method.
Edit:
Depending on the image resolution and quality you might be able to stretch it with an AffineTransform during the WindowResize events without to much distortion. This would let you handle the JOptionPane and image size discrepancies mentioned below.
class ImageBackgroundPane extends JOptionPane
{
private BufferedImage img;
public ImageBackgroundPane (BufferedImage image)
{
this.img = image;
}
#Override
public void paint(Graphics g)
{
//Pick one of the two painting methods below.
//Option 1:
//Define the bounding region to paint based on image size.
//Be careful, if the image is smaller than the JOptionPane size you
//will see a solid white background where the image does not reach.
g.drawImage(img, 0, 0, img.getWidth(), img.getHeight());
//Option 2:
//If the image can be guaranteed to be larger than the JOptionPane's size
Dimension curSize = this.getSize();
g.drawImage(img, 0, 0, curSize.width, curSize.height, null);
//Make sure to paint all the other properties of Swing components.
super.paint(g);
}
}

Background Image in JTextPane

How do I set a background image to a JTextPane - some sort of a watermark.
I tried this option - creating a child class of JTextPane and use the paint method to draw the image.
But then the text is displayed "below" the image than above.
Is there any "standard" or "well known" way to do this?
(BTW, I tried (something silly?) making the content type "text/html", and setting the image as the background image of a <div> but it did not help.)

Here's a working example:
import javax.swing.*;
import java.awt.*;
public class ScratchSpace {
public static void main(String[] args) {
JFrame frame = new JFrame("");
final MyTextPane textPane = new MyTextPane();
frame.add(textPane);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private static class MyTextPane extends JTextPane {
public MyTextPane() {
super();
setText("Hello World");
setOpaque(false);
// this is needed if using Nimbus L&F - see http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6687960
setBackground(new Color(0,0,0,0));
}
#Override
protected void paintComponent(Graphics g) {
// set background green - but can draw image here too
g.setColor(Color.GREEN);
g.fillRect(0, 0, getWidth(), getHeight());
// uncomment the following to draw an image
// Image img = ...;
// g.drawImage(img, 0, 0, this);
super.paintComponent(g);
}
}
}
The important things to note:
your component must not be opaque...
so setOpaque(false);
override paintComponent(Graphics g), not paint.
paint your background, with an image
or drawing BEFORE calling
super.paintComponent(g);
If you want to master this stuff, I recommend reading "Filthy Rich Clients", a book all about how to bend Swing to your will.

Try changing the paint code to this.
public void paint(Graphics g)
{
g.setXORMode(Color.white);
g.drawImage(image,0, 0, this);
super.paint(g);
}
This would make your image to be painted before the text is rendered by the actual component's paint method.

Hmm., put a background image to the JFrame/JPanel containg the JTextPane,.. and keep the JTextPane transparent to some level.