Develop Reference

setting background image for JScrollPane

Intro
I created a class ChatView that extends JPanel. I added it as a parameter to my JScrollPane (to get the scrolling effect) and overrode the paintComponent method in hope of setting a background image:
new JScrollPane(new ChatView){
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
ImageIcon background = new ImageIcon("files/background.png");
Image image = background.getImage();
image.getScaledInstance(980, 600, java.awt.Image.SCALE_SMOOTH);
if (image != null)
{
g.drawImage(image,0,0,this.getWidth(),this.getHeight(),null);
}
}
}
problem
This doesn't seem to do anything; however, the same method works on my class ChatView, which extends JPanel. the problem with adding it to my JPanel is that it stretches every time I add a new component that extends outside of the setPrefferredSize() of my JScrollPane; If I do not revalidate() and repaint() my JPanel, it cuts off or doesn't add the components. That's why I think it is necessary to add it to the JScrollPane, but how? or am i on the wrong track?
Code: attributes of my JScrollPane
public void addScroll(JScrollPane pnl, String str, int w, int h){
pnl.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_NEVER);
pnl.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_AS_NEEDED);
pnl.setSize(new Dimension(w, h));
pnl.setMinimumSize(new Dimension(w, h));
pnl.setPreferredSize(new Dimension(w, h));
pnl.getVerticalScrollBar().setUnitIncrement(16);
pnl.setBorder(BorderFactory.createLineBorder(black));
this.add(pnl, str);
}

Static Image behind JTextPane text in JScrollPane
^^link where I found the solution!! Below is a clean cheatsheet :)
JPanel jPanel = new JPanel() {
this.setOpaque(false);
};
JViewport viewport = new JViewport() {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
ImageIcon background = new ImageIcon("images/background.png");
Image image = background.getImage();
image.getScaledInstance(width, height, java.awt.Image.SCALE_SMOOTH);
if (image != null) {
g.drawImage(image, 0, 0, w, h, null);
}
}
};
jScrollPane.setViewport(viewport);
jScrollPane.setViewportView(jPanel);

Draw border below the text of a component in Swing

I've created a custom border class where I fill a rectangle to act as a background for a component. Note that this border will have a more complex shape in the future, not just a simple rectangle.
When I add my border to a component, the text of the component will appear behind the border and make the text unreadable. (The result is depicted in the image below.)
Is there a way to draw the border below the text?
My border class:
public class CustomBorder extends AbstractBorder {
private static final long serialVersionUID = 1L;
#Override
public void paintBorder(Component c, Graphics g, int x, int y, int width, int height) {
Graphics2D g2d = (Graphics2D) g;
g2d.setColor(new Color(125, 125, 125, 255));
g2d.fillRect(x - 10, y - 10, width + 20, height + 20);
}
#Override
public Insets getBorderInsets(Component c) {
return super.getBorderInsets(c);
}
#Override
public Insets getBorderInsets(Component c, Insets insets) {
return super.getBorderInsets(c, insets);
}
#Override
public boolean isBorderOpaque() {
return super.isBorderOpaque();
}
}
Main:
public static void main(String[] args) {
JLabel label = new JLabel("JLabel text");
label.setBorder(new CompoundBorder(new EmptyBorder(50, 20, 20, 20), new CustomBorder()));
JFrame frame = new JFrame("");
frame.setLayout(new FlowLayout());
frame.setSize(200, 200);
frame.add(label);
frame.setVisible(true);
}
Edit: I should also note that I will be using this border to a chat program, which will be using bubble-shaped messages, so a colored square using setBackground() is a no-no.

See A Closer Look at the Paint Mechanism which explains how the painting is done. The border is painted after the text of the label is painted.
What exactly are you trying to do? Your border painting code doesn't make sense. You are trying to fill a rectangle equal to the width/height of the component + 20 pixels, which means you are trying to paint an area larger than the component.
If you are just trying to paint a background on a label then you can use:
label.setOpaque( true );
label.setBackground(...);
Edit: The code in this answer that was linked in the comment section below solved the problem.

You could always use g2d.drawString().
However, if that is not to be utilised for some reason, you could just do:
JLabel l = new JLabel("foo");
l.setBackground(Color.GRAY);
l.setOpaque(true);

JTextArea not selectable, but still showing a "ghost" cursor

I put a JTextArea in a JPanel. This JPanel has a picture on the background, and the JTextArea is translucent (translucid red) to show the background through. I don't want the user to be able to edit or select the text, I want it to act just as a JLabel (but with multiple lines and easy to word wrap and adjust to screen resize).
I tried all these options:
text.setEditable(false);
text.setFocusable(false);
text.setEnabled(false);
text.setHighlighter(null);
but still some change of color happens as the user drags the mouse over the JTextArea. Anyone knows what is going on?

You can't simply set the background color of a component to "transparent" and expect Swing to deal with it. You need to flag the component as transparent (setOpaque(false)), only then will Swing's repaint manager know that it has to update the components under it.
This then leads you to the problem of how to paint the background (as Swing only has the concept of fully opaque or fully transparent).
To do this, you need to supply your own paint routines (override paintComponent, fill the background, update the component)...this is essentially what Rob Camick's solution is doing, it just provides a nice wrapper component for you...
Below is an example of using a JLabel using text wrapped in HTML and a JTextArea, both updated to support "translucency"...
Using a JLabel
Using a JTextArea
Now, it would be a lot easier to achieve using Rob's wrapper class, but this provides you with the idea of what is going wrong and what you would need to do to fix it.
public class MultiLineLabel {
public static void main(String[] args) {
new MultiLineLabel();
}
public MultiLineLabel() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new BackgroundPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TransclucentLabel extends JLabel {
public TransclucentLabel(String text) {
super(text);
setVerticalAlignment(TOP);
}
#Override
protected void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
Insets insets = getInsets();
int x = insets.left;
int y = insets.top;
int width = getWidth() - (insets.left + insets.right);
int height = getHeight() - (insets.top + insets.bottom);
g2d.setColor(new Color(255, 0, 0, 128));
g2d.fillRect(x, y, width, height);
super.paintComponent(g);
}
}
public class TransclucentTextArea extends JTextArea {
public TransclucentTextArea(String text) {
super(text);
setOpaque(false);
setLineWrap(true);
setWrapStyleWord(true);
}
#Override
protected void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D) g;
Insets insets = getInsets();
int x = insets.left;
int y = insets.top;
int width = getWidth() - (insets.left + insets.right);
int height = getHeight() - (insets.top + insets.bottom);
g2d.setColor(new Color(255, 0, 0, 128));
g2d.fillRect(x, y, width, height);
super.paintComponent(g);
}
}
public class BackgroundPane extends JPanel {
private BufferedImage background;
public BackgroundPane() {
setLayout(new BorderLayout());
// addLabel();
addTextArea();
setBorder(new EmptyBorder(24, 24, 24, 24));
try {
background = ImageIO.read(new File("/path/to/your/image"));
} catch (IOException ex) {
ex.printStackTrace();
}
}
protected void addTextArea() {
StringBuilder sb = new StringBuilder(128);
sb.append("I put a JTextArea in a JPanel. This JPanel has a picture on the background, and the JTextArea is translucent (translucid red) to show the background through. I don't want the user to be able to edit or select the text, I want it to act just as a JLabel (but with multiple lines and easy to word wrap and adjust to screen resize).\n\n");
sb.append("I tried all these options:\n\n");
sb.append("text.setEditable(false);\n");
sb.append("text.setFocusable(false);\n");
sb.append("text.setEnabled(false);\n");
sb.append("text.setHighlighter(null);\n\n");
sb.append("but still some change of color happens as the user drags the mouse over the JTextArea. Anyone knows what is going on?\n");
add(new TransclucentTextArea(sb.toString()));
}
protected void addLabel() {
StringBuilder sb = new StringBuilder(128);
sb.append("<html>");
sb.append("<p>I put a JTextArea in a JPanel. This JPanel has a picture on the background, and the JTextArea is translucent (translucid red) to show the background through. I don't want the user to be able to edit or select the text, I want it to act just as a JLabel (but with multiple lines and easy to word wrap and adjust to screen resize).</p><br>");
sb.append("<p>I tried all these options:</p><br>");
sb.append("<p>text.setEditable(false);<br>");
sb.append("text.setFocusable(false);<br>");
sb.append("text.setEnabled(false);<br>");
sb.append("text.setHighlighter(null);</p><br>");
sb.append("<p>but still some change of color happens as the user drags the mouse over the JTextArea. Anyone knows what is going on?</p>");
add(new TransclucentLabel(sb.toString()));
}
#Override
public Dimension getPreferredSize() {
return background == null ? super.getPreferredSize() : new Dimension(background.getWidth(), background.getHeight());
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (background != null) {
int x = (getWidth() - background.getWidth()) / 2;
int y = (getHeight() - background.getHeight()) / 2;
g.drawImage(background, x, y, this);
}
}
}
}

Problems with setting JPanel's colour

Here's my canvas class extending JPanel:
package start;
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JPanel;
public class Board extends JPanel
{
private static final long serialVersionUID = 1L;
public Board() {}
public void paintComponent(Graphics g)
{
int width = getWidth();
int height = getHeight();
this.setBackground(Color.green);
g.setColor(Color.black);
g.drawOval(0, 0, width, height);
}
}
Here's the method where I'm calling it:
private static void createAndShowGUI()
{
JFrame frame = new JFrame("Hello");
frame.setPreferredSize(new Dimension(700, 700));
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Board b = new Board();
frame.getContentPane().add(b);
frame.pack();
frame.setVisible(true);
}
But this shows the oval on the default colour. I also tried without the this., and then tried setting the colour of b, and setting the colour inside the constructor, but none of these worked. What's wrong?
EDIT: Sorry for not making thing clear, my goal was to display a thin black oval on a green background.

In the paintComponent method you do not have to use setBackground to change the colour of the JPanel. That should be done outside of paintComponent. paintComponent will probably use the colour of the background before you change it.
There are a number of things you can try. One, is to set the colour in the constructor and then call the super class' paintComponent first like this:
public Board() {
this.setBackground(Color.GREEN);
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
int width = getWidth();
int height = getHeight();
g.setColor(Color.BLACK);
g.drawOval(0, 0, width, height);
}
Also note the color constants are all upper case. i.e. BLACK or GREEN.
If you want to change the background colour dynamically then you can do so in the event handler such as mouseEntered or actionPerformed etc.

While the code does not exactly make clear what's your intent i try to fix some issues:
If you want a green background, do as #vincent told you. YOu should see a black oval in green background. The "super.paintComponent" will fill its area with the components background automatically if the panel is opaque.
If you want a green oval on white background, maybe with black border
public void paintComponent(Graphics g)
{
int width = getWidth();
int height = getHeight();
super.paintComponent(g);
g.setColor(Color.GREEN);
g.fillOval(0, 0, width, height);
g.setColor(Color.BLACK);
g.drawOval(0, 0, width, height);
}
EDIT
i forgot super

Make a button round

I'm trying to make a JButton round at the (x,y) coordinates of (150,210). I want the button to be an oval of the size (40,40). And the buttons background color red. It doesn't need text, so I should get a button to whatever size I want, right?
I am using a panel, and I set the setLayout to null:
setLayout(null)
I checked Google, and it brought me here. How can I do this?

JDC Tech Tips: August 26, 1999: Creating Round Swing Buttons
import java.awt.*;
import java.awt.geom.*;
import javax.swing.*;
public class RoundButton extends JButton {
public RoundButton(String label) {
super(label);
// These statements enlarge the button so that it
// becomes a circle rather than an oval.
Dimension size = getPreferredSize();
size.width = size.height = Math.max(size.width,
size.height);
setPreferredSize(size);
// This call causes the JButton not to paint
// the background.
// This allows us to paint a round background.
setContentAreaFilled(false);
}
// Paint the round background and label.
protected void paintComponent(Graphics g) {
if (getModel().isArmed()) {
// You might want to make the highlight color
// a property of the RoundButton class.
g.setColor(Color.lightGray);
} else {
g.setColor(getBackground());
}
g.fillOval(0, 0, getSize().width-1,
getSize().height-1);
// This call will paint the label and the
// focus rectangle.
super.paintComponent(g);
}
// Paint the border of the button using a simple stroke.
protected void paintBorder(Graphics g) {
g.setColor(getForeground());
g.drawOval(0, 0, getSize().width-1,
getSize().height-1);
}
// Hit detection.
Shape shape;
public boolean contains(int x, int y) {
// If the button has changed size,
// make a new shape object.
if (shape == null ||
!shape.getBounds().equals(getBounds())) {
shape = new Ellipse2D.Float(0, 0,
getWidth(), getHeight());
}
return shape.contains(x, y);
}
// Test routine.
public static void main(String[] args) {
// Create a button with the label "Jackpot".
JButton button = new RoundButton("Jackpot");
button.setBackground(Color.green);
// Create a frame in which to show the button.
JFrame frame = new JFrame();
frame.getContentPane().setBackground(Color.yellow);
frame.getContentPane().add(button);
frame.getContentPane().setLayout(new FlowLayout());
frame.setSize(150, 150);
frame.setVisible(true);
}
}