Develop Reference

Can't add Graphics into JPanel in Java

I'm writing the UI for the pet project I've been doing and I'm experimenting with java Graphics, drawing lines, shapes, and stuff. And, I've been trying all day to insert a simple line in a Jpanel but still haven't figured out what went wrong.
package thuake;
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.Menu;
import java.awt.MenuBar;
import java.awt.Paint;
import java.awt.Polygon;
import java.awt.geom.Line2D;
import javax.swing.BorderFactory;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
public class Main extends JFrame{
static Dimension DEFAULT_SIZE = new Dimension(530, 320);
static JFrame Frame1 = new JFrame();
static JScrollPane spanel = new JScrollPane();
static JPanel Panel1 = new JPanel();
static MenuBar menu = new MenuBar();
static Menu menusub1 = new Menu("Open");
public static void main(String[] args)
{
start();
}
public static void start (){
Frame1.setLayout(new FlowLayout(FlowLayout.CENTER,5,10));
spanel.add(new draw());
Frame1.add(spanel);
spanel.setBorder(BorderFactory.createLineBorder(Color.black));
spanel.setPreferredSize(new Dimension(500, 500));
Frame1.add(new JButton("ad"));
Frame1.add(new JButton("ad"));
Frame1.add(new JButton("ad"));
Frame1.add(new draw());
Frame1.setMenuBar(menu);
menu.add(menusub1);
Frame1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
Frame1.pack();
spanel.setVisible(true);
Frame1.setVisible(true);
System.out.println();
}
static class draw extends Component {
public void paint(Graphics g) {
Graphics2D line = (Graphics2D)g;
line.drawLine(0, 0, 120, 120);
}
}
}

Here is a basic framework you should follow when you are doing graphics.
Key points are:
Don't extend JFrame, use a separate instance.
Override paintComponent() and not paint()
Start the process in the EDT. Do all swing stuff in the EDT.
Do not paint outside the EDT or with a graphics context that you retrieved yourself. Always use the one from paintComponent()
Set the width and height (dimension) for the panel and not the JFrame. The reason being that those dimensions on the JFrame include the thick borders. For the JPanel you get the full width.
At some point you can modify this and add additional components to the JFrame and/or JPanel. For now this should provde a basis for experimenting.
You should also read up on this and anything I omitted shown below. Check out the Java Tutorials for more on information on graphics and painting.
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Template extends JPanel {
final static int height = 500;
final static int width = 500;
final static String title = "title";
JFrame frame = new JFrame(title);
public static void main(String[] args) {
// start on the EDT
SwingUtilities.invokeLater(() -> new Template().start());
}
public Template() {
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(this); // add the panel
setPreferredSize(new Dimension(width, height));
frame.pack();
// center on screen
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public void paintComponent(Graphics g) {
super.paintComponent(g); // always do this
Graphics2D g2d = (Graphics2D) g.create();
// Optional. It averages the edges of a figure to give a smoothing effect
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
// do something here.
g2d.setColor(Color.red);
g2d.fillRect(200,200,100,100);
g2d.dispose();
}
}

change JProgressBar color [duplicate]

I'm wondering if any of you know how to display a nice looking progress bar in Java, mostly using Swing, although I don't mind using third-party libraries.
I've been looking at JProgressBar tutorials but none of them refer to styling the bar. Reading the API I found a getUI method that returns ProgressBarUI object but I don't see many ways to customize that one.
What I want is to add rounded corners, change background and foreground color, width, lenght, the usual.
Thanks!

If you don't want to replace the user's chosen Look & Feel, you can just replace the UI delegate with one derived from BasicProgressBarUI.
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.RenderingHints;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JProgressBar;
import javax.swing.plaf.basic.BasicProgressBarUI;
/** #see http://stackoverflow.com/questions/8884297 */
public class ProgressBarUITest extends JPanel {
public ProgressBarUITest() {
JProgressBar jpb = new JProgressBar();
jpb.setUI(new MyProgressUI());
jpb.setForeground(Color.blue);
jpb.setIndeterminate(true);
this.add(jpb);
}
private static class MyProgressUI extends BasicProgressBarUI {
private Rectangle r = new Rectangle();
#Override
protected void paintIndeterminate(Graphics g, JComponent c) {
Graphics2D g2d = (Graphics2D) g;
g2d.setRenderingHint(
RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
r = getBox(r);
g.setColor(progressBar.getForeground());
g.fillOval(r.x, r.y, r.width, r.height);
}
}
private void display() {
JFrame f = new JFrame("ProgressBarUITest");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.add(this);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new ProgressBarUITest().display();
}
});
}
}

The easiest way to do that would be to change the LookAndFeel or maybe even create your own class that extends off of one of the default L&Fs and just changes the UI for the progress bar...

JLabel text gets overwritten on transparent bg

Im a newbie to java, Im trying to create an application like a desktop widget for which i have made the JPanel transparent. I have two JLabels on top of it one for holding an image and other for displaying time. I had a timer to update the time displayed in the JLabel. But With a transparent JPanel behind the jlabel's text gets overwritten instead of replacement. After Googling and Looking up on stackoverflow i tried many methods to override the paintcomponent method of the JLabel. But it didnt affect anything. Later I manually called the paintcomponent method inside the timer which worked out. But I feel its just a workaround. I need to know why the paintcomponent didnt get invoked and when it usually gets invoked.
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.GradientPaint;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.Point;
import java.awt.Toolkit;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.RepaintManager;
import javax.swing.SwingConstants;
import javax.swing.text.SimpleAttributeSet;
import java.awt.BorderLayout;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.Timer;
import java.util.TimerTask;
public class WindowSample {
private JFrame frame;
MyLabel panel1;
// JLabel panel1;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
WindowSample window = new WindowSample();
window.frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
/**
* Create the application.
*/
public WindowSample() {
initialize();
}
/**
* Initialize the contents of the frame.
*/
private void initialize() {
frame = new JFrame();
Dimension dim = Toolkit.getDefaultToolkit().getScreenSize();
frame.setSize(dim);
frame.setBounds(0, 0, 500, 500);
frame.setBackground(new Color(0, 255, 0, 0));
frame.setUndecorated(true);
frame.setContentPane(new ContentPane());
frame.getContentPane().setBackground(Color.WHITE);
frame.getContentPane().setLayout(null);
// ImagePanel panel = new ImagePanel();
JLabel panel = new JLabel(
scale(new ImageIcon("Science Drops.png").getImage()));
panel.setBounds(0, 0, 200, 200);
panel1 = new MyLabel();
// panel1 = new JLabel();
panel1.setHorizontalAlignment(SwingConstants.CENTER);
panel1.setAlignmentX(SwingConstants.CENTER);
panel1.setFont(new Font("Calibiri",Font.BOLD,16));
panel1.setBounds(0, 205, 200, 50);
Timer n = new Timer();
panel1.setBackground(Color.white);
n.scheduleAtFixedRate(new TimerTask() {
#Override
public void run() {
DateFormat df = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
// this manual call to paintComponent did the trick. If i remove this line the text gets overwritten over itself for every second.
panel1.paintComponents(panel1.getGraphics());
panel1.setText(df.format(new Date()));
}
}, 1000, 1000);
frame.getContentPane().add(panel1);
frame.getContentPane().add(panel);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
#SuppressWarnings("serial")
public class MyLabel extends JLabel {
MyLabel() {
setOpaque(false);
}
#Override
public void paintComponents(Graphics arg0) {
Graphics2D g2d = (Graphics2D) arg0.create();
g2d.clearRect(0, 0, getWidth(), getHeight());
g2d.dispose();
super.paintComponents(arg0);
}
}
public class ContentPane extends JPanel {
public ContentPane() {
setOpaque(false);
}
#Override
protected void paintComponent(Graphics g) {
Graphics2D g2d = (Graphics2D) g.create();
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.0f));
g2d.setColor(getBackground());
g2d.fill(getBounds());
g2d.dispose();
super.paintComponent(g);
}
}
public ImageIcon scale(Image src) {
int w = 200;
int h = 200;
int type = BufferedImage.TYPE_INT_ARGB;
BufferedImage dst = new BufferedImage(w, h, type);
Graphics2D g2 = dst.createGraphics();
g2.drawImage(src, 0, 0, w, h, frame);
g2.dispose();
return new ImageIcon(dst);
}
}

Read Backgrounds With Transparency for information on how transparency works and for some possible solutions.
Also, some other comments with your code:
Don't use a null layout. Swing was designed to be used with layout managers for to many reasons to list here.
Custom painting is done by overriding paintComponent() (no "s"). However, in your case I don't see any reason to do custom painting if you follow the advice in the link I provided above. I also don't think you need to do custom painting in your panel, but I don't totally understand what you are attempting to do.

Use javax.swing.Timer instead of java.util.Timer. Have a look at this tutorial from oracle about timers and swing.

You seem to be going about it the hard way...
labels are transparent by default.
labels support icons out of the box (include animated gifs ;))
null layouts are never a good idea, they might seem like a good idea, but you will spend more time correcting for funny little inconsistencies which be resolved using an appropriate layout manager...
java.util.Timer is not a suitable timer for Swing, instead you want to use javax.swing.Timer instead. It will trigger it's updates within the context of the EDT.
Based off what I think you want to do...
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.text.DateFormat;
import java.text.SimpleDateFormat;
import java.util.Date;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class MyClock {
public static void main(String[] args) {
new MyClock();
}
public MyClock() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
final DateFormat df = new SimpleDateFormat("dd-MM-yyyy HH:mm:ss");
final JLabel label = new JLabel(df.format(new Date()));
label.setIcon(new ImageIcon("Clock.png"));
Timer timer = new Timer(500, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
label.setText(df.format(new Date()));
}
});
timer.start();
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.setUndecorated(true);
frame.setBackground(new Color(0, 255, 0, 0));
frame.add(label);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
}
Take a look at How to use icons for more details about icon support in Swing.
You may also find Window#alwaysOnTop useful (remember, all frames lead to Window)

I can't believe there is still nobody who answered the right answer. Here's how you get away with this kind of problem :
Apply setOpaque(false) to your components, but also to all the parents.
It will prevent painting problems on your components with transparent backgrounds.

Java own components visually connecting per drag and drop

I'm working on a software solution for a small workflow editor. For this I created an own JPanel with some functionality like deleting itself or editing the main information.
This is how it looks:
The point is, that i need a dynamic connector like a arrow or something like that.
I tried it with drawline but its not dynamic and looks not well. I mean if I move one of the boxes so the drawed line have to change its position too.
The boxes in the big JPanel are movable and resizable. The connection point right and left are JButtons. The structure is that any outgoing connections startes from the right and incomes to the left JButton.
Any ideas how to set it up?
I can't post much of the source code, because the software is for a company.

Did you convert Graphics object to Graphics2D and set the RenderHints? i.e
Graphics2D g2d=(Graphics2D)g;
g2d.setRenderingHint(RenderHints.KEY_ANTIALIASING,RenderHints.VALUE_ANTIALIASING _ON);
This will add some nice anti aliasing effects and might make the line appearance straighter.
Also increasing the stroke width via Graphics2D#setStroke will make the jaggeder edges disappear as its now thicker.
See this example (press, drag and release mouse to create a line):
With g2d.setRenderingHint(..) and g2d.setStroke(..) within paintComponent(..) commented out:
With g2d.setRenderingHint(..) and g2d.setStroke(..) uncommented:
import java.awt.BasicStroke;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.RenderingHints;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Line2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Test {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
Test gui = new Test();
}
});
}
public Test() {
initComponents();
}
private void initComponents() {
JFrame frame = new JFrame("Line Demo");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new MyPanel());
frame.pack();
frame.setVisible(true);
}
}
class MyPanel extends JPanel {
Point point1;
Point point2;
Line2D line2d;
public MyPanel() {
addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent me) {
super.mousePressed(me);
point1 = me.getPoint();
}
});
addMouseMotionListener(new MouseAdapter() {
#Override
public void mouseDragged(MouseEvent me) {
super.mouseDragged(me);
point2 = me.getPoint();
line2d = new Line2D.Double(point1, point2);
repaint();
}
});
}
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
//Set anti-alias!
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
if (point1 != null && point2 != null) {
g2d.setPaint(Color.RED);
g2d.setStroke(new BasicStroke(1.5f));//set stroke size
g2d.draw(line2d);
}
}
}
If above does not help, posting an SSCCE would enable us to test and see what could be at fault/make it better.

How to save window contents as an image

I want to capture the contents of a JPanel as an image so that I can store it exactly as the user sees it. Is there a relatively simple way to do this with swing?

From here http://forums.oracle.com/forums/thread.jspa?threadID=2156176&tstart=0
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class SavePaint extends JPanel
{
public SavePaint()
{
JFrame frame = new JFrame("TheFrame");
frame.add(this);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400,400);
frame.setVisible(true);
try
{
BufferedImage image = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_RGB);
Graphics2D graphics2D = image.createGraphics();
frame.paint(graphics2D);
ImageIO.write(image,"jpeg", new File("/home/deniz/Desktop/jmemPractice.jpeg"));
}
catch(Exception exception)
{
//code
}
}
protected void paintComponent(Graphics g)
{
g.drawRect(50,50,50,50);
}
public static void main(String[] args)
{
new SavePaint();
}
}

Use Robot and public BufferedImage createScreenCapture(Rectangle screenRect). and here is the link how to use it

use new java.awt.Robot().createScreenCapture(screenRect)