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Java Drawing to a JPanel (debugging)

I'm trying to draw a basic object to a JPanel
although it doesn't seem to be working.
I'm certain I am doing something wrong with where the paint method
is being called
import javax.swing.*;
import java.awt.*;
import java.awt.image.*;
public class testGui {
static colors gc_colors;
static gui gc_gui;
public static void main(String[] args) {
gc_colors = new colors();
gc_gui = new gui();
gc_gui.cv_frame.setVisible(true);
}
public static class colors {
Color cv_ltGrey;
Color cv_mdGrey;
Color cv_dkGrey;
public colors() {
cv_ltGrey = Color.decode("#DDDDDD");
cv_mdGrey = Color.decode("#CCCCCC");
cv_dkGrey = Color.decode("#111111");
}
}
public static class gui {
JFrame cv_frame;
JPanel cv_panel;
JPanel cv_content;
public gui() {
cv_frame = new JFrame();
cv_frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
cv_frame.setTitle("Test GUI");
cv_frame.setSize(600, 400);
cv_frame.setLayout(new FlowLayout());
cv_panel = new JPanel();
cv_panel.setBackground(gc_colors.cv_ltGrey);
cv_panel.setPreferredSize(new Dimension(500, 300));
cv_frame.add(cv_panel);
cv_content = new content();
cv_panel.add(cv_content);
}
}
public static class content extends JPanel {
public void paint(Graphics graphic) {
super.paint(graphic);
draw(graphic);
}
public void update() {
repaint();
}
public void draw(Graphics graphic) {
Graphics2D graphic2D = (Graphics2D) graphic;
graphic2D.setPaint(gc_colors.cv_ltGrey);
graphic2D.fillRect(10, 10, 100, 100);
}
}
}
I have a class for my gui which I am adding a JPanel to (a light grey one).
Which I am then trying to add my drawing to using a JPanel extended class
called content.
When I run it though it seems to create the grey JPanel which I want but
the drawing is just a tiny white square and I'm not sure why.

So, you content panel has a default preferred size of 0x0, FlowLayout honours the preferredSize of its components (with a little margin), hence the reason why you have a nice little small white rectangle.
What you need to do is override the getPreferredSize method of the content panel and return a suitable size, for example
public static class content extends JPanel {
#Override
public Dimension getPreferredSize() {
return new Dimension(120, 120);
}
public void paint(Graphics graphic) {
super.paint(graphic);
draw(graphic);
}
public void update() {
repaint();
}
public void draw(Graphics graphic) {
Graphics2D graphic2D = (Graphics2D) graphic;
graphic2D.setPaint(gc_colors.cv_ltGrey);
graphic2D.fillRect(10, 10, 100, 100);
}
}

I've decided to just leave out the second JPanel altogether.
It was too much of a hassle to put the JPanel inside of another JPanel
so instead I am only going to use a single JPanel
public static class gui {
JFrame cv_frame;
JPanel cv_panel;
JPanel cv_content;
public gui() {
cv_frame = new JFrame();
cv_frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
cv_frame.setTitle("Test GUI");
cv_frame.setSize(600, 400);
cv_frame.setLayout(new FlowLayout());
cv_content = new content();
cv_content.setBackground(gc_colors.cv_ltGrey);
cv_content.setPreferredSize(new Dimension(500, 300));
cv_frame.add(cv_content);
}
}

Drawing Captured Screen Image in JPanel ,Image is displayed one more time ?How can I fix it to be display one timw?

I Want to capture Image from screen and draw it in JPanel , it works but it is displayed one more time like entering in a loop , I am confused by this , How can I fix it ,Please?
Varibles Iwidth,Ihieght ares above initiaized, but I take the block of code that cause the problem
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
Image img;
ImageIcon i = null;
Rectangle screenRect=new Rectangle(Toolkit.getDefaultToolkit().getScreenSize());
try {
BufferedImage capture=new Robot().createScreenCapture(screenRect);
capture.getHeight();
capture.getWidth();
i=new ImageIcon(capture);
} catch (AWTException ex) {
Logger.getLogger(TestDrawing.class.getName()).log(Level.SEVERE, null, ex);
}
img = i.getImage();
g.drawImage(img,Iwidth,Ihieght,null);
super.repaint();
}

Never have code like that inside of paintComponent. That method should be reserved for painting and painting only, and is a method that you don't really have full control over since it is called by the JVM in response to both your request, and to requests from the OS, and even if you request a repaint, there's no guarantee that it will be complied with, especially if the requests are stacking up. Also, your GUI's perceived responsiveness will often depend on how quick painting is done, which is while file reading and image capturing should never be done inside of paintComponent.
Instead, you should read the image in as a reaction to some event, perhaps a Timer, then after the image is read, call repaint() and in paintComponent draw the obtained image.
Never call repaint() inside of paintComponent either.
Something like in pseudo code
// inside of the ActionListener of a Swing Timer (if you want to do this repeatedly)
get screen image from robot and feed it into the capture BufferedImage field
consider doing this in a SwingWorker
call repaint() when SwingWorker is done (via a PropertyChangeListener)
Inside of paintComponent:
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (capture != null) {
g.drawImage(capture, capture.getWidth(), capture.getHeight());
}
}
Edit
For example:
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.image.BufferedImage;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.concurrent.ExecutionException;
import javax.swing.*;
import javax.swing.SwingWorker.StateValue;
public class ScreenCaptureTest extends JPanel {
private static final int PREF_W = 600;
private static final int PREF_H = 400;
private JButton btn = new JButton(new ScreenCaptureAction(this,
"Capture Screen", KeyEvent.VK_C));
private ImagePanel imagePanel = new ImagePanel();
public ScreenCaptureTest() {
JPanel buttonPanel = new JPanel();
buttonPanel.add(btn);
setLayout(new BorderLayout());
add(new JScrollPane(imagePanel), BorderLayout.CENTER);
add(buttonPanel, BorderLayout.SOUTH);
}
public void setImagePanelImage(BufferedImage img) {
imagePanel.setImage(img);
revalidate();
repaint();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
private static void createAndShowGui() {
ScreenCaptureTest mainPanel = new ScreenCaptureTest();
JFrame frame = new JFrame("ScreenCaptureTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class ImagePanel extends JPanel {
private BufferedImage image;
public void setImage(BufferedImage image) {
this.image = image;
revalidate();
repaint();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (image != null) {
g.drawImage(image, 0, 0, null);
}
}
#Override
public Dimension getPreferredSize() {
if (image != null) {
return new Dimension(image.getWidth(), image.getHeight());
}
return super.getPreferredSize();
}
}
class ScreenCaptureAction extends AbstractAction {
private ScreenCaptureTest screenCaptureTest;
public ScreenCaptureAction(ScreenCaptureTest screenCaptureTest, String name,
int mnemonic) {
super(name);
putValue(MNEMONIC_KEY, mnemonic);
this.screenCaptureTest = screenCaptureTest;
}
#Override
public void actionPerformed(ActionEvent e) {
setEnabled(false);
final SwingWorker<BufferedImage, Void> mySwingWorker = new SwingWorker<BufferedImage, Void>() {
#Override
protected BufferedImage doInBackground() throws Exception {
Toolkit toolkit = Toolkit.getDefaultToolkit();
Dimension screenSize = toolkit.getScreenSize();
Robot robot = new Robot();
BufferedImage capture = robot.createScreenCapture(new Rectangle(
screenSize));
return capture;
}
};
mySwingWorker.addPropertyChangeListener(new PropertyChangeListener() {
#Override
public void propertyChange(PropertyChangeEvent pcEvt) {
if ("state".equals(pcEvt.getPropertyName())
&& pcEvt.getNewValue() == StateValue.DONE) {
setEnabled(true);
try {
screenCaptureTest.setImagePanelImage(mySwingWorker.get());
} catch (InterruptedException | ExecutionException e) {
e.printStackTrace();
}
}
}
});
mySwingWorker.execute();
}
}
Edit
Note, that if this were my program, I'd display the image as an ImageIcon in a JLabel as it is much simpler to code. Then you could do away with the ImagePanel class and its paintComponent method, and simply code the main as:
public class ScreenCaptureTest extends JPanel {
private static final int PREF_W = 600;
private static final int PREF_H = 400;
private JButton btn = new JButton(new ScreenCaptureAction(this,
"Capture Screen", KeyEvent.VK_C));
//!! private ImagePanel imagePanel = new ImagePanel();
private JLabel screenLabel = new JLabel(); //!!
public ScreenCaptureTest() {
JPanel buttonPanel = new JPanel();
buttonPanel.add(btn);
setLayout(new BorderLayout());
//!! add(new JScrollPane(imagePanel), BorderLayout.CENTER);
add(new JScrollPane(screenLabel), BorderLayout.CENTER); //!!
add(buttonPanel, BorderLayout.SOUTH);
}
public void setImagePanelImage(BufferedImage img) {
//!! imagePanel.setImage(img);
Icon icon = new ImageIcon(img);
screenLabel.setIcon(icon);
//!! revalidate();
//!! repaint();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
private static void createAndShowGui() {
ScreenCaptureTest mainPanel = new ScreenCaptureTest();
JFrame frame = new JFrame("ScreenCaptureTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}

What is the proper way to swap out an existing JPanel in a JFrame with another?

I'm building a program that requires swapping out the current, visible JPanel with another. Unfortunately there seems to be multiple to go about this and all of my attempts have ended in failure. I can successfully get the first JPanel to appear in my JFrame, but swapping JPanels results in a blank JFrame.
My Main JFrame:
public class ShellFrame {
static CardLayout cl = new CardLayout(); //handles panel switching
static JFrame frame; //init swing on EDT
static MainMenu mm;
static Panel2 p2;
static Panel3 p3;
public static void main(String[] args) {
initFrame();
}
public static void initFrame() {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
frame = new JFrame();
frame.setDefaultCloseOperation(3);
frame.setLayout(cl);
mm = new MainMenu();
pp = new PlacementPanel();
//first panel added to frame will always show first
frame.add(mm, "MainMenu");
frame.pack(); //sizes frame to fit the panel being shown
frame.setVisible(true);
}
});
}
public static void switchPanel(String name) {
cl.show(frame.getContentPane(), name);
frame.pack();
}
public static void updatePanel2(/* args */) {
frame.removeAll();
p2 = new Panel2(/* args */);
frame.add(pp, "PlacementPanel");
frame.pack();
frame.validate();
frame.repaint();
}
I'm trying to use updatePanel2 to swap out the existing panel with a new Panel2 but It doesn't seem to be working. Panel2 works fine on it's own but trying to use it in conjunction with my program simply yields a blank window. Any help would be greatly appreciated!

that requires swapping out the current, visible JPanel with another
Have a look at CardLayout for a complete example of how to do it properly.

I have a Swing app which 'swaps' Panels when the user press the 'SPACE' key, showing a live plot of a running simulation. What i did goes like this:
public class MainPanel extends JPanel implements Runnable {
// Called when the JPanel is added to the JFrame
public void addNotify() {
super.addNotify();
animator = new ScheduledThreadPoolExecutor(1);
animator.scheduleAtFixedRate(this, 0, 1000L/60L, TimeUnit.MILLISECONDS);
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
if (spacePressed)
plot.render(g);
else
simulation.render(g);
}
public void run() {
simulation.update();
repaint();
}
}
public class PlotView {
public void render(Graphics g) {
//draw the plot here
}
}
public class SimulationView {
public void render(Graphics g) {
//draw simulation here
}
}
This works very well for my 'show live plot' problem. And there's also the CardLayout approach, which you may turn into a new separate question if you having trouble. Good luck!

You should do .setVisible(false); to the panel which you want to be replaced.
Here is a working example, it switches the panels when you press "ENTER";
If you copy this in an IDE, automatically get the imports (shift+o in Eclipse);
public class MyFrame extends JFrame implements KeyListener {
private JButton button = new JButton("Change Panels");
private JPanel panelOnFrame = new JPanel();
private JPanel panel1 = new JPanel();
public MyFrame() {
// adding labels to panels, to distinguish them
panelOnFrame.add(new JLabel("panel on frame"));
panel1.add(new JLabel("panel 1"));
setSize(new Dimension(250,250));
setDefaultCloseOperation(EXIT_ON_CLOSE);
add(button);
add(panelOnFrame);
setVisible(true);
addKeyListener(this);
addKeyListener(this);
setFocusable(true);
}
public static void main(String[] args) {
MyFrame frame = new MyFrame();
}
#Override
public void keyPressed(KeyEvent k) {
if(k.getKeyCode() == KeyEvent.VK_ENTER){
//+-------------here is the replacement:
panelOnFrame.setVisible(false);
this.add(panel1);
}
}
#Override
public void keyReleased(KeyEvent arg0) {
}
#Override
public void keyTyped(KeyEvent arg0) {
}
}

How do I paint an image on the screen?

I want to add an image to the screen using the paint method? I do not want to use a JLabel because I want to set the location myself.
Board.class:
public class Board extends JPanel{
BufferedImage image;
public Board() {
try {
image = ImageIO.read(new File("C:\\Users\\alexa_000\\Pictures\\RocketShip.png"));
}catch(IOException e) {
e.printStackTrace();
}
}
protected void paintComponent(Graphics g) {
super.paintComponents(g);
g.drawImage(image, 0, 0, this);
}
public Dimension getPreferredSize() {
return new Dimension(image.getWidth(),image.getHeight());
}
}
RType.class:
public class RType extends JFrame{
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(EXIT_ON_CLOSE);
Panel panel = new Panel();
frame.setContentPane(panel);
frame.setSize(800,600);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
}

You have so many mistakes I don't know even where to start... Instead of displaying image on JLabel you can display your image on some container. Like JPanel.
Here is a small demo which demonstrates how to display image on JPanel. Explanation in code.
import javax.imageio.ImageIO;
import javax.swing.*;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
//No need to extend your class with JFrame
public class Board {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
//Instantiate Panel class.
Panel panel = new Panel();
//Set instance of Panel class as a content pane for your JFrame
frame.setContentPane(panel);
//Avoid calling setSize. Call pack instead
frame.pack();
//If you want to position your frame on center of screen, no need
//for fancy calculations. This is how you can do it.
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
/*Image will be displayed on JPanel*/
private static class Panel extends JPanel {
BufferedImage image;
public Panel() {
try {
//String you are passing in "new File()" is a path to your image
image = ImageIO.read(new File("path-to-your-image"));
} catch (IOException e) {
e.printStackTrace();
}
}
/*Override this method to display graphics on JPanel.
* Do not override paint method!*/
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image,0,0,this);
}
/*Override getPreferredSize method so it returns dimensions of your image.
* Size of your container (Panel) will be equal to size of that image*/
#Override
public Dimension getPreferredSize() {
return new Dimension(image.getWidth(),image.getHeight());
}
}
}

How to Remove JFrame Border as to Let an Image Touch The Edge

I had a friend make a background for the program I made so that it wouldn't look so plain, and I thought the best way to place the images would be to make a JLabel, fill it with an image, and set it to the size of the screen. This worked fine, except there is a small border around the JFrame and I can't get the JLabel to touch the edges of the frame. Thoughts? I have attached a picture.
public class ProgramDriver extends JFrame {
private JPanel contentPane;
private static CardLayout cardLayout;
private JTextField addGradeN;
private JTextField addGradeD;
/**
* Launch the application.
*/
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
try {
ProgramDriver frame = new ProgramDriver();
frame.setVisible(true);
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
//Global Variables
...
manager = new StateManager(gb);
//JFrame Settings
setTitle("Grade Book");
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
setBounds(100, 100, 656, 530);
contentPane = new JPanel();
contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
setContentPane(contentPane);
cardLayout = new CardLayout(0,0);
contentPane.setLayout(cardLayout);
setResizable(false);
//Home Panel
final JPanel Home = new JPanel();
contentPane.add(Home, "Home");
Home.setLayout(null);
JButton btnSeeGrades = new JButton("See Grades");
...
//Grades Panel
JPanel Grades = new JPanel();
contentPane.add(Grades, "Grades");
Grades.setLayout(null);'

The problem isn't with the JFrame, the problem is with your code. We can spend the rest of our natural life at guessing what's wrong or you can post some example code.
Now it's up to you, we can keep trying to throw wrong guess after wrong guess at you, frustrating us all, or you can help us help you...
Here are two examples I did. The first uses a JLabel as the primary content for a JPanel, where the child components are placed on it. Nice and simple.
The second uses a custom JPanel which paints the image onto the background of the component. I then use this to replace the frames content pane. This is a little more involved, but it has the added benefit of been easily updated (replacing the content pane won't effect the rest of the program)
Example 1: JLabel used as background
public class TestBackground {
public static final String BACKGROUND_PATH = "/Volumes/Macintosh HD2/Dropbox/MT015.jpg";
public static void main(String[] args) {
new TestBackground();
}
public TestBackground() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException ex) {
} catch (InstantiationException ex) {
} catch (IllegalAccessException ex) {
} catch (UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setLayout(new BorderLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new LabelPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
protected class LabelPane extends JPanel {
public LabelPane() {
BufferedImage bg = null;
try {
bg = ImageIO.read(new File(BACKGROUND_PATH));
} catch (IOException ex) {
ex.printStackTrace();
}
JLabel label = new JLabel(new ImageIcon(bg));
setLayout(new BorderLayout());
add(label);
label.setLayout(new GridBagLayout());
JLabel lblMessage = new JLabel("Look at me!");
lblMessage.setForeground(Color.WHITE);
lblMessage.setFont(lblMessage.getFont().deriveFont(Font.BOLD, 48));
label.add(lblMessage);
}
}
}
Example 2: Image used as background, replacing content pane...
public class TestBackground {
public static final String BACKGROUND_PATH = "/Volumes/Macintosh HD2/Dropbox/MT015.jpg";
public static void main(String[] args) {
new TestBackground();
}
public TestBackground() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException ex) {
} catch (InstantiationException ex) {
} catch (IllegalAccessException ex) {
} catch (UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setLayout(new BorderLayout());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setContentPane(new BackgroundPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
protected class BackgroundPane extends JPanel {
private BufferedImage bg = null;
public BackgroundPane() {
try {
bg = ImageIO.read(new File(BACKGROUND_PATH));
} catch (IOException ex) {
ex.printStackTrace();
}
setLayout(new GridBagLayout());
JLabel lblMessage = new JLabel("Look at me!");
lblMessage.setForeground(Color.WHITE);
lblMessage.setFont(lblMessage.getFont().deriveFont(Font.BOLD, 48));
add(lblMessage);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(1153, 823);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (bg != null) {
g.drawImage(bg, 0, 0, this);
}
}
}
}

To expand on Eng.Fouad's answer, you'll want to use the drawImage(...) method that takes 6 parameters, image, x and y location, image width and height, and image observer, and draw it like so from within a JPanel:
g.drawImage(img, 0, 0, getWidth(), getHeight(), this);
For example, my sscce:
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.*;
#SuppressWarnings("serial")
public class ExpandingImage extends JPanel {
public static final String GUITAR = "http://duke.kenai.com/Oracle/OracleStrat.png";
BufferedImage img;
public ExpandingImage(String imgUrlPath) throws IOException {
URL imgUrl = new URL(imgUrlPath);
img = ImageIO.read(imgUrl);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (img != null) {
g.drawImage(img, 0, 0, getWidth(), getHeight(), this);
}
}
private static void createAndShowGui() {
ExpandingImage mainPanel;
try {
mainPanel = new ExpandingImage(GUITAR);
JFrame frame = new JFrame("ExpandingImage");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
frame.setVisible(true);
} catch (IOException e) {
e.printStackTrace();
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
Edit
I see that you're using an EmptyBorder around the contentPane. Why if you don't want this border to be present?

As an alternative, you can override the method paintComponent(Graphics g) of JPanel (the contentPane) and use drawImage() on the Graphics object g as in this example.

have you tried JFrame function setUndecorated() ?

Make the frame undecorated. frame.setUndecorated(true)
If you want to make it move, you can use the ComponentMover of the Java2S.
Make sure that it is undecorated before it is visible.
Next, use setContentPane(new JLabel(new ImageIcon("myimage.jpg")));
After, that you can add contents as usual.