Develop Reference

How can I add an image to a panel

edit// my question is simpler than the other one so please just answer here. the other question looks too complicated for me to understand.
I want to add an image to a panel, but not sure how it's done. I don't want to do it from the design page because I didn't Design my panel I only coded it to show up. so does anyone know what code I need to add for an image to show up on there? and where do I save the image so that it can be included. here is the code I've done so far
JFrame frame = new JFrame("JButton");
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(500,200);
JPanel panel = new JPanel();
frame.add(panel);
JButton button = new JButton("London");
panel.add(button);
JLabel label = new JLabel("Click", JLabel.CENTER);

import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JPanel;
public class ImagePanel extends JPanel{
private BufferedImage image;
public ImagePanel() {
try {
image = ImageIO.read(new File("image name and path"));
} catch (IOException ex) {
// handle exception...
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, 0, 0, this); // see javadoc for more info on the parameters
}
}

All you need to do is,
Read image file.
Draw image to background with help of Graphics object.
just replace JPanel panel = new JPanel(); with below code.
JPanel panel = new JPanel() {
#Override
protected void paintComponent(Graphics g) {
Image image = null;
try {
image = ImageIO.read(new URL("https://www.google.co.in/images/branding/googlelogo/2x/googlelogo_color_120x44dp.png"));
} catch (IOException e) {
e.printStackTrace();
}
super.paintComponent(g);
g.drawImage(image, 0, 0, null);
}
};

Alright, there are 2 ways to add your image:
Using custom painting by overriding JPanel#paintComponent(...) method.
Using a JLabel to display the image and applying to it various layout managers to get the desired GUI.
I'm going to expand on how to use the 1st way with some comments in the code, the original idea was given in this answer so, be sure to give credits to the author.
You need to either:
Create a custom JPanel object
Create a class that extends JPanel
In any case you need to override the paintComponent(...) method.
Later, in that paintComponent() method you need to draw the image using Graphics#drawImage(...) method. This will make the JPanel to draw the image as the background.
After that you should override your JPanel's getPreferredSize() method, so you can call JFrame#pack(), which will resize your JFrame's size to its preferred size (which is the minimum size where all your components are visible).
After doing that, you can easily add components as you've always done:
panel.add(...);
And the second way is to make a JLabel to act as a Container, where you can add more Components to it (just like you do in a JPanel) (As shown in this answer)
The way to do this is:
Create a JLabel with an ImageIcon
Set its layout manager
Add components to it
Depending on which one you choose you have some differences:
Using the custom painting option, you need to take care of the preferred size of your container but you have more control over your component. However the image will fill all the space available on the window.
Using the JLabel option you can simply call pack() on your JFrame and it will resize to the image size, but if your image is too big your JFrame will be the same size too. If you resize your window to be shorter the image will be cropped and show "white" space if you make your window bigger.
This is how the image looks like with the 2 options, on the left the custom painting, on the right the label approach. At first they both look the same...
But... If we resize the window, this is what we get:
I like the custom painting approach more, but it depends on your needs and likes.
The code that produces the above output is:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class JPanelWithBackgroundImageExample {
private JFrame frame; //Our window
private JPanel panel; //The panel where we're going to draw the background image
private Image image;
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new JPanelWithBackgroundImageExample().createAndShowGui();
}
});
}
public void createAndShowGui() {
frame = new JFrame(getClass().getSimpleName());
try {
image = ImageIO.read(new URL("https://i.stack.imgur.com/XZ4V5.jpg")); //We read the image from the Internet
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
panel = new JPanel() { //We need to open the curly braces so we can change the default behavior of the JPanel
/*
* This method is the one that paints the background, by default it paints it with gray color,
* so, we need to tell it to draw an image instead. (This method belongs to JPanel already, so we need to add
* "#Override" before it, so the compiler knows we're overriding it
*/
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g); //Never forget this line or you could break the paint chain
/*
* This method belongs to the Graphics class and draws an image, this is what we want the JPanel to draw as our background
* The parameters are: the image to be drawn, the starting position (x, y) coords, the width and height and the observer
*/
g.drawImage(image, 0, 0, this.getWidth(), this.getHeight(), this);
}
/*
* This method is part of the JPanel, we're overriding it's preferred size and return the size we want
*/
#Override
public Dimension getPreferredSize() {
return new Dimension(300, 200);
}
};
JLabel label = new JLabel(new ImageIcon(image)); //We create a JLabel that will act as a container for our components
panel.setBorder(BorderFactory.createLineBorder(Color.WHITE)); //We create a border just for visibility of both ways
label.setBorder(BorderFactory.createLineBorder(Color.WHITE)); //We create a border just for visibility of both ways
label.setLayout(new BoxLayout(label, BoxLayout.PAGE_AXIS)); //We set the layout manager for the label
label.add(new JLabel("I'm a label inside a label")); //We add a new label to our label (that is acting as a container)
label.add(new JButton("I'm a button inside a label")); //We add a button to our label (that is acting as a container)
//You can add your components to the panel, as you always do it
panel.add(new JButton("HEY! I'm a button!")); //We add a button to our jpanel
panel.add(new JLabel("Click the button next to me! :D")); //We add a label to our jpanel
frame.add(panel, BorderLayout.WEST); //We add the pane which has a size of 300 x 200 to the left part of our JFrame
frame.add(label, BorderLayout.EAST); //We add the label (which acts as a container / jpanel) to the right part of our JFrame
frame.pack(); //We pack the frame, so it takes its preferred size (and as we only added a single component to it (the JPanel)
//As the panel has a size of 300 x 200, the frame will also have this size
frame.setVisible(true); //We set the visibility of the frame
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
Now, as a general tip, place your program on the Event Dispatch Thread (EDT) by changing your main() method as follows:
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
//Your constructor here
}
});
}
And now, to answer your question in the comments:
everything works except the image because I don't have that image. so I copied an image url from google and pasted it in and it didn't appear? what can I do
Well, I think you took the code from the linked answer and changed this line:
frame.setContentPane(new JLabel(new ImageIcon("C:/Users/Frakcool/workspace/StackOverflowProjects/src/test/Air.jpg")));
To something like this:
frame.setContentPane(new JLabel(new ImageIcon("https://i.stack.imgur.com/XZ4V5.jpg")));
Well in that case, it's obvious that the code won't work that way, Swing doesn't know how to interpret a http in a String, but URL class does, and thus, you should change the above line like:
frame.setContentPane(new JLabel(new ImageIcon(new URL("https://i.stack.imgur.com/XZ4V5.jpg"))));
And import:
import java.net.URL;
In your class.
I hope this helps you in understanding how the code works, if not, well, I think you need to put more effort in understanding it.

repaint() call from the constructor

I'm trying to display loaded resource-image.
And it works, but only after user resized the window.
import javax.swing.*; import java.awt.*;
class MyMainWindow extends JFrame{
Image img;
public MyMainWindow(){
setSize(300,300);
setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
img = MyResourceLoader.getImage("res.jpg");
repaint();
setVisible(true);
}
#Override
public void paint (Graphics g){
super.paint(g);
if (img != null)
g.drawImage(img, 0,0, null);
}
}
public class ResourcesProgram {
public static void main(String[] args) {
new MyMainWindow();
}
}
Why the constructor's repaint() call doesn't work?
And what should I do to show this image from the start?
Resource Loader class:
import java.awt.*;
public class MyResourceLoader{
static MyResourceLoader rl = new MyResourceLoader();
static public Image getImage(String fileName){
return Toolkit.getDefaultToolkit().getImage(rl.getClass().getResource("images/" + fileName));
}
}

Okay, so a bunch of things...
First...
Because the window has not yet been realised on the screen (attached to a native peer), there is nothing for repaint to paint...
Second...
Toolkit.getDefaultToolkit().getImage(rl.getClass().getResource("images/" + fileName));
Passes the actually loading of the image to a background thread, meaning that while you get a non-null value returned, the actual image data might not have been fully loaded.
You should consider using ImageIO.read instead, it will only return AFTER the image data has been fully loaded and will also throw an exception if something goes wrong (unlike Toolkit.getImage). See Reading/Loading an Image for more details...
Third...
All Swing components implement the ImageObserver interface, this means when you call Graphics#drawImage, you should pass the object as the ImageObserver parameter
g.drawImage(img, 0,0, this);
This allows the component to monitor updates from the loading of the image and reschedule repaint as required.
Fourth...
You should avoid overriding paint of top level containers, apart from not been double buffered, there is a bunch of components between the frame and the user, which can interfere with the painting process.
Instead, you should extend from something like JPanel and override it's paintComponent method, performing your custom painting there. You should then add this panel to an instance of JFrame (or some other component as needed)
Take a look at Painting in AWT and Swing and Performing Custom Painting for more details
Fifth...
You should be making sure that you create and modify your UI only from within the context of the Event Dispatching Thread, see Initial Threads for more details

Paint is immediately called when the code is initialized. To see this, get rid of repaint(); in your constructor, and add in your paint method, g.drawLine(0, 0, 300, 300);

Try this, you may have to add some imports:
import javax.swing.*; import java.awt.*;
class MyMainWindow extends JFrame{
Image img;
public MyMainWindow(){
setSize(300,300);
setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
img = MyResourceLoader.getImage("res.jpg");
setVisible(true);
}
#Override
public void paint (Graphics g){
super.paint(g);
if (img != null)
g.drawImage(img, 0,0, this);
}
}
public class ResourcesProgram {
public static void main(String[] args) {
new MyMainWindow();
}
}
Resource Loader:
import javax.swing.*; import java.awt.*;
public class MyResourceLoader {
public static Image getImage(String fileName){
ImageIcon icon = new ImageIcon(getClass().getResource(fileName));
return icon.getImage();
}
}

How to access repaint from the main?

I am working on a Java program that basically renders an image from a file source and then paints that image onto a panel (which is on a frame).
Now what I am able to do is invoke a line of code of the form
printpanel.getGraphics().drawImage(myimage.globalimage, 0,0, null);
where myimage is a class that contains the image.
As many of you know, this only prints the image 1 time, and should I resize the frame, the image disappears.
Now the way to fix this would be to put the line into the repaint method, but i'm in the main method right now so how do I access the definition of the repaint method and change it from within the main method?
Thanks!
=====================================================================================================
My code:
MAIN CLASS:
package imagetester;
import java.awt.image.*;
import javax.swing.*;
import javax.imageio.*;
import java.awt.Graphics2D.*;
import java.io.*;
public class Imagetester
{
public static void main(String[] args)
{
JFrame printframe = new JFrame("The drawing frame");
JPanel printpanel = new JPanel();
printframe.setSize(700,700);
printpanel.setSize(700,700);
printframe.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
printframe.add(printpanel);
printpanel.setVisible(true);
printframe.setVisible(true);
Imageobject myimage = new Imageobject();
try
{
myimage.setImage("word.jpg");
}
catch(IOException e)
{
System.out.println("the image failed!");
}
printpanel.getGraphics().drawImage(myimage.globalimage, 0,0, null);
printpanel.repaint();
System.out.println("hi");
}
}
myimage class:
package imagetester;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
public class Imageobject
{
BufferedImage globalimage;
public void setImage(String filename) throws IOException
{
globalimage = ImageIO.read(new File(filename));
}
public void Imagebject()
{
}
}

I'm not sure I understand fully, but if what you want to do is display a panel with an image inside a window, you should subclass JPanel (or whatever other panel you'd like), and override the paintComponent method to paint the image. Something along the lines of:
public class ImagePanel extends JPanel {
private Image image;
public ImagePanel(Image image) {
this.image = image;
}
#Override
protected void paintComponent(graphics g) {
g.drawImage(image, 0, 0, this);
}
}

Now what i am able to do is invoke a line of code of the form
printpanel.getGraphics().drawImage(myimage.globalimage, 0,0, null);
No don't do that. Your printPanel should already have it's paintComponent method, with the a drawImage in it.
Image image;
...
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (image != null) {
g.drawImage(image, ..., this); // this is the ImageObserver. Should not be null
}
}
Then you can just have a setter for it if you want to change it
public void setImage(Image image) {
this.image = image;
repaint();
}
Just call that method with the image you want to change
EDIT
There's no way around it. You need to #Override the paintComponent method of the JPanel. When you resize the frame, repaint() will automatically be called, leaving the image there. The image should be drawn in the paintComponent method. You can have the panel's constructor take an Image argument if you want to instantiate that way, with the image from the ImageObject

As many of you know, this only prints the image 1 time, and should I resize the frame, the image disappears.
What is your requirement when the frame resizes?
Do you paint the image at its original size? If so then just use a JLabel with an ImageIcon and add the label to the frame
Do you want the image to scale with the size of the frame? Then you need to do custom painting. You can create a custom component as demonstrated in other answers. Or you can use a JLabel with a Stretch Icon which will stretch to fill the space available to the label.

Change Images such as look like video

I want to load images in JFrame such a way that it should look like it is video.
For that I thought that I will change Images so much faster (20 images/sec.)
but Problem is when new Image get load its shows fully black window.
I dont know Why it happens.
Suggest me where I goes wrong.
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import java.io.*;
import javax.imageio.ImageIO;
class VideoI extends JPanel {
private Image img;
private Graphics graphics;
ImageIcon icon;
VideoI(){
icon=new ImageIcon("D:\\Videos\\1.jpg");
add(icon);
}
public void paintComponent(Graphics g) {
graphics=g;
repeatImgs();
}
public void repeatImgs(){
for(int i=0;i<25;i++)
{ try{
img=ImageIO.read(new File("D:\\Videos\\"+i+".jpg"));
graphics.drawImage(img, 0, 0, null);
System.out.println(""+i);
Thread.sleep(1000);
}catch(Exception e){System.out.println(""+i+":"+e);}
}
}
}
public class Video extends JFrame
{
public static void main(String args[])
{
new Video().start();
}
public void start()
{
VideoI panel = new VideoI();
add(panel);
setVisible(true);
setSize(1300,800);
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
}

You are blocking the event dispatch thread. Use a swing Timer to repaint the component at the desired frequency.
You should never, ever sleep() in the EDT. What you want is essentially
public void paintComponent(Graphics g) {
// No loops or delays, just fetch the next image, preferrably it has been
// already been loaded by another thread.
g.drawImage(getNextImage(), 0, 0, null);
}
And a timer task:
ActionListener timerTask = new ActionListener() {
#Override
public void actionPerformed(final ActionEvent e) {
panel.repaint();
}
};
Timer timer = new Timer(50, timerTask);
When you want to start the video, just call timer.start().
Finally, you should also wrap creating the GUI with SwingUtilities.invokeLater().

You're sending the Event Dispatch Thread (the UI update thread) to sleep, that's why you get screen issues.
Try loading and switching images in a worker thread (have a look at the SwingWorker JavaDoc).

I'm no Swing expect, but I would guess this happens because you stop the Swing thread with the Thread.sleep. You should do the image changing and timing outside of the swing thread and use SwingUtilities.invokeLater to draw the Image. Also you need to sleep 50ms, not a whole second for 20fps. Using a ScheduledExecutorService whould fit here.
Also you always load the image from disc, when it needs to be rendered. This could be to slow. It would be better to load all image on start up and then just change the image.

Swing overriding object's paintComponent

If I have a JPanel object that I can't modify, is there a way I can modify the paintComponent method of it without using injection?
One approach I was thinking of was getting the JPanel's Graphics object, passing it to paintComponent(), performing operations on this Graphics object, and finally painting that in my custom JPanel. The problem with this, is I need to be able to do this every time the original JPanel's paintComponent() is called.
I don't need to replace what's in paintComponent(), I just need to add on to it.
For example:
JFrame frame = null;
for (Frame f : JFrame.getFrames()) {
if (((JFrame) f).getTitle().equals("Title")) {
JPanel panel = null;
// ... Cycle through all components and get the one that's a JPanel
// I want to use ColorConvertOp to make panel greyscale
}
}

One approach would be to use the Decorator Pattern to wrap the existing class. Your decorator can then implement paintComponent to first delegate to the original component and after that paint on top of it. For this approach you need to actually gain control over the creation of the components, or you need to replace them after the component hierarchy has been created (using getComponents() of the parent container to find the components to be altered).

I think one possibility is to use a GlassPane and position it exactly over your JPanel (maybe let it follow the panel using listeners if the panel changes its location). Then you can simply draw your stuff in the glasspane and it will be overlayed.
Of course this is not really elegant... But I don't see any possibility to change the paintComponents behaviour of an already existing instance without injection. (Proof me wrong, Java geeks of this world! :P)

I guess this would complete #Durandal's answer:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.GridBagLayout;
import java.awt.color.ColorSpace;
import java.awt.image.BufferedImage;
import java.awt.image.ColorConvertOp;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class TestPanels {
private static final boolean GRAY_SCALE = true;
protected void initUI() {
final JFrame frame = new JFrame(TestPanels.class.getSimpleName());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel unmodifiablePanel = new JPanel(new GridBagLayout());
JLabel label = new JLabel("Some unmodifiable test label");
unmodifiablePanel.add(label);
unmodifiablePanel.setBackground(Color.GREEN);
JPanel wrappingPanel = new JPanel(new BorderLayout()) {
private ColorConvertOp op = new ColorConvertOp(ColorSpace.getInstance(ColorSpace.CS_GRAY), null);
private BufferedImage image;
#Override
public void paint(Graphics g) {
if (!GRAY_SCALE) {
super.paint(g);
return;
}
BufferedImage bi = getImage();
if (bi != null) {
Graphics big = bi.createGraphics();
super.paint(big);
big.dispose();
bi = op.filter(bi, null);
g.drawImage(bi, 0, 0, null);
}
}
protected BufferedImage getImage() {
if (image == null) {
if (getWidth() > 0 && getHeight() > 0) {
image = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_RGB);
}
} else if (image.getWidth() != getWidth() || image.getHeight() != image.getHeight()) {
image = new BufferedImage(getWidth(), getHeight(), BufferedImage.TYPE_INT_RGB);
}
return image;
}
};
wrappingPanel.add(unmodifiablePanel);
frame.add(wrappingPanel);
frame.setSize(200, 200);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new TestPanels().initUI();
}
});
}
}
You can turn the GRAY_SCALE flag to false, to see how it renders normally.

If you had the ability to modify the construction of your class, you could extend that class and then call super.paintComponent(g) in your extended class. Example:
public class NewPanel extends OldPanel{
public void paintComponent(Graphics g){
super.paintComponent(g);
// Insert additional painting here
}
}
In this case you will need a new class in order to build onto the existing class's painting.
What this does is execute everything that was done in the parent class's painting, and give you the option to do more (which seems to be what you're looking for).
EDIT
BUT... given that you don't have access to this, your options get more limited. If the panel uses a null layout manager, you could add a child jpanel who paints over the parent (a layout manager would restrict the amount of area the child could paint over though). This is a long shot.
You can also use reflection to but about the only option you've got (besides byte code injection). This seems about equally ugly as byte code injection - here's a decent overview of what you'd be looking to do: Java reflection: How do I override or generate methods at runtime?
My personal preference is to decompile the class, modify it the way you want, recompile it and insert it back into the original jar. This will probably void some warrenties, licenses and get you in other trouble... but at least it's maintainable.