I have read a lot of answers about this problem but I can't manage to find my error even on a simple code. Here is the problem : I'd like to draw an Image in a JLabel which is in a JPanel, but the paintComponent() method of the JLabel isn't called.
Here is the code :
The ImagePainter class should draw an image
public class ImagePainter extends JLabel{
private Image image;
public ImagePainter(){
try {
image = ImageIO.read(new File("src/testgui/image.png"));
} catch (IOException exception) {
exception.printStackTrace();
}
}
#Override
protected void paintComponent(Graphics g){
super.paintComponent(g);
g.drawImage(image, 0, 0, null);
System.out.println("in paintComponent");
}
}
Here is a standard JFrame. I took care to add the JPanel to the contentPane
public class Display extends JFrame{
public Display(){
JPanel jp = new JPanel();
ImagePainter i = new ImagePainter();
getContentPane().add(jp);
jp.add(i);
jp.repaint();
setSize(800, 800);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
And finally the main. I instanciate Display on the EDT like everyone tell to do :
public class Main {
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable(){
#Override
public void run(){
Display d = new Display();
}
});
}
}
Finally, I observed that if I directly add the ImagePainter to the contentPane, the image is drawn correctly. It's probably a stupid error but I spend literally hours trying to find it and really can't see it. Thank you in advance !
The label does not account for the preferred size of the image when the image is custom painted! The panel by default has a flow layout. A flow layout does not stretch components to fit. So that label would have size of 0 x 0 pixels. You can confirm that by adding a visible border to the label.
But given the image is displayed in a label, why not just set the image as the icon of the label?
Also, the jp.repaint() statement in the Display constructor is useless, since you have not yet set the frame visible.
Related
I have two panels defined like:
public class JPanel_with_BG extends JPanel
{
private Image bg_image;
public JPanel_with_BG(Image bg_image)
{
this.bg_image = bg_image;
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
if (bg_image != null)
{
g.drawImage(bg_image, 0, 0, this);
}
}
}
and,
public class MPanel extends JPanel
{
public void paint(Graphics g)
{
super.paint(g);
// draw something...
}
}
Then, I want to add the second panel over the bg_pnl. The top panel is smaller like bg_pnl.size = pnl + 2*padding.
MPanel pnl = new MPanel();
JPanel bg_pnl = new JPanel_with_BG(image);
int pad = 50;
bg_pnl.setBorder(new EmptyBorder(pad, pad, pad, pad));
bg_pnl.add(pnl);
The problem is that what I'm drawing on the top panel is not visible. What I can see is only the background image. Any ideas? Thanks.
You Code seems ok. I tried this at my end and I can see a small area on my UI showing MPanel. You need to validate the size of your panel on which you are showing this component.
It might happen that the area is not visible because of the dimension of the window. Also a panel's default layout is flow layout and it arranges the components added on it based on their size and if they are really small, It might not be visible
I'm trying to draw something on a Canvas, add it to a JFrame and then set this JFrame to Fullscreen. My problem is: in fullscreenmode I only see a black screen.
Before the screen turns black I shortly can see the pink background of the canvas.
Drawing directly on a JFrame and then setting it to fullscreen works perfectly fine and I can see the testtext. I assume there is a problem with displaying the Canvas properly.
Here is my code:
public class FullscreenTest extends Canvas {
private JFrame mainFrame;
public FullscreenTest(){
this.mainFrame = new JFrame();
JPanel contentPane = (JPanel) mainFrame.getContentPane();
contentPane.add(this);
}
public void run(DisplayMode dm){
setBackground(Color.PINK);
setForeground(Color.WHITE);
setFont(new Font("Arial", Font.PLAIN, 24));
Screen s = new Screen();
s.setFullScreen(dm, this.mainFrame);
try {
Thread.sleep(5000);
} catch (InterruptedException exc) { exc.printStackTrace(); }
s.closeFullScreenWindow();
}
public void paint(Graphics g){
g.drawString("This is some testtext", 200, 200);
}
public static void main(String[] args){
DisplayMode dm = new DisplayMode(800, 600, 32, DisplayMode.REFRESH_RATE_UNKNOWN);
FullscreenTest test = new FullscreenTest();
test.run(dm);
}
}
Here is what the Screen.setFullScreen(DisplayMode dm, JFrame window) method does:
//graphicsDevice = GraphicsEnvironment.getLocalGraphicsEnvironment()
// .getDefaultScreenDevice();
public void setFullScreen(DisplayMode dm, JFrame window){
window.setUndecorated(true);
window.setResizable(false);
graphicsDevice.setFullScreenWindow(window);
if(dm != null && graphicsDevice.isDisplayChangeSupported()){
graphicsDevice.setDisplayMode(dm);
}
}
Does anyone have a clue why I don't see the JFrame's content in fullscreen?
1) you have three general issues
never block EDT by using Thread.sleep(5000); use Swing Timer instead, demonstrations here
(if aren't there really important reasons) don't mixing AWT with Swing the rest is here, and use JPanel instead of Canvas (for Canvas is there paint method, for JPanel is there paintComponent)
your public void paint(Graphics g){ is to the JFrame instead of Canvas and locked by Thread.sleep(5000);
2) Swing GUI rellated should be wrapped into invokeLater() meaning
public static void main(String[] args){
more in the Initial Thread
3) in linked code example you can find out demostrations how to use background thread in the Swing
I agree with mKorbel (actually, I have your code working with corrections he suggest). Just one hint to achieve more predictable results further: take control on colors in paint() method. Default color for background may vary on different systems. On my system it draws white text on light-red background. But if it will draw black text on black background, test will look like "not working".
hey i had he same problem and the screen turns black every time i run the program.
in the part of the paint method , you wrote, which i think that it is from Bucky tutorial which is amazing by the way :
public void paint(Graphics g){
g.drawString("This is some testtext", 200, 200);
}
all you have to do is to use "super"
public void paint(Graphics g){
super.paint(g);
g.drawString("This is some testtext", 200, 200);
}
I tried it myself and it is working just fine.
I've been working on a drinking game program for school.
//this is the game //http://sotallytober.com/games/verbal/mexican/
Anyway, I painted a image in an JPanel using the following code (it's an class that extends JPanel)
public class iconPanel extends JPanel {
ImageIcon image;
Image pic;
public iconPanel(String startScreenImage) {
image = new ImageIcon(startScreenImage);
pic = image.getImage();
this.setBackground(new Color(0, true));
}
#Override
public void paintComponent(Graphics g) {
//Paint background first
g.drawImage (pic, 0, 0, getWidth (), getHeight (), this);
}
Now in my other class, where I have the layout and all the components I declare on top my JPanels like this :
private JPanel pnDrinkPlayerBW;
Then in a method in the same class named MakeComponents I set the JPanel to :
pnDrinkPlayerBW = new iconPanel("img/glass.jpg");
pnDrinkPlayerBW.setPreferredSize(new Dimension(183,61));
Afterwards I add it to the Panel where it has to come, and that panel onto the frame in the method makeLayout() (I don't think that it's useful code, so if you want to see it, ask me)
Then if a button gets pressed, I want to change the glass.jpg image to another image, for example beerGlass0.png, so in the actionlistener in another method actionEvents() I do this:
pnDrinkPlayerBW = new iconPanel("img/beerGlass.png");
pnDrinkPlayerBW.setPreferredSize(new Dimension(183,61));
pnDrinkPlayerBW.repaint();
I'll put the constructor of this class also here, just if people need it :
public SpelScreen(){
makeComponents();
makeLayout();
actionEvents();
} // note : this is'nt the full constructor, just the call for the methods I talked about, SpelScreen extends JFrame..
So what I want to do, is to set in the class SpelScreen a new image for the iconPanel and repaint it using the same instance of the spelscreen.
I am quite new to Java, so don't expect me to rapidly understand complicated code :)
Thanks!
First off you're forgetting to call super.paintComponent in your paintComponent method. Also paintComponent should be protected not public
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(..);
}
Second, I don't think you want to create a new iconPanel and immediately call repaint on it. That will probably do nothing.
Instead have a setter for your pic, then just repaint(); inside that method.
public void setPic(Image pic) {
this.pic = pic;
repaint();
}
Then you can just call the setPic from the the class you created the iconPanel in. For example
iconPanel panel = new iconPanel("...");
... // then in some listener
public void actionPerformed(ActionEvent e) {
Image pic = null;
try {
pic = ImageIO.read(...);
panel.setPic(pic);
} catch ...
}
Another option is just to have an array of images you initialize in the iconPanel. Then in a a listener, you can just change the index the if the image array then call repaint. Something like this
Image[] images = new Image[5];
int imageIndex = 0;
// fill the array with images
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(images[imageIndex], ...);
}
Then you could just change the imageIndex and repaint()
Side Note
You should be using Java naming convention. Class names being with capital letters i.e. iconPanel → IconPanel
Update
Using ImageIcon
public void setImage(ImageIcon img) {
pic = img.getImage();
repaint();
}
I have a GUI with a created JPanel and a "Start" button. All I need is when I click "Start", an image will be loaded and appear on that JPanel.
But my problem is when I click "Start", nothing happens.
Can anyone help me fix this problem?
Here is my code:
private BufferedImage image;
public class ImagePanel extends JPanel {
public ImagePanel() {
try {
image = ImageIO.read(new File("C:\\Users\\HienTran\\Desktop\\Miranda-Kerr-16-240x320.jpg"));
} catch (IOException ex) {
// handle exception...
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, 0, 0, null);
}
}
private void startBtnActionPerformed(java.awt.event.ActionEvent evt) {
stopBtn.setEnabled(true);
startBtn.setEnabled(false);
imageArea.add(new ImagePanel()); // imageArea is the JPanel in the GUI
}
When I replace 2 lines of imageArea by creating a new JFrame as below, that JFrame shows up with the image I added.
private void startBtnActionPerformed(java.awt.event.ActionEvent evt) {
stopBtn.setEnabled(true);
startBtn.setEnabled(false);
JFrame test = new JFrame("Window");
test.add(new ImagePanel());
test.setSize(image.getWidth(), image.getHeight() + 30);
test.setVisible(true);
}
When you add components to a visible GUI the basic code is:
panel.add(...);
panel.revalidate();
panel.repaint();
However, that probably won't help because by default a JPanel uses a FlowLayout and a FlowLayout respects the size of the component. Your ImagePanel will have a size of (0, 0) since you did not override the getPreferredSize() method.
There is no need to create a custom panel to paint your image. Just use a JLabel with an Icon then you let the label worry about the size. Don't reinvent the wheel.
I suggest you read the Swing tutorial for the basics. Maybe the section on How to Use Labels would be a good place to start. The tutorial will also show you a better way to design your class wo that you follow Swing guidelines.
First fix a bit:
try {
image = ImageIO.read(new File("C:\\Users\\HienTran\\Desktop\\Miranda-Kerr-16-240x320.jpg"));
} catch (IOException ex) {
ex.printStacktrace(); // see if there is an exception, like not finding or something
}
than:
If you add a panel, than need a layout refresh and a gui refresh:
imageArea.add(new ImagePanel());
imageArea.revalidate(); // refresh layout
imageArea.repaint(); // shedule painting
I have this JFrame containing a children of JPanel wherein it displays the image which is declared in this manner.
BufferedImage image = ImageIO.read(filename);
The program displays the image properly. But the only thing is, it requires to resize the frame to display the image.
Is there a possible way to display the image once the frame appears?
You should override paintComponent(Graphics g) and draw the image therein. In this case, you should do this for the JPanel component (I think? If not, do this for the JComponent(s) you're referring to). Also, since Swing is not thread-safe, ensure these modifications are performed in the EDT.
EXAMPLE
public class Demo{
private static BufferedImage bi;
public static void main(String[] args){
try{
loadImage();
SwingUtilities.invokeLater(new Runnable(){
#Override
public void run(){
createAndShowGUI();
}
});
}
catch (IOException e){
// handle exception
}
}
private static void loadImage() throws IOException{
bi = ImageIO.read(new File("src/resource/braveheart.PNG"));
}
private static void createAndShowGUI(){
final JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
final JPanel panel = new JPanel(){
#Override
protected void paintComponent(Graphics g){
Graphics g2 = g.create();
g2.drawImage(bi, 0, 0, getWidth(), getHeight(), null);
g2.dispose();
}
#Override
public Dimension getPreferredSize(){
return new Dimension(bi.getWidth(), bi.getHeight());
}
};
frame.add(panel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
OUTPUT
It's important to keep in mind that this example ignores rendering hints, so when you maximize the JFrame, the image quality will be very poor. :)
EDIT
When answering this question, I assumed you had a basic understanding of Swing. I suppose I assumed too much. It is important to mention that all components should be added to the top-level container before it's been realized (i.e. made visible). This will ensure that everything is rendered without having to resize your frame. As others have suggested, you could have simply used a JLabel to render the image, and then added it to your JPanel. Instead, I promoted custom painting, which is perfectly acceptable, and to me, cleaner.
for dispaly Image or ImageIcon is better look for JLabel (basic stuff)