I have created a subclass of JPanel to display images. I instantiate this in the constructor of a JFrame and add it to that JFrame. This works perfectly. Then I have added a button with an ActionListener to change that Image. My problem is that the JFrame won´t update although I have tried repainting etc.
The subclass of JPanel:
public class ImagePanel extends JPanel {
BufferedImage bf;
public ImagePanel(String dateiname)
{
try {
bf = ImageIO.read(new File(dateiname));
} catch (IOException e) {
e.printStackTrace();
}
}
public void paint(Graphics g)
{
g.drawImage(bf.getScaledInstance(300,200,1),0,0,null );
}
}
The JFrame is basically this
public class Hauptfenster extends JFrame {
private JButton changeImage;
private JPanel buttonPanel;
private ImagePanel ip;
public Hauptfenster {
ip = new ImagePanel("first_image.jpg");
buttonPanel = new JPanel();
buttonPanel.add(changeImage);
changeImage.addActionListener((e) -> {
ip = new ImagePanel("new_image.jpg");
ip.setVisible(true);
});
this.add(buttonPanel);
this.add(ip);
this.setVisible(true);
}
}
Why doesn´t the method in the ActionListener update the ip component in the JFrame Hauptfenster?
When you do ip = new ImagePanel("new_image.jpg"); you're creating a whole new ImagePanel that has nothing to do with your current layout. You could.
remove(ip);
ip = new ImagePanel("new_image.jpg");
add(ip);
repaint();
Another way you could do it is to just change the buffered image.
Add the following method to your image panel.
public void loadImage(String dateiname) {
try {
bf = ImageIO.read(new File(dateiname));
} catch (IOException e) {
e.printStackTrace();
}
}
Then in your action listener.
ip.loadNewImage("new_image.jpg");
ip.repaint();
You have a bunch of bad habits going on in your code though.
Such as, override paintComponent instead of paint and it should look like.
#Override
public void paintComponent(Graphics g){
super.paintComponent(g);
g.drawImage(bf.getScaledInstance(300,200,1),0,0,null );
}
That way transparency will be handled correctly.
You shouldn't extend JFrame, you should just create a JFrame.
When you add components, you there is a layout manager involved. It's good to be aware of that and handle things accordingly. I would change your constructor to.
public Hauptfenster() {
JFrame frame = new JFrame();
ip = new ImagePanel("first_image.jpg");
buttonPanel = new JPanel();
changeImage = new JButton("change image");
buttonPanel.add(changeImage);
changeImage.addActionListener((e) -> {
frame.remove(ip);
ip = new ImagePanel("new_image.jpg");
frame.add(ip, BorderLayout.CENTER);
frame.repaint();
});
frame.add(buttonPanel, BorderLayout.SOUTH);
frame.add(ip, BorderLayout.CENTER);
frame.setVisible(true);
}
If you need more help, you'll need to actually make your example compilable. There are too many errors right now.
Related
i have been extensively researching on stackoverflow and other platforms to find out the solution to my problem.I do understand that this is a duplicate question and I totally understand how to convert JPanel to an image based on Java tutorial and other existing post on stackoverflow . However, i'm trying to do it in OOP as i don't want to chunk all my codes within the same method. The result i keep getting is blank and it doesn't show my component in PNG file that ive exported.
File 2, imageOutput.java
public class imageOutput {
public JPanel panel() {
JPanel panel = new JPanel();
JButton btn = new JButton("Click");
JLabel label = new JLabel("Exporting image example");
// -----Add to panel ---
panel.add(label);
panel.add(btn);
panel.setSize(200,200);
btn.addActionListener(new saveImageListener());
return panel;
}
public void frame() {
JFrame frame = new JFrame();
JPanel panel = panel();
// --- Add to frame ---
frame.add(panel);
frame.setSize(200, 200);
frame.setVisible(true);
}
}
class saveImageListener implements ActionListener {
#Override
public void actionPerformed(ActionEvent arg0) {
JPanel panel = new imageOutput().panel();
System.out.println("Step 1.. ");
BufferedImage image = new BufferedImage(panel.getWidth(), panel.getHeight(), BufferedImage.TYPE_INT_RGB);
System.out.println("Step 2.. ");
Graphics2D g = image.createGraphics();
panel.printAll(g);
g.dispose();
try {
ImageIO.write(image, "jpg", new File("Paint2.jpg"));
ImageIO.write(image, "png", new File("Paint2.png"));
System.out.println("save");
} catch (IOException exp) {
exp.printStackTrace();
}
}
}
Main class, main.java
public class main{
public static void main(String[] args) {
new imageOutput().frame();
}
}
When i run the program, it results blank as mentioned above. ive been trying to figure out whats the cause of it for the past week and i have not come out with any solution. Has anyone encounter this problem and able to solve ?
BUT when i do it this way , it's perfectly fine. However, it's not oop for me.
public void frame() {
JFrame frame = new JFrame();
JPanel panel = new JPanel();
JButton btn = new JButton("Click");
JLabel label = new JLabel("Exporting image example");
//-----Add to panel ---
panel.add(label);
panel.add(btn);
btn.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
BufferedImage image = new BufferedImage(panel.getWidth(), panel.getHeight(), BufferedImage.TYPE_INT_RGB);
Graphics2D g = image.createGraphics();
panel.printAll(g);
g.dispose();
try {
ImageIO.write(image, "jpg", new File("Paint2.jpg"));
ImageIO.write(image, "png", new File("Paint2.png"));
System.out.println("save");
} catch (IOException exp) {
exp.printStackTrace();
}
}
});
//--- Add to frame ---
frame.add(panel);
frame.setSize(200, 200);
frame.setVisible(true);
//btn.addActionListener(new saveImageListener());
}
Thank you in advance. :)
The problem is a compounding one.
When you call panel() on an instance of imageOutput, it's create another instance of the JPanel, in of itself, this isn't a bad thing, but you need to remember that this new instance has nothing to do with what's on the screen.
In the example you've provided, this means that no layout pass has been done on the component, so all the components are at there default position/size (which is 0x0x0x0), so nothing gets rendered
If you're going to continue creating a new instance of the panel each time you call panel(), then you're going to have to force a layout pass, maybe something like...
JPanel panel = new imageOutput().panel();
panel.setSize(panel.getPreferredSize());
panel.doLayout();
Now, personally, I'd avoid setSize and passing it "magic" numbers and instead use the components preferredSize, but that's me
I have a JFrame. It uses a JPanel as its content pane, and that JPanel uses GridBagLayout as its LayoutManager. That JPanel contains two more items: a button, and another JPanel. On program start, an image is loaded from file into the lowest-level JPanel as a BufferedImage using ImageIO.read(...). Here is where everything goes to pieces.
The image loads correctly, I can see a small corner of it on screen (14px square as specified in debugger). There is nothing I can figure out that will cause the layout to grow and fit the entire image in the lowest level JPanel on screen. The image in debuggers shows correct size of 500px. The preferred size of the CardImagePanel shows up correctly as the same size as the image. But the layout will not respect the preferred size unless I manually set the CardImagePanel size using setSize(...) which I'm pretty sure is not supposed to be necessary with GBL.
I have tried putting revalidate() and repaint() calls on every single JFrame, JPanel, layout, grid bag, image, etc throughout the entire program and just can't find the correct place or time to call them to make this thing work. Currently I've been trying to just let the image load incorrectly and use the button to force revalidation and repaint, but even this explicit call is not doing anything.
I'm losing my mind, I'll do anything to get this thing working.
Here is all my code for the whole stupid thing (minus imports and package specification.
P1s1.java:
public class P1s1 {
public static void main(String[] args) {
// TODO code application logic here
build();
}
public static void build()
{
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(new Dimension(640, 480));
frame.setContentPane(new GuiPanel(frame));
frame.setVisible(true);
}
}
GuiPanel.java:
public class GuiPanel extends JPanel {
JFrame parentFrame;
JButton imageLoaderButton;
CardImagePanel cardImagePanel;
LayoutManager layout;
GridBagLayout gridBagLayout;
GridBagConstraints constraints;
public GuiPanel(JFrame frame)
{
parentFrame = frame;
constraints = new GridBagConstraints();
gridBagLayout = new GridBagLayout();
layout = gridBagLayout;
this.setLayout(layout);
this.setBorder(BorderFactory.createLineBorder(Color.black));
setupImageLoaderButton(imageLoaderButton);
cardImagePanel = new CardImagePanel();
this.add(cardImagePanel);
}
private void setupImageLoaderButton(JButton button)
{
button = new JButton("Click to load image!");
ActionListener imageLoaderListener;
imageLoaderListener = new ActionListener() {
#Override
public void actionPerformed(ActionEvent ae) {
System.out.println("Button clicked.");
cardImagePanel.revalidate();
cardImagePanel.repaint();
GuiPanel.this.revalidate();
GuiPanel.this.repaint();
parentFrame.revalidate();
parentFrame.repaint();
}
};
button.addActionListener(imageLoaderListener);
this.add(button);
}
}
CardImagePanel.java:
public class CardImagePanel extends JPanel {
BufferedImage cardImage;
public CardImagePanel()
{
this.setBorder(BorderFactory.createLineBorder(Color.black));
try {
cardImage = ImageIO.read(new File("c:\\dev\\cards\\2_of_clubs.png"));
this.setPreferredSize(new Dimension(cardImage.getWidth(), cardImage.getHeight()));
} catch (IOException ex) {
System.out.println("Exception trying to load image file.");
}
}
// The getPreferredSize() override was suggested by MadProgrammer.
// It did not solve the issue, but see MadProgrammer's updated,
// accepted answer below for the correct solution. The rest of the
// code reflects my original attempt to solve the issue.
#Override
public Dimension getPreferredSize()
{
return cardImage != null ? new Dimension(cardImage.getWidth(), cardImage.getHeight()) : super.getPreferredImage();
}
#Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
g.drawImage(cardImage, 0, 0, this);
}
}
GridBagLayout relies on a component telling it what size it would like to be (along with it's minimum and maximum size when it's relievent). You need to override the getPreferredSize method of the CardImagePanel, returning the size you would like the component to be
public class CardImagePanel extends JPanel {
BufferedImage cardImage;
public CardImagePanel() {
this.setBorder(BorderFactory.createLineBorder(Color.black));
try {
cardImage = ImageIO.read(new File("c:\\dev\\cards\\2_of_clubs.png"));
} catch (IOException ex) {
System.out.println("Exception trying to load image file.");
}
}
#Override
public Dimension getPreferredSize() {
return cardImage != null ? new Dimension(cardImage.getWidth(), cardImage.getHeight()) : super.getPreferredSize();
}
#Override
public Dimension getMinimumSize() {
return getPreferredSize();
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(cardImage, 0, 0, this);
}
}
Have a look at How to Use GridBagLayout for more details
You CardImagePanel has no preferred size, so the layout manager doesn't know how to handle the size properly.
A couple of solutions:
There is no need to create a custom class to display the image. Just use a JLabel to display the image. The JLabel will return the preferred size of the image.
If you do use the CardImagePane, then you need to override the getPreferredsize() method of the CardImagePanel to return the size of the image.
I'm using IntelliJ GUIDesigner.
I have JScrollPanel which contains JPanel.
The idea is that I want to add image to JPanel and to have it load at full size so I can use scrollers to move around and see whole image.
And My problem is that it paints itself alright if I won't change the size of JPanel. But the moment I'm chaning JPanel size it just repaints itself to orginal state (I suppose, IntelliJ hides a lot of code from me).
The code is:
private JPanel panel1;
private JButton button1;
private JPanel drawingPanel;
public MainPanel(){
button1.addActionListener(e -> {
JFileChooser openFile = new JFileChooser();
File chosenFile;
if(openFile.showSaveDialog(panel1) == JFileChooser.APPROVE_OPTION){
chosenFile = openFile.getSelectedFile();
drawImage(chosenFile);
}
});
}
private void drawImage(File file){
try {
BufferedImage image = ImageIO.read(file);
//Works OK if line belowed is removed, but doesn't adjust size so I can't scroll.
drawingPanel.setSize(image.getWidth(), image.getHeight());
Graphics g = drawingPanel.getGraphics();
g.drawImage(image, 0, 0, null);
drawingPanel.paintComponents(g);
}
catch (IOException e) {
e.printStackTrace();
}
}
As I wrote in comment, if the line below the comment is removed then I can load the image and it shows OK but it's too big and I can't see whole image.
If I add the line then it just clears everything and I can't see nothing.
This is important - I need to get the image to show in full size.
How do I do it?
I have JScrollPanel which contains JPanel.
Don't do custom painting.
Just create a JLabel and add the label to the viewport of the scroll pane. Then when you want to change the image you use the setIcon(...) method of the JLabel and the label will automatically repaint itself and scrollbars will appear if necessary.
Maybe you can share your IntelliJ GUI forms? Otherwise it's difficult to reproduce the scrolling problem that you're facing. Without the custom painting and using a label as camickr suggested, you can get scrolling working like this:
public class MainPanel {
private static JFrame frame;
private JPanel panel1;
private JButton button1;
private JPanel drawingPanel;
private JLabel drawingLabel;
public static void main(String[] args) {
MainPanel.test();
}
private static void test() {
frame = new JFrame("");
frame.setBounds(100, 100, 640, 480);
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
new MainPanel();
frame.setVisible(true);
}
public MainPanel() {
initializeGui();
button1.addActionListener(e -> {
JFileChooser openFile = new JFileChooser("[...]");
File chosenFile;
if (openFile.showSaveDialog(panel1) == JFileChooser.APPROVE_OPTION) {
chosenFile = openFile.getSelectedFile();
System.out.println("chosenFile: " + chosenFile);
drawImage(chosenFile);
}
});
}
private void initializeGui() {
panel1 = new JPanel(new BorderLayout());
frame.getContentPane().add(panel1);
button1 = new JButton("Open image");
panel1.add(button1, BorderLayout.NORTH);
drawingPanel = new JPanel(new BorderLayout());
panel1.add(drawingPanel, BorderLayout.CENTER);
drawingLabel = new JLabel();
drawingPanel.add(new JScrollPane(drawingLabel), BorderLayout.CENTER);
}
private void drawImage(File file){
try {
BufferedImage image = ImageIO.read(file);
//Works OK if line below is removed, but doesn't adjust size so I can't scroll.
// drawingPanel.setSize(image.getWidth(), image.getHeight());
// Graphics g = drawingPanel.getGraphics();
// g.drawImage(image, 0, 0, null);
// drawingPanel.paintComponents(g);
drawingLabel.setIcon(new ImageIcon(image));
drawingPanel.validate();
}
catch (IOException e) {
e.printStackTrace();
}
}
}
Not sure how easy it is to do something similar with the IntelliJ GUI designer; I do prefer IntelliJ (over Eclipse and NetBeans) but I also prefer to create my Java GUIs in code... ;-)
I Have two files. One extends JFrame, and another Extends JPanel.
Whenever I change the size of the frame, whether it be maximizing, dragging, whatever, i want the ScrollPane to fit itself to the current size of the frame.
There's more to it, there's a top menubar and a bottom bar as well, but i left those out for simplicity.
Essentially, i want it to work like notepad.
right now, I use a ComponentListener on the frame that calls a setSize method in the the other class.
The setSize method is just:
public void resize(int x, int y)
{
textA.setPreferredSize(new Dimension(x, y-50));
areaScrollPane.setPreferredSize(new Dimension(x,y-50));
}
also, for reference:
public void componentResized(ComponentEvent e)
{
textA.resize(panel.getWidth(),panel.getHeight());
}
FYI, it extends JPanel because of the way I add it to the frame:
panel = (JPanel) this.getContentPane();
panel.setLayout(new BorderLayout());
panel.add(textA, BorderLayout.CENTER);
so what's the best way to do this?
Thanks!
Edit: Here's the scrollpane file. It's called textA in my main.
public class TextArea extends JPanel
{
JTextArea textA=new JTextArea(500,500);
JScrollPane areaScrollPane = new JScrollPane(textA);
Toolkit toolkit = Toolkit.getDefaultToolkit ();
Dimension dim = toolkit.getScreenSize();
Dimension dim2=(new Dimension((int)(dim.getWidth()),(int)(dim.getHeight()-120)));
public TextArea()
{
//textA.setLineWrap(true);
//textA.setWrapStyleWord(true);
textA.setEditable(true);
textA.setForeground(Color.WHITE);
textA.setBackground(Color.DARK_GRAY);
this.setFont(null);
areaScrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED);
areaScrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
areaScrollPane.setMinimumSize(new Dimension(300,300));
areaScrollPane.setSize(new Dimension(800,800));
textA.setPreferredSize(dim2);
areaScrollPane.setPreferredSize(dim2);
areaScrollPane.setMaximumSize(dim2);
add(areaScrollPane);
}
#Override
public void resize(int x, int y)
{
textA.setPreferredSize(new Dimension(x, y-50));
areaScrollPane.setPreferredSize(new Dimension(x,y-50));
}
}
and the main:
public class JEdit extends JFrame implements ComponentListener
{
TextArea textA=new TextArea();
JPanel panel;
/**
* #param args the command line arguments
*/
public static void main(String[] args)
{
JEdit run=new JEdit();
}
public JEdit()
{
setTitle("JEdit");
setLayout(new BorderLayout());
setSize(1100, 1000);
this.setMinimumSize(new Dimension(100,100));
//setBackground(Color.BLACK);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException ex) {
System.out.println("error1");
} catch (InstantiationException ex) {
System.out.println("error2");
} catch (IllegalAccessException ex) {
System.out.println("error3");
} catch (UnsupportedLookAndFeelException ex) {
System.out.println("error4");
}
panel = (JPanel) this.getContentPane();
panel.setLayout(new BorderLayout());
//TopBar top=new TopBar();
// PositionBar posB=new PositionBar();
panel.add(textA, BorderLayout.CENTER);
// add(top,BorderLayout.NORTH);
// add(posB,BorderLayout.SOUTH);
addComponentListener(this);
setVisible(true);
}
public void componentResized(ComponentEvent e)
{
textA.resize(panel.getWidth(),panel.getHeight());
}
public void componentMoved(ComponentEvent e) {
textA.resize(panel.getWidth(),panel.getHeight());
}
public void componentShown(ComponentEvent e) {
textA.resize(panel.getWidth(),panel.getHeight());
}
public void componentHidden(ComponentEvent e) {
textA.resize(panel.getWidth(),panel.getHeight());
}
}
Regarding the code you've posted, for one get rid of all calls to setSize -- these are generally not honored when using layout managers and get rid of all of your ComponentListener stuff as it's superfluous since you are using layout managers to resize things. The biggest problem I see though is that your allow your TextArea JPanel to use its default layout, which is FlowLayout, and doing so will prevent the JScrollPane that it holds from resizing. Give this class a BorderLayout (or better simply return a JScrollPane from the class), and you're set. e.g. with quick modifications and with renaming of classes to prevent clashes with the standard Java classes,
import java.awt.*;
import javax.swing.*;
#SuppressWarnings("serial")
public class JEdit2 extends JFrame {
TextArea2 textA = new TextArea2();
JPanel panel;
public static void main(String[] args) {
new JEdit2();
}
public JEdit2() {
setTitle("JEdit 2");
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
panel = (JPanel) this.getContentPane();
panel.add(textA, BorderLayout.CENTER);
pack(); //!! added
setLocationRelativeTo(null);
setVisible(true);
}
}
#SuppressWarnings("serial")
class TextArea2 extends JPanel {
JTextArea textA = new JTextArea(500, 500); // !! this is one friggin' huge JTextArea!
JScrollPane areaScrollPane = new JScrollPane(textA);
public TextArea2() {
textA.setEditable(true);
textA.setForeground(Color.WHITE);
textA.setBackground(Color.DARK_GRAY);
this.setFont(null);
setLayout(new BorderLayout()); //!! added
add(areaScrollPane, BorderLayout.CENTER);
}
}
By default a JFrame uses a BorderLayout (so there is no need to reset it). All you need to do is add the JScrollPane to the CENTER of the BorderLayout and it will resize automatically.
And the basic code would be:
JTextArea textArea = new JTextArea(...);
JScrollPane scrollPane = new JScrollPane();
frame.add(scrollPane, BorderLayout.CENTER);
I'm not sure why you are adding the text area to the center.
There is no need to use setPreferredSize() on any component or use a listener on any component.
If you need more help then you need to post a SSCCE.
I am doing slideshow of images program in java using timer.
In timer event listner i have added code to chnage image but image is not changing.
Below is the code i have written
class ImagePanel extends JPanel {
private Image backgroundImage;
public ImagePanel(Image backgroundImage) {
super();
this.backgroundImage = backgroundImage;
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(this.backgroundImage, 0, 0, null);
}
}
public class A extends JFrame{
static int counter;
List<String> imagePaths;
int nimgpaths=0;
static A frame = new A();
public static void main(String[] args) {
frame.setSize(1024, 768);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getPath();
/* Getting required image */
Image backgroundImage = null;
String pathToTheImage = "C:\\Documents and Settings\\Administrator\\My Documents\\My Pictures\\civ1.JPG";
try {
backgroundImage = ImageIO.read(new File(pathToTheImage));
} catch (IOException e) {
e.printStackTrace();
}
/* Initializing panel with the our image */
ImagePanel panel = new ImagePanel(backgroundImage);
frame.getContentPane().add(panel);
frame.setVisible(true);
frame.timerEvent();
//frame.show();
}
public void timerEvent(){
Timer timer = new Timer(5000, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("Time event occured");
if(counter > nimgpaths)
counter=0;
String imgPath=imagePaths.get(counter);
Image backgroundImage = null;
try {
backgroundImage = ImageIO.read(new File(imgPath));
}catch (Exception e1) {
e1.printStackTrace();
}
/* Initializing panel with the our image */
frame.removeAll();
ImagePanel panel = new ImagePanel(backgroundImage);
panel.repaint();
//panel.setBackground(backgroundImage);
frame.getContentPane().add(panel);
}
});
timer.start();
}
// To get path of images
public void getPath(){
DbOps db=new DbOps();
imagePaths=db.getPath();
nimgpaths=imagePaths.size();
for(Iterator i=imagePaths.iterator();i.hasNext();){
System.out.println((String)i.next());
}
}
}
Why are you using a custom panel and painting?
Your code is simply painting the image at its preferred size. This functionality is available when you use a JLabel. Then when you use the label all you need to do is use:
label.setIcon(....);
when you want to change the image. Read the section from the Swing tutorial on How to Use Icons for more information.
The only reason to create a custom component is if you plan to scale the image or do something fancy like that. If this is the case then you can use something like the Background Panel which supports scaled images as well as a setImage() method so you can change the image dynamically.
A much better design for ImagePanel would let you just replace the image, rather than removing the component. If you do have to replace a visible component, though, you have to call validate() on its container, or the new one isn't going to show up (most of the time, anyway.) I think that's your problem here.
frame.removeAll() is not doing what you would expect - it is removing the components from the frame itself rather than removing the components from the content pane of the frame. Change the code at the end of the timer's action listener to something like this to fix it:
ImagePanel panel = new ImagePanel(backgroundImage);
frame.getContentPane().removeAll();
frame.getContentPane().add(panel);
frame.getContentPane().invalidate();
frame.getContentPane().validate();
Your concept itself is wrong.
You can refresh the panel like so:
public void refreshPanel(JPanel panel){
panel.removeAll();
panel.invalidate();
panel.validate();
}
Problem:
I see in your code that you are trying to create more than one object of the same panel, which you need to refresh.
It would be better to create one panel object and refresh that object.
ImagePanel panel = new ImagePanel(backgroundImage);
Hope you can understand what I wanted to explain to you.
If you are still confused then let me know.