Current state:
I have a JPanel object which contains complex components(3D-canvas written by myself).
Problem:
There is two screen devices now. I want to use one for control, another just for display, just like PowerPoint. How can I display this JPanel on another screen efficiently(static view is enough, but I want it to reflect the change on control screen?
What I have tried:
I have tried to draw the static picture to another JPanel every 200ms.
Graphics2D g2 = (Graphics2D) contentPanel.getGraphics();
g2.translate(x, y);
g2.scale(scale, scale);
displayPanel.paintAll(g2);
Notes: contentPanel is in a JFrame of display screen, displayerPanel is the panel I want to copy
But I get a problem that the display screen flicker so seriously that I can not accept this...Is it the problem of my CPU or graphics card? Or is these any efficient method I can use? Please help, thanks so much!
And here is the MCVE (sorry, this is my first time asking question in stackoverflow, but I am touched by your helps! Thanks again!)
import javax.swing.*;
import java.awt.*;
import java.util.*;
import java.util.Timer;
public class DisplayWindow {
private static JFrame frame = new JFrame();
private static JPanel contentPanel = new JPanel();
private static JPanel displayPanel = null;
private static Timer timerDisplay = null;
static {
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setBounds(50, 50, 1366, 768);
frame.getContentPane().add(contentPanel);
frame.setVisible(true);
if (timerDisplay == null) {
timerDisplay = new java.util.Timer();
timerDisplay.schedule(new DisplayAtFixedRate(), 1000, 250);
}
}
public static void display(JPanel panel) {
displayPanel = panel;
}
private static class DisplayAtFixedRate extends TimerTask {
#Override
public void run() {
if (displayPanel != null && displayPanel.getWidth() != 0) {
double windowWidth = frame.getWidth();
double windowHeight = frame.getHeight();
double panelWidth = displayPanel.getWidth();
double panelHeight = displayPanel.getHeight();
double scale = Math.min(windowWidth / panelWidth, windowHeight / panelHeight);
int x = (int) (windowWidth - panelWidth * scale) / 2;
int y = (int) (windowHeight - panelHeight * scale) / 2;
Graphics2D g2 = (Graphics2D) contentPanel.getGraphics();
g2.translate(x, y);
g2.scale(scale, scale);
displayPanel.paintAll(g2);
}
}
}
public static void main(String[] args) {
JFrame controlFrame = new JFrame();
controlFrame.setBounds(50, 50, 1366, 768);
JPanel controlPanel = new JPanel();
controlFrame.getContentPane().add(controlPanel, BorderLayout.CENTER);
controlPanel.add(new JLabel("Hello Stackoverflow!"));
controlFrame.setVisible(true);
DisplayWindow.display(controlPanel);
}
}
Here is an example for you:
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Image;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferedImage;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.JTree;
import javax.swing.SwingUtilities;
import javax.swing.Timer;
import javax.swing.WindowConstants;
public class PaintImage {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
startUI();
}
});
}
private static void startUI() {
final JFrame mainFrm = new JFrame("Main");
final JFrame paintFrame = new JFrame("Copy");
mainFrm.add(new JScrollPane(new JTree()), BorderLayout.WEST);
mainFrm.add(new JScrollPane(new JTextArea("Write your text here...")), BorderLayout.CENTER);
mainFrm.pack();
mainFrm.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
mainFrm.setLocationRelativeTo(null);
final JLabel label = new JLabel("");
paintFrame.add(label);
paintFrame.setSize(mainFrm.getSize());
paintFrame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
mainFrm.setVisible(true);
paintFrame.setVisible(true);
final Timer t = new Timer(200, new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
final Image img = getScreenShot(mainFrm.getContentPane());
label.setIcon(new ImageIcon(img));
}
});
t.start();
}
public static BufferedImage getScreenShot(Component component) {
final BufferedImage image = new BufferedImage(
component.getWidth(),
component.getHeight(),
BufferedImage.TYPE_INT_RGB
);
// call the Component's paint method, using
// the Graphics object of the image.
component.paint( image.getGraphics() ); // alternately use .printAll(..)
return image;
}
}
Origin of method getScreenShot is here
The painting can be done by passing the displayPanel to draw itself.
class DuplicatePanel extends JPanel {
private final JPanel displayPanel;
DuplicatePanel(JPanel displayPanel) {
this.displayPanel = displayPanel;
}
#Override
public void paintComponent(Graphics g) {
displayPanel.paintComponent(g);
}
}
To trigger the repaints, like repaint(50L) either use a SwingTimer or your own manual repaints.
Related
I want to have a text field to input an integer, then select 1) Grow or 2) Shrink, and then click the button so that the circle gets redrawn on the screen based on the selected options.
I don't know why it isn't repaining. (Don't worry about the layout, just want to get it to work first)
My Frame:
public class Main {
public static void main(String[] args) {
var frame = new JFrame();
frame.setSize(400,400);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setVisible(true);
var circleComp = new circleComponent();
var panel1 = new JPanel();
var multiplierLabel = new JLabel("Grow Multiplier");
var multiplierField = new JTextField(20);
var radio1 = new JRadioButton("Grow Circle");
var radio2 = new JRadioButton("Shrink Circle");
var bg = new ButtonGroup();
bg.add(radio1);
bg.add(radio2);
JButton button = new JButton("Rivizato");
button.addActionListener(
new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if(radio1.isSelected()){
rrComp.repaint(0,0,Integer.parseInt(multiplierField.getText())*rrComp.getWidth(), Integer.parseInt(multiplierField.getText())*rrComp.getHeight());
}
else if(radio2.isSelected()){
rrComp.repaint(0,0,Integer.parseInt(multiplierField.getText())/rrComp.getWidth(), Integer.parseInt(multiplierField.getText())/rrComp.getHeight());
}
}
}
);
panel1.add(multiplierLabel);
panel1.add(multiplierField);
panel1.add(button);
panel1.add(radio1);
panel1.add(radio2);
frame.add(panel1);
frame.add(circleComp);
}
}
My CircleComponent class:
public class CircleComponent extends JComponent {
public void paintComponent(Graphics g){
super.paintComponent(g);
var g2 = (Graphics2D) g;
var circle = new Ellipse2D.Double(0,0,100,100);
g2.draw(circle);
}
}
var circle = new Ellipse2D.Double(0,0,100,100); means that your circle will never change size.
You should also be careful with repaint(x, y, width, height) as it could leave regions of your component "dirty". Better to just use repaint.
As a conceptual example...
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Ellipse2D;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public final class Main {
public static void main(String[] args) {
new Main();
}
public Main() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.add(new MainPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class MainPane extends JPanel {
private CirclePane circlePane;
public MainPane() {
setLayout(new BorderLayout());
JPanel actionsPane = new JPanel(new GridBagLayout());
JButton growButton = new JButton("Grow");
growButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
circlePane.grow();
}
});
JButton shrinkButton = new JButton("Shrink");
shrinkButton.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
circlePane.shrink();
}
});
actionsPane.add(growButton);
actionsPane.add(shrinkButton);
circlePane = new CirclePane();
add(circlePane);
add(actionsPane, BorderLayout.SOUTH);
}
}
public class CirclePane extends JPanel {
private Ellipse2D circle;
public CirclePane() {
circle = new Ellipse2D.Double(0, 0, 100, 100);
}
public void grow() {
double width = circle.getWidth() + 10;
double height = circle.getHeight() + 10;
circle.setFrame(0, 0, width, height);
repaint();
}
public void shrink() {
double width = Math.max(0, circle.getWidth() - 10);
double height = Math.max(0, circle.getHeight() - 10);
circle.setFrame(0, 0, width, height);
repaint();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
double x = (getWidth() - circle.getWidth()) / 2d;
double y = (getHeight() - circle.getHeight()) / 2d;
g2d.translate(x, y);
g2d.draw(circle);
g2d.dispose();
}
}
}
nb: I know I've not used JTextField to specify the size of the circle, that's on purpose. You will need to adapt your requirements to work in a similar way - can you see where you might pass parameters to the CirclePane?
After learning that dispose() should be called on Graphics/Graphics2D object after use, I went about changing my game to incorporate this.
When I added g2d.dispose() in overridden paintComponent(Graphics g) of JPanel, my components which I added (extensions of JLabel class) where not rendered I was able to still click on them etc but they would not be painted.
I tested with a normal JLabel and JButton with same effect (though JButton is rendered when mouse is over it).
So my question is why does this happen?
Here is an SSCCE to demonstrate:
after uncommenting call to dispose() in paintComponent of MainMenuPanel class:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.net.URL;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Test {
public Test() {
try {
initComponents();
} catch (Exception ex) {
Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Test();
}
});
}
private void initComponents() throws Exception {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(false);
MainMenuPanel mmp = new MainMenuPanel();
frame.add(mmp);
frame.pack();
frame.setVisible(true);
}
}
class MainMenuPanel extends JPanel {
//create labels for Main Menu
private PopUpJLabel versusesModeLabel;
private PopUpJLabel singlePlayerModeLabel;
private PopUpJLabel optionsLabel;
private PopUpJLabel helpLabel;
private PopUpJLabel aboutLabel;
//create variable to hold background
private Image background;
private Dimension preferredDimensions;
public static String gameType;
public static final String SINGLE_PLAYER = "Single Player", VERSUS_MODE = "VS Mode";
/**
* Default constructor to initialize double buffered JPanel with
* GridBagLayout
*/
public MainMenuPanel() {
super(new GridBagLayout(), true);
try {
initComponents();
} catch (Exception ex) {
JOptionPane.showMessageDialog(null, "Could not load main menu background!", "Main Menu Error: 0x004", JOptionPane.ERROR_MESSAGE);
System.exit(4);
}
}
/*
* Create JPanel and its components
*/
private void initComponents() throws Exception {
//set prefered size of JPanel
preferredDimensions = new Dimension(800, 600);
background = scaleImage(800, 600, ImageIO.read(new URL("http://photos.appleinsider.com/12.08.30-Java.jpg")));
//create label instances
singlePlayerModeLabel = new PopUpJLabel("Single Player Mode");
singlePlayerModeLabel.setEnabled(false);
versusesModeLabel = new PopUpJLabel("Versus Mode");
optionsLabel = new PopUpJLabel("Options");
helpLabel = new PopUpJLabel("Help");
aboutLabel = new PopUpJLabel("About");
//create new constraints for gridbag
GridBagConstraints gc = new GridBagConstraints();
gc.fill = GridBagConstraints.HORIZONTAL;
gc.ipady = 50;//vertical spacing
//add newGameLabel to panel with constraints
gc.gridx = 0;
gc.gridy = 0;
add(singlePlayerModeLabel, gc);
gc.gridy = 1;
add(versusesModeLabel, gc);
//add optionsLabel to panel with constraints (x is the same)
gc.gridy = 2;
add(optionsLabel, gc);
//add helpLabel to panel with constraints (x is the same)
gc.gridy = 3;
add(helpLabel, gc);
//add aboutLabel to panel with constraints (x is the same)
gc.gridy = 4;
add(aboutLabel, gc);
}
public static BufferedImage scaleImage(int w, int h, BufferedImage img) throws Exception {
BufferedImage bi;
//bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
bi = new BufferedImage(w, h, img.getType());
Graphics2D g2d = (Graphics2D) bi.createGraphics();
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY));
g2d.drawImage(img, 0, 0, w, h, null);
g2d.dispose();
return bi;
}
/*
* Will return the preffered size of JPanel
*/
#Override
public Dimension getPreferredSize() {
return preferredDimensions;
}
/*
* Will draw the background to JPanel with anti-aliasing on and quality rendering
*/
#Override
protected void paintComponent(Graphics grphcs) {
super.paintComponent(grphcs);
//convert graphics object to graphics2d object
Graphics2D g2d = (Graphics2D) grphcs;
//set anti-aliasing on and rendering etc
//GamePanel.applyRenderHints(g2d);
//draw the image as the background
g2d.drawImage(background, 0, 0, null);
//g2d.dispose();//if I uncomment this no LAbels will be shown
}
}
class PopUpJLabel extends JLabel {
public final static Font defaultFont = new Font("Arial", Font.PLAIN, 50);
public final static Font hoverFont = new Font("Arial", Font.BOLD, 70);
PopUpJLabel(String text) {
super(text);
setHorizontalAlignment(JLabel.CENTER);
setForeground(Color.ORANGE);
setFont(defaultFont);
//allow component to be focusable
setFocusable(true);
//add focus adapter to change fints when focus is gained or lost (used for transversing labels with keys)
addFocusListener(new FocusAdapter() {
#Override
public void focusGained(FocusEvent fe) {
super.focusGained(fe);
if (isEnabled()) {
setFont(getHoverFont());
}
}
#Override
public void focusLost(FocusEvent fe) {
super.focusLost(fe);
setFont(getDefaultFont());
}
});
addMouseListener(new MouseAdapter() {
#Override
public void mouseEntered(MouseEvent me) {
super.mouseEntered(me);
if (isEnabled()) {
setFont(getHoverFont());
}
//call for focus mouse is over this component
requestFocusInWindow();
}
});
}
Font getDefaultFont() {
return defaultFont;
}
Font getHoverFont() {
return hoverFont;
}
}
The thing is that the Graphics context you are using in paintComponent is created and provided by the caller (the framework), which is also responsible for disposing of it.
You only need to dispose of Graphics when you actually create it yourself (for example by calling Component.getGraphics()). In your case, you're not creating it, you're just casting it, so do not call dispose in this case.
Because .dispose() releases your resources. Yes, everything.
After learning that dispose() should be called on Graphics/Graphics2D object after use, I went about changing my game to incorporate this.
When I added g2d.dispose() in overridden paintComponent(Graphics g) of JPanel, my components which I added (extensions of JLabel class) where not rendered I was able to still click on them etc but they would not be painted.
I tested with a normal JLabel and JButton with same effect (though JButton is rendered when mouse is over it).
So my question is why does this happen?
Here is an SSCCE to demonstrate:
after uncommenting call to dispose() in paintComponent of MainMenuPanel class:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.event.FocusAdapter;
import java.awt.event.FocusEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.net.URL;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JOptionPane;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class Test {
public Test() {
try {
initComponents();
} catch (Exception ex) {
Logger.getLogger(Test.class.getName()).log(Level.SEVERE, null, ex);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new Test();
}
});
}
private void initComponents() throws Exception {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setResizable(false);
MainMenuPanel mmp = new MainMenuPanel();
frame.add(mmp);
frame.pack();
frame.setVisible(true);
}
}
class MainMenuPanel extends JPanel {
//create labels for Main Menu
private PopUpJLabel versusesModeLabel;
private PopUpJLabel singlePlayerModeLabel;
private PopUpJLabel optionsLabel;
private PopUpJLabel helpLabel;
private PopUpJLabel aboutLabel;
//create variable to hold background
private Image background;
private Dimension preferredDimensions;
public static String gameType;
public static final String SINGLE_PLAYER = "Single Player", VERSUS_MODE = "VS Mode";
/**
* Default constructor to initialize double buffered JPanel with
* GridBagLayout
*/
public MainMenuPanel() {
super(new GridBagLayout(), true);
try {
initComponents();
} catch (Exception ex) {
JOptionPane.showMessageDialog(null, "Could not load main menu background!", "Main Menu Error: 0x004", JOptionPane.ERROR_MESSAGE);
System.exit(4);
}
}
/*
* Create JPanel and its components
*/
private void initComponents() throws Exception {
//set prefered size of JPanel
preferredDimensions = new Dimension(800, 600);
background = scaleImage(800, 600, ImageIO.read(new URL("http://photos.appleinsider.com/12.08.30-Java.jpg")));
//create label instances
singlePlayerModeLabel = new PopUpJLabel("Single Player Mode");
singlePlayerModeLabel.setEnabled(false);
versusesModeLabel = new PopUpJLabel("Versus Mode");
optionsLabel = new PopUpJLabel("Options");
helpLabel = new PopUpJLabel("Help");
aboutLabel = new PopUpJLabel("About");
//create new constraints for gridbag
GridBagConstraints gc = new GridBagConstraints();
gc.fill = GridBagConstraints.HORIZONTAL;
gc.ipady = 50;//vertical spacing
//add newGameLabel to panel with constraints
gc.gridx = 0;
gc.gridy = 0;
add(singlePlayerModeLabel, gc);
gc.gridy = 1;
add(versusesModeLabel, gc);
//add optionsLabel to panel with constraints (x is the same)
gc.gridy = 2;
add(optionsLabel, gc);
//add helpLabel to panel with constraints (x is the same)
gc.gridy = 3;
add(helpLabel, gc);
//add aboutLabel to panel with constraints (x is the same)
gc.gridy = 4;
add(aboutLabel, gc);
}
public static BufferedImage scaleImage(int w, int h, BufferedImage img) throws Exception {
BufferedImage bi;
//bi = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
bi = new BufferedImage(w, h, img.getType());
Graphics2D g2d = (Graphics2D) bi.createGraphics();
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2d.addRenderingHints(new RenderingHints(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY));
g2d.drawImage(img, 0, 0, w, h, null);
g2d.dispose();
return bi;
}
/*
* Will return the preffered size of JPanel
*/
#Override
public Dimension getPreferredSize() {
return preferredDimensions;
}
/*
* Will draw the background to JPanel with anti-aliasing on and quality rendering
*/
#Override
protected void paintComponent(Graphics grphcs) {
super.paintComponent(grphcs);
//convert graphics object to graphics2d object
Graphics2D g2d = (Graphics2D) grphcs;
//set anti-aliasing on and rendering etc
//GamePanel.applyRenderHints(g2d);
//draw the image as the background
g2d.drawImage(background, 0, 0, null);
//g2d.dispose();//if I uncomment this no LAbels will be shown
}
}
class PopUpJLabel extends JLabel {
public final static Font defaultFont = new Font("Arial", Font.PLAIN, 50);
public final static Font hoverFont = new Font("Arial", Font.BOLD, 70);
PopUpJLabel(String text) {
super(text);
setHorizontalAlignment(JLabel.CENTER);
setForeground(Color.ORANGE);
setFont(defaultFont);
//allow component to be focusable
setFocusable(true);
//add focus adapter to change fints when focus is gained or lost (used for transversing labels with keys)
addFocusListener(new FocusAdapter() {
#Override
public void focusGained(FocusEvent fe) {
super.focusGained(fe);
if (isEnabled()) {
setFont(getHoverFont());
}
}
#Override
public void focusLost(FocusEvent fe) {
super.focusLost(fe);
setFont(getDefaultFont());
}
});
addMouseListener(new MouseAdapter() {
#Override
public void mouseEntered(MouseEvent me) {
super.mouseEntered(me);
if (isEnabled()) {
setFont(getHoverFont());
}
//call for focus mouse is over this component
requestFocusInWindow();
}
});
}
Font getDefaultFont() {
return defaultFont;
}
Font getHoverFont() {
return hoverFont;
}
}
The thing is that the Graphics context you are using in paintComponent is created and provided by the caller (the framework), which is also responsible for disposing of it.
You only need to dispose of Graphics when you actually create it yourself (for example by calling Component.getGraphics()). In your case, you're not creating it, you're just casting it, so do not call dispose in this case.
Because .dispose() releases your resources. Yes, everything.
I'm trying to call my paintComponent method by using repaint but it is never being called. This is my first class:
public class start
{
public static void main(String[] args){
Frame f = new Frame();
f.createFrame();
}
}
And this is the class that I want the paintComponent method to be called to but all that happens is a blank frame appears:
import javax.swing.JButton;
import javax.swing.JComponent;
import java.awt.Graphics;
import javax.swing.JFrame;
import java.awt.image.*;
import javax.swing.Icon;
import javax.swing.ImageIcon;
import java.awt.event.*;
import java.awt.*;
import javax.swing.*;
import javax.swing.Timer;
public class Frame implements Runnable,ActionListener
{
JFrame window = new JFrame("Frame");
int i = 0;
Canvas myCanvas = new Canvas();
public void createFrame(){
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setBounds(30, 30, 700, 500);
window.setFocusable(true);
window.setFocusTraversalKeysEnabled(false);
window.setVisible(true);
(new Thread(new Frame())).start();
}
public void run(){
Timer timer = new Timer (17,this);
timer.start();
}
public void actionPerformed(ActionEvent e){
myCanvas.updateGame();
myCanvas.render();
window.add(myCanvas);
}
}
class Canvas extends JPanel{
int x = 10;
int y = 10;
public void updateGame(){
x++;
}
public void render(){
repaint();
System.out.println("repaint");
}
#Override
protected void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g.drawString("hi",x,y);
System.out.println("paint");
}
}
Repaint is called multiple times but paint is never called. Why isn't the paintComponent method being called by repaint?
Instead of creating a new frame, pass in the existing frame, I've commented the line below:
public void createFrame(){
window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
window.setBounds(30, 30, 700, 500);
window.setFocusable(true);
window.setFocusTraversalKeysEnabled(false);
window.setVisible(true);
(new Thread(new Frame())).start(); <--- instead of creating a new frame, pass in the existing frame
}
You should really consider the following improvements as well:
1) Don't name your class Frame, as it collides with Frame
2) Move the body of createFrame as well as the following three lines:
JFrame window = new JFrame("Frame");
int i = 0;
Canvas myCanvas = new Canvas();
Into a constructor and make these local variables like Canvas into member fields.
3) Remove the last line that creates the thread out of the constructor, and expose it as a method (e.g 'startAnimation') and call it after you've created your object.
EDIT:
Try this:
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
public class Frame implements Runnable, ActionListener
{
final JFrame window;
final Canvas myCanvas;
public Frame(){
this.window = new JFrame("Frame");
this.myCanvas = new Canvas();
this.window.add(this.myCanvas);
this.window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.window.setBounds(30, 30, 700, 500);
this.window.setFocusable(true);
this.window.setFocusTraversalKeysEnabled(false);
this.window.setVisible(true);
}
public void startApp() {
final Thread t = new Thread(this);
t.start();
}
public void run(){
final Timer timer = new Timer (1000,this);
timer.start();
}
public void actionPerformed(ActionEvent e){
myCanvas.updateGame();
window.repaint();
}
public static void main(String[] args) {
final Frame f = new Frame();
f.startApp();
}
}
class Canvas extends JPanel {
int x = 10;
int y = 10;
public void updateGame() {
x++;
}
#Override
protected void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D g2 = (Graphics2D) g;
g.drawString("hi", this.x, this.y);
System.out.println("paint");
}
}
There is a window in which I want to place a button, and then paint the whole area beneath it. In other words, button should cover a piece of painting.
import java.awt.*;
import javax.swing.*;
class Window
{
private JFrame frame;
private JButton launchButton;
private JPanel pnllaunchButton;
private JPanel paintingPanel;
//width and height of client area
private Rectangle dim;
//w,h - width and height of the whole window
public Window(String title,int w,int h)
{
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocation(0,0);
frame.setMinimumSize( new Dimension(110,110));
frame.setSize(w, h);
frame.setVisible(true);
frame.setTitle(title);
frame.setResizable(false);
addLaunchButton();
}
private void addLaunchButton()
{
pnllaunchButton = new JPanel();
launchButton = new JButton("Plot!");
dim = new Rectangle();
frame.getContentPane().getBounds(dim);
pnllaunchButton.setBounds(dim.width-100,dim.height-25,100,25);
launchButton.setBounds(dim.width-100,dim.height-25,100,25);
pnllaunchButton.setLayout(null);
pnllaunchButton.add(launchButton);
frame.getContentPane().add(pnllaunchButton);
frame.getContentPane().setComponentZOrder(pnllaunchButton, new Integer(2));
}
public void drawCoordinateSystem()
{
paintingPanel = new JPanel();
paintingPanel.add(new CoordinateSystem());
frame.getContentPane().add(paintingPanel);
frame.getContentPane().setComponentZOrder(paintingPanel,new Integer(3));
}
}
class CoordinateSystem extends JPanel
{
#Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
Dimension size = this.getSize();
g.setColor(Color.BLACK);
g.drawLine(0,size.height/2,size.width, size.height/2);
g.drawLine(size.width/2, 0, size.width/2, size.height);
}
}
public class GC {
public static void main(String[] args)
{
Window h = new Window("GC",800,600);
h.drawCoordinateSystem();
}
}
This code doesn't fulfill the specification. Program creates an empty window and outputs:
run:
Exception in thread "main" java.lang.IllegalArgumentException: illegal component position
at java.awt.Container.checkAdding(Container.java:504)
at java.awt.Container.setComponentZOrder(Container.java:759)
at Window.addLaunchButton(Window.java:46)
at Window.<init>(Window.java:26)
at GC.main(GC.java:10)
Could you point out my mistake? setComponentZOrder() method doesn't seem to be described precisely in javadoc.
Rename your class. The Window class is already part of the standard core Java libraries, and your class name could cause present or future problems.
Don't us null layouts and setBounds(...). This is bad, bad, bad, and will make it very difficult to maintain or upgrade your application. Instead, learn about and use the layout managers.
Consider making a JLabel the contentPane, make it opaque, give it a layout and an ImageIcon and add your components to it.
The ImageIcon can hold a BufferedImage with a grid.
For example:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.GradientPaint;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import javax.swing.*;
public class MyWindow {
private static final int PREF_W = 800;
private static final int PREF_H = 600;
private static final Color COLOR0 = Color.red;
private static final Color COLOR1 = Color.blue;
private static final float COLOR_REPEAT_DIST = 30f;
private JLabel backGroundLabel = new JLabel();
public MyWindow() {
backGroundLabel.setOpaque(true);
backGroundLabel.setLayout(new BorderLayout());
int eb = 15;
BufferedImage bkgrndImg = createBkgrndImage();
ImageIcon icon = new ImageIcon(bkgrndImg);
backGroundLabel.setIcon(icon);
JPanel bottomPanel = new JPanel();
bottomPanel.setLayout(new FlowLayout(SwingConstants.RIGHT, eb, eb));
bottomPanel.setOpaque(false);
bottomPanel.add(new JButton("Plot"));
backGroundLabel.add(bottomPanel, BorderLayout.PAGE_END);
}
private BufferedImage createBkgrndImage() {
BufferedImage img = new BufferedImage(PREF_W, PREF_H, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = img.createGraphics();
g2.setPaint(new GradientPaint(0f, 0f, COLOR0, COLOR_REPEAT_DIST, COLOR_REPEAT_DIST, COLOR1, true));
g2.fillRect(0, 0, PREF_W, PREF_H);
g2.dispose();
return img;
}
public JComponent getMainPane() {
return backGroundLabel;
}
private static void createAndShowGui() {
MyWindow mainPanel = new MyWindow();
JFrame frame = new JFrame("MyWindow");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel.getMainPane());
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
Which looks like so:
Pass an int instead of an Integer to the setComponentZOrder method.
private void addLaunchButton()
{
pnllaunchButton = new JPanel();
launchButton = new JButton("Plot!");
dim = new Rectangle();
frame.getContentPane().getBounds(dim);
pnllaunchButton.setBounds(dim.width-100,dim.height-25,100,25);
launchButton.setBounds(dim.width-100,dim.height-25,100,25);
pnllaunchButton.setLayout(null);
pnllaunchButton.add(launchButton);
frame.getContentPane().add(pnllaunchButton);
frame.getContentPane().setComponentZOrder(pnllaunchButton, 2);
}