I am trying to make a simple java game, and i got stumped on this. The game requires that you play in a square window, but can resize the sprites on the canvas. I though it would be really annoying if I used a ComponentListener and didn't let the user change size, so I thought that I would just offset the canvas from the left and right side so that it is centered until it is square.
Right now I understand that I need to create a Canvas object for the Game, and then offset it but I'm not sure how.
Game Canvas:
public class GameCanvas extends Canvas {
public Vector size;
public GameCanvas(Vector size) {
this.size = size;
setBackground(Color.BLUE);
setSize(size.x, size.y);
}
}
Any help is appreciated :) thank you.
You could...
Make your own layout manager which maintained the Canvas in a square shape based on the available space of the parent Container.
This might be a little bit of over kill, but, it's generally more efficient and means you can keep using the properties of the Canvas (ie getWidth and getHeight), so it's more de-coupled from other solutions
You could...
Calculate a "playable area" based on the size of the Canvas and use that as the bounds range checking, for example...
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
protected Rectangle getPlayableBounds() {
Dimension size = getSize();
int playableSize = Math.min(size.width, size.height);
int x = (size.width - playableSize) / 2;
int y = (size.height - playableSize) / 2;
return new Rectangle(x, y, playableSize, playableSize);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(Color.BLACK);
g2d.draw(getPlayableBounds());
g2d.dispose();
}
}
}
This example is not optimised, as calling getPlayableBounds recalculates the playable area, regardless if its changed since the last call or not.
I'd be tempted to use a ComponentListener and make the playableBounds an instance field. When the component is resized, I'd simply invalidate the playableBounds property, which would force the getPlayableBounds to recalculate the value and cache the result
Related
I started programming in SWING class recently and I try to set Image (like Space) and on it image(like spaceShip) like background. I
would love for you to help me,
Here is my code
public class SpaceWar {
static JFrame frame = new JFrame("Space War");
static JPanel panel = new JPanel();
public static void main(String[] args) {
new SpaceWar();
//frame.setResizable(false);
frame.setVisible(true);
}
public SpaceWar() {
frame.setExtendedState(JFrame.MAXIMIZED_BOTH);
Dimension size
= Toolkit.getDefaultToolkit().getScreenSize();
frame.setPreferredSize(size);
frame.setLayout(null);
panel.setLayout(null);
panel.setBounds(frame.getPreferredSize().width/4,0,
frame.getPreferredSize().width/2,frame.getPreferredSize().height);
frame.add(panel);
frame.add(new Background());
spaceShip sp1 = new spaceShip();
panel.setBackground(Color.black);
panel.add(sp1);
System.out.println(panel.getPreferredSize().width);
}
}
class spaceShip extends JLabel{
static ImageIcon img = new ImageIcon("spaceShip.png");
public spaceShip(){
sizeIcon(100,100,img);
setIcon(img);
}
public static ImageIcon sizeIcon(int w,int h,ImageIcon image1){
Image image = image1.getImage(); // transform it
Image newimg = image.getScaledInstance(w,h, java.awt.Image.SCALE_SMOOTH); // scale it the smooth way
ImageIcon img1 = new ImageIcon(newimg); // transform it back
return img1;
}
}
class Background extends JPanel{
public void paint(Graphics g) { // paint() method
super.paint(g);
ImageIcon image = new ImageIcon("space.jpg");
Image bg = image.getImage();
g.drawImage(bg,0,0,null);
}
}
So, your "core" problem is the use of null layouts and a lack of understand of how components are sized and positioned. Having said that, if your aim is to make a game, this probably isn't the best approach anyway.
Instead, I'd focus on creating a "surface", onto which you can paint all your assets directly, this will give you much greater control.
Start by taking a look at Painting in AWT and Swing and Performing Custom Painting to get a better understanding how the paint system works and how you can work with it to perform custom painting.
I'd also avoid ImageIcon, it's not the best way to handle images, instead, take a look at ImageIO (Reading/Loading an Image), it will generate an IOException if the image can't be loaded and will return a fully realised image (unlike ImageIcon which off loads the image loading to a background thread).
For example...
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Main {
public static void main(String[] args) {
new Main();
}
public Main() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
JFrame frame = new JFrame();
frame.add(new MainPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (IOException ex) {
Logger.getLogger(Main.class.getName()).log(Level.SEVERE, null, ex);
}
}
});
}
public class MainPane extends JPanel {
private BufferedImage ufo;
private BufferedImage background;
private int horizontalPosition = 106;
public MainPane() throws IOException {
ufo = ImageIO.read(getClass().getResource("/images/ufo.png"));
background = ImageIO.read(getClass().getResource("/images/starfield.png"));
System.out.println("background = " + background);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
paintBackground(g2d);
paintUFO(g2d);
g2d.dispose();
}
protected void paintBackground(Graphics2D g2d) {
int x = (getWidth() - background.getWidth()) / 2;
int y = (getHeight() - background.getHeight()) / 2;
g2d.drawImage(background, x, y, this);
}
protected void paintUFO(Graphics2D g2d) {
int x = (getWidth() - ufo.getWidth()) / 2;
int y = (getHeight() - ufo.getHeight()) / 2;
g2d.drawImage(ufo, x, y, this);
}
}
}
The example makes use of embedded resources (something to read up on). Managing your assets this way will save you countless hours of wondering why they aren't loading/working. How you achieve this will come down to your IDE and build system, for example, Netbeans and Eclipse will allow you to add resources directly to the src directory, when you're not using maven.
At some point, you're going to want to learn about How to Use Swing Timers and How to Use Key Bindings
When I try to draw a JLabel or my GUI, whatever I add to my JFrame last is drawn and the rest is just never drawn or painted over. I would appreciate if you could help me find a solution to draw the JLabel at a specific place along with my GUI. I have heard about layout and how it could help me with that, but there were many different people saying different things about this subject. Here is my code.
import java.util.*;
import java.awt.*;
import javax.swing.*;
import javax.swing.Timer;
import javax.swing.JPanel;
import javax.swing.JFrame;
import static java.lang.System.*;
import java.awt.event.*;
import java.awt.Graphics.*;
public class Main extends JPanel
{
Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
double w = screenSize.getWidth();
double h = screenSize.getHeight();
static JFrame f = new JFrame("Tic-Tac-Toe");
static JPanel p = new JPanel();
int width = (int)w;
int height = (int)h;
int width1a = width/2 - 300;
int width2a = width/2 - 100;
int width3a = width/2 + 100;
int width4a = width/2 + 300;
int height1from = (int)height - 100;
int height1to = (int)height - (int)(height/1.05);
public void paintComponent(Graphics g)
{
super.paintComponent(g);
JLabel l = new JLabel("Hello World !");
f.add(l);
Graphics2D g2 = (Graphics2D) g;
g2.setStroke(new BasicStroke(10));
g.setColor(Color.black);
g2.drawLine(width1a, height1from, width1a, height1to);
g2.drawLine(width2a, height1from, width2a, height1to);
g2.drawLine(width3a, height1from, width3a, height1to);
g2.drawLine(width4a, height1from, width4a, height1to);
}
public static void main(String[] args)
{
Main m = new Main();
f.setSize(400,300);
f.setExtendedState(Frame.MAXIMIZED_BOTH);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
JLabel l = new JLabel("Hello World !");
f.add(p);
f.add(m);
}
}
Please tell me if I was unclear or anything. I just want the JLabel and the GUI drawings to appear on the JFrame. Feel free to suggest anything I should redo and thank you for your time!
You don't, ever, add components to a component from within a paint method. You should never modify the state of a component in any way from within a paint method, painting is for painting, nothing else.
See Painting in AWT and Swing and
Performing Custom Painting for more details about how painting works in Swing...
You are adding three components to the same position within a BorderLayout, generally, only the last component would normally be shown, as it's the one that is been managed by the BorderLayout
See Laying Out Components Within a Container and How to Use BorderLayout for more details.
You should also make sure that you are creating your UI from within the context of the Event Dispatching Thread, see Initial Threads for more details
Painting is also contextual to the component been painted, that is, the 0x0 is the top left corner of the component, any painting done beyond the visual range of the component is simply lost.
You should also avoid the use of static, generally, this is a good indication that you have a problem with your design, it gets especially messy within a UI. If you really want to hear me whinge about the evils of static, check out this answer
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JPanel blue = new JPanel();
blue.setBackground(Color.BLUE);
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new JLabel("Hello world"), BorderLayout.NORTH);
frame.add(new TestPane());
frame.add(blue, BorderLayout.SOUTH);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setLayout(new GridBagLayout());
add(new JLabel("Hello World"));
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
// This could actually be achieved using a EmptyBorder and a LineBorder
// but this demonstrates the point...
g2d.setColor(Color.RED);
g2d.drawRect(10, 10, getWidth() - 20, getHeight() - 20);
g2d.dispose();
}
}
}
I'd like to make a Java panel that creates objects where the user clicks. Since my actual application uses a MVC approach I'd like also for these objects to be able to repaint themselves when a model is changed, and provide menus to change their properties.
I think that the best way to control their x and y locations would be to take a canvas based approach whereby the JPanel calls a draw method on these objects from the paintComponent method. This however will only draw the shape on the canvas and does not add the object itself loosing all abilities to control object properties. I'd be very grateful if someone could tell me the best approach for what I want to do.
I've created some sample code which can be seen below. When clicked I'd like the circle to change colour, which is implemented using a MouseListener (it basically represents changing the models properties in this small example). Also I'd just like to make sure that zooming in/out still works with any sample code/advice can provide so I've added buttons to zoom the objects in and out as a quick test.
import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import javax.swing.*;
import java.awt.geom.Ellipse2D;
public class Main {
public static void main(String args[]) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ExamplePanel panel = new ExamplePanel();
frame.add(panel);
frame.pack();
frame.setVisible(true);
}
});
}
//I could not get this to with when it extended JLayeredPane
private static class ExamplePanel extends JPanel {
private static final int maxX = 500;
private static final int maxY = 500;
private static double zoom = 1;
private static final Circle circle = new Circle(100, 100);
public ExamplePanel() {
this.setPreferredSize(new Dimension(maxX, maxY));
this.setFocusable(true);
Button zoomIn = new Button("Zoom In");
zoomIn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
zoom += 0.1;
repaint();
}
});
add(zoomIn);
Button zoomOut = new Button("Zoom Out");
zoomOut.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
zoom -= 0.1;
repaint();
}
});
add(zoomOut);
// add(circle); // Comment back in if using JLayeredPane
}
#Override
public void paintComponent(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.scale(zoom, zoom);
super.paintComponent(g);
circle.paint(g); // Comment out if using JLayeredPane
}
}
static class Circle extends JPanel {
private Color color = Color.RED;
private final int x;
private final int y;
private static final int DIMENSION = 100;
public Circle(int x, int y) {
// setBounds(x, y, DIMENSION, DIMENSION);
this.x = x;
this.y = y;
addMouseListener(new MouseAdapter() {
#Override
public void mousePressed(MouseEvent e) {
color = Color.BLUE;
}
#Override
public void mouseReleased(MouseEvent e) {
}
});
}
public void paint(Graphics g) {
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
g2.setPaint(color);
g2.fillOval(x, y, DIMENSION, DIMENSION);
}
// I had some trouble getting this to work with JLayeredPane even when setting the bounds
// In the constructor
// #Override
// public void paintComponent(Graphics g) {
// Graphics2D g2 = (Graphics2D) g;
// g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
// g2.setPaint(color);
// g2.fillOval(x, y, DIMENSION, DIMENSION);
// }
#Override
public Dimension getPreferredSize(){
return new Dimension(DIMENSION, DIMENSION);
}
}
}
As an aside I did try using a JLayeredPane(useful because I'd also like to layer my objects) but could not get my objects to even render. I know it has no default layout manager so tried calling setBounds in the circle in the constructor, but sadly it did not work. I know it's better to use a layout manager but can't seem to find one suitable for my needs!
Thanks in advance.
Don't override paint components, use paintComponent and don't forget to call super.paintComponent
A component already has a concept of "location", so when painting, the top left position of your component is actually 0x0
What you are doing is actually painting beyond the boundaries of you component
For example, if you place your Circle at 100x100 and then did...
g2.fillOval(x, y, DIMENSION, DIMENSION);
You would actually start painting at 200x200 (100 for the actual location of the component and 100 for you additional positioning).
Instead use
g2.fillOval(x, y, DIMENSION, DIMENSION);
And go back and try using JLayeredPane.
You could actually write your own layout manager that takes the location of the component and it's preferred size and updates the components bounds and then apply this to a JLayeredPane. This gives you the "benefits" of an absolute layout, but keeps you within how Swing works to update its components when things change.
You should also be careful with doing anything like...
Graphics2D g2 = (Graphics2D) g;
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
The Graphics context is a shared resource. That means, anything you apply to, will still be in effect when the next component is painted. This may produce some strange results.
Instead try using...
Graphics2D g2 = (Graphics2D) g.create();
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
//...
g2.dispose();
Updated
For zooming I would take a closer look at JXLayer (or JLayer in Java 7)
The JXLayer (and excellent PBar extensions) have gone quite on the net, so you can grab a copy from here
(I tried finding a better example, but this is the best I could do with the limited time I have available)
Updated with working zooming example
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.RenderingHints;
import java.util.HashMap;
import java.util.Map;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import org.jdesktop.jxlayer.JXLayer;
import org.pbjar.jxlayer.demo.TransformUtils;
import org.pbjar.jxlayer.plaf.ext.transform.DefaultTransformModel;
public class TestJLayerZoom {
public static void main(String[] args) {
new TestJLayerZoom();
}
public TestJLayerZoom() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new BorderLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
private JXLayer<JComponent> layer;
private DefaultTransformModel transformModel;
private JPanel content;
public TestPane() {
content = new JPanel(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridy = 0;
JLabel label = new JLabel("Hello");
JTextField field = new JTextField("World", 20);
content.add(label, gbc);
content.add(field, gbc);
gbc.gridy++;
gbc.gridwidth = GridBagConstraints.REMAINDER;
final JSlider slider = new JSlider(50, 200);
slider.addChangeListener(new ChangeListener() {
#Override
public void stateChanged(ChangeEvent e) {
int value = slider.getValue();
double scale = value / 100d;
transformModel.setScale(scale);
}
});
content.add(slider, gbc);
transformModel = new DefaultTransformModel();
transformModel.setScaleToPreferredSize(true);
Map<RenderingHints.Key, Object> hints = new HashMap<>();
//hints.put(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
//hints.put(RenderingHints.KEY_DITHERING, RenderingHints.VALUE_DITHER_ENABLE);
//hints.put(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
layer = TransformUtils.createTransformJXLayer(content, transformModel, hints);
setLayout(new BorderLayout());
add(layer);
}
}
}
I've left the rendering hints in to demonstrate their use, but I found that they screwed with the positing of the cursor within the text field, but you might like to have a play
I'd just like to add that I fixed the zooming issue not in the way suggested by the answer, but just by keeping the line that applied a scaled transform call in the ExamplePanel paintComponent method:
g2.scale(zoom, zoom);
I thought that this was the nicest implementation since none of the components require any knowledge about zooming and it seemed far simpler than JLayer since I only required basic zooming functionalities.
I have created a KeyAdapter class within my JPanel class, and I tried debugging the click using System.out.println(String par1);
However it doesnt seem to work...
Here is the class:
package net.ryanshah;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.RenderingHints;
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.ImageIcon;
import javax.swing.JPanel;
public class Menu extends JPanel
{
private GameFrame gf;
private Image bg = new ImageIcon("res/bg.png").getImage();
public Menu(final GameFrame parent) {
this.gf = parent;
int width = parent.getWidth();
int height = parent.getHeight();
setFocusable(true);
addKeyListener(new MenuOperator());
setBackground(Color.black);
setLayout(null);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D)g;
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
int w = getWidth();
int h = getHeight();
g2d.drawImage(bg, 0, 0, null);
}
public class MenuOperator extends KeyAdapter {
#Override
public void keyPressed(KeyEvent event) {
int keyCode = event.getKeyCode();
if(keyCode == KeyEvent.VK_SPACE) {
System.out.println("LOL");
}
}
}
}
Does anyone know what the problem might be? I have set the key handler in the frame as well as setting the frame to be focusable..
Thanks in advance
~RyanS.
Things not considered right in the code (IMHO) :
The way you accessing the images in your code. Consider ImageIO, over using the constructor of ImageIcon, as the former will notify you, in case something goes wrong. For more info, please refer, Loading Image Icon Exception, for more insight.
KeyListeners are for AWT, Swing on the other hand uses KeyBindings.
Before, setting background on any JComponent prefer to first set the opaque property of the said JComponent to true. Since, opaque property is usually dependent on LookAndFeel used.
Avoid the use of setLayout(null), as much as possible. Please walk through the first paragraph of Absolute Positioning for more information :-)
THe use of ImageObserver as already mentioned in the comments.
This blog Motion Using the Keyboard by #camickr, will again add loads to your knowledge, as to why KeyListeners are not considered a better option and why KeyBindings is more suited for such needs :-)
Please have a look at this example :
import java.awt.*;
import java.awt.event.*;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.swing.*;
public class TestMenu extends JPanel {
private Image bg;
public TestMenu() {
try {
bg = ImageIO.read(
new URL("http://i.imgur.com/Aoluk8n.gif"));
} catch (Exception e) {
e.printStackTrace();
}
getInputMap().put(KeyStroke.getKeyStroke("SPACE"), "SPACE key");
getActionMap().put("SPACE key", keyAction);
setOpaque(true);
setBackground(Color.black);
}
private Action keyAction = new AbstractAction() {
#Override
public void actionPerformed(ActionEvent ae) {
System.out.println("LOL");
}
};
/*
* Make this a customary habbit to override
* this method for the JPanel/JComponent,
* when ever you extend any of the above classes
*/
#Override
public Dimension getPreferredSize() {
return (new Dimension(200, 200));
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D)g;
g2d.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
int w = getWidth();
int h = getHeight();
/*
* Here the last part of the drawImage is the
* ImageObserver, here it is a good practise
* to keep the instance of the JPanel on which
* we drawing the image to be notified, till the
* end, till the image loading is not complete
*/
g2d.drawImage(bg, 0, 0, this);
}
private void displayGUI() {
JFrame frame = new JFrame("Painting Example");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setContentPane(this);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
Runnable runnable = new Runnable() {
#Override
public void run() {
new TestMenu().displayGUI();
}
};
EventQueue.invokeLater(runnable);
}
}
Setting your panel focusable is not enough - panel cannot get focus on its own - you have to request the focus on some kind of event. For example you can add a mouse listener to your panel and call panel.requestFocusInWindow() when you click on it.
Key listener will work only if component on which you add it has focus.
I'm new to java. I do have a java class but I want to get ahead. I really like it! This is my problem. I'm trying to draw the two paddles needed for the game. I did create 2 objects for them, and they both "Show" but the following happens:
Main Runner
import javax.swing.JFrame;
public class PongRunner {
public static void main (String[] args)
{
new PongRunner();
}
public PongRunner()
{
JFrame PongFrame= new JFrame();
PongFrame.setSize(800,600);
PongFrame.add(new PaddleB());
PongFrame.add(new PaddleA());
PongFrame.setLocationRelativeTo(null);
PongFrame.setTitle("My Pong Game");
PongFrame.setResizable(false);
PongFrame.setVisible(true);
PongFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}
PaddleA and PaddleB are both drawRect Graphics and draw a specific rectangle.
The graphics that I tell JFrame to add first are the only ones visible. The one under it doesnt get added into the Frame I wanted to know why,and how i can draw both paddles in the same JFrame... I'm reading my book and looking over the internet as much as possible, but no luck within these 2 days. Some help would be nice. I just started learning java and I think I'm making progress. Some tips would be nice too thanks :), specialy on actionListener since im going to have to use them to move the paddles!
SOURCE CODE OF BOTH PADDLES:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JPanel;
import javax.swing.Timer;
public class PaddleA extends JPanel implements ActionListener
{
private Timer timer;
public void timer()
{
timer = new Timer(25, this);
timer.start();
}
public void actionPerformed(ActionEvent e)
{
repaint();
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
g.setColor(Color.RED);
g.fillRect(70,200,20,100);
}
}
PaddleB:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JPanel;
import javax.swing.Timer;
public class PaddleB extends JPanel implements ActionListener
{
private Timer timer;
public void timer()
{
timer = new Timer(25, this);
timer.start();
}
public void actionPerformed(ActionEvent e)
{
repaint();
}
public void paintComponent(Graphics g)
{
super.paintComponent(g);
g.setColor(Color.BLUE);
g.fillRect(500, 200, 20, 100);
}
}
As you've added the 2 paddles into the same BorderLayout.CENTER location of the main PongFrame, only the second paddle will be displayed.
This type of painting is more easily done using one Graphics object on one JComponent.
Swing components aren't really designed to be used like this. Each of your paddle JPanels is trying to paint a rectangle, but the container (the JFrame) and its layout manager will control the size and location of the JPanels. So the rectangle they paint may be outside their bounds, and won't appear at all.
Some Layout Managers will only show one of the JPanels if you add them one after another like this - see answer by Reimus.
To do animated graphics like this, you probably need to start with a single JComponent (e.g. a JPanel) that fills the JFrame, and paint both paddles as rectangles onto it.
This is because you add the first paddle and then add the second paddle over the first thus replacing them:
PongFrame.add(new PaddleB());
PongFrame.add(new PaddleA());
try using LayoutManagers here is just a quick sample:
PongFrame.getContentPane().add(new PaddleB(),BorderLayout.WEST);
PongFrame.getContentPane().add(new PaddleA(),BorderLayout.EAST);
also your g.fillRect(...); has x and y co-ordinates that are too large for the JFrame and thus are not displayed. Change it like so:
g.fillRect(0,0, 20, 100);
Not related though:
dont use JFrame.add() rather JFrame.getContentPane().add()
UPADTE:
As others have mentioned the logic for the game is a bit off. You should have a single drawing panel which is added to the JFrame and all drawing is done on the single JPanel using Graphics and not JPanels. Here is a small example:
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Rectangle;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
public class PongRunner {
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
new PongRunner();
}
});
}
public PongRunner() {
JFrame PongFrame = new JFrame();
PongFrame.setTitle("My Pong Game");
PongFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
PongFrame.setResizable(false);
PongFrame.setSize(400,400);
//PongFrame.setLocationRelativeTo(null);
PongFrame.getContentPane().add(new DrawingPanel());
PongFrame.setVisible(true);
}
}
class DrawingPanel extends JPanel {
Rect rect1, rect2;
public DrawingPanel() {
super(true);
rect1 = new Rect(80, 80, 20, 100, Color.yellow);
rect2 = new Rect(100, 200, 20, 100, Color.red);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(rect1.getColor());
g.fillRect(rect1.getX(), rect1.getY(), rect1.getWidth(), rect1.getHeight());
g.setColor(rect2.getColor());
g.fillRect(rect2.getX(), rect2.getY(), rect2.getWidth(), rect2.getHeight());
}
}
class Rect {
private Color color;
private int x, y, height, width;
Rect(int x, int y, int width, int height, Color color) {
this.x = x;
this.y = y;
this.height = height;
this.width = width;
this.color = color;
}
public Color getColor() {
return color;
}
public int getX() {
return x;
}
public int getY() {
return y;
}
public int getWidth() {
return width;
}
public int getHeight() {
return height;
}
public Rectangle getBounds() {
return new Rectangle(x, y, width, height);
}
}
Please note this snippet is not perfect and merely demonstrates the stereotypical logic needed for drawing rectangles to form a game of sorts
I don't have time to try running your code, but try setting the size and position of the "paddle" objects, or set them as non-opaque. I believe that Swing tries to speed up rendering by not drawing components which are completely covered by another opaque component. It may not be drawing one of your paddles for that reason.
If you do set the size and position of your paddles, you may have to modify your paintComponent methods: if my memory is correct, I think the Graphics object which is passed in is clipped to the area of the component, so 0,0 would be the top-left corner of the component.
you shouldn't add your JPanels to your JFrame by the JFrame#add(Component) method. Better add them to the contentPane: frame.getContentPane().add(panel); You should although read about LayoutManagers. They can help you by positining Components in your Frame or mess things up if you use them incorrect.