I'm trying to create a super simple component, and it's not appearing.
Component class:
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JComponent;
public class Player extends JComponent{
public Player()
{
}
public void paint(Graphics g)
{
g.setColor(Color.green);
g.fillRect(40,40,150,150);
}
}
Panel Class im adding it to:
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Rectangle;
import javax.swing.JPanel;
public class Game extends JPanel{
public Game()
{
this.setBackground(Color.yellow);
this.setPreferredSize(new Dimension(500,500));
Player p = new Player();
this.add(p);
}
}
And the JFrame:
import javax.swing.JFrame;
public class Launcher {
public static void main(String[] args) {
JFrame frame = new JFrame("Key Collector Demo");
frame.add(new Game());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
frame.setDefaultCloseOperation(frame.EXIT_ON_CLOSE);
}
}
The only thing showing up is the yellow background.
JFrame and JPanel are working fine; this problem consistently happens to me when building jcomponents. What am I missing?
Any help would be greatly appreciated!
Coordinates that you are using to draw a component are defined in the space of that component.
If you do this:
public void paint(Graphics g)
{
g.setColor(Color.green);
System.out.println(getSize());
g.fillRect(40,40,150,150);
}
You will see that at the moment it is attempted to get drawn its size is 1x1. So drawing it from 40,40 obviously takes it out of the visible area of the component.
Now change the method to:
public void paint(Graphics g)
{
g.setColor(Color.green);
System.out.println(getSize());
setSize(45, 45);
g.fillRect(40,40,150,150);
}
Now you can see small filled rectangle. This is because you forced the size to be 45x45 and now there are 5 pixels to show in the space of the component while the remaining part is still out of the area.
Do not assume the Player panel to have a fixed size.
For a first test your paint method could look like this:
public void paint(Graphics g) {
g.setColor(Color.green);
g.fillRect(0,0,getWidth(),getHeight());
}
The next problem is that the component probably has no size or position. Add a LayoutManager to your panel and add the component:
public Game() {
this.setBackground(Color.yellow);
this.setPreferredSize(new Dimension(500,500));
this.setLayout(new BorderLayout());
Player p = new Player();
this.add(p, BorderLayout.CENTER);
}
With that, your player might take the full space and you see green instead of yellow. Play around with the LayoutManager and the player's preferredSize.
Related
To provide some background info that might help, I am creating the game pong and I decided to add an escape/pause menu (when you press escape on the keyboard a menu pops up with some settings), I looked around and found that the best way to do this is to use JLayeredPane and add another JPanel on top. However, when I added my 'painter' class to the JLayeredPane, the paint(Graphics g) method stopped getting called (it worked fine when I just added it to the JFrame).
import javax.swing.*;
public class Game extends JFrame {
public static Painter painter;
public Game() {
setSize(500, 500);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JLayeredPane lp = getLayeredPane();
painter = new Painter();
add(lp);
}
public static void main(String[] args) {
Game frame = new Game();
frame.setVisible(true);
painter.repaint();
}
}
And here is my Painter class
import java.awt.*;
import javax.swing.*;
public class Painter extends JPanel {
public void paint(Graphics g) {
System.out.println("Working");
super.paint(g);
}
}
Instead of add(lp);, I originally tried lp.add(painter); in which case the paint method never got called. By doing add(lp) I get an IllegalArgumentException for adding container's parent to itself.
Here is mcve of using LayeredPane :
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
public class Game extends JFrame {
public Game() {
setSize(250, 150);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JLayeredPane lp = getLayeredPane();
//assign layout manager. otherwise you need to set content
//bounds (not recommended)
lp.setLayout(new BorderLayout());
Painter painter = new Painter();
lp.add(painter,1);
}
public static void main(String[] args) {
Game frame = new Game();
frame.setVisible(true);;
}
}
class Painter extends JPanel {
#Override
protected void paintComponent(Graphics g) { //do not override paint
super.paintComponent(g);
g.drawString("Working",50,50);
}
}
Im trying to add a JScrollpane to my JPanel. The problem is that the scrollpane doesn't recognize that my drawing is outside the frame. So how do I add the JScrollpane correctly?
Main class:
public MainFrame() extends JFrame{
public MainFrame() {
Container container = getContentPane();
container(new BorderLayout());
container.add(new JScrollPane(new Drawing()));
setSize(1280,720);
setVisible(true);
}
Drawing class:
public class Drawing() extends JPanel {
#Override
protected void paintComponent(Graphics g) {
g.drawLine(10, 100, 30000, 10);
}
}
There are a couple of errors in your code, let's step through each of them:
You're extending JFrame, and you should avoid it, see: Extends JFrame vs. creating it inside the program for more information about it. You're actually not changing its behavior so it's not needed to extend it.
For your JScrollPane to show the whole line, you need to change your window's size to be the same size of your line (as shown in this answer by #MadProgrammer).
Related to point 2, avoid the use of setSize(...) and instead override getPreferredSize(): See Should I avoid the use of set(Preferred|Maximum|Minimum)Size methods in Java Swing? for more information
You forgot to call super.paintComponent(...) method in your paintComponent() method.
Related to points 2, 3, you need to call pack() so Swing calculates the best preferred size for your component.
See this example:
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;
public class LongDraw {
private JFrame frame;
private Drawing drawing;
public static void main(String[] args) {
SwingUtilities.invokeLater(new LongDraw()::createAndShowGui);
}
private void createAndShowGui() {
frame = new JFrame(getClass().getSimpleName());
drawing = new Drawing();
JScrollPane scroll = new JScrollPane(drawing);
frame.add(scroll);
frame.pack();
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
class Drawing extends JPanel {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
g2d.drawLine(10, 100, 3000, 10);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(3000, 500);
}
}
}
Which produces something similar to this:
I am trying to draw some simple shapes onto a JPanel but am having some difficulty. Apologies if this question appears to have been answered before but the other answers don't seem to help.
I followed a simple tutorial and was successful in drawing some basic shapes onto a JFrame, but when I moved the code how it was into a new class which extends JPanel, nothing appears on screen.
public class TestingGraphics extends JFrame{
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
// TODO code application logic here
new TestingGraphics();
}
public TestingGraphics(){
this.setSize(1000,1000);
this.setPreferredSize(new Dimension(1000,1000));
this.setTitle("Drawing tings");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.add(new TestingPanelGraphics(), BorderLayout.CENTER);
this.setVisible(true);
}
public class TestingPanelGraphics extends JPanel {
public TestingPanelGraphics(){
this.setSize(1000,1000);
this.setPreferredSize(new Dimension(1000,1000));
this.add(new DrawStuff(), BorderLayout.CENTER);
revalidate();
repaint();
this.setVisible(true); //probably not necessary
}
private class DrawStuff extends JComponent{
#Override
protected void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D graph2 = (Graphics2D) g;
graph2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
Shape rootRect = new Rectangle2D.Float(100, 100, 1000, 500);
graph2.setColor(Color.BLACK);
graph2.draw(rootRect);
}
I've tried setting preferred size, and revalidating and repainting.
I've added a call to super.paintComponent, although neither of those two were necessary when I was drawing straight onto a JFrame.
I ensured I was overriding paintComponent and changed it from public to protected. All following advice from similar threads, but nothing seems to work. I've stepped through in debugger mode and ensured it goes into the right method, and even watched it go into the paintManager, but still nothing appears on the window.
You've forget to set the appropriate layout manager.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.RenderingHints;
import java.awt.Shape;
import java.awt.geom.Rectangle2D;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class TestingGraphics extends JFrame{
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
// TODO code application logic here
new TestingGraphics();
}
public TestingGraphics(){
this.setSize(1000,1000);
this.setPreferredSize(new Dimension(1000,1000));
this.setTitle("Drawing tings");
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
this.add(new TestingPanelGraphics(), BorderLayout.CENTER);
this.setVisible(true);
}
public class TestingPanelGraphics extends JPanel {
public TestingPanelGraphics(){
setLayout(new BorderLayout());
this.setPreferredSize(new Dimension(1000,1000));
this.add(new DrawStuff(), BorderLayout.CENTER);
revalidate();
repaint();
this.setVisible(true); //probably not necessary
}
private class DrawStuff extends JComponent{
#Override
protected void paintComponent(Graphics g){
super.paintComponent(g);
Graphics2D graph2 = (Graphics2D) g;
graph2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
Shape rootRect = new Rectangle2D.Float(100, 100, 1000, 500);
graph2.setColor(Color.BLACK);
graph2.draw(rootRect);
}
}
}
}
When you extends JFrame your default layout is the BorderLayout, but when you extends JPanel your default layout is the FlowLayout.
I am currently still learning Java GUI and stumped on this problem. I just wonder why can't i load it anywhere except on center and how do i load my image anywhere else?
import java.awt.*;
import javax.swing.*;
public class GUI {
public static void main(String[] args) {
GUI gui = new GUI();
gui.go();
}
public void go() {
JFrame frame = new JFrame();
JPanel panel = new JPanel();
Player player = new Player();
panel.setBackground(Color.darkGray);
JButton button = new JButton("shock me");
panel.add(button);
frame.getContentPane().add(BorderLayout.EAST, panel);
frame.getContentPane().add(BorderLayout.NORTH, player);
//frame.getContentPane().add(BorderLayout.CENTER, player);
frame.setSize(200,200);
frame.setVisible(true);
}
}
Here's my player class
import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.util.Random;
import javax.swing.*;
public class Player extends JPanel{
public void paintComponent(Graphics g) {
Image image = new ImageIcon("Source/hero.jpg").getImage();
g.drawImage(image, 3, 4 , this);
}
}
Player does not override getPreferredSize() to return a value. Since it does not do that, the BorderLayout will not assign it any height in the PAGE_START or PAGE_END constraints, and no width in the LINE_START and LINE_END constraints. The component is being added, it just has no width/height.
The CENTER will stretch both a component's width and height to the available space, that is why it is visible there.
Im trying to simplify some basic code, an I've come across a small problem. I was under the impression that the paint method was called automatically, and i based that off every other basic program i have written. I dont get any erros, just the code doesn't work, and i cant call repaint() either.
Code:
public class Dynamic_Bg_Color{
JFrame frame;
public Dynamic_Bg_Color(){
frame = new JFrame("BG Color Changer");
}
public void paint(Graphics g1){
Graphics g = (Graphics)g1;
g.setColor(Color.pink);
g.fillRect(20,20,frame.getWidth()-20,100);
}
public static void main(String[] args){
Dynamic_Bg_Color d = new Dynamic_Bg_Color();
Dimension size = new Dimension(500,400);
d.frame.setPreferredSize(new Dimension(size));
d.frame.setMinimumSize(new Dimension(size));
d.frame.setMaximumSize(new Dimension(size));
d.frame.setLocationRelativeTo(null);
d.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
d.frame.setLayout(new FlowLayout());
d.frame.setVisible(true);
d.frame.getContentPane().setBackground(Color.cyan);
}
}
The paint method only gets called if it is an override, and the class extends another class where the paint method has meaning. Your class does not do this, and so your paint method is meaningless.
Having said that, I'm going to suggest that you don't overload paint but rather paintComponent(...) in a class that extends JComponent or one of its children. And most importantly, read the painting with Swing tutorial. Please start here.
As an aside, casting a Graphics object to a Graphics object achieves nothing. Perhaps you copied your code incorrectly and were meaning to cast it to a Graphics2D type?
I made the class extend JComponent, and added the override, but nothing has changed.
I don't see where you add the component to the frame.
Even if you did add the component to the frame is wouldn't paint because the default size of your component is (0, 0) so there is nothing to paint.
You also need to restructure your code. A JFrame variable does not belong to the component where you do custom painting. I suggest you read the section from the Swing tutorial on Custom Painting. It will show you:
How to do custom painting including how you specify a preferred size for your component
How to better structure your program, included executing your code on the Event Dispatch Thread
With minimal changes made the working code:
import javax.swing.*;
import java.awt.*;
public class Dynamic_Bg_Color extends JPanel{
JFrame frame;
public Dynamic_Bg_Color(){
frame = new JFrame("BG Color Changer");
}
public void paint(Graphics g1){
Graphics g = (Graphics2D)g1;
g.setColor(Color.pink);
g.fillRect(20,20,frame.getWidth()-20,100);
}
public static void main(String[] args){
Dynamic_Bg_Color d = new Dynamic_Bg_Color();
Dimension size = new Dimension(500,400);
d.setPreferredSize(new Dimension(size));
d.setMinimumSize(new Dimension(size));
d.setMaximumSize(new Dimension(size));
d.frame.add(d);
d.frame.setLocationRelativeTo(null);
d.frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
d.frame.setLayout(new FlowLayout());
d.frame.pack();
d.frame.setVisible(true);
d.frame.getContentPane().setBackground(Color.cyan);
}
}
But, as others said, I don't suggest you use this cause it is very very bad structure of the program. And read the tutorial on painting, even if I think that Oracles tutorial on this is bad (frame.pack() just sets the size of the JFrame window as big as to hold the components it contains).
Heres the final working code. A few changes being it extended JPanel, setting the size of the JPanel, and adding the panel to the JFrame. Yes i know as everybody stated, this is not an optimal way of doing this, but for right now, it works.
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Dynamic_Bg_Color extends JPanel{
private static final long serialVersionUID = 1L;
static Dimension size = new Dimension(500,400);
static JFrame frame;
public Dynamic_Bg_Color(){
setPreferredSize(size);
setBackground(Color.cyan);
addMouseListener(new Handler());
}
#Override
public void paintComponent(Graphics g){
System.out.println("Click");
super.paintComponent(g);
g.setColor(Color.blue);
g.fillRect(20,20,getWidth()-40,100);
g.setColor(Color.green);
g.fillRect(20,140,getWidth()-40,100);
g.setColor(Color.orange);
g.fillRect(20,260,getWidth()-40,100);
}
public static void main(String[] args){
Dynamic_Bg_Color d = new Dynamic_Bg_Color();
frame = new JFrame("BG Color Changer");
frame.setPreferredSize(new Dimension(size));
frame.setMinimumSize(new Dimension(size));
frame.setMaximumSize(new Dimension(size));
frame.setLayout(new FlowLayout());
frame.setLocationRelativeTo(null);
frame.add(d);
frame.pack();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().setBackground(Color.cyan);
frame.setVisible(true);
}
public class Handler extends MouseAdapter{
public void mousePressed(MouseEvent e) {
int x = e.getX();
int y = e.getY();
if(x>= 20 && x<=getWidth()-40 && y>=20 && y<= 120){
frame.getContentPane().setBackground(Color.blue);
setBackground(Color.blue);
frame.setTitle("Blue");
}
if(x>= 20 && x<=getWidth()-40 && y>=140 && y<= 240){
frame.getContentPane().setBackground(Color.green);
setBackground(Color.green);
frame.setTitle("Green");
}
if(x>= 20 && x<=getWidth()-40 && y>=260 && y<= 360){
frame.getContentPane().setBackground(Color.orange);
setBackground(Color.orange);
frame.setTitle("Orange");
}
}
}
}