I'm creating an application in which I have a class with a main frame (JFrame), and a class which is a JPanel subclass called OvalPanelClass. I say main frame because the user has the option to open up another JFrame (window). This OvalPanelClass is dynamic and displays its images using a BufferStrategy. It is both launched into a separate JFrame on some occasions and appears at the bottom right section of the main frame at some points too, so I didn't feel it made sense to make this class an inner class of the class containing the main frame.
The problem is that as this JPanel is not a part of a class with a JFrame it cannot make the call to get the BufferStrategy and so on. So to get over this I tried passing a reference to the main frame to the OvalPanelClass constructor but I'm not getting results. My question is what is flawed with my reasoning?
FrameClass
import java.awt.BorderLayout;
import java.awt.Dimension;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class FrameClass extends JFrame {
public static void main(String[] args) {
FrameClass test = new FrameClass();
test.setup();
}
void setup() {
setPreferredSize(new Dimension(800, 800));
JPanel background = new JPanel(new BorderLayout());
getContentPane().add(background);
setVisible(true);
OvalPanelCanvas shape = new OvalPanelCanvas(this);
//shape.setup(this);
background.add(BorderLayout.CENTER, shape);
pack();
shape.repaint();
}
}
OvalPanelCanvas
import java.awt.Color;
import java.awt.Graphics;
import java.awt.image.BufferStrategy;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class OvalPanelCanvas extends JPanel {
JFrame frame;
BufferStrategy bs;
public OvalPanelCanvas(JFrame frame) {
this.frame = frame;
setOpaque(false);
}
public void paintComponent(Graphics g) {
frame.createBufferStrategy(2);
bs = frame.getBufferStrategy();
Graphics bufferG = bs.getDrawGraphics();
for (int i = 0; i < 5; i++) {
int width = 50;
int height = 50;
bufferG.setColor(new Color(i*5,i*6,i*50));
bufferG.fillOval(0, 0, width*i, height*i);
}
bufferG.dispose();
bs.show();
}
}
Thanks for your time! I'm being vague about what the project is and have stripped away what I felt were irrelevant details but if you need some more context let me know.
I'm having a similar issue. I think it has more to do with not using Canvas vs. using JPanel. For instance I have images on a sprite sheet that I cannot use because my class extends JFrame and not Canvas. The reason that being is because I am using the JFrame addon from within eclipse that automatically extends JFrame on the creation of the JFrame in the window class.
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);
}
}
package Main;
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;
public class Main extends JFrame{
public static void main(String[] args) {
int width = 800;
int height = 600;
String title = "Test";
JFrame display = new JFrame();
display.setTitle(title);
display.setSize(width, height);
display.setVisible(true);
display.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void paint(Graphics g) {
g.setColor(Color.white);
g.drawLine(0, 100, 800, 300);
getContentPane().setBackground(Color.black);
}
}
I'm using Java's JFrame. So this isn't recognising the paint method and cant figure out why. I've been looking on YouTube videos and having a look to see if anyone has had similar problems, however everything I've found doesn't seem to help the problem.
when i set the background colour in the main part, it works, bit in paint, it doesn't seem to do anything and leaves it blank.
Its a white line over a black background, so i should easily be able to see it.
Admittedly, I don't know much about Swing (I prefer JavaFX). However, it's clear that your Main class is a JFrame, so you should not make a new one within it. All of those methods you call on display are built in your current class. Basically, within your JFrame you made a new JFrame. However, your paint method was being called on the parent JFrame, which you never made visible. This solves your problem (you may have to fullscreen the window):
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;
public class Main extends JFrame{
public static void main(String[] args) {
new Main();
}
public Main() {
int width = 800;
int height = 600;
String title = "Test";
setTitle(title);
setSize(width, height);
setVisible(true);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
public void paint(Graphics g) {
super.paint(g);
g.setColor(Color.WHITE);
g.drawLine(100, 100, 800, 300);
getContentPane().setBackground(Color.black);
}
}
You are creating an instance of JFrame with
JFrame display = new JFrame();
But the JFrame class has no logic to draw a white line on a black background. That logic is in your custom class Main. So instead, you should create an instance of Main:
JFrame display = new Main();
However, that change along still won't fix the problem because you are setting the background color of the "content pane" but trying to draw directly on the JFrame itself. The preferred solution here is to extend JPanel instead of JFrame and override its paintComponent() method. Then create an instance of your new class to use as the content pain:
import java.awt.Color;
import java.awt.Graphics;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class MainPanel extends JPanel{
public static void main(String[] args) {
int width = 800;
int height = 600;
String title = "Test";
JFrame display = new JFrame();
display.setTitle(title);
display.setSize(width, height);
display.setVisible(true);
display.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
display.setContentPane(new MainPanel());
}
public MainPanel() {
setBackground(Color.black);
}
#Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.white);
g.drawLine(0, 100, 800, 300);
}
}
Notes:
I call setBackground() in the constructor because it does not rely on the Graphics instance passed to paintComponent(). This also avoids the overhead of another function call for each render.
In paintComponent(), I call super.panitComponent(). This allows JPanel to clear the area to be painted and any other necessary initialization.
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:
Some time ago I wrote a code in a single main class which worked fine. Later I added JPanel and JFrame in again its single main it again worked fine.
Now I am trying to break the code down and move them into packages.
here is my main
-( src/start/Main.java)-
package start;
import javax.swing.JFrame;
import frames.*;
public class Main {
public static void main(String[] args) {
MainFrame.createFrame();
LogoPanel.createLogoPanel(); //this line is the problem
}
}
here is MainFrame
-(src/frames/MainFrame.java)-
package frames;
import javax.swing.JFrame;
public class MainFrame {
public static JFrame createFrame() {
JFrame frame = new JFrame ("App");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setResizable(false);
frame.setBounds(140,140, 1000, 580);
frame.setVisible(true);
frame.setLayout(null);
return frame;
}
}
here is LogoPanel
-(src/frames/LogoPanel.java)-
package frames;
import java.awt.Color;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class LogoPanel {
public static JPanel createLogoPanel(JFrame frame) {
JPanel logoPanel = new JPanel ();
logoPanel.setVisible(true);
logoPanel.setBounds(0, 0, 1000, 80);
logoPanel.setBackground(Color.gray);
logoPanel.setLayout(null);
frame.add(logoPanel);
return logoPanel;
}
}
as I said LogoPanel.createLogoPanel(); is the problem . It does not accept createLogoPanel(JFrame frame) from me ? setting it to null doesn't show the panel at all . anyway I can make this work ?
Your createLogoPanel takes a JFrame type argument.
But I don't see you passing an argument when you are actually invoking the method.
Do something along the lines of :
JFrame frame = MainFrame.createFrame();
LogoPanel.createLogoPanel(frame);
This error seem to suggest a lack of understanding about basic Java syntax and concepts. If you are able to accumulate knowledge in this area it will benefit you greatly in the future.
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");
}
}
}
}