Paint everything at once?

[Lionlev]

Yello, I've made a simple program that paints black fillRect with the size of the window and and then it paints an image
I've made thread that makes the image move to the right, but the problem is that sometimes the image blinks which I think that it's noticeable how the image paints in the black rectangle.. Well basically I can't figure out how do I make it render everything at once so the image would be clearly seen that it's moving.

(Program is two classes Window(main) and Photo)

So here how I made it:
Window:

import java.awt.*;
import javax.swing.*;

public class Window implements Runnable{
	public static Dimension wSize = new Dimension(1024, 600);
	public static Photo photo = new Photo();
	public static double charX = 30.0; 
	public static double charY = 30.0; 
	public void start(){
		new Thread(this).start();
	}
	public static void main(String[] args){
		Window window = new Window();
		JFrame w = new JFrame();
		w.setSize(wSize);
		w.setVisible(true);
		w.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		w.setResizable(false);
		w.add(photo);
		window.start();
	}
	public void create(){
		Graphics g = photo.getGraphics();
		g.setColor(Color.BLACK);
		g.fillRect(0, 0, wSize.width, wSize.height);
		charX += 5;
		photo.render(g);
	}
	public void run() {
		while(true){
			create();
			try {
				Thread.sleep(10);
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
	}
}

And Photo:

import javax.swing.*;
import java.awt.*;
import java.awt.image.*;
import java.io.*;
import javax.imageio.*;

public class Photo extends JPanel{
	private static final long serialVersionUID = 1L;
	public static BufferedImage myImage;
	
	public Photo() {
		System.out.println("User working directory: " + System.getProperty("user.dir"));
		try{
			myImage = ImageIO.read(new File("house.png"));
		}catch(Exception e){ 
			System.out.println("ERROR");
			e.printStackTrace();
		}
	}
	public void render(Graphics g){
		if (myImage != null) {
			g.drawImage(myImage,(int) Window.charX,(int) Window.charY,50,50,null);
		}
	}
}

(Again, sorry for posting the full code, but it's not so huge..)


UPDATE: as they say it called "flickering problem"

[Lionlev]

Anyone?

[KevinWorkman]

Please don't bump your thread. It's only been a couple hours, and now people will see that your thread has a reply and will assume you already received help.

You don't want to specifically get a Graphics instance from your JPanel like that. Instead, override paintComponent() and use that to do all your painting. Recommended reading: Lesson: Performing Custom Painting (The Java™ Tutorials > Creating a GUI With JFC/Swing)

[Lionlev]

Please don't bump your thread. It's only been a couple hours, and now people will see that your thread has a reply and will assume you already received help.

You don't want to specifically get a Graphics instance from your JPanel like that. Instead, override paintComponent() and use that to do all your painting. Recommended reading: Lesson: Performing Custom Painting (The Java™ Tutorials > Creating a GUI With JFC/Swing)

Ok sorry..
But I can't override paintcomponent because I am planning to do multiple classes with graphics methods..

[KevinWorkman]

Ok sorry..
But I can't override paintcomponent because I am planning to do multiple classes with graphics methods..

I'm not sure exactly what you mean, but you can call other render methods from paintComponent and pass the Graphics instance around that way.

[Lionlev]

I'm not sure exactly what you mean, but you can call other render methods from paintComponent and pass the Graphics instance around that way.

Ok, but that doesn't solve the flickering problem...

[KevinWorkman]

Ok, but that doesn't solve the flickering problem...

Are you sure? Have you actually tried it? If so, you're going to have to post an updated SSCCE that demonstrates exactly what you're doing.

[Lionlev]

Are you sure? Have you actually tried it? If so, you're going to have to post an updated SSCCE that demonstrates exactly what you're doing.

Here, I changed the Photo class

public void paintComponent(Graphics g){
		super.paintComponent(g);
		g.setColor(Color.BLACK);
		g.fillRect(0, 0, Window.wSize.width, Window.wSize.height);
		g.setColor(Color.WHITE);
		g.drawString("LOL", 300, 100);
		if (myImage != null) {
			g.drawImage(myImage,(int) Window.charX,(int) Window.charY,50,50,null);
		}
		
	}

And changed the main class (Window):

public void create(){
		Graphics g = photo.getGraphics();
		charX += speedX;
		charY += speedY;
		photo.paintComponent(g);
	}
	public void run() {
		while(true){
			create();
			try {
				Thread.sleep(mSec);
			} catch (Exception e) {
				e.printStackTrace();
			}
		}
	}

Still same problem :P

[Lionlev]

Are you sure? Have you actually tried it? If so, you're going to have to post an updated SSCCE that demonstrates exactly what you're doing.

HOLD ON ONE MINUTE! I think it's not flickering anymore because I changed photo.paintComponent(g); to photo.repaint();
Thanks! (and tell me if I did the right thing or not)

[KevinWorkman]

Yeah, you don't want to call getGraphics() on a component. You just want to call repaint() and let Swing take care of it for you. Calling getGraphics() and using that is working against Swing, which is what's causing the flickering.

[Lionlev]

Ohh, ok thanks!

[DarrylBurke]

Moved from Advanced Java

db