Question

I want to use graphics2D but I can’t get I get it to display my graphics. Is there a better way to go about this that would allow me to use repaint()? Eventually I want to make have a image set as a background and be able to draw on it then save the contents of the frame as a image.

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

import java.io.File;
import java.io.IOException;
import java.net.URL;

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

// assume that the drawing area is 150 by 150
public class test extends JApplet
{
  final int radius = 25;
  int width = 200, height = 200;

 BufferedImage img = new BufferedImage(
   width, height, BufferedImage.TYPE_INT_ARGB);

  public void paint (  )
  { 
    Graphics2D g = img.createGraphics();
    g.setColor( Color.orange );
    g.fillRect( 0, 0, 150, 150 );
    g.setColor( Color.black );

    g.drawOval( (150/2 - radius), (150/2 - radius), radius*2, radius*2 );
   }
}

Answer 1

Ok so,

1. You have public void paint( ) what the hell is this doing lol? You need a graphics object. public void paint(Graphics g) is like the default method which gets called automatically when your applet is initialised.

2. You have Graphics2D g = img.createGraphics(); when you need to use your default Graphics g object and cast it into a Graphics2D object like so Graphics2D g2d = (Graphics2D) g;

3. You should search for a little more information on double buffering too 🙂

anyway… This code works so take from it what you want 🙂

P.S Note how I implemented Runnable; You do not need to do this if you only want to use the Graphics2D code. It is just making the class a thread and is used for game frame rates 🙂

Hope this helped.

import java.applet.*;
import java.awt.*;


public class Test extends Applet implements Runnable{

public boolean isRunning = false;
public int radius = 25;


public void start() {
    isRunning = true;
    new Thread(this).start();
}

public void stop() {
    isRunning = false;
}

public void paint(Graphics g) {
    //Create Graphics2D object, cast g as a Graphics2D
    Graphics2D g2d = (Graphics2D) g;
    g2d.setColor(Color.ORANGE);
    g2d.fillRect(0, 0, 150, 150);

    g2d.setColor(Color.BLACK);
    g2d.drawOval((150/2 - radius), (150/2 - radius), radius * 2, radius * 2);
}

public void run() {

    while (isRunning) {
        repaint();
        try {
            Thread.sleep(17);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}


}