Can someone test my Java 2D application? Something gone abit weird/wrong..

Question

Hi there
I have just written a Java 2D Graphics Application. I think its complete but the problem is when i run it, it come out with weird result.
Below is my code:
import java.awt.*;
import javax.swing.*;
public class GraphicsView extends JPanel{
     private double px = 50;
     private double py = 50;
     private double qx = 200;
     private double qy = 50;
     private double rx = 50;
     private double ry = 200;
     private double sx = 200;
     private double sy = 200;
     public GraphicsView(){
     public void paintComponent(Graphics g){
          super.paintComponent(g);
          g.drawLine((int)px, (int)py, (int)qx, (int)qy);
          g.drawLine((int)px, (int)py, (int)rx, (int)ry);
          g.drawLine((int)qx, (int)qy, (int)sx, (int)sy);
          g.drawLine((int)rx, (int)ry, (int)sx, (int)sy);
          double u = 0.1;
          for(int k = 0; k < 55; k++){
               px = ((1 - u) * px) + (u * qx);
               py = ((1 - u) * py) + (u * qy);
               qx = ((1 - u) * qx) + (u * sx);
               qy = ((1 - u) * qy) + (u * sy);
               sx = ((1 - u) * sx) + (u * rx);
               sy = ((1 - u) * sy) + (u * ry);
               rx = ((1 - u) * rx) + (u * px);
               ry = ((1 - u) * ry) + (u * py);
               g.drawLine((int)px, (int)py, (int)qx, (int)qy);
               g.drawLine((int)qx, (int)qy, (int)sx, (int)sy);
               g.drawLine((int)sx, (int)sy, (int)rx, (int)ry);
               g.drawLine((int)rx, (int)ry, (int)px, (int)py);
import java.awt.*;
import javax.swing.*;
public class Program extends JFrame {
     public Program(){
          makeStuff();
     public void makeStuff(){
          setPreferredSize(new Dimension(350,300));
          getContentPane().add(new GraphicsView());
          pack();
          setVisible(true);
        public static void main(String[] args) {
          Program program = new Program();
}The problem is that:
When i maximise it the 2D drawing appears weird, out of position, fuzzy & totally messed up! AND when i minimize it back to original window frame size - The 2D drawing totally disappeared/Gone!!!
Anyone know why is that a problem?
Is it a Swing problem? Or Java 2D problem?
oh- above 2 segments of code represent a class each respectively...

Answer 1

You're trying to do program logic within the paintComponent method. When your paintComponent method ends, lord knows what the final value of your different x and y variables are. They certainly aren't the same values as when you first did the drawing. What ends up happening is that hte drawing is likely done, but is very very small. Throw in some System.out. println's and you'll see.
I recommend that you do all your equations outside of the paintComponent, and save the line coordinates in an ArrayList of objects of a class you can create. Then have the paintComponent simply iterate through the arraylist drawing based on the values in the objects held by the list.
Edit: one easy object to use is a Line2D and then have your arraylist hold these objects. Then simply use a Graphics2D object to draw all the Line2D's held in the list.
Edited by: Encephalopathic on Oct 7, 2008 8:33 PM