Java and Graphics... update screen...

[Homer_simpson]

let's say i gots this:

code:

import java.io.*; import javax.swing.*; import java.awt.*; import java.awt.event.*; import java.math.*; class gui {     public static void main (String args [])     {         JFrame frame = new JFrame ("Someshit");         frame.addWindowListener (new WindowAdapter ()         {             public void windowClosing (WindowEvent e)             {                 System.exit (0);             }         }         );         frame.setSize (600, 400);         JPanel pane = (JPanel) frame.getContentPane ();         pane.add (new SysDraw ());         frame.setVisible (true);     } } class SysDraw extends JComponent {     public SysDraw ()     {         repaint ();     }     public void paint (Graphics g)     {       for (int i=0;i<600;i++)       {         g.drawLine(0,0,i,400);       }     } }

got my gui window setup and everything but when i draw stuffs on the page... in this case a line...it doesn't update the screen so i can delete that and draw again... now i'm wondering if there is a command like View.Update in turing for java?

[Homer_simpson]

basically all i need is an equivalent for View.Update for java!

[Dan]

i know there is one in the java 2d api, i will check when i get home on how to use it....

[Homer_simpson]

awesome!

[rizzix]

extending my previous example.. (once again)

Java:

import javax.swing.*; import java.awt.*; class DrawView extends Canvas {         private Image bImage;     // offscreen buffer     private Graphics bg;      // offscreen graphics context     private Graphics2D g2d;   // onscreen graphics context     private int w, h;         // width and height of canvas (Component)         DrawView(int width, int height) {         super();         setBackground(Color.black);         w = width;         h = height;     }         public void paint(Graphics g) {         g2d    = (Graphics2D) g;         // cast to Graphics2D (just in case)         bImage = createImage(w, h);      // create a new buffer image         bg     = bImage.getGraphics();   // get Graphics context for image                 bg.setXORMode(Color.white);      // set white as the XORed colour                 for (int i = 0; i < 600; i++)         {             bg.drawLine(0,0,i,400);     // drawn in white (on buffer)             updateScreen();             bg.drawLine(0,0,i,400);     // drawn in background color (XORed)         }                 bg.dispose();                   // dispose graphics context         bImage.flush();                 // flush (empty) image     }         private void updateScreen() {         g2d.drawImage(bImage, 0, 0, this);  // load buffer to screen     } }

[Homer_simpson]

ummm... dude... how do i run a program that doesn't have a main method :S

[rizzix]

Java:

import javax.swing.*; import java.awt.Dimension; public class Test {     public static void main(String[] args) {         // initialised with the title for the title bar         JFrame frame = new JFrame("Test Application");         Dimension screenSize = frame.getToolkit().getScreenSize();         frame.setBounds(screenSize.width/4, screenSize.height/4,                         screenSize.width/2, screenSize.height/2);         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);                    int w = frame.getBounds().width;          int h = frame.getBounds().height;         frame.getContentPane().add(new DrawView(w, h));         frame.show();     } }

[Homer_simpson]

makes me feel such a noobie at this...

[rizzix]

yea, it might take awhile to get used to. u basically need to think Objects heh.

anyways..
the DrawView class i wrote above is basically this:
i create an image (its better if you use a BufferedImage.. but Image will do)
now i do all my drawing onto this image. when i need to update the screen, i just load the image on to the screen.

to make this process simpler i wrote this: http://www.compsci.ca/v2/viewtopic.php?t=3817

try it out.. i've wraped a turing like syntax over the java methods.. so it should be easier to concentrate on drawing than the actual process of buffering etc..

here's an example using that class:

Java:

import java.awt.*; import javax.swing.JFrame; class DrawView extends BufferedCanvas {                 DrawView(JFrame parent) {             super(parent);         }                 protected void offscreenPaint() {             for (int i = 0; i < maxx(); i++)             {                 drawline(0, 0 ,i, 400, Color.white);                 drawfilloval(0, 0, i, i, Color.red);                 update();                 drawline(0, 0, i, 400);                 drawfilloval(0, 0, i, i);             }         } }

and here's the application class:

Java:

import javax.swing.*; import java.awt.Dimension; import java.awt.Color; public final class Test {     public static void main(String[] args) {         JFrame frame = new JFrame("Test Application");         Dimension screenSize = frame.getToolkit().getScreenSize();         frame.setBounds(screenSize.width/4, screenSize.height/4,                         screenSize.width/2, screenSize.height/2);         frame.getContentPane().add(new DrawView(frame));         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);         frame.show();     } }