Hello
I’m new to graphics and am in the process of bringing myself up to speed on
java 2d. I am now looking at how to use the BufferStratergy to manage the
offscreen buffer.
I’ve written a test program but nothing appears in my canvas/frame. Any idea
what I’m doing wrong? I’m sure it must be something trivial.
I’m using Java 1.6.0_6 on windows XP
[code]
package waterfall;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.image.BufferStrategy;
import java.util.Random;
public class Waterfall05 extends java.awt.Canvas implements Runnable {
final int WATERFALL_WIDTH = 701;
final int WATERFALL_HEIGHT = 300;
Random rnd = new Random();
final int width;
final int height;
BufferStrategy bufferStratergy=null;
Color[] newLine = null;
int numLines=0;
public Waterfall05() {
setPreferredSize(new java.awt.Dimension(701, 300));
setIgnoreRepaint(true);
Dimension size = getPreferredSize();
width = size.width;//- insets.left - insets.right;
height = size.height;// - insets.top - insets.bottom;
newLine = new Color[0];
ActionListener taskPerformer = new ActionListener()
{
public void actionPerformed(ActionEvent evt)
{
generateNewData();
}
};
javax.swing.Timer t = new javax.swing.Timer(500, taskPerformer);
t.start();
}
private void generateNewData()
{
newLine = new Color[WATERFALL_WIDTH];
for(int i=0; i<WATERFALL_WIDTH; i++)
{
newLine[i] = getColor();
}
if (numLines<300)
numLines++;
}
private Color getColor() {
return new Color(rnd.nextInt(0x1000000));
}
private void render()
{
System.out.println("render!");
if (bufferStratergy==null)
{
bufferStratergy = getBufferStrategy();
System.out.println("....created buffer stratergy...");
}
// Render single frame
do
{
// The following loop ensures that the contents of the drawing
buffer
// are consistent in case the underlying surface was recreated
do
{
// Get a new graphics context every time through the loop
// to make sure the strategy is validated
Graphics graphics = bufferStratergy.getDrawGraphics();
// Render to graphics
render(graphics);
// Dispose the graphics
graphics.dispose();
// Repeat the rendering if the drawing buffer contents
// were restored
} while (bufferStratergy.contentsRestored());
// Display the buffer
bufferStratergy.show();
// Repeat the rendering if the drawing buffer was lost
} while (bufferStratergy.contentsLost());
}
private void render(Graphics g)
{
Graphics2D g2d = (Graphics2D)g;
System.out.println("painting frame");
g2d.setColor(Color.ORANGE);
g2d.fillRect(0, 0, width, height);
}
private void renderX(Graphics g)
{
Graphics2D g2d = (Graphics2D)g;
System.out.println("painting frame: "+g2d);
g2d.copyArea(0, 0, width, height-1, 0, 1);
for(int i=0; i<newLine.length; i++)
{
g2d.setColor(newLine[i]);
g2d.drawRect(i, 0, 1, 1);
}
}
public void startRendering()
{
System.out.println("startRendering....");
Thread thread = new Thread(this);
thread.start();
}
public void run()
{
while (true) {
render();
try
{
Thread.sleep(300);
}
catch (InterruptedException e)
{
System.out.println("interrupt");
}
}
}
}
package waterfall;
import java.awt.Canvas;
public class TestWaterfall05 extends javax.swing.JFrame {
/** Creates new form TestWaterfall05 */
public TestWaterfall05() {
initComponents();
Waterfall05 waterfall = new Waterfall05();
this.getContentPane().add(waterfall);
this.setSize(waterfall.getPreferredSize().width,
waterfall.getPreferredSize().height);
//this.setIgnoreRepaint(true);
waterfall.createBufferStrategy(2);
waterfall.setVisible(true);
waterfall.startRendering();
}
/** This method is called from within the constructor to
* initialize the form.
* WARNING: Do NOT modify this code. The content of this method is
* always regenerated by the Form Editor.
*/
@SuppressWarnings("unchecked")
// <editor-fold defaultstate="collapsed" desc="Generated Code">
private void initComponents() {
setDefaultCloseOperation(javax.swing.WindowConstants.EXIT_ON_CLOSE);
javax.swing.GroupLayout layout = new
javax.swing.GroupLayout(getContentPane());
getContentPane().setLayout(layout);
layout.setHorizontalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 400, Short.MAX_VALUE)
);
layout.setVerticalGroup(
layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
.addGap(0, 300, Short.MAX_VALUE)
);
pack();
}// </editor-fold>
/**
* @param args the command line arguments
*/
public static void main(String args[]) {
java.awt.EventQueue.invokeLater(new Runnable() {
public void run() {
new TestWaterfall05().setVisible(true);
}
});
}
}
[/code]
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