DoubleBuffering in Java
- by DDP
Hello there, I'm having some trouble implementing DoubleBuffer into my program. Before you faint from the wall of text, you should know that a lot of it is there just in case you need to know. The actual place where I think I'm having problems is in one method.
I've recently looked up a tutorial on the gpwiki about double buffering, and decided to try and implement the code they had into the code I have that I'm trying to implement doublebuffer in. I get the following error: "java.lang.IllegalStateException: Component must have a valid peer".
I don't know if it makes any difference if you know it or not, but the following is the code with the main method. This is just a Frame that displays the ChronosDisplay class inside it. I omitted irrelevant code with "..."
public class CDM extends JFrame
{
public CDM(String str)
{
super("CD:M - "+str);
try
{
...
ChronosDisplay theGame = new ChronosDisplay(str);
((Component)theGame).setFocusable(true);
add(theGame);
}
catch(Exception e)
{
System.out.println("CDM ERROR: " +e);
}
}
public static void main( String args[] )
{
CDM run = new CDM("DP_Mini");
}
}
Here is the code where I think the problem resides (I think the problem is in the paint() method). This class is displayed in the CDM class
public class ChronosDisplay extends Canvas implements Runnable
{
String mapName;
public ChronosDisplay (String str)
{
mapName = str;
new Thread(this).start();
setVisible(true);
createBufferStrategy(2);
}
public void paint( Graphics window )
{
BufferStrategy b = getBufferStrategy();
Graphics g = null;
window.setColor(Color.white);
try
{
g = b.getDrawGraphics();
paintMap(g);
paintUnits(g);
paintBullets(g);
}
finally
{ g.dispose(); }
b.show();
Toolkit.getDefaultToolkit().sync();
}
public void paintMap( Graphics window )
{
TowerMap m = new TowerMap();
try
{
m = new TowerMap(mapName);
for(int x=0; x<m.getRows()*50; x+=50)
{
for(int y = 0; y<m.getCols()*50; y+=50)
{
int tileType = m.getLocation(x/50,y/50);
Image img;
if(tileType == 0)
{
Tile0 t = new Tile0(x,y);
t.draw(window);
}
...// More similar if statements for other integers
}
catch(Exception e) ...
}
...// Additional methods not shown here
public void run()
{
try
{
while(true)
{
Thread.currentThread().sleep(20);
repaint();
}
}
catch(Exception e) ...
}
}
If you're curious (I doubt it matters), the draw() method in the Tile0 class is:
public void draw( Graphics window )
{
window.drawImage(img,getX(),getY(),50,50,null);
}
Any pointers, tips, or solutions are greatly appreciated. Thanks for your time! :D
