Thread: Problems with Double Buffering -- BufferStrategy

Alright I have programmed in Java many times and made games before but I always made applets so this is my first time using JPanel/JFrame. I have gotten everything underway and have been stuck on getting this different style of drawing working for me. Usually I just create an image and use paint() drawImage to display the the buffered image. I decided to try using the BufferStrategy method but I am having the hardest time getting it to work. I know my code is gonna be pretty botched up now since I went through all kinds of different tutorials and what not trying to figure it out. Anyway I'm sure someone can help and trust me I have been working on this all day (roughly 6-8hrs). Posting on the forums is always the last thing I do but sometimes I just need someones help to make it click.

package bttg;
 
import javax.swing.JPanel;
import javax.swing.JFrame;
import java.awt.*;
import java.awt.image.BufferStrategy;
 
public class BTTG extends JPanel
{
    BufferStrategy bufferStrat;
    Boolean running = true;
 
    private short screenSize = 800;
 
 
    public void render()
    {
 
        Graphics2D buffer = (Graphics2D) bufferStrat.getDrawGraphics();
 
	buffer.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
        RenderingHints.VALUE_ANTIALIAS_ON);
 
        buffer.setColor(Color.darkGray);
        buffer.fillRect(0,0,screenSize,screenSize);
 
        Font monospaced = new Font("MONOSPACED", Font.BOLD, 15);
        buffer.setFont(monospaced);
	buffer.setColor(Color.BLACK);
        buffer.fillRect(0,0,screenSize,19);
        buffer.setColor(Color.WHITE);
        buffer.drawString("BTTG",5,13);
 
        buffer.dispose();
        bufferStrat.show();
    }
 
 
    public BTTG()
    {
 
        JFrame container = new JFrame("BTTG");
        JPanel panel = (JPanel) container.getContentPane();
        panel.setPreferredSize(new Dimension(screenSize,screenSize));
        panel.setLayout(null);
 
        setBounds(0,0,screenSize,screenSize);
        panel.add(this);
 
        container.pack();
        container.setResizable(false);
        container.setVisible(true);
 
        setIgnoreRepaint(true);
 
       	container.createBufferStrategy(2);
	bufferStrat = container.getBufferStrategy();
 
         while(running)
        {  
        render();
        try { Thread.sleep(10); } catch (Exception e) {}
        }
 
 
    }
 
 
 
 
    public static void main(String[] args) {
    new BTTG();
    }
}

Woah woah woah I moved my drawString() to 50 , 50 and its there everything isn't being placed properly. Is there a reason for this? I thought the white on the edges were kinda weird.

I moved my drawString() to 50 , 50 and its there everything isn't being placed properly.

I ran the code (using both sets of coordinates) and the string was placed properly both times.

---

Is it normal to construct the gui in the initial thread rather than the EDT (and not give main() a chance to finish)? That's a genuine question: I've never used anything other than the default strategy where using the EDT is nonnegotiable.

Everything is still shifted up and to the left leaving a white reversed L on the right side. Anyone got any idea of whats going on I put the project on my bros computer and it does the same thing. There should be a black bar that runs along the top and if the string should be inside it. I'm using netbeans for the first time as well if that has got anything to do with it, but I doubt it should.

Originally Posted by pbrockway2

I ran the code (using both sets of coordinates) and the string was placed properly both times.

You didn't change anything cause, like I said, I tried it on my brothers computer and its doing the same thing to me.

Attachment 2033
Just shows the displacement highlighted green in paint.

In your constructor you are adding "this" before "this" has been fully constructed.

Sorry I'm gonna need you to elaborate a little more.

I changed this since I don't think I actually need JPanel. It fit the fillRect to the screen right for some reason but the cords for the string and the black rectangle are still off.

 
    public BTTG()
    {
        JFrame container = new JFrame("BTTG");
        container.setPreferredSize(new Dimension(screenSize,screenSize));
        container.setLayout(null);
        container.setBackground(Color.yellow);
        container.setBounds(0,0,screenSize,screenSize);
        container.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        container.add(this);
        container.pack();
        container.setResizable(false);
        container.setVisible(true);
        setIgnoreRepaint(true);
 
       	container.createBufferStrategy(2);
	bufferStrat = container.getBufferStrategy();
 
 
        while(running)
        {  
        render();
        try { Thread.sleep(10); } catch (Exception e) {}
        }
 
 
    }

Sorry I'm gonna need you to elaborate a little more.

public BTTG()
{
    JFrame container = new JFrame("BTTG");
    container.setPreferredSize(new Dimension(screenSize,screenSize));
    container.setLayout(null);
    container.setBackground(Color.yellow);
    container.setBounds(0,0,screenSize,screenSize);
    container.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    container.add(this); // <--- ?
    // etc

I think jps is referring to the fact that you use the panel (specifically, you add it to the frame) before the BTTG() constructor has finished. That is, before the panel has been constructed.

You didn't change anything cause, like I said, I tried it on my brothers computer and its doing the same thing to me.

the cords for the string and the black rectangle are still off.

As I said, I ran your original code both "buffer.drawString("BTTG",5,13);" and with "buffer.drawString("BTTG",50,50);". And in both cases it appeared (or failed to appear) exactly where it ought to appear (or fail to appear) according to the various API docs. I can't access the attachment, but in any case it would help if you elaborated on "the same thing", "off", "placed properly" etc: where do you intend the text to be painted? and where have you assumed the point x=5,y=13 is on the screen?

---

No-one has addressed the question I posed in #4. I would suggest (a) you (fully) construct the gui on the event dispatch thread and not the initial thread and (b) use Swing's default double buffering rather than rolling your own. If there are performance problems then it might be time to consider a different buffering strategy, but even then my every instinct (uninformed by any actual experience with using buffering strategies...) would be to have it render in its own thread which would sleep when it's not doing anything to let the rest of the runtime do its thing.

Can you show what a bare application setup would look like for a 800,800. Maybe if I can see how some one has made a window with no errors I can see what I'm doing wrong. If there is a example in some tutorial that I could look at instead that would be cool to. Although I just got done trying to get all my code in with another tutorial and had problems the whole way just to find out that when I tried just using the code shown in the tut it didn't work and was the problem to begin with. If I can just get past getting the main window up where it can draw correctly the rest would be not a problem.

I suggest you check out any of the wealth of samples available through a search engine and the tutorials. Here is a link to the Oracle custom painting tutorial. Then start your project code over once you have a better understanding.
You will want to make sure each component's constructor has returned before using that component. You can search using keywords including "displayable" for more information on JComponents, but I basically stated what you need to know on that. Also, in the posted code the BTTG constructor only returns when the infinite loop ends, that loop will need to be moved out of the constructor so the constructor can return.