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Java面板双缓冲

javaswingawtdoublebuffered
8

想知道是否有人能为我指明正确的方向，我开发了一个乒乓球游戏，由于闪烁需要使用双缓冲。我尝试了这里的一些帖子来尝试使它工作，但我仍然是Swing AWT的初学者，任何帮助都将是惊人的，谢谢。

public class PongPanel extends JPanel implements Runnable {

private int screenWidth = 500;
private int screenHeight = 300;

private boolean isPaused = false;
private boolean isGameOver = false;

private int playToPoints = 10;

private Padel player1,player2;
private Ball ball;

private Thread gameThread;
private Image dbImage;
private Graphics dbg; 

public PongPanel() {
   setPreferredSize(new Dimension(screenWidth,screenHeight));
   setBackground(Color.BLACK);
   setDoubleBuffered(true);
   setFocusable(true);
   requestFocus();

   player1 = new Padel(Position.LEFT,screenWidth,screenHeight);
   player2 = new Padel(Position.RIGHT,screenWidth,screenHeight);
   ball = new Ball(10,screenWidth/2,screenHeight/2,Color.WHITE);
}

public void addNotify(){
 super.addNotify();
   startGame();
}

private void startGame(){
  gameThread = new Thread(this);
  gameThread.start();
}

@Override
public void run() {
 while (!isGameOver) {   
 dbImage = createImage(screenWidth,screenHeight);
 dbg = this.getGraphics();
 if(!isPaused){
   if(!gameOverCheck()){
     updateGame();
     paintComponents(dbg);   
    }
 }else if(isPaused){
    dbg.setColor(Color.ORANGE);
    dbg.setFont(new Font("serif",Font.BOLD,50));
    dbg.drawString("Paused", screenWidth/2-82, screenHeight/2);
 } 
 try {
     Thread.sleep(30);
    } catch (InterruptedException e) {e.printStackTrace();}
   }
   }

  private boolean gameOverCheck(){
  if(player1.getScore() == playToPoints){
   dbg.setColor(player1.getColour());
   dbg.setFont(new Font("serif",Font.BOLD,50));
   dbg.drawString("Player 1 Wins!", screenWidth/2 - 161, screenHeight/2);
   setGameOver(true);
   return true;
  }else if(player2.getScore() == playToPoints){
   dbg.setColor(player2.getColour());   
   dbg.setFont(new Font("serif",Font.BOLD,50));
   dbg.drawString("Player 2 Wins!", screenWidth/2 - 161, screenHeight/2);
   setGameOver(true);
   return true;
  }

  return false;
 }

 private void updateGame(){
  ball.move(screenWidth,screenHeight,player1,player2);
  player1.aiForPadel(screenWidth, screenHeight, ball.getX(), ball.getY());
  player2.aiForPadel(screenWidth, screenHeight, ball.getX(), ball.getY());

 }

  @Override
  public void paintComponents(Graphics g) {
  super.paintComponents(g);
  dbg.setColor(Color.BLACK);
  dbg.fillRect(0, 0, screenWidth+20, screenHeight+20);
  dbg.setColor(Color.WHITE);
  dbg.drawLine(screenWidth/2, 0, screenWidth/2, screenHeight);
  dbg.setFont(new Font("serif",Font.BOLD,32));
  dbg.drawString(player1.getScore()+"", screenWidth/2-40, screenHeight - 20);
  dbg.drawString(player2.getScore()+"", screenWidth/2+20, screenHeight - 20);
  ball.drawBall(dbg);
    player1.drawPadel(dbg);
    player2.drawPadel(dbg);
 }
}
4个回答
6

这里有一篇非常好的教程（链接），其中介绍了如何使用BufferStrategy来制作不闪烁的动画。

重点是：

  • 在顶层Canvas上调用setIgnoreRepaint(true)，以防止AWT重新绘制它，因为通常你会在动画循环内自己进行绘制。
  • 从BufferStrategy中获取Graphics2D对象（而不是使用通过paintComponent(Graphics g)传递的实例）。
3
4
尽管这样理论上可以回答问题，但最好包含回答的核心部分并提供链接作为参考。 - Duncan Jones
2
基本问题是，您正在违反Swing的基本绘画系统。Swing使用“被动渲染”算法，只有在需要时才执行绘制操作。您可以通过调用repaint来向API建议何时更新某个内容。
根据您的代码，基本问题是，您正在使用自己的Graphics上下文调用paintComponents，但是系统会在绘制过程中将其丢弃，这样您就会与绘画系统相冲突而不是与其合作。
如果正确执行，Swing组件已经具有双缓冲功能，因此您不需要做任何“额外”的工作，只需使用API /系统即可。
我强烈建议您查看以下内容： 以更好地了解Swing中的绘画工作原理。
所以，让我们开始吧...
@Override
public void run() {
    while (!isGameOver) {
        dbImage = createImage(screenWidth, screenHeight);
        dbg = this.getGraphics();
        if (!isPaused) {
            if (!gameOverCheck()) {
                updateGame();
                paintComponents(dbg);
            }
        } else if (isPaused) {
            dbg.setColor(Color.ORANGE);
            dbg.setFont(new Font("serif", Font.BOLD, 50));
            dbg.drawString("Paused", screenWidth / 2 - 82, screenHeight / 2);
        }
        try {
            Thread.sleep(30);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
    }
}
  • Swing不是线程安全的，您不应该在事件分派线程之外的上下文中更新UI。
  • 您永远不应该直接调用任何paint方法。系统会在需要更新组件时执行此操作。

我强烈建议阅读以下内容：

例如...

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.text.Position;

public class PongPanel extends JPanel implements Runnable {

    private int screenWidth = 500;
    private int screenHeight = 300;

    private boolean isPaused = false;
    private boolean isGameOver = false;

    private int playToPoints = 10;

    private Padel player1, player2;
    private Ball ball;

    private Timer gameThread;

    public PongPanel() {
        setPreferredSize(new Dimension(screenWidth, screenHeight));
        setBackground(Color.BLACK);
        setDoubleBuffered(true);
        setFocusable(true);
        requestFocus();

        player1 = new Padel(Position.LEFT, screenWidth, screenHeight);
        player2 = new Padel(Position.RIGHT, screenWidth, screenHeight);
        ball = new Ball(10, screenWidth / 2, screenHeight / 2, Color.WHITE);
    }

    public void addNotify() {
        super.addNotify();
        startGame();
    }

    private void startGame() {
        gameThread = new Timer(30, new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                updateGame();
                gameOverCheck();
                if (isGameOver) {
                    repaint();
                    return;
                }
                if (!isPaused) {
                    if (!gameOverCheck()) {
                        updateGame();
                    }
                }
                repaint();
            }
        });
        gameThread.start();
    }

    private boolean gameOverCheck() {
        if (player1.getScore() == playToPoints) {
            setGameOver(true);
            return true;
        } else if (player2.getScore() == playToPoints) {
            setGameOver(true);
            return true;
        }

        return false;
    }

    private void updateGame() {
        ball.move(screenWidth, screenHeight, player1, player2);
        player1.aiForPadel(screenWidth, screenHeight, ball.getX(), ball.getY());
        player2.aiForPadel(screenWidth, screenHeight, ball.getX(), ball.getY());

    }

    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponents(g);
        Graphics2D g2d = (Graphics2D) g.create();
        g2d.setColor(Color.BLACK);
        g2d.fillRect(0, 0, screenWidth + 20, screenHeight + 20);
        g2d.setColor(Color.WHITE);
        g2d.drawLine(screenWidth / 2, 0, screenWidth / 2, screenHeight);
        g2d.setFont(new Font("serif", Font.BOLD, 32));
        g2d.drawString(player1.getScore() + "", screenWidth / 2 - 40, screenHeight - 20);
        g2d.drawString(player2.getScore() + "", screenWidth / 2 + 20, screenHeight - 20);
        ball.drawBall(g2d);
        player1.drawPadel(g2d);
        player2.drawPadel(g2d);

        if (isGameOver) {
            if (player1.getScore() == playToPoints) {
                g2d.setColor(player1.getColour());
                g2d.setFont(new Font("serif", Font.BOLD, 50));
                g2d.drawString("Player 1 Wins!", screenWidth / 2 - 161, screenHeight / 2);
            } else if (player2.getScore() == playToPoints) {
                g2d.setColor(player2.getColour());
                g2d.setFont(new Font("serif", Font.BOLD, 50));
                g2d.drawString("Player 2 Wins!", screenWidth / 2 - 161, screenHeight / 2);
            }
        } else if (isPaused) {
            g2d.setColor(Color.ORANGE);
            g2d.setFont(new Font("serif", Font.BOLD, 50));
            g2d.drawString("Paused", screenWidth / 2 - 82, screenHeight / 2);
        }

        g2d.dispose();
    }
}

BufferedStrategy

已经有人建议过，BufferStrategy 是一种可行的解决方案，适用于您想要完全控制绘图系统的情况。它更复杂，但可以避免Swing使用的被动渲染系统的奇怪问题。

-1

我认为你可以首先调用super(true);，这只是告诉JPanel它是双缓冲的...因为JPanel的构造函数之一是：

public Jpanel(boolean isDoubleBuffered) {...}

虽然已经过去将近四年，但我希望这能对某些人有所帮助。

2
JPanel的默认构造函数已经调用它：public JPanel() { this(true); } - André Willik Valenti
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