[英]How to use double buffering inside a thread and applet
我有一个关于何时调用paint and update方法的问题? 我有要使用双缓冲的游戏小程序,但我不能使用它。问题是在我的游戏中有一个正在run()方法内移动的球。我想知道如何使用双缓冲来交换屏幕外图片和当前图片。请帮助。
当同时有update()和paint()方法时,什么时候以及为什么?
可以使用的方法是将Canvas添加到小程序,然后为该Canvas创建缓冲策略。 抽象代码,您可能会获得硬件加速。
代码在这里: http ://www.gamedev.net/community/forums/topic.asp?topic_id=405663-扩展AppletGameCore并定义实现所需方法的自己的子类。
import java.awt.Canvas;
import java.awt.Graphics2D;
import java.awt.Dimension;
import java.awt.image.BufferStrategy;
import java.applet.Applet;
/**
*AppletGameCore.java
*@author David Graham
*/
public abstract class AppletGameCore extends Applet implements Runnable
{
private BufferStrategy bufferStrategy;
private Canvas drawArea;/*Drawing Canvas*/
private boolean stopped = false;/*True if the applet has been destroyed*/
private int x = 0;
public void init()
{
Thread t = new Thread(this);
drawArea = new Canvas();
setIgnoreRepaint(true);
t.start();
}
public void destroy()
{
stopped = true;
/*Allow Applet to destroy any resources used by this applet*/
super.destroy();
}
public void update()
{
if(!bufferStrategy.contentsLost())
{
//Show bufferStrategy
bufferStrategy.show();
}
}
//Return drawArea's BufferStrategy
public BufferStrategy getBufferStrategy()
{
return bufferStrategy;
}
//Create drawArea's BufferStrategies
public void createBufferStrategy(int numBuffers)
{
drawArea.createBufferStrategy(numBuffers);
}
//Subclasses should override this method to do any drawing
public abstract void draw(Graphics2D g);
public void update(Graphics2D g)
{
g.setColor(g.getBackground());
g.fillRect(0,0,getWidth(),getHeight());
}
//Update any sprites, images, or primitives
public abstract void update(long time);
public Graphics2D getGraphics()
{
return (Graphics2D)bufferStrategy.getDrawGraphics();
}
//Do not override this method
public void run()
{
drawArea.setSize(new Dimension(getWidth(),getHeight()));
add(drawArea);
createBufferStrategy(2);
bufferStrategy = drawArea.getBufferStrategy();
long startTime = System.currentTimeMillis();
long currTime = startTime;
//animation loop
while(!stopped)
{
//Get time past
long elapsedTime = System.currentTimeMillis()-currTime;
currTime += elapsedTime;
//Flip or show the back buffer
update();
//Update any sprites or other graphical objects
update(elapsedTime);
//Handle Drawing
Graphics2D g = getGraphics();
update(g);
draw(g);
//Dispose of graphics context
g.dispose();
}
}
}
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