了解BufferStrategy [英] Understand BufferStrategy

问题描述

我是java的新手。我想做一个游戏。经过大量的研究，我无法理解bufferstrategy的工作原理..
我知道基础知识..它创建了一个离屏图像，以后可以放入你的windows对象..我得到了这个

I'm kind of new to java. I want to make a game. After a lot of research, I can't understand how bufferstrategy works.. I know the basics.. it creates an off-screen image that you can later put into your windows object.. I got this

public class Marco extends JFrame {
    private static final long serialVersionUID = 1L;
    BufferStrategy bs; //create an strategy for multi-buffering.

    public Marco() {
       basicFunctions(); //just the clasics setSize,setVisible,etc
       createBufferStrategy(2);//jframe extends windows so i can call this method 
       bs = this.getBufferStrategy();//returns the buffer strategy used by this component
    }

   @Override
   public void paint(Graphics g){
      g.drawString("My game",20,40);//some string that I don't know why it does not show
      //guess is 'couse g2 overwrittes all the frame..
      Graphics2D g2=null;//create a child object of Graphics
      try{
         g2 = (Graphics2D) bs.getDrawGraphics();//this new object g2,will get the
         //buffer of this jframe?
         drawWhatEver(g2);//whatever I draw in this method will show in jframe,
         //but why??
      }finally{
         g2.dispose();//clean memory,but how? it cleans the buffer after
         //being copied to the jframe?? when did I copy to the jframe??
      }
      bs.show();//I never put anything on bs, so, why do I need to show its content??
      //I think it's a reference to g2, but when did I do this reference??
   }

   private void drawWhatEver(Graphics2D g2){
       g2.fillRect(20, 50, 20, 20);//now.. this I can show..
   }
  }

我不知道..我一直在学习这个很长一段时间了......而且根本没有运气..我不知道......也许它就在那里，而且它非常简单明了，而且我看起来太傻了......

I don't know.. I've been studying this for a long time now.. and with no luck at all.. I don't know.. maybe it's all there, and it's really clear and simple, and I'm just too stupid to see it..

感谢所有帮助.. :)

Thanks for all the help.. :)

推荐答案

以下是它的工作原理：

1. JFrame 构造一个 BufferStrategy 当你打电话给 createBufferStrategy（2）; 。 BufferStrategy 知道它属于 JFrame 的特定实例。您正在检索它并将其存储在 bs 字段中。


2. 当需要绘制您的东西时，您正在检索 Graphics2D 来自 bs 。此 Graphics2D 对象与 bs 所拥有的内部缓冲区之一相关联。当您绘制时，一切都进入缓冲区。


3. 当您最终调用 bs.show（）时， bs 将导致您刚刚绘制的缓冲区成为 JFrame 的当前缓冲区。它知道如何做到这一点，因为（见第1点）它知道它正在服务的 JFrame 。

1. The JFrame constructs a BufferStrategy when you call createBufferStrategy(2);. The BufferStrategy knows that it belongs to that specific instance of JFrame. You are retrieving it and storing it in the bs field.
2. When it comes time to draw your stuff, you are retrieving a Graphics2D from bs. This Graphics2D object is tied to one of the internal buffers owned by bs. As you draw, everything goes into that buffer.
3. When you finally call bs.show(), bs will cause the buffer that you just drew to become the current buffer for the JFrame. It knows how to do this because (see point 1) it knows what JFrame it is in service to.

这就是所有这些。

通过评论你的代码...你应该稍微改变你的绘图程序。而不是：

By way of comment to your code...you should change your drawing routine a bit. Instead of this:

try{
    g2 = (Graphics2D) bs.getDrawGraphics();
    drawWhatEver(g2);
} finally {
       g2.dispose();
}
bs.show();

你应该有这样一个循环：

you should have a loop like this:

do {
    try{
        g2 = (Graphics2D) bs.getDrawGraphics();
        drawWhatEver(g2);
    } finally {
           g2.dispose();
    }
    bs.show();
} while (bs.contentsLost());

这样可以防止丢失的缓冲帧，根据文档，偶尔会发生。

That will safeguard against lost buffer frames, which, according to the docs, can happen occasionally.

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