Question

我在Processing中寻找void draw()函数的源代码。有什么建议吗？

谢谢

Answer 1

您可以在GitHub上找到整个Processing库的源代码here。

Here是PApplet类的直接链接，它定义了draw()函数。搜索＆＃34; void draw＆＃34;找到这个：

public void draw() {
    // if no draw method, then shut things down
    //System.out.println("no draw method, goodbye");
    finished = true;
  }

它并不重要，因为您应该定义自己的draw()函数覆盖这个函数。这就是Processing的工作原理。您编写draw()函数的代码。

修改：根据您的评论判断，我猜测您正在尝试了解Processing如何每秒调用draw()函数60次。这有点复杂。

查看PSurfaceAWT，这是处理中使用的默认渲染器。搜索＆＃34; handleDraw＆＃34;找到这段代码：

public Thread createThread() {
    return new AnimationThread() {
      @Override
      public void callDraw() {
        sketch.handleDraw();
        render();
      }
    };
  }

AnimationThread在PSurfaceNone类中定义：

public class AnimationThread extends Thread {

    public AnimationThread() {
      super("Animation Thread");
    }

    public void callDraw() {
      sketch.handleDraw();
    }


    @Override
    public void run() {  
      long beforeTime = System.nanoTime();
      long overSleepTime = 0L;

      int noDelays = 0;
      final int NO_DELAYS_PER_YIELD = 15;

      sketch.start();

      while ((Thread.currentThread() == thread) && !sketch.finished) {
        checkPause();

        callDraw();

        long afterTime = System.nanoTime();
        long timeDiff = afterTime - beforeTime;
        long sleepTime = (frameRatePeriod - timeDiff) - overSleepTime;

        if (sleepTime > 0) {  // some time left in this cycle
          try {
            Thread.sleep(sleepTime / 1000000L, (int) (sleepTime % 1000000L));
            noDelays = 0;  // Got some sleep, not delaying anymore
          } catch (InterruptedException ex) { }

          overSleepTime = (System.nanoTime() - afterTime) - sleepTime;

        } else {    // sleepTime <= 0; the frame took longer than the period
          overSleepTime = 0L;
          noDelays++;

          if (noDelays > NO_DELAYS_PER_YIELD) {
            Thread.yield();   // give another thread a chance to run
            noDelays = 0;
          }
        }

        beforeTime = System.nanoTime();
      }

      sketch.dispose(); 

      // If the user called the exit() function, the window should close,
      // rather than the sketch just halting.
      if (sketch.exitCalled) {
        sketch.exitActual();
      }
    }
  }

我删除了一些已注释掉的部分。这可能看起来像很多代码，但它所做的只是设置一个每秒触发60次的线程，通过测量已经过了多少时间并睡眠正确的数量。一个更基本的例子是这样的：

new Thread(){
   public void run(){
      while(true){
         draw();
         Thread.sleep(16);
      }
   }
}

这些是基础知识，但它可以得到更多参与。我推荐谷歌搜索＆＃34;动画线程＆＃34;或者＆＃34;游戏循环＆＃34;或者＆＃34;游戏动画线程＆＃34;并尝试一些事情。

处理：void draw（）函数源

1 个答案: