android - 为什么SurfaceView的onTouchEvent调用会延迟几秒？

Question

我有一个非常简单的 SurfaceView 游戏，有时游戏会在几秒钟内不响应触摸事件，然后它会立即响应所有这些触摸事件。我已经在 Galaxy S3 和 Nexus 4 上测试了我的游戏，它运行良好，似乎这个问题只出现在 Galaxy S5 上。

1. 主要 Activity :

   public class DroidzActivity extends Activity {
   /** Called when the activity is first created. */
   
   private static final String TAG = DroidzActivity.class.getSimpleName();
   
   @Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       // requesting to turn the title OFF
       requestWindowFeature(Window.FEATURE_NO_TITLE);
       // making it full screen
       getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
       // set our MainGamePanel as the View
       setContentView(new MainGamePanel(this));
       Log.d(TAG, "View added");
   }
   
   @Override
   protected void onDestroy() {
       Log.d(TAG, "Destroying...");
       super.onDestroy();
   }
   
   @Override
   protected void onStop() {
       Log.d(TAG, "Stopping...");
       super.onStop();
   }     
   
   }
   

   1. 主游戏面板

公共(public)类 MainGamePanel 扩展 SurfaceView 实现 SurfaceHolder.Callback {

private static final String TAG = MainGamePanel.class.getSimpleName();

private MainThread thread;

public MainGamePanel(Context context) {
    super(context);
    // adding the callback (this) to the surface holder to intercept events
    getHolder().addCallback(this);

    // create the game loop thread
    thread = new MainThread(getHolder(), this);

    // make the GamePanel focusable so it can handle events
    setFocusable(true);
}

@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
        int height) {
}

@Override
public void surfaceCreated(SurfaceHolder holder) {
    // at this point the surface is created and
    // we can safely start the game loop
    thread.setRunning(true);
    thread.start();
}

@Override
public void surfaceDestroyed(SurfaceHolder holder) {
    Log.d(TAG, "Surface is being destroyed");
    // tell the thread to shut down and wait for it to finish
    // this is a clean shutdown
    boolean retry = true;
    while (retry) {
        try {
            thread.setRunning(false);
            thread.join();
            retry = false;
        } catch (InterruptedException e) {
            // try again shutting down the thread
        }
    }
    Log.d(TAG, "Thread was shut down cleanly");
}

public void render(Canvas canvas){
    if(canvas!=null)
        canvas.drawColor(colorList[colorIndex]);
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    if (event.getAction() == MotionEvent.ACTION_DOWN) {
        colorIndex++;
        colorIndex = colorIndex % colorList.length;
    }

    return super.onTouchEvent(event);
}
int [] colorList = {Color.RED, Color.GREEN, Color.BLUE, Color.GRAY};
    int colorIndex = 0;

}

1. 主线程

   公共(public)类 MainThread 扩展线程 {

   private static final String TAG = MainThread.class.getSimpleName();
   
   // Surface holder that can access the physical surface
   private SurfaceHolder surfaceHolder;
   // The actual view that handles inputs
   // and draws to the surface
   private MainGamePanel gamePanel;
   
   // flag to hold game state 
   private boolean running;
   public void setRunning(boolean running) {
       this.running = running;
   }
   
   public MainThread(SurfaceHolder surfaceHolder, MainGamePanel gamePanel) {
       super();
       this.surfaceHolder = surfaceHolder;
       this.gamePanel = gamePanel;
   }
   
   
   // desired fps
   private final static int    MAX_FPS = 50;   
   // maximum number of frames to be skipped
   private final static int    MAX_FRAME_SKIPS = 5;    
   // the frame period
   private final static int    FRAME_PERIOD = 1000 / MAX_FPS;  
   
   
   @Override
   public void run() {
       Canvas canvas;
       Log.d(TAG, "Starting game loop");
   
       long beginTime;     // the time when the cycle begun
       long timeDiff;      // the time it took for the cycle to execute
       int sleepTime;      // ms to sleep (<0 if we're behind)
       int framesSkipped;  // number of frames being skipped 
   
       sleepTime = 0;
   
       while (running) {
           canvas = null;
           // try locking the canvas for exclusive pixel editing
           // in the surface
           try {
               canvas = this.surfaceHolder.lockCanvas();
               synchronized (surfaceHolder) {
                   beginTime = System.currentTimeMillis();
                   framesSkipped = 0;  // resetting the frames skipped
                   // update game state 
               //  this.gamePanel.update();
                   // render state to the screen
                   // draws the canvas on the panel
                   this.gamePanel.render(canvas);              
                   // calculate how long did the cycle take
                   timeDiff = System.currentTimeMillis() - beginTime;
                   // calculate sleep time
                   sleepTime = (int)(FRAME_PERIOD - timeDiff);
   
                   if (sleepTime > 0) {
                       // if sleepTime > 0 we're OK
                       try {
                           // send the thread to sleep for a short period
                           // very useful for battery saving
                           Thread.sleep(sleepTime);    
                       } catch (InterruptedException e) {}
                   }
   
                   while (sleepTime < 0 && framesSkipped < MAX_FRAME_SKIPS) {
                       // we need to catch up
                       // update without rendering
                   //  this.gamePanel.update(); 
                       // add frame period to check if in next frame
                       sleepTime += FRAME_PERIOD;  
                       framesSkipped++;
                   }
               }
           } finally {
               // in case of an exception the surface is not left in 
               // an inconsistent state
               if (canvas != null) {
                   surfaceHolder.unlockCanvasAndPost(canvas);
               }
           }   // end finally
       }
   }   
   

这是最简单的应用程序版本，我已经尝试过并且能够再次重现同样的问题。有时在 S5 上加载需要 5-10 秒，而在 Nexus 4 和 S3 上加载不到 1 秒。

Answer 1

看起来 MainThread 正在使 UI 线程处于饥饿状态。

最终执行的代码(删除了很​​多东西)如下所示:

canvas = this.surfaceHolder.lockCanvas();
// Do a ton of stuff
surfaceHolder.unlockCanvasAndPost(canvas);
canvas = this.surfaceHolder.lockCanvas();
// Do a ton of stuff
surfaceHolder.unlockCanvasAndPost(canvas);
canvas = this.surfaceHolder.lockCanvas();
// Do a ton of stuff
surfaceHolder.unlockCanvasAndPost(canvas);

这是android源码支持的。请注意 SurfaceHolder#lock 调用 mSurfaceLock.lock() .这也称为 SurfaceHolder#updateWindow ，在该文件的许多其他地方被调用。

mSurfaceLock 是一个 ReentrantLock ，文档说明:

The constructor for this class accepts an optional fairness parameter. When set true, under contention, locks favor granting access to the longest-waiting thread. Otherwise this lock does not guarantee any particular access order.

SurfaceView 没有指定公平性，所以它应该使用默认值，这可能会导致这种饥饿。

尝试转移一些工作，尤其是在锁定/解锁调用之外的 sleep 时间。