SurfaceView为空，而不是在画布上绘制对象

Question

我不知道为什么但我的表面视图是空黑屏。它应该有红色背景。

我错了什么？

SurfaceView ：

public class GameView extends SurfaceView implements SurfaceHolder.Callback
{
    private GameThread gameThread;

    public GameView(Context context)
    {
        super(context);

        getHolder().addCallback(this);
        gameThread = new GameThread(getHolder(), this);
    }

    @Override
    protected void onDraw(Canvas canvas)
    {
        canvas.drawColor(Color.RED);
    }

    @Override
    public void surfaceChanged(SurfaceHolder holder, int format, int width, int height)
    {
        Utils.logI("Surface changed!");
    }

    @Override
    public void surfaceCreated(SurfaceHolder holder)
    {
        Utils.logI("Surface created !");
        gameThread.start();
    }

    @Override
    public void surfaceDestroyed(SurfaceHolder holder)
    {
        Utils.logI("Surface destroyed");
        boolean retry = true;

        gameThread.stopThread();

        while(retry)
        {
            try
            {
                gameThread.join();
                retry = false;
            }
            catch (InterruptedException e){}
        }
    }
}

GameThread ：

public class GameThread extends Thread
{
    private boolean isQutting = false;

    private SurfaceHolder surfaceHolder;
    private GameView gameView;

    public GameThread(SurfaceHolder surfaceHolder, GameView gameView)
    {
        this.surfaceHolder = surfaceHolder;
        this.gameView = gameView;

        setName("Game thread");
    }

    @Override
    public void run()
    {
        Canvas canvas = null;

        while(!isQuitting())
        {

            try
            {
                canvas = surfaceHolder.lockCanvas(null);

                synchronized (surfaceHolder)
                {
                    gameView.draw(canvas);
                }
            }
            finally
            {
                if (canvas != null)
                {
                    surfaceHolder.unlockCanvasAndPost(canvas);
                }
            }
        }
    }

    private boolean isQuitting() { return this.isQutting; }

    public synchronized void stopThread()
    {
        this.isQutting = true;
    }
}

ActivityMain ：

public class ActivityMain extends BaseFragmentActivity
{

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
        setContentView(new GameView(this));
    }

}