Android - OnDraw（）方法永遠不會被調用

Question

我是新來的android編程，我不明白爲什麼我的渲染器中的OnDraw（）方法沒有被調用invalidate（）被調用。然而，最終設置的背景資源確實被調用。有兩個類，Game.java和Renderer.java。看來無效呼叫沒有時間在遊戲循環中得到處理。

Game.Java

public class Game extends Activity 
{ 
    Level currentLevel; 
    private static List<Entity> _renderList = new ArrayList<Entity>(); 


    public void StartLevel(View view) 
    { 
     System.out.println("I HAVE STARTED THE LEVEL!"); 
     // Hide the play button 
     Button playButton = (Button) findViewById(R.id.start_game); 
     playButton.setVisibility(View.GONE); 
     // Load the level 
     currentLevel = new Level1(this); 
     // Create the initial entities 

     // Add the entities to the screen 
     List<Bitmap> bitmapList; 
     bitmapList = new ArrayList<Bitmap>(); 
     Bitmap enemy = BitmapFactory.decodeResource(getResources(), R.drawable.enemy); 
     bitmapList.add(enemy); 
     System.out.println("CREATING RENDERER!"); 
     Renderer renderer = new Renderer(this, _renderList, bitmapList); 
     renderer.setBackgroundResource(R.drawable.beachbackground); 
     setContentView(renderer); 
     System.out.println("STARTING TRAVEL!"); 
     while (currentLevel.GetDistTravelled() < currentLevel.GetDist()) 
     { 
      Retrieve(); 
      currentLevel.AddDistance(1); 
      System.out.println("DISTANCE +1!"); 
      renderer.RenderFrame(_renderList); 
      System.out.println("RENDER LEVEL FRAME!"); 
      try 
      { 
       Thread.currentThread().sleep(50); 
      } 
      catch (InterruptedException e) 
      { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
     } 
     System.out.println("SET BACKGROUND!"); 
     renderer.setBackgroundResource(R.drawable.menubackground); 
    } 

    public List<Entity> GetRenderList() 
    { 
     return _renderList; 
    } 

    private void Retrieve() 
    { 
     // get the array 
     Entity[] enemies; 
     enemies = currentLevel.CheckSpawn(); 
     if(enemies != null) 
     { 
      // parse the array into entities 
      int length = enemies.length; 
      System.out.println(length); 

      // remember to Get enemy strings 
      for(int i = 0; i < length; i++) 
      { 
       // add them to our array 
       _renderList.add(enemies[i]); 
      } 

     } 
    } 
} 

Renderer.java

class Renderer extends SurfaceView implements SurfaceHolder.Callback 
{ 
    PanelThread _thread; 
    List<Entity> _renderList = new ArrayList<Entity>(); 
    List<Bitmap> _bitmapList = new ArrayList<Bitmap>(); 

    public Renderer(Context context, List<Entity> renderList, List<Bitmap> bitmapList) 
    { 
     super(context); 
     getHolder().addCallback(this); 
     _bitmapList = bitmapList; 
    } 

    public void RenderFrame(List<Entity> renderList) 
    { 
     for (int i = 0; i < renderList.size(); i++) 
      { 
       _renderList.add(renderList.get(i)); 
      } 
     invalidate(); 
    } 


    @Override 
    public void onDraw(Canvas canvas) 
    { 
     Paint paint = null; 

     // Draw enemies 

     if(_renderList.size() != 0 && _renderList != null) 
     { 
      int size = _renderList.size(); 
      for(int i = 0; i < size; i++) 
      { 
       canvas.drawBitmap(_bitmapList.get(_renderList.get(i).GetBitmapID()), _renderList.get(i).GetX(), _renderList.get(i).GetY(), paint); 
      } 
     } 
    } 

     // position the train on the screen in the appropriate place  



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

    } 

    @Override 
    public void surfaceCreated(SurfaceHolder holder) 
    { 
     setWillNotDraw(false); //Allows us to use invalidate() to call onDraw() 

     _thread = new PanelThread(getHolder(), this); //Start the thread that 
     _thread.setRunning(true);      //will make calls to 
     _thread.start();        //onDraw() 
    } 


    @Override 
    public void surfaceDestroyed(SurfaceHolder holder) 
    { 
     try 
     { 
      _thread.setRunning(false);    //Tells thread to stop 
      _thread.join();       //Removes thread from mem. 
     } 
     catch (InterruptedException e) {} 
    } 

    class PanelThread extends Thread 
    { 
     private SurfaceHolder _surfaceHolder; 
     private Renderer _renderer; 
     private boolean _run = false; 

     public PanelThread(SurfaceHolder surfaceHolder, Renderer renderer) 
     { 
      _surfaceHolder = surfaceHolder; 
      _renderer = renderer; 
     } 


     public void setRunning(boolean run) 
     { 
      _run = run; 
     } 


     @Override 
     public void run() 
     { 
      Canvas c; 
      while (_run) 
      {  
       c = null; 

       try 
       { 
        c = _surfaceHolder.lockCanvas(null); 
        synchronized (_surfaceHolder) 
        { 
        //Insert methods to modify positions of items in onDraw() 
        postInvalidate(); 

        } 
       } 
       finally { 
        if (c != null) { 
         _surfaceHolder.unlockCanvasAndPost(c); 
        } 
       } 
      } 
     } 
    } 
} 

上解決這個問題的任何幫助，將不勝感激。如果需要更多的信息，請詢問。

Answer 1

嗨，我有像你一樣的錯誤。但是我發現了。但我不清楚這一點。

但你可以嘗試

屬性機器人添加：背景到您的佈局。