Canvas not drawing Android

Question

我一直在嘗試開始一個新項目，當我去啓動時，我無法獲得任何工作。我已經查看了過去幾個小時的代碼並使用了它，但我不記得最後一次發生這種情況的原因。

package org.waldev.canvascollisiontest; 

import android.app.Activity; 
import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.PixelFormat; 
import android.os.Bundle; 
import android.view.Menu; 
import android.view.SurfaceHolder; 
import android.view.SurfaceView; 

public class CollisionTest extends Activity { 
private Panel game; 
@Override 
public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    game = new Panel(this); 
    setContentView(game); 
} 

public class Panel extends SurfaceView implements SurfaceHolder.Callback{ 
    Threads thread; 

    public Panel(Context context) { 
     super(context); 
     thread = new Threads(this.getHolder(), this); 
     setFocusable(true); 
    } 

    public void onDraw(Canvas c) 
    { 
     c.drawColor(Color.BLUE); 
    } 
    @Override 
    public void surfaceChanged(SurfaceHolder holder, int format, int width, 
      int height) { 
     // TODO Auto-generated method stub 
    } 

    //when the game starts, run the thread\ 
    @Override 
    public void surfaceCreated(SurfaceHolder holder) { 
     // TODO Auto-generated method stub 
     holder.setFormat(PixelFormat.RGB_565); 
     thread.setRunning(true); 
     thread.start(); 
    } 

    //if its destroyed, then destroy the thread 
    @Override 
    public void surfaceDestroyed(SurfaceHolder holder) { 
     // TODO Auto-generated method stub 
     boolean retry = true; 
     thread.setRunning(false); 
     while (retry) { 
      try { 
       thread.join(); 
       //     bitmaps.recycleAll(); 
       retry = false; 
      } catch (InterruptedException e) { 
       // we will try it again and again... 
      } 
     } 
    } 

} 
} 

和螺紋：

package org.waldev.canvascollisiontest; 

import org.waldev.canvascollisiontest.CollisionTest.Panel; 

import android.graphics.Canvas; 
import android.view.SurfaceHolder; 

public class Threads extends Thread{ 
SurfaceHolder surfaceHolder; 
private Panel game; 

private Canvas c; 
private boolean isRunning = true; 

// desired fps 
private final static int MAX_FPS = 24; 
// maximum number of frames to be skipped 
private final static int MAX_FRAME_SKIPS = 0; 
// the frame period 
private final static int FRAME_PERIOD = 1000/MAX_FPS; 


public Threads(SurfaceHolder surfaceHolder, Panel panel){ 
    this.surfaceHolder = surfaceHolder; 
    game = panel; 
} 

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

public boolean getRunning(){ 
    return isRunning(); 
} 

public SurfaceHolder getSurface(){ 
    return surfaceHolder; 
} 

@Override 
public void run() { 
    Canvas canvas; 

    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 
    boolean updated = false; 

    sleepTime = 0; 

    while (isRunning) { 
     canvas = null; 
     try { 
      canvas = this.surfaceHolder.lockCanvas(); 
      synchronized (surfaceHolder) { 
       beginTime = System.currentTimeMillis(); 
       framesSkipped = 0; 
       if(canvas != null) 
       { 
        game.onDraw(canvas); 
       } 
       timeDiff = System.currentTimeMillis() - beginTime; 
       sleepTime = (int)(FRAME_PERIOD - timeDiff); 

       if (sleepTime > 0) { 
        try { 
         Thread.sleep(sleepTime); 
        } catch (InterruptedException e) {} 
       } 
       else 
       { 
        updated = false; 
       } 
      } 
     } finally { 
      // in case of an exception the surface is not left in 
      // an inconsistent state 
      if (canvas != null) { 
       surfaceHolder.unlockCanvasAndPost(canvas); 
      } 
     } // end finally 
    } 
} 
public boolean isRunning() { 
    return isRunning; 
} 
} 

我在裏面撒了一些破發點，並且這是從來沒有在CollisionTest調用surfaceCreated。我知道這是我在這裏失蹤的一些愚蠢的東西，所以如果你看到它，讓我知道。謝謝！

威廉

Answer 1

我得到它的工作，我忘了加上：

getHolder().addCallback(this); 

的構造面板，這是什麼導致它無法正常工作。謝謝！