我用下面的代码来实现菜单栏的功能，但发现图片截屏保存后，却显示为黑色。请帮我看看代码，是哪个环节我写错了。

case R.id.id_menu_Save:

           Bitmap bmp = SavePixels(0, 0, 800, 400, CCDirector.sharedDirector().gl);

           File file = new File("/sdcard/test.jpg");

           try

           {

               file.createNewFile();

               FileOutputStream fos = new FileOutputStream(file);

               bmp.compress(CompressFormat.JPEG, 100, fos);

               Toast.makeText(getApplicationContext(), "Image Saved", 0).show();

               Log.i("Menu Save Button", "Image saved as JPEG");

           }

           catch (Exception e)

           {

               e.printStackTrace();

           }

           break;

下面是保存图片的功能代码：

public static Bitmap SavePixels(int x, int y, int w, int h, GL10 gl)

{  

    int b[]=new int[w*(y+h)];

    int bt[]=new int[w*h];

    IntBuffer ib=IntBuffer.wrap(b);

    ib.position(0);

    gl.glReadPixels(x, 0, w, y+h, GL10.GL_RGBA, GL10.GL_UNSIGNED_BYTE, ib);

    for(int i=0, k=0; i<h; i++, k++)

    {//remember, that OpenGL bitmap is incompatible with Android bitmap

     //and so, some correction need.        

         for(int j=0; j<w; j++)

         {

              int pix=b[i*w+j];

              int pb=(pix>>16)&0xff;

              int pr=(pix<<16)&0x00ff0000;

              int pix1=(pix&0xff00ff00) | pr | pb;

              bt[(h-k-1)*w+j]=pix1;

         }

    }

   Bitmap sb = Bitmap.createBitmap(bt, w, h, Bitmap.Config.ARGB_8888);

   return sb;

}

除此之外，我还希望大家不吝赐教，指点我一条正确的方向。比如我想获取屏幕的像素，我需要应用到哪些类和实体呢？

原问题：COCOS 2D screen shot is black in Android