たとえば、キャンバスに2つのビットマップを描画する際にこの問題があります(ライブ壁紙用です)。問題は、前面にある小さなビットマップを背景ビットマップの正しい場所に正確に配置する必要があるということです。もちろん、エミュレーターでは見栄えがします(480x800の解像度としましょう)。しかし、携帯電話 (800x1280 解像度) で確認すると、適切な場所に収まりません。
私はthiseを使用しようとしました:
    int pixel = 120;
final float scale = getResources().getDisplayMetrics().density;
int dip = (int) (pixel* scale + 0.5f);
ハードピクセルの代わりに、それもうまくいきませんでした。以下はクラスコード全体です。
public class DemoWallpaperService extends WallpaperService {
@Override
public Engine onCreateEngine() {
    return new DemoWallpaperEngine();
}
private class DemoWallpaperEngine extends Engine {
    private boolean mVisible = false;
    private final Handler mHandler = new Handler();
     int x=0,y=0,a=255,i=-1, a1=255, i1=-1;
     float r=0,rs=1;
     float rx1=10, rxs=-1;
     private Matrix mMatrix = new Matrix();
     private Matrix mMatrix1 = new Matrix();
     private Matrix mMatrixRotate1 = new Matrix();
     private Matrix mMatrixRotate2 = new Matrix();
     public Bitmap spaceShip = BitmapFactory.decodeResource(getResources(), R.drawable.spaceship);
     public Bitmap background= BitmapFactory.decodeResource(getResources(), R.drawable.back2short2j);
     public Bitmap wyspa= BitmapFactory.decodeResource(getResources(), R.drawable.wyspa22g);
     public Bitmap ksiezyc = BitmapFactory.decodeResource(getResources(), R.drawable.ksiezyc);
     public Bitmap reflektorfront= BitmapFactory.decodeResource(getResources(), R.drawable.reflektorwyspa);
     private float mPixels;
     private float mPixels1;
    private final Runnable mUpdateDisplay = new Runnable() {
    @Override
    public void run() {
        draw();
    }};
    private void draw() {
       SurfaceHolder holder = getSurfaceHolder();
       Canvas c = null;
       Display d = ((WindowManager)getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
       int wx= d.getWidth();
       int wy= d.getHeight();
       try {
           Runtime.getRuntime().gc();
          c = holder.lockCanvas();
          c.save();
          if (c != null) {
              Paint paintMoon = new Paint();
              if(a1<=15){
                  i1=1;
              }
              else if(a1>=255){
                  i1=-1;
              }
              a1+=5*i1;
              paintMoon.setAlpha(a1);
              c.translate((float)mPixels, 0f);
              c.drawBitmap(background, mMatrix, null);
              c.drawBitmap(ksiezyc, 1027*wx/480,15*wy/800, paintMoon);
              if(rx1<=-15){
                  rxs=1;
              }
              else if(rx1>=15){
                  rxs=-1;
              }
              rx1+=rxs*0.7;
              c.translate((float)mPixels1, 0f);
              //reflektor wyspa back
              mMatrixRotate2.setTranslate(340*wx/480,300*wy/800);
              mMatrixRotate2.preRotate(rx1,reflektorfront.getWidth()/2,20);
              c.drawBitmap(reflektorfront, mMatrixRotate2, null);
              c.drawBitmap(wyspa, mMatrix1, null);
              if(r<=-15){
                  rs=1;
              }
              else if(r>=15){
                  rs=-1;
              }
              r+=rs*0.5;
              mMatrixRotate1.setTranslate(160*wx/480,380*wy/800);
              mMatrixRotate1.preRotate(r,reflektorfront.getWidth()/2,20);
              c.drawBitmap(reflektorfront, mMatrixRotate1, null);
              if(x<c.getWidth()){
              x+=3;}
              else{x=0;}
              if(y<c.getHeight()){
              y+=3;}
              else{y=0;}
              Paint paint = new Paint();
              if(a<=5){
                  i=1;
              }
              else if(a>=255){
                  i=-1;
              }
              a+=10*i;
              paint.setAlpha(a);
              c.drawBitmap(spaceShip,x,y,paint);
                 c.restore();
          }
       } finally {
          if (c != null)
             holder.unlockCanvasAndPost(c);
       }
       mHandler.removeCallbacks(mUpdateDisplay);
       if (mVisible) {
           mHandler.postDelayed(mUpdateDisplay, 10);
       }
    }
    @Override
    public void onOffsetsChanged(float xOffset, float yOffset,
             float xStep, float yStep, int xPixels, int yPixels){
        super.onOffsetsChanged(xOffset, yOffset, xStep, yStep, xPixels, yPixels);                   
         mPixels = xPixels*7/4;
         mPixels1 = 500+xPixels;
            draw();
    }
    @Override
    public void onVisibilityChanged(boolean visible) {
        mVisible = visible;
        if (visible) {
            draw();
        } else {
            mHandler.removeCallbacks(mUpdateDisplay);
        }
    }
     @Override
      public void onSurfaceChanged(SurfaceHolder holder, int format, int width, int height) {
         super.onSurfaceChanged(holder, format, width, height);
         float w = background.getWidth();
         float h = background.getHeight();
         float s = height / (float)h;
         float z = height / (float)h;
         mMatrix.reset();
         mMatrix1.reset();
         mMatrixRotate1.reset();
         mMatrixRotate2.reset();
         mMatrix.setScale(s, s);
         mMatrix1.setScale(z, z);
         mMatrixRotate1.setScale(s, s);
         draw();
      }
    @Override
    public void onSurfaceDestroyed(SurfaceHolder holder) {
        super.onSurfaceDestroyed(holder);
        mVisible = false;
        mHandler.removeCallbacks(mUpdateDisplay);
    }
    @Override
     public void onCreate(SurfaceHolder surfaceHolder) {
         super.onCreate(surfaceHolder);
         setTouchEventsEnabled(false);
     }
    @Override
    public void onDestroy() {
         super.onDestroy();
         mVisible = false;
         mHandler.removeCallbacks(mUpdateDisplay);
    }
}    
できれば誰か助けてください。