이미지뷰 확대 축소 여백관련 질문입니다.

Question

public boolean onTouchEvent(MotionEvent event) {
        scaleGestureDetector.onTouchEvent(event);
        
        //for drag
        final float X = event.getRawX();
        final float Y = event.getRawY();
          switch (event.getAction() & MotionEvent.ACTION_MASK) {
            case MotionEvent.ACTION_DOWN:
                RelativeLayout.LayoutParams lParams = (RelativeLayout.LayoutParams) this.getLayoutParams();
                _xDelta = X - lParams.leftMargin;
                _yDelta = Y - lParams.topMargin;
                break;
            case MotionEvent.ACTION_UP:
                break;
            case MotionEvent.ACTION_POINTER_DOWN:
                break;
            case MotionEvent.ACTION_POINTER_UP:
                break;
            case MotionEvent.ACTION_MOVE:
                RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) this
                        .getLayoutParams();
                layoutParams.leftMargin = (int) (X - _xDelta);
                layoutParams.topMargin = (int) (Y - _yDelta);
            layoutParams.rightMargin = -250;
                layoutParams.bottomMargin = -250;
            
                
                this.setLayoutParams(layoutParams);
                break;
            }

        invalidate();
        return true;
      }

 

이런식으로 이미지를 확대하고 축소하고 여백을이용해서 화면이동을하는데요 여백색이 하얀바탕으로 나오는데 이색을 바꿀수 없을까요? 백그라운드에 색을입혀도 아래쪽이랑 오른쪽만 변하고 윗쪽이랑 왼쪽화면의 여백은 여전히 하얀색이네요...