private void center(float dx,float dy){
  if ((mCenterPointX + dx - mRadius < 0) || (mCenterPointY + dy - mRadius < 0) || (Math.min(mDrawableWidth,mScreenWidth) - (mCenterPointX + dx + mRadius) < 0)|| (Math.min(mDrawableHeight,mScreenHeight) - (mCenterPointY + dy + mRadius) < 0)) {
    return;
  }
  mCenterPointX+=dx;
  mCenterPointY+=dy;
}

private void center ( float dx , float dy ) { if ( ( mCenterPointX + dx - mRadius < 0 ) || ( mCenterPointY + dy - mRadius < 0 ) || ( Math . min ( mDrawableWidth , mScreenWidth ) - ( mCenterPointX + dx + mRadius ) < 0 ) || ( Math . min ( mDrawableHeight , mScreenHeight ) - ( mCenterPointY + dy + mRadius ) < 0 ) ) { return ; } mCenterPointX += dx ; mCenterPointY += dy ; }
move the circle view .
