public void add(T graphic){
synchronized (mLock) {
    mGraphics.add(graphic);
    if (mFirstGraphic == null) {
      mFirstGraphic=graphic;
    }
  }
  postInvalidate();
}

public void add ( T graphic ) { synchronized ( mLock ) { mGraphics . add ( graphic ) ; if ( mFirstGraphic == null ) { mFirstGraphic = graphic ; } } postInvalidate ( ) ; }
adds a graphic to the overlay .
