def mouth_move
    
    return if @mouth_move_duration > 0
    return if bitmap[@face_index] == nil
    return if bitmap[@face_index].size == 1
    
    @mouth_move_duration = MOUTH_MOVE_DURATION
    
    if @mouth_index == 0 and bitmap[@face_index][1] != nil
      @mouth_index = 1
    else      
      loop do
        @mouth_index += 1
        @mouth_index %= 20  #总共需要几张动嘴动作这里就填几
        break if bitmap[@face_index][@mouth_index]
      end
    end
    @pic_sprite.bitmap = bitmap[@face_index][@mouth_index]
  end