Make it easier to play JianPu (numbered music notation) music. A user can set music key signature. In accordance with the setting, the seven keys corresponding to the natural musical scale are displayed using distinct colors.
方便弹奏简谱乐曲。用户可设置调号。根据设置的调号，对应简谱七个自然音阶的按键会以不同的颜色显示。