开源PianoView原理研究

https://gitee.com/h128/PianoView

处理键盘按下逻辑部分代码：PianoView.java

  private void handleWhiteKeyDown(int which, MotionEvent event, PianoKey key) {
    key.getKeyDrawable().setState(new int[] { android.R.attr.state_pressed });
    key.setPressed(true);
    if (event != null) {
      key.setFingerID(event.getPointerId(which));
    }
    pressedKeys.add(key);
    invalidate(key.getKeyDrawable().getBounds());
    //utils.playMusic(key);
    if (pianoListener != null) {
      pianoListener.onPianoClick(key.getType(), key.getVoice(), key.getGroup(),
          key.getPositionOfGroup());
    }
  }

  /**
   * 处理黑键点击
   *
   * @param which 那个触摸点
   * @param event 事件
   * @param key 钢琴按键
   */
  private void handleBlackKeyDown(int which, MotionEvent event, PianoKey key) {
    key.getKeyDrawable().setState(new int[] { android.R.attr.state_pressed });
    key.setPressed(true);
    if (event != null) {
      key.setFingerID(event.getPointerId(which));
    }
    pressedKeys.add(key);
    invalidate(key.getKeyDrawable().getBounds());
    //utils.playMusic(key);
    if (pianoListener != null) {
      pianoListener.onPianoClick(key.getType(), key.getVoice(), key.getGroup(),
          key.getPositionOfGroup());
    }
  }

 钢琴按下监听

OnPianoListener

  /**
   * 点击钢琴键
   *
   * @param type 钢琴键类型（黑、白）
   * @param voice 钢琴音色（DO,RE,MI,FA,SO,LA,SI）
   * @param group 钢琴键所在组（白：9组；黑：7组）
   * @param positionOfGroup 钢琴在组内位置
   */
  void onPianoClick(Piano.PianoKeyType type, Piano.PianoVoice voice, int group,
      int positionOfGroup);
}

 钢琴键类型和音高定义

    public static enum PianoKeyType {
        @SerializedName("0")
        BLACK(0),
        @SerializedName("1")
        WHITE(1);

        private int value;

        private PianoKeyType(int value) {
            this.value = value;
        }

        public int getValue() {
            return this.value;
        }

        public String toString() {
            return "PianoKeyType{value=" + this.value + '}';
        }
    }

    public static enum PianoVoice {
        DO,
        RE,
        MI,
        FA,
        SO,
        LA,
        SI;