tp-midi-store.html

<link rel="import" href="../bower_components/polymer/polymer.html">

<!--
`tp-midi-store`


@demo demo/index.html 
-->

<dom-module id="tp-midi-store">
  <template>
  </template>

  <script>
    Polymer({

      is: 'tp-midi-store',

      properties: {
        /* Specifies time resolution for each beat. Cannot be chaned dynamically now.*/
        resolution: {
          type: Number,
          value: 24,
        },
      },

      _starttime: 0,
      // FIXME: We may want to consider a de facto JSON based format.
      _data: {
        resolution: 24,
        messages: [],
      },
      // FIXME: Should consider channel.
      _hangingNotes: [],

      data: function () {
        return this._data.messages;
      },

      ready: function () {
      },

      /**
       * Appends MIDI messages at time.
       * @param {MidiTime} time
       * @param {sequence<octet>} message
       */
      append: function (time, message) {
        var status = message[0] & 0xf0;
        var channel = message[0] & 0x0f;

        // Note on with velocity 0 should be handled as a note off.
        if (status == 0x90 && message[2] == 0)
          status = 0x80;

        var data = {};
        switch (status) {
          case 0x80:
            // FIXME: Merging note-on/off could be optional.
            if (!this._hangingNotes[message[1]] ||
                this._hangingNotes[message[1]].length == 0) {
              console.error('unexpected note off received.');
              break;
            }
            // FIXME: Should consider channels.
            data = this._hangingNotes[message[1]].shift();
            data.offAt = {
              measure: time.measure,
              beat: time.beat,
              tick: time.tick
            };
            return data;
          case 0x90:
            data.type = 'note';
            data.number = message[1];
            data.velocity = message[2];
            data.onAt = {
              measure: time.measure,
              beat: time.beat,
              tick: time.tick
            };
            data.offAt = data.onAt;
            this._data.messages.push(data);
            if (!this._hangingNotes[data.number])
              this._hangingNotes[data.number] = [];
            this._hangingNotes[data.number].push(data);
            break;
          default:
            // do not support it.
            break;
        }
        return undefined;
      },
    });
  </script>
</dom-module>