add onnote to trigger custom events on note on

src/hydra-api/note.js

@@ -7,7 +7,7 @@ import { getMidiId, resolveNote, resolveInput } from '../midiAccess'
 
 const noteIsPlaying = noteId => state.playingNotes.has(noteId)
 
-const getNoteId = (note, channel, input) =>
+export const getNoteId = (note, channel, input) =>
   getMidiId(
     resolveNote(note),
     channel ?? state.defaults.channel,

src/hydra-api/onnote.js

@@ -0,0 +1,9 @@
+// @ts-check
+
+import state from '../state'
+import { getNoteId } from './note'
+
+export const onnote = (note, channel, input, event) => {
+  const noteId = getNoteId(note, channel, input)
+  noteOnEvents[noteId] = event;
+}

src/midiAccess.js

@@ -82,6 +82,7 @@ midiAccess.on(MidiAccess.TypeNoteOn, ({ data, channel, input }) => {
   const noteId = getMidiId(note, channel, input.id)
   playingNotes.add(noteId)
   envelopes[noteId]?.trigger()
+  noteOnEvents[noteId]?.call()
 
   getMidiWildcards(note, channel, input.id).forEach(wildcard => {
     playingNotes.add(wildcard)

src/state.js

@@ -5,6 +5,9 @@ export default {
   /** @type {Set<string>} */
   playingNotes: new Set(),
 
+  /** @type {Record<string, function>} */
+  noteOnEvents: {},
+
   initialDefaults: {
     channel: 0,
     input: 0,

src/transforms/channel.js

@@ -2,6 +2,7 @@
 
 import { cc } from '../hydra-api/cc'
 import { note } from '../hydra-api/note'
+import { onnote } from '../hydra-api/onnote'
 
 /**
  * Channel is chainable to `midi` and `input()` and provides a channel for all
@@ -17,5 +18,8 @@ export const channel = (channel, input = null) => ({
     note(_note, _channel ?? channel, _input ?? input),
 
   cc: (_index, _channel, _input) =>
-    cc(_index, _channel ?? channel, _input ?? input)
+    cc(_index, _channel ?? channel, _input ?? input),
+
+  onnote: (_note, _event) =>
+    onnote(_note, channel, input, _event)
 })

src/transforms/input.js

@@ -1,6 +1,6 @@
 // @ts-check
 
-import { cc, note } from '../hydra-api'
+import { cc, note, onnote } from '../hydra-api'
 import { channel } from './channel'
 
 /**
@@ -14,5 +14,6 @@ import { channel } from './channel'
 export const input = input => ({
   note: (_note, _channel, _input) => note(_note, _channel, _input ?? input),
   cc: (_index, _channel, _input) => cc(_index, _channel, _input ?? input),
+  onnote: (_note, _event) => onnote(_note, '*', input, _event),
   channel: _channel => channel(_channel, input)
 })