feat: piano loads subset of audio notes in layers (#53)

src/splendid-grand-piano.ts

@@ -18,6 +18,10 @@ export type SplendidGrandPianoConfig = {
   detune: number;
   velocity: number;
   decayTime: number;
+  notesToLoad?: {
+    notes: number[],
+    velocityRange: [number, number]
+  }
 } & Partial<DefaultPlayerConfig>;
 
 const BASE_URL = "https://danigb.github.io/samples/splendid-grand-piano";
@@ -45,7 +49,8 @@ export class SplendidGrandPiano {
     this.player = new DefaultPlayer(context, this.options);
     const loader = splendidGrandPianoLoader(
       this.options.baseUrl,
-      this.options.storage
+      this.options.storage,
+      this.options.notesToLoad
     );
     this.load = loader(context, this.player.buffers).then(() => this);
   }
@@ -114,13 +119,29 @@ function findNearestMidiInLayer(
 
 function splendidGrandPianoLoader(
   baseUrl: string,
-  storage: Storage
+  storage: Storage,
+  notesToLoad?: {
+    notes: number[],
+    velocityRange: [number, number]
+  }
 ): AudioBuffersLoader {
   const format = findFirstSupportedFormat(["ogg", "m4a"]) ?? "ogg";
+  let layers = notesToLoad 
+    ? LAYERS.filter(
+        (layer) =>
+          layer.vel_range[0] <= notesToLoad.velocityRange[1] &&
+          layer.vel_range[1] >= notesToLoad.velocityRange[0]
+      )
+    : LAYERS;
+
   return async (context, buffers) => {
-    for (const layer of LAYERS) {
+    for (const layer of layers) {
+      const samples = notesToLoad 
+        ? layer.samples.filter(sample => notesToLoad.notes.includes(sample[0] as number))
+        : layer.samples;
+
       await Promise.all(
-        layer.samples.map(async ([midi, name]) => {
+        samples.map(async ([midi, name]) => {
           const url = `${baseUrl}/${name}.${format}`;
           const buffer = await loadAudioBuffer(context, url, storage);
           if (buffer) buffers[layer.name + midi] = buffer;

src/splendid-grand-piano/splendid-grand-piano.spec.ts

@@ -0,0 +1,76 @@
+import { InternalPlayerMock, createAudioContextMock, createFetchMock } from "../test-helpers";
+import { SplendidGrandPiano } from "../splendid-grand-piano";
+
+function setup() {
+  createFetchMock({
+    "https://danigb.github.io/samples/splendid-grand-piano/PP-C3.ogg":
+      "PP-C3",
+    "https://danigb.github.io/samples/splendid-grand-piano/Mp-C3.ogg":
+      "Mp-C3",
+    "https://danigb.github.io/samples/splendid-grand-piano/Mf-C3.ogg":
+      "Mf-C3",
+    "https://danigb.github.io/samples/splendid-grand-piano/FF-C3.ogg":
+      "FF-C3",
+    "https://danigb.github.io/samples/splendid-grand-piano/FF-G3.ogg":
+      "FF-G3",
+  });
+  const mock = createAudioContextMock();
+  const context = mock.context;
+
+  return { context, mock };
+}  
+
+describe("Splendid grand piano", () => {
+  it("only specified notes are loaded", async () => {
+    const { context } = setup();
+    const piano = await new SplendidGrandPiano(context, {
+      notesToLoad: {
+        notes: [60, 67],
+        velocityRange: [105, 106]
+      }
+    }).load;
+
+    expect(Object.keys(piano.buffers)).toHaveLength(2);
+    expect(piano.buffers).toEqual({ 'FF60': { arrayBuffer: 'FF-C3' }, 'FF67': { arrayBuffer: 'FF-G3' } });
+
+    const start = jest.fn();
+
+    (piano as any).player.start = start;
+    piano.start({ note: 'C4', velocity: 105 });
+    expect(start).toHaveBeenCalledWith({ note: 'FF60', stopId: 60, detune: 0, velocity: 105 });
+  });
+
+  it("specified notes are loaded across multiple velocity ranges when given", async () => {
+    const { context } = setup();    
+    const piano = await new SplendidGrandPiano(context, {
+      notesToLoad: {
+        notes: [60],
+        velocityRange: [1, 109]
+      }
+    }).load;
+
+    expect(Object.keys(piano.buffers)).toHaveLength(5);
+    expect(piano.buffers).toEqual({ 
+        'FF60': { arrayBuffer: 'FF-C3' },
+        'MF60': { arrayBuffer: 'Mf-C3' },
+        'MP60': { arrayBuffer: 'Mp-C3' },
+        'PP60': { arrayBuffer: 'PP-C3' },
+        'PPP60': { arrayBuffer: 'PP-C3' }
+    });
+  });
+
+  it("detuning is based on loaded notes", async () => {
+    const { context } = setup();
+    const piano = await new SplendidGrandPiano(context, {
+      notesToLoad: {
+        notes: [60],
+        velocityRange: [105, 106]
+      }
+    }).load;
+    const start = jest.fn();
+
+    (piano as any).player.start = start;
+    piano.start({ note: 'C6', velocity: 105 });
+    expect(start).toHaveBeenCalledWith({ note: 'FF60', stopId: 84, detune: 2400, velocity: 105 });
+  });
+});