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Add a virtual keyboard to the visualiser

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This commit is contained in:
Matt Spencer
2026-03-26 09:14:25 +00:00
parent c8ef3df460
commit d00ac70e1c
6 changed files with 459 additions and 37 deletions
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210
www/bootstrap.js vendored
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@@ -2,8 +2,9 @@
* bootstrap.js — ES module entry point.
*
* Initialises the WASM module, wires canvas elements to Rust-exported types,
* keeps canvas drawing buffers in sync with their CSS size, and provides a
* draggable resize handle for the patch bay panel.
* keeps canvas drawing buffers in sync with their CSS size, provides a
* draggable resize handle for the patch bay, and drives a monophonic
* synthesiser from the virtual keyboard and computer keyboard.
*/
import init, {
@@ -11,16 +12,14 @@ import init, {
OscilloscopeView,
SpectrumView,
PatchBay,
VirtualKeyboard,
SynthParams,
} from "./pkg/synth_visualiser.js";
// ── Canvas buffer sizing ──────────────────────────────────────────────────────
// A <canvas> has two independent sizes:
// - CSS display size (width/height CSS properties) — how large it appears
// - Drawing buffer (width/height HTML attributes) — actual pixel resolution
//
// We must keep them in sync; if the buffer is smaller than the display size the
// browser stretches it and everything looks blurry / oversized.
// The canvas *attribute* (width/height) sets the drawing-buffer resolution.
// The CSS size only controls how it's displayed. We keep them in sync so the
// Rust code always draws at 1:1 pixels.
function fitCanvas(canvas) {
const w = Math.round(canvas.clientWidth);
@@ -34,11 +33,9 @@ function fitCanvas(canvas) {
// ── Resize handle ─────────────────────────────────────────────────────────────
function initResizeHandle() {
const handle = document.getElementById("resize-handle");
const panel = document.getElementById("patchbay-panel");
let dragging = false;
let startY = 0;
let startH = 0;
const handle = document.getElementById("resize-handle");
const panel = document.getElementById("patchbay-panel");
let dragging = false, startY = 0, startH = 0;
handle.addEventListener("pointerdown", e => {
dragging = true;
@@ -47,19 +44,81 @@ function initResizeHandle() {
handle.setPointerCapture(e.pointerId);
handle.classList.add("active");
});
handle.addEventListener("pointermove", e => {
if (!dragging) return;
// Dragging up (negative dy) increases the panel height
const dy = e.clientY - startY;
const h = Math.max(80, startH - dy);
panel.style.height = h + "px";
panel.style.height = Math.max(80, startH - (e.clientY - startY)) + "px";
});
handle.addEventListener("pointerup", () => { dragging = false; handle.classList.remove("active"); });
handle.addEventListener("pointercancel",() => { dragging = false; handle.classList.remove("active"); });
const stopDrag = () => { dragging = false; handle.classList.remove("active"); };
handle.addEventListener("pointerup", stopDrag);
handle.addEventListener("pointercancel", stopDrag);
}
// ── Monophonic synthesiser ────────────────────────────────────────────────────
// Uses the Web Audio API directly. All notes are routed through the engine's
// input GainNode → AnalyserNode → speakers so the oscilloscope and spectrum
// analyser reflect the keyboard output.
function createSynth(audioCtx, inputNode) {
let osc = null;
let envGain = null;
let noteCache = -1;
function midiToHz(n) {
return 440 * Math.pow(2, (n - 69) / 12);
}
async function ensureRunning() {
if (audioCtx.state !== "running") await audioCtx.resume();
}
return {
async noteOn(midiNote) {
await ensureRunning();
if (midiNote === noteCache) return;
const now = audioCtx.currentTime;
if (!osc) {
// Fresh attack
osc = audioCtx.createOscillator();
envGain = audioCtx.createGain();
osc.type = "sawtooth";
osc.frequency.value = midiToHz(midiNote);
envGain.gain.setValueAtTime(0.0001, now);
envGain.gain.exponentialRampToValueAtTime(0.3, now + 0.015);
osc.connect(envGain);
envGain.connect(inputNode);
osc.start();
} else {
// Glide to new pitch without retriggering the envelope
osc.frequency.setTargetAtTime(midiToHz(midiNote), now, 0.015);
}
noteCache = midiNote;
},
noteOff() {
if (!osc) return;
const now = audioCtx.currentTime;
envGain.gain.cancelScheduledValues(now);
envGain.gain.setValueAtTime(envGain.gain.value, now);
envGain.gain.exponentialRampToValueAtTime(0.0001, now + 0.28);
const o = osc, g = envGain;
setTimeout(() => { try { o.stop(); o.disconnect(); g.disconnect(); } catch (_) {} }, 400);
osc = null; envGain = null; noteCache = -1;
},
activeNote() { return noteCache; },
};
}
// ── Computer keyboard map (standard DAW layout) ───────────────────────────────
// Lower row Z–M → C3–B3, with S D G H J for sharps
// Upper row Q–U → C4–B4, with 2 3 5 6 7 for sharps
const KEY_NOTE = {
z:48, s:49, x:50, d:51, c:52, v:53, g:54, b:55, h:56, n:57, j:58, m:59,
q:60, 2:61, w:62, 3:63, e:64, r:65, 5:66, t:67, 6:68, y:69, 7:70, u:71,
};
// ── Bootstrap ─────────────────────────────────────────────────────────────────
const loader = document.getElementById("loader");
@@ -73,40 +132,111 @@ async function bootstrap() {
try {
await init();
const engine = new AudioEngine();
// ── WASM objects ──────────────────────────────────────────────────────
const engine = new AudioEngine();
await engine.attach();
const analyser = engine.analyser_node();
const analyser = engine.analyser_node();
const oscilloscope = new OscilloscopeView("oscilloscope-canvas", analyser);
const spectrum = new SpectrumView("spectrum-canvas", analyser);
const patchbay = new PatchBay("patchbay-canvas");
const keyboard = new VirtualKeyboard("keyboard-canvas");
// Fit all canvas buffers to their current CSS layout size before we
// ask Rust for canvas.width() to position the default modules.
const pbCanvas = document.getElementById("patchbay-canvas");
const oscCanvas = document.getElementById("oscilloscope-canvas");
const specCanvas = document.getElementById("spectrum-canvas");
const allCanvases = [oscCanvas, specCanvas, pbCanvas];
// ── Canvas sizing ─────────────────────────────────────────────────────
const pbCanvas = document.getElementById("patchbay-canvas");
const oscCanvas = document.getElementById("oscilloscope-canvas");
const spCanvas = document.getElementById("spectrum-canvas");
const kbCanvas = document.getElementById("keyboard-canvas");
const allCanvases = [oscCanvas, spCanvas, pbCanvas, kbCanvas];
allCanvases.forEach(fitCanvas);
// Seed a default patch using the now-correct canvas width.
// Keep buffers in sync when panels are resized
const ro = new ResizeObserver(() => allCanvases.forEach(fitCanvas));
allCanvases.forEach(c => ro.observe(c));
// ── Default patch bay layout ──────────────────────────────────────────
const cw = pbCanvas.width || pbCanvas.clientWidth || 800;
patchbay.add_module("vco", cw * 0.12, 80);
patchbay.add_module("adsr", cw * 0.32, 80);
patchbay.add_module("svf", cw * 0.55, 80);
patchbay.add_module("vca", cw * 0.76, 80);
// Keep canvas buffers in sync whenever the panel is resized.
const ro = new ResizeObserver(() => allCanvases.forEach(fitCanvas));
allCanvases.forEach(c => ro.observe(c));
// Patch bay pointer events
// ── Patch bay pointer events ──────────────────────────────────────────
pbCanvas.addEventListener("pointerdown", e => patchbay.on_pointer_down(e.offsetX, e.offsetY));
pbCanvas.addEventListener("pointermove", e => patchbay.on_pointer_move(e.offsetX, e.offsetY));
pbCanvas.addEventListener("pointerup", e => patchbay.on_pointer_up(e.offsetX, e.offsetY));
pbCanvas.addEventListener("dblclick", e => patchbay.on_double_click(e.offsetX, e.offsetY));
// ── Synthesiser ───────────────────────────────────────────────────────
const audioCtx = engine.audio_context();
const inputNode = engine.input_node();
const synth = createSynth(audioCtx, inputNode);
// ── Virtual keyboard pointer events ───────────────────────────────────
let pointerDown = false;
kbCanvas.addEventListener("pointerdown", e => {
pointerDown = true;
kbCanvas.setPointerCapture(e.pointerId);
const note = keyboard.on_pointer_down(e.offsetX, e.offsetY);
if (note >= 0) synth.noteOn(note);
else synth.noteOff();
});
kbCanvas.addEventListener("pointermove", e => {
const result = keyboard.on_pointer_move(e.offsetX, e.offsetY);
if (result === -2) return; // hover only, no synthesis change
if (pointerDown) {
if (result >= 0) synth.noteOn(result); // noteOn handles glide
else synth.noteOff();
}
});
kbCanvas.addEventListener("pointerup", e => {
pointerDown = false;
keyboard.on_pointer_up(e.offsetX, e.offsetY);
synth.noteOff();
});
kbCanvas.addEventListener("pointerleave", () => {
const result = keyboard.on_pointer_leave();
if (result === -1) synth.noteOff(); // was pressing
});
// ── Computer keyboard events ──────────────────────────────────────────
const heldKeys = new Set();
document.addEventListener("keydown", e => {
if (e.repeat || e.ctrlKey || e.metaKey || e.altKey) return;
const note = KEY_NOTE[e.key.toLowerCase()];
if (note === undefined) return;
heldKeys.add(e.key.toLowerCase());
keyboard.set_active_note(note);
synth.noteOn(note);
});
document.addEventListener("keyup", e => {
const key = e.key.toLowerCase();
heldKeys.delete(key);
const note = KEY_NOTE[key];
if (note === undefined) return;
// Only stop if no other mapped key is still held
const anyHeld = [...heldKeys].some(k => KEY_NOTE[k] !== undefined);
if (!anyHeld) {
keyboard.set_active_note(-1);
synth.noteOff();
} else {
// Switch to the last remaining held key
const lastKey = [...heldKeys].filter(k => KEY_NOTE[k] !== undefined).at(-1);
const lastNote = KEY_NOTE[lastKey];
keyboard.set_active_note(lastNote);
synth.noteOn(lastNote);
}
});
// ── Params + engine start ─────────────────────────────────────────────
const params = new SynthParams();
engine.set_params(params.to_json());
@@ -114,11 +244,13 @@ async function bootstrap() {
status.textContent = "Running";
engine.start();
// ── Render loop ───────────────────────────────────────────────────────
let last = performance.now();
function frame(now) {
oscilloscope.draw();
spectrum.draw();
patchbay.draw();
keyboard.draw();
frameTime.textContent = `frame: ${(now - last).toFixed(1)} ms`;
last = now;
requestAnimationFrame(frame);
@@ -127,6 +259,14 @@ async function bootstrap() {
loader.classList.add("hidden");
// Show keyboard hint briefly then fade it
const hint = document.getElementById("kb-hint");
if (hint) {
hint.style.transition = "opacity 1s";
setTimeout(() => { hint.style.opacity = "1"; }, 2000);
setTimeout(() => { hint.style.opacity = "0"; }, 6000);
}
} catch (err) {
console.error("[bootstrap] Fatal:", err);
loader.textContent = `Error: ${err.message ?? err}`;