move scope to webaudio package

packages/webaudio/scope.mjs

@@ -0,0 +1,88 @@
+import { Pattern, getDrawContext, clamp } from '@strudel.cycles/core';
+import { analyser } from 'superdough';
+
+export function drawTimeScope(
+  analyser,
+  { align = true, color = 'white', thickness = 3, scale = 0.25, pos = 0.75, next = 1, trigger = 0 } = {},
+) {
+  const ctx = getDrawContext();
+  const dataArray = getAnalyzerData('time');
+
+  ctx.lineWidth = thickness;
+  ctx.strokeStyle = color;
+
+  ctx.beginPath();
+  let canvas = ctx.canvas;
+
+  const bufferSize = analyser.frequencyBinCount;
+  let triggerIndex = align
+    ? Array.from(dataArray).findIndex((v, i, arr) => i && arr[i - 1] > -trigger && v <= -trigger)
+    : 0;
+  triggerIndex = Math.max(triggerIndex, 0); // fallback to 0 when no trigger is found
+
+  const sliceWidth = (canvas.width * 1.0) / bufferSize;
+  let x = 0;
+
+  for (let i = triggerIndex; i < bufferSize; i++) {
+    const v = dataArray[i] + 1;
+    const y = (scale * (v - 1) + pos) * canvas.height;
+
+    if (i === 0) {
+      ctx.moveTo(x, y);
+    } else {
+      ctx.lineTo(x, y);
+    }
+    x += sliceWidth;
+  }
+  ctx.stroke();
+}
+
+export function drawFrequencyScope(
+  analyser,
+  { color = 'white', scale = 0.25, pos = 0.75, lean = 0.5, min = -150, max = 0 } = {},
+) {
+  const dataArray = getAnalyzerData('frequency');
+  const ctx = getDrawContext();
+  const canvas = ctx.canvas;
+
+  ctx.fillStyle = color;
+  const bufferSize = analyser.frequencyBinCount;
+  const sliceWidth = (canvas.width * 1.0) / bufferSize;
+
+  let x = 0;
+  for (let i = 0; i < bufferSize; i++) {
+    const normalized = clamp((dataArray[i] - min) / (max - min), 0, 1);
+    const v = normalized * scale;
+    const h = v * canvas.height;
+    const y = (pos - v * lean) * canvas.height;
+
+    ctx.fillRect(x, y, Math.max(sliceWidth, 1), h);
+    x += sliceWidth;
+  }
+}
+
+function clearScreen(smear = 0, smearRGB = `0,0,0`) {
+  const ctx = getDrawContext();
+  if (!smear) {
+    ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height);
+  } else {
+    ctx.fillStyle = `rgba(${smearRGB},${1 - smear})`;
+    ctx.fillRect(0, 0, ctx.canvas.width, ctx.canvas.height);
+  }
+}
+
+Pattern.prototype.fscope = function (config = {}) {
+  return this.analyze(1).draw(() => {
+    clearScreen(config.smear);
+    analyser && drawFrequencyScope(analyser, config);
+  });
+};
+
+Pattern.prototype.tscope = function (config = {}) {
+  return this.analyze(1).draw(() => {
+    clearScreen(config.smear);
+    analyser && drawTimeScope(analyser, config);
+  });
+};
+
+Pattern.prototype.scope = Pattern.prototype.tscope;