perf: calculate voice waveform peaks without slice allocations

resources/js/lib/voice-notes.ts

@@ -88,15 +88,23 @@ export function waveformOf(samples: Float32Array, bars = voiceBars): number[] {
  */
 export function barsOf(levels: number[], bars = voiceBars): number[] {
     return Array.from({ length: bars }, (_, bar) => {
+        if (levels.length === 0) {
+            return 0;
+        }
+
         const from = Math.floor((levels.length * bar) / bars);
         const to = Math.max(
             from + 1,
             Math.floor((levels.length * (bar + 1)) / bars),
         );
 
-        return Math.round(
-            Math.min(1, Math.max(0, ...levels.slice(from, to))) * 100,
-        );
+        let peak = 0;
+
+        for (let index = from; index < to; index++) {
+            peak = Math.max(peak, levels[index] as number);
+        }
+
+        return Math.round(Math.min(1, peak) * 100);
     });
 }
 

tests/Unit/VoiceNotes.test.ts

@@ -85,3 +85,23 @@ void test('reads the saved volume as a whole percent, at full volume until a sen
     assert.equal(voiceVolumeOf('-0.3'), 0);
     assert.equal(voiceVolumeOf('1.5'), 1);
 });
+
+void test('samples long voice level sequences without changing peak bars', () => {
+    const levels = Array(4800).fill(0.1);
+    levels[2000] = 0.8;
+    const bars = barsOf(levels);
+
+    assert.equal(bars.length, voiceBars);
+    assert.equal(bars[20], 80);
+    assert.equal(bars[19], 10);
+    assert.equal(bars[21], 10);
+});
+
+void test('keeps clamping and NaN behavior for voice level bars', () => {
+    assert.deepEqual(barsOf([-0.5], 1), [0]);
+    assert.equal(Number.isNaN(barsOf([Number.NaN], 1)[0]), true);
+
+    const sparse = Array<number>(2);
+    sparse[1] = 0.5;
+    assert.equal(Number.isNaN(barsOf(sparse, 1)[0]), true);
+});