Add sound: fifteen synthesized cues, mute, volume, recent log

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

sound/synth.go

@@ -0,0 +1,81 @@
+package sound
+
+import "math"
+
+const rate = 48000
+
+type wave uint8
+
+const (
+	sine wave = iota
+	triangle
+)
+
+// note is one tone sweeping from f0 to f1 Hz.
+type note struct {
+	at, dur float64
+	f0, f1  float64
+	gain    float64
+	wave    wave
+}
+
+var scores = [cueCount][]note{
+	Tap:     {{0, 0.025, 1800, 1200, 0.5, sine}},
+	Toggle:  {{0, 0.03, 880, 880, 0.4, sine}, {0.035, 0.03, 1320, 1320, 0.4, sine}},
+	Select:  {{0, 0.05, 1046, 1046, 0.4, sine}},
+	Tick:    {{0, 0.008, 3000, 3000, 0.3, sine}},
+	Open:    {{0, 0.09, 500, 900, 0.4, sine}},
+	Close:   {{0, 0.09, 900, 500, 0.4, sine}},
+	Pop:     {{0, 0.04, 400, 1200, 0.5, sine}},
+	Drop:    {{0, 0.08, 700, 200, 0.5, sine}},
+	Success: {{0, 0.12, 523, 523, 0.3, sine}, {0.07, 0.12, 659, 659, 0.3, sine}, {0.14, 0.18, 784, 784, 0.3, sine}},
+	Warning: {{0, 0.09, 660, 660, 0.35, triangle}, {0.13, 0.09, 660, 660, 0.35, triangle}},
+	Error:   {{0, 0.08, 220, 180, 0.4, triangle}, {0.1, 0.08, 220, 180, 0.4, triangle}},
+	Notify:  {{0, 0.25, 784, 784, 0.3, sine}, {0.1, 0.3, 1046, 1046, 0.3, sine}},
+	Send:    {{0, 0.12, 300, 1500, 0.35, triangle}},
+	Delete:  {{0, 0.14, 600, 150, 0.4, triangle}},
+	Swipe:   {{0, 0.07, 1200, 400, 0.25, sine}},
+}
+
+// synth renders a cue's notes to mono samples.
+func synth(c Cue) []float32 {
+	score := scores[c]
+	if len(score) == 0 {
+		panic("sound: no score for " + c.String())
+	}
+	end := 0.0
+	for _, n := range score {
+		end = max(end, n.at+n.dur)
+	}
+	out := make([]float32, int(end*rate)+1)
+	for _, n := range score {
+		start, frames := int(n.at*rate), int(n.dur*rate)
+		phase := 0.0
+		for i := range frames {
+			t := float64(i) / rate
+			f := n.f0 + (n.f1-n.f0)*t/n.dur
+			phase += 2 * math.Pi * f / rate
+			out[start+i] += float32(n.gain * envelope(t, n.dur) * shape(n.wave, phase))
+		}
+	}
+	return out
+}
+
+// envelope: 3 ms attack, decay, 2 ms fade.
+func envelope(t, dur float64) float64 {
+	e := math.Exp(-5 * t / dur)
+	if t < 0.003 {
+		e *= t / 0.003
+	}
+	if left := dur - t; left < 0.002 {
+		e *= left / 0.002
+	}
+	return e
+}
+
+func shape(w wave, phase float64) float64 {
+	if w == triangle {
+		return 2 / math.Pi * math.Asin(math.Sin(phase))
+	}
+	return math.Sin(phase)
+}