feat: round max on delay graph

README.md

@@ -7,4 +7,5 @@ This template should help get you started developing with Tauri, React and Types
 - [VS Code](https://code.visualstudio.com/) + [Tauri](https://marketplace.visualstudio.com/items?itemName=tauri-apps.tauri-vscode) + [rust-analyzer](https://marketplace.visualstudio.com/items?itemName=rust-lang.rust-analyzer)
 
 # TODO
-- Move meters polling logic outside dsp state because it causes re-render of everything tied to dsp constantly
+- Move meters polling logic outside dsp state because it causes re-render of everything tied to dsp constantly
+- Check render to improve perfoormances 

src/components/VerticalSlider/VerticalSlider.tsx

@@ -170,7 +170,10 @@ export default function VerticalSlider({
   async function endDrag(e: React.PointerEvent<HTMLDivElement>) {
     if (!dragging.current) return;
 
+    const target = e.currentTarget;
+    const pointerId = e.pointerId;
     const finalValue = dragValue.current;
+
     const success = await onChange?.(finalValue);
 
     dragging.current = false;
@@ -181,8 +184,8 @@ export default function VerticalSlider({
       onInput?.(value);
     }
 
-    if (e.currentTarget.hasPointerCapture(e.pointerId)) {
+    if (target.hasPointerCapture(pointerId)) {
-      e.currentTarget.releasePointerCapture(e.pointerId);
+      target.releasePointerCapture(pointerId);
     }
   }
 

src/features/dsp408/components/CompressorSection/CompressorSection.tsx

@@ -263,19 +263,44 @@ function CompressorPanel({
   );
 }
 
-// Soft-knee compressor transfer curve, in dB.
+// Compressor transfer curve, in dB.
+//
+// The knee is NOT a smooth/quadratic blend. It is three straight
+// (piecewise-linear) segments:
+//   1) input <= kneeStart          -> 1:1 line (output = input)
+//   2) kneeStart < input < kneeEnd -> a straight line connecting the
+//                                     point on segment (1) at kneeStart
+//                                     to the point on segment (3) at kneeEnd
+//   3) input >= kneeEnd            -> ratio line (output = threshold + (input-threshold)/ratio)
+//
+// kneeStart/kneeEnd are simply the threshold shifted down/up by half the
+// knee width, so increasing "knee" widens the middle straight segment
+// symmetrically around the threshold.
 function compressorOutputDb(input: number, threshold: number, ratio: number, knee: number): number {
   const kneeStart = threshold - knee / 2;
   const kneeEnd = threshold + knee / 2;
 
-  if (knee <= 0 || input <= kneeStart) {
+  // No knee: simple two-segment (hard-knee) curve.
+  if (knee <= 0) {
     return input <= threshold ? input : threshold + (input - threshold) / ratio;
   }
+
+  // Segment 1: below the knee, straight 1:1 line.
+  if (input <= kneeStart) {
+    return input;
+  }
+
+  // Segment 3: above the knee, straight ratio line.
   if (input >= kneeEnd) {
     return threshold + (input - threshold) / ratio;
   }
-  const x = input - kneeStart;
+
-  return input + ((1 / ratio - 1) * x * x) / (2 * knee);
+  // Segment 2: straight line between the two boundary points
+  // (kneeStart, kneeStart) and (kneeEnd, threshold + (kneeEnd - threshold) / ratio).
+  const y1 = kneeStart;
+  const y2 = threshold + (kneeEnd - threshold) / ratio;
+  const t = (input - kneeStart) / (kneeEnd - kneeStart);
+  return y1 + t * (y2 - y1);
 }
 
 function CompressorSection({ dsp, set_compressor }: { dsp: DSP; set_compressor: SetCompressorFn }) {
@@ -339,7 +364,7 @@ function CompressorSection({ dsp, set_compressor }: { dsp: DSP; set_compressor:
     const steps = 120;
     const points: [number, number][] = [];
     for (let i = 0; i <= steps; i++) {
-      const x = -60 + (60 * i) / steps;
+      const x = -100 + (100 * i) / steps;
       points.push([x, compressorOutputDb(x, threshold, ratioNumeric, knee)]);
     }
     return points;
@@ -352,9 +377,9 @@ function CompressorSection({ dsp, set_compressor }: { dsp: DSP; set_compressor:
           <div className="compressor-graph__title">{activeOutputState.name} - RMS Compressor</div>
 
           <LinearGraph
-            xMin={-60}
+            xMin={-100}
             xMax={0}
-            yMin={-60}
+            yMin={-100}
             yMax={0}
             xLabel="in dB"
             yLabel="out dB"
@@ -365,7 +390,7 @@ function CompressorSection({ dsp, set_compressor }: { dsp: DSP; set_compressor:
               ctx.strokeStyle = '#6b7280';
               ctx.lineWidth = 1;
               ctx.setLineDash([4, 4]);
-              const [ux0, uy0] = toPx(-60, -60);
+              const [ux0, uy0] = toPx(-100, -100);
               const [ux1, uy1] = toPx(0, 0);
               ctx.beginPath();
               ctx.moveTo(ux0, uy0);
@@ -377,7 +402,7 @@ function CompressorSection({ dsp, set_compressor }: { dsp: DSP; set_compressor:
               ctx.strokeStyle = '#fbbf24';
               ctx.lineWidth = 1;
               ctx.setLineDash([2, 3]);
-              const [tx0, ty0] = toPx(activeComp.threshold, -60);
+              const [tx0, ty0] = toPx(activeComp.threshold, -100);
               const [tx1, ty1] = toPx(activeComp.threshold, 0);
               ctx.beginPath();
               ctx.moveTo(tx0, ty0);

src/features/dsp408/components/DelaySection/DelaySection.tsx

@@ -79,6 +79,7 @@ function DelayGraph({
   unit: DelayUnit;
 }) {
   const [min, max] = DELAY_RANGES[unit];
+  const roundedMax = (Math.floor(max / 100) + 1) * 100;
   const labelByX = useMemo(() => {
     const map = new Map<number, string>();
     rows.forEach((row, i) => map.set(i + 1, row.label));
@@ -93,7 +94,7 @@ function DelayGraph({
         xMax={rows.length + 0.5}
         xStep={1}
         yMin={min}
-        yMax={max}
+        yMax={roundedMax}
         xLabel="Channel"
         yLabel={UNIT_LABEL[unit]}
         showGrid={true}

src/features/dsp408/components/GainSection/GainSection.tsx

@@ -5,6 +5,8 @@ import Button from '../../../../components/Button/Button';
 import ChannelGroup from '../../../../components/ChannelGroup/ChannelGroup';
 import { LinearGraph } from '../../../../components/LinearGraph/LinearGraph';
 import './GainSection.css';
+import { DiscreteFrequency } from '../../types';
+import { DISCRETE_FREQUENCIES } from '../../constants';
 
 function GainPanel({
   dsp,
@@ -48,6 +50,7 @@ function GainPanel({
         step={(v) => (v >= -20 ? 0.1 : 0.5)}
         unit=" dB"
         value={gain}
+        formatValue={(v, d) => (v > 0 ? `+${v.toFixed(d)}` : v.toFixed(d))}
         onChange={(value) => setGain(channel, value)}
       />
 
@@ -116,6 +119,8 @@ function GainSection({
     { channel: { Output: OutputChannel.Out8 }, title: 'Out 8' },
   ];
 
+  const currentChannel = dsp.state.current_config.input_states[InputChannel.InA];
+
   return (
     <>
       <div className="gain-linear-graph-section">
@@ -131,13 +136,46 @@ function GainSection({
             xLabel="Hz"
             yLabel="dB"
             draw={({ ctx, toPx }) => {
+              const geq = currentChannel.geq;
+
+              if (geq.bypass) {
+                return;
+              }
+
+              const points = Object.entries(geq.gains)
+                .map(([frequency, gain]) => ({
+                  frequency: DISCRETE_FREQUENCIES[frequency as DiscreteFrequency],
+                  gain,
+                }))
+                .sort((a, b) => a.frequency - b.frequency)
+                .map(({ frequency, gain }) => {
+                  const [x, y] = toPx(frequency, gain);
+                  return { x, y };
+                });
+
+              if (points.length < 2) {
+                return;
+              }
+
               ctx.strokeStyle = '#4ade80';
               ctx.lineWidth = 2;
-              const [x0, y0] = toPx(20, 0);
+              ctx.lineJoin = 'round';
-              const [x1, y1] = toPx(20000, 0);
+              ctx.lineCap = 'round';
+
               ctx.beginPath();
-              ctx.moveTo(x0, y0);
+              ctx.moveTo(points[0].x, points[0].y);
-              ctx.lineTo(x1, y1);
+
+              for (let i = 1; i < points.length; i++) {
+                const previous = points[i - 1];
+                const current = points[i];
+
+                const midX = (previous.x + current.x) / 2;
+
+                ctx.quadraticCurveTo(previous.x, previous.y, midX, (previous.y + current.y) / 2);
+
+                ctx.quadraticCurveTo(current.x, current.y, current.x, current.y);
+              }
+
               ctx.stroke();
             }}
           />

src/features/dsp408/components/GateSection/GateSection.tsx

@@ -187,7 +187,7 @@ function GateSection({ dsp, set_gate }: { dsp: DSP; set_gate: SetGateFn }) {
               const inputState = dsp.state.current_config.input_states[input];
               const idx = INPUT_METER_INDEX[input];
               const meter = dsp.meters.channels[idx];
-              return <MeterBar label={inputState.name} meter={meter} />;
+              return <MeterBar key={input} label={inputState.name} meter={meter} />;
             })}
           </div>
         </div>

src/features/dsp408/components/GeqSection/GeqSection.css

@@ -141,3 +141,29 @@
   flex: 1;
   min-height: 0;
 }
+
+.geq-graph-canvas-wrap {
+  position: relative;
+}
+
+.geq-bypass-overlay {
+  position: absolute;
+  inset: 0;
+  display: flex;
+  align-items: center;
+  justify-content: center;
+  pointer-events: none;
+  z-index: 2;
+  padding-bottom: 40cqh;
+}
+
+.geq-bypass-overlay span {
+  font-size: 8cqh;
+  font-weight: 800;
+  letter-spacing: 0.15em;
+  color: #f87171;
+  text-shadow: 0 0 12px rgba(0, 0, 0, 0.6);
+  transform: rotate(-8deg);
+  opacity: 0.85;
+  user-select: none;
+}

src/features/dsp408/components/GeqSection/GeqSection.tsx

@@ -4,54 +4,22 @@ import { DSP408 as DSP } from '../../../../types';
 import Button from '../../../../components/Button/Button';
 import ChannelGroup from '../../../../components/ChannelGroup/ChannelGroup';
 import { LinearGraph } from '../../../../components/LinearGraph/LinearGraph';
-import { useMemo, useState } from 'react';
+import { GEQ_BAND_HZ, buildGeqCurveDraw } from '../../utils/geqCurve';
+import {
+  INPUT_ORDER,
+  GRAPH_X_MIN,
+  GRAPH_X_MAX,
+  GRAPH_Y_MIN,
+  GRAPH_Y_MAX,
+  GRAPH_GEQ_CURVE_Q,
+  GEQ_GAIN_MIN,
+  GEQ_GAIN_MAX,
+  GEQ_GAIN_STEP,
+  GEQ_BANDS_LABEL,
+} from '../../constants';
+import { useState } from 'react';
 import './GeqSection.css';
 
-const GEQ_BANDS = [
-  { frequency: DiscreteFrequency.F20, label: '20' },
-  { frequency: DiscreteFrequency.F25, label: '25' },
-  { frequency: DiscreteFrequency.F31_5, label: '31.5' },
-  { frequency: DiscreteFrequency.F40, label: '40' },
-  { frequency: DiscreteFrequency.F50, label: '50' },
-  { frequency: DiscreteFrequency.F63, label: '63' },
-  { frequency: DiscreteFrequency.F80, label: '80' },
-  { frequency: DiscreteFrequency.F100, label: '100' },
-  { frequency: DiscreteFrequency.F125, label: '125' },
-  { frequency: DiscreteFrequency.F160, label: '160' },
-  { frequency: DiscreteFrequency.F200, label: '200' },
-  { frequency: DiscreteFrequency.F250, label: '250' },
-  { frequency: DiscreteFrequency.F315, label: '315' },
-  { frequency: DiscreteFrequency.F400, label: '400' },
-  { frequency: DiscreteFrequency.F500, label: '500' },
-  { frequency: DiscreteFrequency.F630, label: '630' },
-  { frequency: DiscreteFrequency.F800, label: '800' },
-  { frequency: DiscreteFrequency.F1000, label: '1k' },
-  { frequency: DiscreteFrequency.F1250, label: '1.25k' },
-  { frequency: DiscreteFrequency.F1600, label: '1.6k' },
-  { frequency: DiscreteFrequency.F2000, label: '2k' },
-  { frequency: DiscreteFrequency.F2500, label: '2.5k' },
-  { frequency: DiscreteFrequency.F3150, label: '3.15k' },
-  { frequency: DiscreteFrequency.F4000, label: '4k' },
-  { frequency: DiscreteFrequency.F5000, label: '5k' },
-  { frequency: DiscreteFrequency.F6300, label: '6.3k' },
-  { frequency: DiscreteFrequency.F8000, label: '8k' },
-  { frequency: DiscreteFrequency.F10000, label: '10k' },
-  { frequency: DiscreteFrequency.F12500, label: '12.5k' },
-  { frequency: DiscreteFrequency.F16000, label: '16k' },
-  { frequency: DiscreteFrequency.F20000, label: '20k' },
-] as const;
-
-const GEQ_GAIN_MIN = -12;
-const GEQ_GAIN_MAX = 12;
-const GEQ_GAIN_STEP = 0.1;
-
-const INPUT_ORDER: InputChannel[] = [
-  InputChannel.InA,
-  InputChannel.InB,
-  InputChannel.InC,
-  InputChannel.InD,
-];
-
 type LiveBands = Partial<Record<DiscreteFrequency, number>>;
 
 type SetGeqBandFn = (
@@ -78,7 +46,7 @@ function GeqBandPanel({
 
   return (
     <div className="geq-band-panel">
-      {GEQ_BANDS.map(({ frequency, label }) => (
+      {GEQ_BANDS_LABEL.map(({ frequency, label }) => (
         <div className="geq-band-cell" key={frequency}>
           <VerticalSlider
             min={GEQ_GAIN_MIN}
@@ -112,13 +80,7 @@ function GeqGraph({
 }) {
   const geq = dsp.state.current_config.input_states[channel].geq;
 
-  const labelByX = useMemo(() => {
+  const values = GEQ_BANDS_LABEL.map(
-    const map = new Map<number, string>();
-    GEQ_BANDS.forEach((band, i) => map.set(i + 1, band.label));
-    return map;
-  }, []);
-
-  const values = GEQ_BANDS.map(
     ({ frequency }) => liveBands?.[frequency] ?? geq.gains[frequency] ?? 0
   );
 
@@ -126,31 +88,31 @@ function GeqGraph({
     <div className="geq-graph-panel">
       <div className="geq-graph-title">{title}</div>
       <LinearGraph
-        xMin={0.5}
+        xMin={GRAPH_X_MIN}
-        xMax={GEQ_BANDS.length + 0.5}
+        xMax={GRAPH_X_MAX}
-        xStep={1}
+        xScale="log"
-        yMin={GEQ_GAIN_MIN}
+        yMin={GRAPH_Y_MIN}
-        yMax={GEQ_GAIN_MAX}
+        yMax={GRAPH_Y_MAX}
+        yStep={3}
         xLabel="Band Hz"
         yLabel="dB"
         showGrid={true}
-        formatX={(v) => labelByX.get(Math.round(v)) ?? ''}
+        draw={buildGeqCurveDraw({
-        formatY={(v) => v.toFixed(0)}
+          values,
-        draw={({ ctx, toPx, plot }) => {
+          bandHz: GEQ_BAND_HZ,
-          const barWidth = (plot.width / GEQ_BANDS.length) * 0.6;
+          q: GRAPH_GEQ_CURVE_Q * 0.5,
-
+          xMin: GRAPH_X_MIN,
-          values.forEach((gain, i) => {
+          xMax: GRAPH_X_MAX,
-            const x = i + 1;
+          yMin: GRAPH_Y_MIN,
-            const [xPx, zeroY] = toPx(x, 0);
+          yMax: GRAPH_Y_MAX,
-            const [, gainY] = toPx(x, gain);
+          dimmed: geq.bypass,
-
+        })}
-            ctx.fillStyle = gain >= 0 ? '#4ade80' : '#f87171';
-            const top = Math.min(zeroY, gainY);
-            const height = Math.abs(gainY - zeroY);
-            ctx.fillRect(xPx - barWidth / 2, top, barWidth, height);
-          });
-        }}
       />
+      {geq.bypass && (
+        <div className="geq-bypass-overlay">
+          <span>BYPASSED</span>
+        </div>
+      )}
     </div>
   );
 }
@@ -274,7 +236,7 @@ function GeqSection({
     if (resetting) return;
     setResetting(true);
 
-    for (const { frequency } of GEQ_BANDS) {
+    for (const { frequency } of GEQ_BANDS_LABEL) {
       // Skip bands already at 0 to save a round trip.
       const current = dsp.state.current_config.input_states[channel].geq.gains[frequency] ?? 0;
       if (current === 0) continue;

src/features/dsp408/constants.ts

@@ -0,0 +1,89 @@
+import { DiscreteFrequency, InputChannel } from './types';
+
+export const INPUT_ORDER: InputChannel[] = [
+  InputChannel.InA,
+  InputChannel.InB,
+  InputChannel.InC,
+  InputChannel.InD,
+];
+
+export const DISCRETE_FREQUENCIES: Record<DiscreteFrequency, number> = {
+  [DiscreteFrequency.F20]: 20,
+  [DiscreteFrequency.F25]: 25,
+  [DiscreteFrequency.F31_5]: 31.5,
+  [DiscreteFrequency.F40]: 40,
+  [DiscreteFrequency.F50]: 50,
+  [DiscreteFrequency.F63]: 63,
+  [DiscreteFrequency.F80]: 80,
+  [DiscreteFrequency.F100]: 100,
+  [DiscreteFrequency.F125]: 125,
+  [DiscreteFrequency.F160]: 160,
+  [DiscreteFrequency.F200]: 200,
+  [DiscreteFrequency.F250]: 250,
+  [DiscreteFrequency.F315]: 315,
+  [DiscreteFrequency.F400]: 400,
+  [DiscreteFrequency.F500]: 500,
+  [DiscreteFrequency.F630]: 630,
+  [DiscreteFrequency.F800]: 800,
+  [DiscreteFrequency.F1000]: 1000,
+  [DiscreteFrequency.F1250]: 1250,
+  [DiscreteFrequency.F1600]: 1600,
+  [DiscreteFrequency.F2000]: 2000,
+  [DiscreteFrequency.F2500]: 2500,
+  [DiscreteFrequency.F3150]: 3150,
+  [DiscreteFrequency.F4000]: 4000,
+  [DiscreteFrequency.F5000]: 5000,
+  [DiscreteFrequency.F6300]: 6300,
+  [DiscreteFrequency.F8000]: 8000,
+  [DiscreteFrequency.F10000]: 10000,
+  [DiscreteFrequency.F12500]: 12500,
+  [DiscreteFrequency.F16000]: 16000,
+  [DiscreteFrequency.F20000]: 20000,
+};
+
+// ------ GEQ constants ------
+export const GRAPH_GEQ_CURVE_Q = 8.65;
+
+export const GEQ_BANDS_LABEL = [
+  { frequency: DiscreteFrequency.F20, label: '20' },
+  { frequency: DiscreteFrequency.F25, label: '25' },
+  { frequency: DiscreteFrequency.F31_5, label: '31.5' },
+  { frequency: DiscreteFrequency.F40, label: '40' },
+  { frequency: DiscreteFrequency.F50, label: '50' },
+  { frequency: DiscreteFrequency.F63, label: '63' },
+  { frequency: DiscreteFrequency.F80, label: '80' },
+  { frequency: DiscreteFrequency.F100, label: '100' },
+  { frequency: DiscreteFrequency.F125, label: '125' },
+  { frequency: DiscreteFrequency.F160, label: '160' },
+  { frequency: DiscreteFrequency.F200, label: '200' },
+  { frequency: DiscreteFrequency.F250, label: '250' },
+  { frequency: DiscreteFrequency.F315, label: '315' },
+  { frequency: DiscreteFrequency.F400, label: '400' },
+  { frequency: DiscreteFrequency.F500, label: '500' },
+  { frequency: DiscreteFrequency.F630, label: '630' },
+  { frequency: DiscreteFrequency.F800, label: '800' },
+  { frequency: DiscreteFrequency.F1000, label: '1k' },
+  { frequency: DiscreteFrequency.F1250, label: '1.25k' },
+  { frequency: DiscreteFrequency.F1600, label: '1.6k' },
+  { frequency: DiscreteFrequency.F2000, label: '2k' },
+  { frequency: DiscreteFrequency.F2500, label: '2.5k' },
+  { frequency: DiscreteFrequency.F3150, label: '3.15k' },
+  { frequency: DiscreteFrequency.F4000, label: '4k' },
+  { frequency: DiscreteFrequency.F5000, label: '5k' },
+  { frequency: DiscreteFrequency.F6300, label: '6.3k' },
+  { frequency: DiscreteFrequency.F8000, label: '8k' },
+  { frequency: DiscreteFrequency.F10000, label: '10k' },
+  { frequency: DiscreteFrequency.F12500, label: '12.5k' },
+  { frequency: DiscreteFrequency.F16000, label: '16k' },
+  { frequency: DiscreteFrequency.F20000, label: '20k' },
+] as const;
+
+export const GEQ_GAIN_MIN = -12;
+export const GEQ_GAIN_MAX = 12;
+export const GEQ_GAIN_STEP = 0.1;
+
+// ------ Graph constants ------
+export const GRAPH_X_MIN = 10;
+export const GRAPH_X_MAX = 30000;
+export const GRAPH_Y_MIN = -21;
+export const GRAPH_Y_MAX = 21;

src/features/dsp408/utils/geqCurve.ts

@@ -0,0 +1,144 @@
+export const GEQ_BAND_HZ = [
+  20, 25, 31.5, 40, 50, 63, 80, 100, 125, 160, 200, 250, 315, 400, 500, 630, 800, 1000, 1250, 1600,
+  2000, 2500, 3150, 4000, 5000, 6300, 8000, 10000, 12500, 16000, 20000,
+] as const;
+
+/** Peaking-filter magnitude response (dB) of a single band at a given frequency. */
+export function geqPeakResponseDb(
+  freq: number,
+  bandFreq: number,
+  gainDb: number,
+  q: number
+): number {
+  if (gainDb === 0) return 0;
+  const ratio = freq / bandFreq - bandFreq / freq;
+  return gainDb / (1 + (q * ratio) ** 2);
+}
+
+/** Sum of all bands' contributions at a given frequency. */
+export function geqTotalCurveDb(
+  freq: number,
+  values: number[],
+  bandHz: readonly number[] = GEQ_BAND_HZ,
+  q: number
+): number {
+  let sum = 0;
+  for (let i = 0; i < values.length; i++) {
+    sum += geqPeakResponseDb(freq, bandHz[i], values[i], q);
+  }
+  return sum;
+}
+
+/** Log-spaced sample points from xMin to xMax, for a pixel-smooth curve on a log x-axis. */
+export function logSpace(xMin: number, xMax: number, steps: number): number[] {
+  const logMin = Math.log10(xMin);
+  const logMax = Math.log10(xMax);
+  const out: number[] = [];
+  for (let s = 0; s <= steps; s++) {
+    out.push(Math.pow(10, logMin + ((logMax - logMin) * s) / steps));
+  }
+  return out;
+}
+
+export type GeqCurveColors = {
+  strokeColor: string;
+  fillAbove: string;
+  fillAboveFade: string;
+  fillBelowFade: string;
+  fillBelow: string;
+};
+
+export const DEFAULT_GEQ_CURVE_COLORS: GeqCurveColors = {
+  strokeColor: '#e5e7eb',
+  fillAbove: 'rgba(74, 222, 128, 0.35)',
+  fillAboveFade: 'rgba(74, 222, 128, 0.08)',
+  fillBelowFade: 'rgba(248, 113, 113, 0.08)',
+  fillBelow: 'rgba(248, 113, 113, 0.35)',
+};
+
+export type GeqCurveOptions = {
+  values: number[];
+  bandHz?: readonly number[];
+  q: number;
+  xMin: number;
+  xMax: number;
+  yMin: number;
+  yMax: number;
+  steps?: number;
+  colors?: GeqCurveColors;
+  lineWidth?: number;
+  dimmed?: boolean;
+};
+
+/**
+ * Returns a `draw` callback compatible with LinearGraph's `draw` prop:
+ * ({ ctx, toPx }) => void
+ *
+ * Usage:
+ *   <LinearGraph ... draw={buildGeqCurveDraw({ values, q: 8.65, xMin, xMax, yMin, yMax })} />
+ */
+export function buildGeqCurveDraw({
+  values,
+  bandHz = GEQ_BAND_HZ,
+  q,
+  xMin,
+  xMax,
+  yMin,
+  yMax,
+  steps = 500,
+  colors = DEFAULT_GEQ_CURVE_COLORS,
+  lineWidth = 2,
+  dimmed = false,
+}: GeqCurveOptions) {
+  return ({
+    ctx,
+    toPx,
+  }: {
+    ctx: CanvasRenderingContext2D;
+    toPx: (x: number, y: number) => [number, number];
+  }) => {
+    const freqs = logSpace(xMin, xMax, steps);
+    const points = freqs.map((freq) => {
+      const gain = geqTotalCurveDb(freq, values, bandHz, q);
+      return toPx(freq, gain);
+    });
+
+    ctx.save();
+    if (dimmed) ctx.globalAlpha = 0.25; // NEW: fade everything drawn below
+
+    // Fill area under the curve down to 0 dB
+    ctx.beginPath();
+    points.forEach(([xPx, yPx], i) => {
+      if (i === 0) ctx.moveTo(xPx, yPx);
+      else ctx.lineTo(xPx, yPx);
+    });
+    const [xEndPx, zeroYPx] = toPx(xMax, 0);
+    const [xStartPx] = toPx(xMin, 0);
+    ctx.lineTo(xEndPx, zeroYPx);
+    ctx.lineTo(xStartPx, zeroYPx);
+    ctx.closePath();
+
+    const [, topPx] = toPx(xMin, yMax);
+    const [, bottomPx] = toPx(xMin, yMin);
+    const gradient = ctx.createLinearGradient(0, topPx, 0, bottomPx);
+    gradient.addColorStop(0, colors.fillAbove);
+    gradient.addColorStop(0.5, colors.fillAboveFade);
+    gradient.addColorStop(0.5, colors.fillBelowFade);
+    gradient.addColorStop(1, colors.fillBelow);
+    ctx.fillStyle = gradient;
+    ctx.fill();
+
+    // Stroke the curve on top
+    ctx.beginPath();
+    points.forEach(([xPx, yPx], i) => {
+      if (i === 0) ctx.moveTo(xPx, yPx);
+      else ctx.lineTo(xPx, yPx);
+    });
+    ctx.strokeStyle = colors.strokeColor;
+    ctx.lineWidth = lineWidth;
+    if (dimmed) ctx.setLineDash([6, 4]); // dashed = "not actually applied"
+    ctx.stroke();
+
+    ctx.restore();
+  };
+}