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"use client";
import { useCallback, useEffect, useRef } from "react";
import { useResizeObserver } from "@/hooks/use-resize-observer";
import { computeGlobalMaxRms, extractRmsRange } from "@/lib/media/audio";
import { findScrollParent } from "@/utils/browser";
import { cn } from "@/utils/ui";
const BAR_WIDTH = 2;
const BAR_GAP = 1;
const BAR_STEP = BAR_WIDTH + BAR_GAP;
export const WAVEFORM_GAIN_SAMPLE_COUNT = 200;
function sampleGain({
samples,
startFraction,
endFraction,
barIndex,
barCount,
}: {
samples: number[];
startFraction: number;
endFraction: number;
barIndex: number;
barCount: number;
}): number {
if (samples.length === 0) return 1;
const progress =
startFraction +
((barIndex + 0.5) / barCount) * (endFraction - startFraction);
const rawIndex = Math.max(0, Math.min(1, progress)) * (samples.length - 1);
const lo = Math.floor(rawIndex);
const hi = Math.min(samples.length - 1, lo + 1);
return samples[lo] + (samples[hi] - samples[lo]) * (rawIndex - lo);
}
interface AudioWaveformProps {
audioUrl?: string;
audioBuffer?: AudioBuffer;
gainSamples?: number[];
color?: string;
className?: string;
}
export function AudioWaveform({
audioUrl,
audioBuffer,
gainSamples,
color = "rgba(255, 255, 255, 0.7)",
className = "",
}: AudioWaveformProps) {
const canvasRef = useRef<HTMLCanvasElement>(null);
const containerRef = useRef<HTMLDivElement>(null);
const bufferRef = useRef<AudioBuffer | null>(null);
const globalMaxRef = useRef<number>(1);
const gainSamplesRef = useRef<number[] | undefined>(gainSamples);
const scrollParentRef = useRef<HTMLElement | null>(null);
const heightRef = useRef<number>(0);
const drawVisible = useCallback(() => {
const container = containerRef.current;
const canvas = canvasRef.current;
const buffer = bufferRef.current;
const height = heightRef.current;
if (!container || !canvas || !buffer || height <= 0) return;
const elementWidth = container.offsetWidth;
if (elementWidth <= 0) return;
const containerRect = container.getBoundingClientRect();
const scrollParent = scrollParentRef.current;
let clipLeft: number;
let clipRight: number;
if (scrollParent) {
const parentRect = scrollParent.getBoundingClientRect();
clipLeft = Math.max(0, parentRect.left - containerRect.left);
clipRight = Math.min(elementWidth, parentRect.right - containerRect.left);
} else {
clipLeft = Math.max(0, -containerRect.left);
clipRight = Math.min(
elementWidth,
window.innerWidth - containerRect.left,
);
}
const visibleWidth = clipRight - clipLeft;
if (visibleWidth <= 0) return;
const dpr = window.devicePixelRatio || 1;
const canvasW = Math.round(visibleWidth * dpr);
const canvasH = Math.round(height * dpr);
if (canvasW <= 0 || canvasH <= 0) return;
canvas.width = canvasW;
canvas.height = canvasH;
canvas.style.width = `${visibleWidth}px`;
canvas.style.height = `${height}px`;
canvas.style.left = `${clipLeft}px`;
const barCount = Math.max(1, Math.floor(visibleWidth / BAR_STEP));
const startFraction = clipLeft / elementWidth;
const endFraction = clipRight / elementWidth;
const startSample = Math.floor(startFraction * buffer.length);
const endSample = Math.min(
buffer.length,
Math.ceil(endFraction * buffer.length),
);
const peaks = extractRmsRange({
buffer,
count: barCount,
startSample,
endSample,
globalMax: globalMaxRef.current,
});
const ctx = canvas.getContext("2d");
if (!ctx) return;
ctx.clearRect(0, 0, canvasW, canvasH);
ctx.scale(dpr, dpr);
ctx.fillStyle = color;
const maxBarHeight = height * 0.7;
const samples = gainSamplesRef.current;
for (let i = 0; i < barCount; i++) {
const gain =
samples != null
? sampleGain({
samples,
startFraction,
endFraction,
barIndex: i,
barCount,
})
: 1;
const scaledPeak = Math.min(1, Math.max(0, peaks[i] * gain));
const scaled = Math.log1p(scaledPeak) / Math.log1p(1);
const barH = Math.max(1, scaled * maxBarHeight);
ctx.fillRect(i * BAR_STEP, height - barH, BAR_WIDTH, barH);
}
}, [color]);
useEffect(() => {
gainSamplesRef.current = gainSamples;
drawVisible();
}, [gainSamples, drawVisible]);
useEffect(() => {
let isCancelled = false;
async function load() {
let buffer = audioBuffer ?? null;
if (!buffer && audioUrl) {
try {
const resp = await fetch(audioUrl);
const arrayBuffer = await resp.arrayBuffer();
const actx = new AudioContext();
buffer = await actx.decodeAudioData(arrayBuffer);
actx.close();
} catch {
return;
}
}
if (!buffer || isCancelled) return;
bufferRef.current = buffer;
globalMaxRef.current = computeGlobalMaxRms({ buffer });
drawVisible();
}
load();
return () => {
isCancelled = true;
};
}, [audioUrl, audioBuffer, drawVisible]);
useEffect(() => {
const container = containerRef.current;
if (!container) return;
scrollParentRef.current = findScrollParent({ element: container });
const scrollParent = scrollParentRef.current;
if (!scrollParent) return;
scrollParent.addEventListener("scroll", drawVisible, { passive: true });
return () => scrollParent.removeEventListener("scroll", drawVisible);
}, [drawVisible]);
const onResize = useCallback(
(entry: ResizeObserverEntry) => {
heightRef.current = entry.contentRect.height;
drawVisible();
},
[drawVisible],
);
useResizeObserver({ ref: containerRef, onResize });
return (
<div ref={containerRef} className={cn("relative size-full", className)}>
<canvas ref={canvasRef} className="absolute bottom-0" />
</div>
);
}
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