01A Basic Waveform Where Tens of Thousands of Samples Shrink Into Min/Max Buckets and Become Pixel Columns
Tens of thousands of synthetic samples are split into one bucket per column, and only each bucket's highest and lowest values are kept so thin sounds still show above and below the center line.
Best forAudio editor previews and podcast player timelines
BUCKET_PXSAMPLE_NBAR_GAPPEAK_FLOOR
<main class="stage">
<div class="wf is-demo" id="wfRoot">
<canvas class="wf__canvas" data-role="canvas" width="480" height="300" tabindex="0" aria-label="A Basic Waveform Where Tens of Thousands of Samples Shrink Into Min/Max Buckets and Become Pixel Columns"></canvas>
<p class="wf__status" data-role="status" aria-live="polite">Samples → columns</p>
<button class="wf__btn" data-role="btn" type="button">Pause</button>
<p class="wf__caption">A Basic Waveform Where Tens of Thousands of Samples Shrink Into Min/Max Buckets and Become Pixel Columns</p>
</div>
</main>@use "../../../../site/static/demo-tokens" as *;
@include stage($stage-ink);
.wf {
position: relative;
width: min(92vw, calc(160vh - 12.8vw));
aspect-ratio: 480 / 300;
margin: 0 auto;
border-radius: $r-card;
overflow: hidden;
box-shadow: $shadow-raised;
background: $subject-ink;
}
.wf__canvas {
display: block;
width: 100%;
height: 100%;
touch-action: manipulation;
}
.wf__canvas:focus-visible {
outline: 2px solid rgba(255, 255, 255, .85);
outline-offset: -6px;
}
.wf__status {
position: absolute;
left: $sp-3;
top: $sp-3;
max-width: 62%;
margin: 0;
padding: $sp-1 $sp-3;
border-radius: $r-pill;
background: rgba(255, 255, 255, .85);
color: $subject-ink;
font-weight: 500;
font-size: 11px;
line-height: 1.4;
pointer-events: none;
}
.wf__btn {
position: absolute;
right: $sp-3;
bottom: $sp-3;
margin: 0;
padding: $sp-1 $sp-3;
border: 0;
border-radius: $r-pill;
background: rgba(255, 255, 255, .85);
color: $subject-ink;
font: inherit;
font-weight: 500;
font-size: 12px;
line-height: 1.4;
cursor: pointer;
}
.wf__btn:focus-visible {
outline: 2px solid #ffffff;
outline-offset: 2px;
}
.wf__caption {
position: absolute;
left: $sp-3;
bottom: $sp-3;
max-width: 68%;
margin: 0;
padding: $sp-1 $sp-3;
border-radius: $r-pill;
background: rgba(255, 255, 255, .85);
color: $subject-ink;
font-weight: 500;
font-size: 12px;
line-height: 1.4;
pointer-events: none;
}
@media (max-width: 340px) {
.wf__caption, .wf__btn { font-size: 10px; padding: $sp-1 $sp-2; }
.wf__status { font-size: 10px; }
}
@media (prefers-reduced-motion: reduce) {
.wf { cursor: default; }
}html, body {
margin: 0;
overflow: hidden;
}
.stage {
box-sizing: border-box;
min-height: 100vh;
display: grid;
place-items: center;
margin: 0;
background: #17141a;
font-family: -apple-system, "Segoe UI", "Noto Sans KR", sans-serif;
padding: clamp(8px, 4vw, 24px);
}
.wf {
position: relative;
width: min(92vw, 160vh - 12.8vw);
aspect-ratio: 480/300;
margin: 0 auto;
border-radius: 16px;
overflow: hidden;
box-shadow: 0 14px 24px rgba(23, 20, 26, 0.32);
background: #17141a;
}
.wf__canvas {
display: block;
width: 100%;
height: 100%;
touch-action: manipulation;
}
.wf__canvas:focus-visible {
outline: 2px solid rgba(255, 255, 255, 0.85);
outline-offset: -6px;
}
.wf__status {
position: absolute;
left: 12px;
top: 12px;
max-width: 62%;
margin: 0;
padding: 4px 12px;
border-radius: 999px;
background: rgba(255, 255, 255, 0.85);
color: #17141a;
font-weight: 500;
font-size: 11px;
line-height: 1.4;
pointer-events: none;
}
.wf__btn {
position: absolute;
right: 12px;
bottom: 12px;
margin: 0;
padding: 4px 12px;
border: 0;
border-radius: 999px;
background: rgba(255, 255, 255, 0.85);
color: #17141a;
font: inherit;
font-weight: 500;
font-size: 12px;
line-height: 1.4;
cursor: pointer;
}
.wf__btn:focus-visible {
outline: 2px solid #ffffff;
outline-offset: 2px;
}
.wf__caption {
position: absolute;
left: 12px;
bottom: 12px;
max-width: 68%;
margin: 0;
padding: 4px 12px;
border-radius: 999px;
background: rgba(255, 255, 255, 0.85);
color: #17141a;
font-weight: 500;
font-size: 12px;
line-height: 1.4;
pointer-events: none;
}
@media (max-width: 340px) {
.wf__caption, .wf__btn {
font-size: 10px;
padding: 4px 8px;
}
.wf__status {
font-size: 10px;
}
}
@media (prefers-reduced-motion: reduce) {
.wf {
cursor: default;
}
}(function () {
const W = 480;
const H = 300;
const PI2 = Math.PI * 2;
const FIXED_DT = 16;
const IDLE_STEPS = 220;
const REDUCE_STEP_MS = 900;
const REDUCE_WARM_STEPS = 40;
const BTN_PAUSE = 'Pause';
const BTN_PLAY = 'Play';
const BTN_NEXT = 'Next moment';
// 파스텔 팔레트와 어두운 바탕 두 끝 색
const PINK = [255, 170, 196];
const MINT = [150, 226, 196];
const LILAC = [196, 176, 255];
const SKY_BLUE = [150, 214, 255];
const BUTTER = [255, 230, 150];
const CREAM = [255, 247, 230];
const INK = [23, 20, 26];
const BG_TOP = [24, 21, 40];
const BG_BOT = [48, 42, 78];
function clamp(v, lo, hi) { return v < lo ? lo : (v > hi ? hi : v); }
function lerp(a, b, k) { return a + (b - a) * k; }
function smooth(x) { const c = clamp(x, 0, 1); return c * c * (3 - 2 * c); }
function mix(a, b, k) { return [lerp(a[0], b[0], k), lerp(a[1], b[1], k), lerp(a[2], b[2], k)]; }
function rgba(c, a) { return 'rgba(' + Math.round(c[0]) + ',' + Math.round(c[1]) + ',' + Math.round(c[2]) + ',' + a.toFixed(3) + ')'; }
// 시드 고정 난수 — 같은 시드면 언제나 같은 수열 (선형 합동 방식)
function lcg(seed) {
let s = seed >>> 0;
return function () {
s = (Math.imul(s, 1664525) + 1013904223) >>> 0;
return s / 4294967296;
};
}
// 정수 하나와 시드로 0 이상 1 미만의 값을 만드는 해시 (같은 입력은 늘 같은 값)
function hash1(i, seed) {
let h = (Math.imul(i | 0, 374761393) + Math.imul(seed | 0, 668265263)) | 0;
h = Math.imul(h ^ (h >>> 13), 1274126177);
h ^= h >>> 16;
return (h >>> 0) / 4294967296;
}
// 사인 두 개를 음절마다 갈아 끼우고 엔벨로프를 씌운 합성 신호 (소리는 재생하지 않고 수치만 만든다)
function synth(n, seed) {
const rnd = lcg(seed);
const out = new Float32Array(n);
let i = 0;
let p1 = 0;
let p2 = 0;
let peak = 0.0001;
while (i < n) {
const len = 1800 + Math.floor(rnd() * 4200);
const amp = 0.18 + rnd() * 0.82;
const rest = rnd() < 0.18;
const f1 = 0.02 + rnd() * 0.09;
const f2 = f1 * (1.5 + rnd());
const stop = Math.min(n, i + len);
for (let k = i; k < stop; k += 1) {
const x = (k - i) / len;
const env = Math.min(1, x / 0.06) * Math.pow(1 - x, 0.8);
p1 += PI2 * f1;
p2 += PI2 * f2;
const tone = Math.sin(p1) * 0.7 + Math.sin(p2) * 0.3;
const gain = rest ? 0.03 : amp * env;
const v = gain * tone + (rnd() - 0.5) * 0.08 * (rest ? 0.4 : amp);
out[k] = v;
const a = Math.abs(v);
if (a > peak) {
peak = a;
}
}
i = stop;
}
const norm = 0.92 / peak;
for (let k = 0; k < n; k += 1) {
out[k] *= norm;
}
return out;
}
// 표본 구간 [a, b) 의 최솟값과 최댓값 — 결과는 rangeLo, rangeHi 에 둔다
let rangeLo = 0;
let rangeHi = 0;
function scanRange(sig, a, b) {
const from = Math.max(0, Math.floor(a));
const to = Math.min(sig.length, Math.max(from + 1, Math.ceil(b)));
let lo = 1e9;
let hi = -1e9;
for (let i = from; i < to; i += 1) {
const v = sig[i];
if (v < lo) {
lo = v;
}
if (v > hi) {
hi = v;
}
}
if (lo > hi) {
lo = 0;
hi = 0;
}
rangeLo = lo;
rangeHi = hi;
}
function paintBg(ctx, top, bot) {
const g = ctx.createLinearGradient(0, 0, 0, H);
g.addColorStop(0, rgba(top, 1));
g.addColorStop(1, rgba(bot, 1));
ctx.fillStyle = g;
ctx.fillRect(0, 0, W, H);
}
// 가짜 포인터 — 시연 동안 손이 움직이는 것처럼 보이게 그린다
function drawCursor(ctx, x, y, down) {
ctx.save();
ctx.translate(x, y);
ctx.beginPath();
ctx.moveTo(0, 0);
ctx.lineTo(0, 15);
ctx.lineTo(4, 11.5);
ctx.lineTo(7.5, 18);
ctx.lineTo(10, 16.8);
ctx.lineTo(6.6, 10.4);
ctx.lineTo(11.5, 10.2);
ctx.closePath();
ctx.fillStyle = rgba(CREAM, 1);
ctx.strokeStyle = rgba(INK, 1);
ctx.lineWidth = 1.4;
ctx.fill();
ctx.stroke();
if (down) {
ctx.beginPath();
ctx.arc(0, 0, 9, 0, PI2);
ctx.strokeStyle = rgba(PINK, 0.9);
ctx.lineWidth = 2;
ctx.stroke();
}
ctx.restore();
}
function boot(root, make) {
const canvasEl = root.querySelector('[data-role="canvas"]');
const statusEl = root.querySelector('[data-role="status"]');
const btnEl = root.querySelector('[data-role="btn"]');
if (!(canvasEl instanceof HTMLCanvasElement) || !statusEl || !(btnEl instanceof HTMLButtonElement)) {
return function () { };
}
const ctxOrNull = canvasEl.getContext('2d');
if (!ctxOrNull) {
return function () { };
}
const canvas = canvasEl;
const ctx = ctxOrNull;
const status = statusEl;
const btn = btnEl;
const reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
const cleaners = [];
let paused = false;
let idle = IDLE_STEPS + 1;
let clock = 0;
let lastSayAt = -1e9;
let lastText = status.textContent || '';
let scene = null;
let rafId = 0;
let acc = 0;
let lastTs = -1;
function isAuto() { return !reduce && !paused && idle > IDLE_STEPS; }
function sync() {
const on = isAuto();
if (root.classList.contains('is-demo') !== on) {
root.classList.toggle('is-demo', on);
}
}
function fit() {
const r = canvas.getBoundingClientRect();
const dpr = window.devicePixelRatio || 1;
const cw = Math.max(1, Math.round(r.width * dpr));
const ch = Math.max(1, Math.round(r.height * dpr));
canvas.width = cw;
canvas.height = ch;
ctx.setTransform(cw / W, 0, 0, ch / H, 0, 0);
}
const host = {
ctx,
canvas,
root,
reduce,
touch() {
idle = 0;
sync();
},
auto: isAuto,
refresh() {
if (scene) {
scene.draw();
}
},
say(text) {
if (text === lastText) {
return;
}
if (!reduce && clock - lastSayAt < 250) {
return;
}
lastText = text;
lastSayAt = clock;
// 시연이 혼자 돌 때는 읽어 주지 않고, 사람이 만졌을 때만 알린다
status.setAttribute('aria-live', isAuto() ? 'off' : 'polite');
status.textContent = text;
},
local(e) {
const r = canvas.getBoundingClientRect();
return [clamp((e.clientX - r.left) * W / Math.max(1, r.width), 0, W), clamp((e.clientY - r.top) * H / Math.max(1, r.height), 0, H)];
},
listen(target, type, fn, opts) {
target.addEventListener(type, fn, opts);
cleaners.push(function () { target.removeEventListener(type, fn, opts); });
}
};
function advance(ms) {
if (!scene) {
return;
}
const n = Math.max(1, Math.round(ms / FIXED_DT));
for (let i = 0; i < n; i += 1) {
idle += 1;
clock += FIXED_DT;
scene.step();
}
}
function frame(ts) {
if (lastTs < 0) {
lastTs = ts;
}
const dt = Math.min(ts - lastTs, 160);
lastTs = ts;
if (!paused && scene) {
acc += dt;
while (acc >= FIXED_DT) {
idle += 1;
clock += FIXED_DT;
scene.step();
acc -= FIXED_DT;
}
sync();
scene.draw();
}
rafId = requestAnimationFrame(frame);
}
scene = make(host);
btn.textContent = reduce ? BTN_NEXT : BTN_PAUSE;
fit();
if (reduce) {
root.classList.remove('is-demo');
advance(REDUCE_WARM_STEPS * FIXED_DT);
}
scene.draw();
host.listen(btn, 'click', function () {
if (reduce) {
advance(REDUCE_STEP_MS);
host.refresh();
return;
}
paused = !paused;
btn.textContent = paused ? BTN_PLAY : BTN_PAUSE;
sync();
});
host.listen(window, 'resize', function () {
fit();
host.refresh();
});
if (!reduce) {
rafId = requestAnimationFrame(frame);
}
return function () {
cancelAnimationFrame(rafId);
for (let i = 0; i < cleaners.length; i += 1) {
cleaners[i]();
}
};
}
const SAMPLE_N = 86400;
const BUCKET_PX = 3;
const BAR_GAP = 1;
const PEAK_FLOOR = 1;
const VIEW_SAMPLES = 43200;
const SLIDE_STEP = 180;
const MID_Y = 140;
const HALF_Y = 84;
const TXT_RATIO = 'Samples → columns';
const TXT_BUCKET = 'Bucket max / min';
// 구간 [start, start + view) 를 기둥 폭마다 한 묶음으로 줄여 최솟값과 최댓값 두 줄을 돌려준다
function bucketColumns(sig, start, view, bucketPx) {
const n = Math.floor(W / bucketPx);
const per = view / n;
const lo = [];
const hi = [];
for (let c = 0; c < n; c += 1) {
scanRange(sig, start + c * per, start + (c + 1) * per);
lo.push(rangeLo);
hi.push(rangeHi);
}
return { lo, hi };
}
function makeBucketScene(h) {
const sig = synth(SAMPLE_N, 459);
let start = 0;
let dir = 1;
let k = 0;
let lensX = 120;
function move(x) {
lensX = clamp(x, 0, W - 1);
h.touch();
h.refresh();
}
h.listen(h.canvas, 'pointermove', function (e) {
move(h.local(e)[0]);
});
h.listen(h.canvas, 'keydown', function (e) {
const key = e.key;
if (key === 'ArrowLeft') {
e.preventDefault();
move(lensX - BUCKET_PX * 4);
}
else if (key === 'ArrowRight') {
e.preventDefault();
move(lensX + BUCKET_PX * 4);
}
else if (key === 'Home') {
e.preventDefault();
move(0);
}
else if (key === 'End') {
e.preventDefault();
move(W - 1);
}
});
return {
step() {
k += 1;
start += dir * SLIDE_STEP;
if (start > SAMPLE_N - VIEW_SAMPLES) {
start = SAMPLE_N - VIEW_SAMPLES;
dir = -1;
}
else if (start < 0) {
start = 0;
dir = 1;
}
if (h.auto()) {
lensX = W * (0.5 + 0.42 * Math.sin(k * 0.035));
}
},
draw() {
const ctx = h.ctx;
paintBg(ctx, BG_TOP, BG_BOT);
ctx.fillStyle = rgba(CREAM, 0.16);
ctx.fillRect(0, MID_Y, W, 1);
const cols = bucketColumns(sig, start, VIEW_SAMPLES, BUCKET_PX);
const lens = clamp(Math.floor(lensX / BUCKET_PX), 0, cols.hi.length - 1);
for (let c = 0; c < cols.hi.length; c += 1) {
const hi = cols.hi[c];
const lo = cols.lo[c];
let y1 = MID_Y - hi * HALF_Y;
let y2 = MID_Y - lo * HALF_Y;
if (MID_Y - y1 < PEAK_FLOOR) {
y1 = MID_Y - PEAK_FLOOR;
}
if (y2 - MID_Y < PEAK_FLOOR) {
y2 = MID_Y + PEAK_FLOOR;
}
const loud = clamp(Math.max(hi, -lo), 0, 1);
ctx.fillStyle = c === lens ? rgba(BUTTER, 1) : rgba(mix(LILAC, PINK, loud), 0.55 + 0.45 * loud);
ctx.fillRect(c * BUCKET_PX, y1, BUCKET_PX - BAR_GAP, y2 - y1);
}
// 렌즈 아래 묶음 — 이 한 기둥이 표본 몇 개를 대표하는지 표시
ctx.fillStyle = rgba(BUTTER, 0.18);
ctx.fillRect(lens * BUCKET_PX - 2, 44, BUCKET_PX + 3, 192);
h.say(h.auto() && !h.reduce
? TXT_RATIO + ': ' + VIEW_SAMPLES + ' → ' + cols.hi.length
: TXT_BUCKET + ': ' + cols.hi[lens].toFixed(2) + ' / ' + cols.lo[lens].toFixed(2));
}
};
}
boot(document.getElementById('wfRoot'), makeBucketScene);
})();import { useEffect, useRef } from "react";
import styles from "./WfMinmaxBucketPeakColumns.module.scss";
const W = 480;
const H = 300;
const PI2 = Math.PI * 2;
const FIXED_DT = 16;
const IDLE_STEPS = 220;
const REDUCE_STEP_MS = 900;
const REDUCE_WARM_STEPS = 40;
const BTN_PAUSE = '멈춤';
const BTN_PLAY = '재생';
const BTN_NEXT = '다음 순간';
type RGB = [number, number, number];
// 파스텔 팔레트와 어두운 바탕 두 끝 색
const PINK: RGB = [255, 170, 196];
const MINT: RGB = [150, 226, 196];
const LILAC: RGB = [196, 176, 255];
const SKY_BLUE: RGB = [150, 214, 255];
const BUTTER: RGB = [255, 230, 150];
const CREAM: RGB = [255, 247, 230];
const INK: RGB = [23, 20, 26];
const BG_TOP: RGB = [24, 21, 40];
const BG_BOT: RGB = [48, 42, 78];
interface Host {
ctx: CanvasRenderingContext2D;
canvas: HTMLCanvasElement;
root: HTMLElement;
reduce: boolean;
touch(): void;
auto(): boolean;
refresh(): void;
say(text: string): void;
local(e: MouseEvent): [number, number];
listen(target: EventTarget, type: string, fn: (e: Event) => void, opts?: AddEventListenerOptions): void;
}
interface Scene {
step(): void;
draw(): void;
}
function clamp(v: number, lo: number, hi: number): number { return v < lo ? lo : (v > hi ? hi : v); }
function lerp(a: number, b: number, k: number): number { return a + (b - a) * k; }
function smooth(x: number): number { const c = clamp(x, 0, 1); return c * c * (3 - 2 * c); }
function mix(a: RGB, b: RGB, k: number): RGB { return [lerp(a[0], b[0], k), lerp(a[1], b[1], k), lerp(a[2], b[2], k)]; }
function rgba(c: RGB, a: number): string { return 'rgba(' + Math.round(c[0]) + ',' + Math.round(c[1]) + ',' + Math.round(c[2]) + ',' + a.toFixed(3) + ')'; }
// 시드 고정 난수 — 같은 시드면 언제나 같은 수열 (선형 합동 방식)
function lcg(seed: number): () => number {
let s = seed >>> 0;
return function (): number {
s = (Math.imul(s, 1664525) + 1013904223) >>> 0;
return s / 4294967296;
};
}
// 정수 하나와 시드로 0 이상 1 미만의 값을 만드는 해시 (같은 입력은 늘 같은 값)
function hash1(i: number, seed: number): number {
let h = (Math.imul(i | 0, 374761393) + Math.imul(seed | 0, 668265263)) | 0;
h = Math.imul(h ^ (h >>> 13), 1274126177);
h ^= h >>> 16;
return (h >>> 0) / 4294967296;
}
// 사인 두 개를 음절마다 갈아 끼우고 엔벨로프를 씌운 합성 신호 (소리는 재생하지 않고 수치만 만든다)
function synth(n: number, seed: number): Float32Array {
const rnd = lcg(seed);
const out = new Float32Array(n);
let i = 0;
let p1 = 0;
let p2 = 0;
let peak = 0.0001;
while (i < n) {
const len = 1800 + Math.floor(rnd() * 4200);
const amp = 0.18 + rnd() * 0.82;
const rest = rnd() < 0.18;
const f1 = 0.02 + rnd() * 0.09;
const f2 = f1 * (1.5 + rnd());
const stop = Math.min(n, i + len);
for (let k = i; k < stop; k += 1) {
const x = (k - i) / len;
const env = Math.min(1, x / 0.06) * Math.pow(1 - x, 0.8);
p1 += PI2 * f1;
p2 += PI2 * f2;
const tone = Math.sin(p1) * 0.7 + Math.sin(p2) * 0.3;
const gain = rest ? 0.03 : amp * env;
const v = gain * tone + (rnd() - 0.5) * 0.08 * (rest ? 0.4 : amp);
out[k] = v;
const a = Math.abs(v);
if (a > peak) { peak = a; }
}
i = stop;
}
const norm = 0.92 / peak;
for (let k = 0; k < n; k += 1) { out[k] *= norm; }
return out;
}
// 표본 구간 [a, b) 의 최솟값과 최댓값 — 결과는 rangeLo, rangeHi 에 둔다
let rangeLo = 0;
let rangeHi = 0;
function scanRange(sig: Float32Array, a: number, b: number): void {
const from = Math.max(0, Math.floor(a));
const to = Math.min(sig.length, Math.max(from + 1, Math.ceil(b)));
let lo = 1e9;
let hi = -1e9;
for (let i = from; i < to; i += 1) {
const v = sig[i];
if (v < lo) { lo = v; }
if (v > hi) { hi = v; }
}
if (lo > hi) { lo = 0; hi = 0; }
rangeLo = lo;
rangeHi = hi;
}
function paintBg(ctx: CanvasRenderingContext2D, top: RGB, bot: RGB): void {
const g = ctx.createLinearGradient(0, 0, 0, H);
g.addColorStop(0, rgba(top, 1));
g.addColorStop(1, rgba(bot, 1));
ctx.fillStyle = g;
ctx.fillRect(0, 0, W, H);
}
// 가짜 포인터 — 시연 동안 손이 움직이는 것처럼 보이게 그린다
function drawCursor(ctx: CanvasRenderingContext2D, x: number, y: number, down: boolean): void {
ctx.save();
ctx.translate(x, y);
ctx.beginPath();
ctx.moveTo(0, 0);
ctx.lineTo(0, 15);
ctx.lineTo(4, 11.5);
ctx.lineTo(7.5, 18);
ctx.lineTo(10, 16.8);
ctx.lineTo(6.6, 10.4);
ctx.lineTo(11.5, 10.2);
ctx.closePath();
ctx.fillStyle = rgba(CREAM, 1);
ctx.strokeStyle = rgba(INK, 1);
ctx.lineWidth = 1.4;
ctx.fill();
ctx.stroke();
if (down) {
ctx.beginPath();
ctx.arc(0, 0, 9, 0, PI2);
ctx.strokeStyle = rgba(PINK, 0.9);
ctx.lineWidth = 2;
ctx.stroke();
}
ctx.restore();
}
function boot(root: HTMLElement, make: (h: Host) => Scene): () => void {
const canvasEl = root.querySelector('[data-role="canvas"]');
const statusEl = root.querySelector('[data-role="status"]');
const btnEl = root.querySelector('[data-role="btn"]');
if (!(canvasEl instanceof HTMLCanvasElement) || !statusEl || !(btnEl instanceof HTMLButtonElement)) {
return function (): void { /* 필요한 요소가 없으면 아무것도 하지 않는다 */ };
}
const ctxOrNull = canvasEl.getContext('2d');
if (!ctxOrNull) {
return function (): void { /* 2d 문맥이 없으면 아무것도 하지 않는다 */ };
}
const canvas: HTMLCanvasElement = canvasEl;
const ctx: CanvasRenderingContext2D = ctxOrNull;
const status: Element = statusEl;
const btn: HTMLButtonElement = btnEl;
const reduce = window.matchMedia('(prefers-reduced-motion: reduce)').matches;
const cleaners: Array<() => void> = [];
let paused = false;
let idle = IDLE_STEPS + 1;
let clock = 0;
let lastSayAt = -1e9;
let lastText = status.textContent || '';
let scene: Scene | null = null;
let rafId = 0;
let acc = 0;
let lastTs = -1;
function isAuto(): boolean { return !reduce && !paused && idle > IDLE_STEPS; }
function sync(): void {
const on = isAuto();
if (root.classList.contains('is-demo') !== on) {
root.classList.toggle('is-demo', on);
}
}
function fit(): void {
const r = canvas.getBoundingClientRect();
const dpr = window.devicePixelRatio || 1;
const cw = Math.max(1, Math.round(r.width * dpr));
const ch = Math.max(1, Math.round(r.height * dpr));
canvas.width = cw;
canvas.height = ch;
ctx.setTransform(cw / W, 0, 0, ch / H, 0, 0);
}
const host: Host = {
ctx,
canvas,
root,
reduce,
touch(): void {
idle = 0;
sync();
},
auto: isAuto,
refresh(): void {
if (scene) { scene.draw(); }
},
say(text: string): void {
if (text === lastText) { return; }
if (!reduce && clock - lastSayAt < 250) { return; }
lastText = text;
lastSayAt = clock;
// 시연이 혼자 돌 때는 읽어 주지 않고, 사람이 만졌을 때만 알린다
status.setAttribute('aria-live', isAuto() ? 'off' : 'polite');
status.textContent = text;
},
local(e: MouseEvent): [number, number] {
const r = canvas.getBoundingClientRect();
return [clamp((e.clientX - r.left) * W / Math.max(1, r.width), 0, W), clamp((e.clientY - r.top) * H / Math.max(1, r.height), 0, H)];
},
listen(target: EventTarget, type: string, fn: (e: Event) => void, opts?: AddEventListenerOptions): void {
target.addEventListener(type, fn, opts);
cleaners.push(function (): void { target.removeEventListener(type, fn, opts); });
}
};
function advance(ms: number): void {
if (!scene) { return; }
const n = Math.max(1, Math.round(ms / FIXED_DT));
for (let i = 0; i < n; i += 1) {
idle += 1;
clock += FIXED_DT;
scene.step();
}
}
function frame(ts: number): void {
if (lastTs < 0) { lastTs = ts; }
const dt = Math.min(ts - lastTs, 160);
lastTs = ts;
if (!paused && scene) {
acc += dt;
while (acc >= FIXED_DT) {
idle += 1;
clock += FIXED_DT;
scene.step();
acc -= FIXED_DT;
}
sync();
scene.draw();
}
rafId = requestAnimationFrame(frame);
}
scene = make(host);
btn.textContent = reduce ? BTN_NEXT : BTN_PAUSE;
fit();
if (reduce) {
root.classList.remove('is-demo');
advance(REDUCE_WARM_STEPS * FIXED_DT);
}
scene.draw();
host.listen(btn, 'click', function (): void {
if (reduce) {
advance(REDUCE_STEP_MS);
host.refresh();
return;
}
paused = !paused;
btn.textContent = paused ? BTN_PLAY : BTN_PAUSE;
sync();
});
host.listen(window, 'resize', function (): void {
fit();
host.refresh();
});
if (!reduce) {
rafId = requestAnimationFrame(frame);
}
return function (): void {
cancelAnimationFrame(rafId);
for (let i = 0; i < cleaners.length; i += 1) { cleaners[i](); }
};
}
const SAMPLE_N = 86400;
const BUCKET_PX = 3;
const BAR_GAP = 1;
const PEAK_FLOOR = 1;
const VIEW_SAMPLES = 43200;
const SLIDE_STEP = 180;
const MID_Y = 140;
const HALF_Y = 84;
const TXT_RATIO = '표본 → 기둥';
const TXT_BUCKET = '묶음 최대 / 최소';
// 구간 [start, start + view) 를 기둥 폭마다 한 묶음으로 줄여 최솟값과 최댓값 두 줄을 돌려준다
function bucketColumns(sig: Float32Array, start: number, view: number, bucketPx: number): { lo: number[]; hi: number[] } {
const n = Math.floor(W / bucketPx);
const per = view / n;
const lo: number[] = [];
const hi: number[] = [];
for (let c = 0; c < n; c += 1) {
scanRange(sig, start + c * per, start + (c + 1) * per);
lo.push(rangeLo);
hi.push(rangeHi);
}
return { lo, hi };
}
function makeBucketScene(h: Host): Scene {
const sig = synth(SAMPLE_N, 459);
let start = 0;
let dir = 1;
let k = 0;
let lensX = 120;
function move(x: number): void {
lensX = clamp(x, 0, W - 1);
h.touch();
h.refresh();
}
h.listen(h.canvas, 'pointermove', function (e: Event): void {
move(h.local(e as PointerEvent)[0]);
});
h.listen(h.canvas, 'keydown', function (e: Event): void {
const key = (e as KeyboardEvent).key;
if (key === 'ArrowLeft') {
e.preventDefault();
move(lensX - BUCKET_PX * 4);
}
else if (key === 'ArrowRight') {
e.preventDefault();
move(lensX + BUCKET_PX * 4);
}
else if (key === 'Home') {
e.preventDefault();
move(0);
}
else if (key === 'End') {
e.preventDefault();
move(W - 1);
}
});
return {
step(): void {
k += 1;
start += dir * SLIDE_STEP;
if (start > SAMPLE_N - VIEW_SAMPLES) {
start = SAMPLE_N - VIEW_SAMPLES;
dir = -1;
}
else if (start < 0) {
start = 0;
dir = 1;
}
if (h.auto()) {
lensX = W * (0.5 + 0.42 * Math.sin(k * 0.035));
}
},
draw(): void {
const ctx = h.ctx;
paintBg(ctx, BG_TOP, BG_BOT);
ctx.fillStyle = rgba(CREAM, 0.16);
ctx.fillRect(0, MID_Y, W, 1);
const cols = bucketColumns(sig, start, VIEW_SAMPLES, BUCKET_PX);
const lens = clamp(Math.floor(lensX / BUCKET_PX), 0, cols.hi.length - 1);
for (let c = 0; c < cols.hi.length; c += 1) {
const hi = cols.hi[c];
const lo = cols.lo[c];
let y1 = MID_Y - hi * HALF_Y;
let y2 = MID_Y - lo * HALF_Y;
if (MID_Y - y1 < PEAK_FLOOR) { y1 = MID_Y - PEAK_FLOOR; }
if (y2 - MID_Y < PEAK_FLOOR) { y2 = MID_Y + PEAK_FLOOR; }
const loud = clamp(Math.max(hi, -lo), 0, 1);
ctx.fillStyle = c === lens ? rgba(BUTTER, 1) : rgba(mix(LILAC, PINK, loud), 0.55 + 0.45 * loud);
ctx.fillRect(c * BUCKET_PX, y1, BUCKET_PX - BAR_GAP, y2 - y1);
}
// 렌즈 아래 묶음 — 이 한 기둥이 표본 몇 개를 대표하는지 표시
ctx.fillStyle = rgba(BUTTER, 0.18);
ctx.fillRect(lens * BUCKET_PX - 2, 44, BUCKET_PX + 3, 192);
h.say(h.auto() && !h.reduce
? TXT_RATIO + ': ' + VIEW_SAMPLES + ' → ' + cols.hi.length
: TXT_BUCKET + ': ' + cols.hi[lens].toFixed(2) + ' / ' + cols.lo[lens].toFixed(2));
}
};
}
export default function WfMinmaxBucketPeakColumns() {
const rootRef = useRef<HTMLDivElement | null>(null);
useEffect(() => {
const root = rootRef.current;
if (!root) return;
return boot(root, makeBucketScene);
}, []);
return (
<main className={styles.stage}>
<div className={`${styles.wf} is-demo`} ref={rootRef}>
<canvas className={styles.canvas} data-role="canvas" width={480} height={300} tabIndex={0} aria-label="표본 수만 개가 최대·최소 묶음으로 줄어 픽셀 기둥이 되는 기본 파형" />
<p className={styles.status} data-role="status" aria-live="polite">표본 → 기둥</p>
<button className={styles.btn} data-role="btn" type="button">멈춤</button>
<p className={styles.caption}>표본 수만 개가 최대·최소 묶음으로 줄어 픽셀 기둥이 되는 기본 파형</p>
</div>
</main>
);
}01 A Basic Waveform Where Tens of Thousands of Samples Shrink Into Min/Max Buckets and Become Pixel Columns — Measured area 38.376% · moving frames 23/23Original by GODRICH · SCSS and React ship in the zip · CSS Waveform: 9 Peak Columns and Trim Pickers
The post this demo lives in
CSS Waveform: 9 Peak Columns and Trim PickersA css waveform starts with squeezing thousands of samples into pixel columns — scene 01's min/max buckets and scene 05's See all demos in this post
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