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blur.js
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blur.js
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import {floor, max, min} from "./math.js";
function blurTransfer(V, r, n, vertical) {
if (!r) return; // radius 0 is a noop
const iterations = 3, r0 = Math.floor(r);
// for a non-integer radius, interpolate between floor(r) and ceil(r)
if (r === r0) {
for (let i = 0; i < iterations; i++) {
blurTransferInt(V, r, n, vertical);
}
} else {
const frac = r - r0, frac_1 = 1 - frac;
const data = V[0].slice();
for (let i = 0; i < iterations; i++) {
blurTransferInt(V, r0 + 1, n, vertical);
}
const data_ceil = V[0];
V[0] = data;
if (r0 > 0) {
for (let i = 0; i < iterations; i++) {
blurTransferInt(V, r0, n, vertical);
}
}
for (let i = 0; i < data.length; i++) {
V[0][i] = V[0][i] * frac_1 + data_ceil[i] * frac;
}
}
}
function blurTransferInt(V, r, n, vertical) {
const [source, target] = V,
m = floor(source.length / n),
w = 2 * r + 1,
w1 = 1 / w,
ki = vertical ? m : 1,
kj = vertical ? 1 : n,
W = w * ki,
R = r * ki;
for (let j = 0; j < m; ++j) {
const k0 = kj * j,
kn = k0 + ki * (n - 1);
for (let i = 0, sr = w * source[k0]; i < n + r; ++i) {
const k = ki * i + kj * j;
sr += source[min(k, kn)] - source[max(k - W, k0)];
target[max(k - R, k0)] = sr * w1;
}
}
V.reverse(); // target becomes V[0] and will be used as source in the next iteration
}
export default function blur() {
let rx = 5,
ry = rx,
value,
width;
function blur(data) {
const n = width || data.length,
m = Math.round(data.length / n),
V = [
value ? Float32Array.from(data, value) : Float32Array.from(data),
new Float32Array(data.length)
];
blurTransfer(V, rx, n, false);
blurTransfer(V, ry, m, true);
V[0].width = n;
V[0].height = m;
return V[0];
}
blur.radius = _ => _ === undefined
? (rx + ry) / 2
: (rx = ry = +_, blur);
blur.radiusX = _ => _ === undefined
? rx : (rx = +_, blur);
blur.radiusY = _ => _ === undefined
? ry : (ry = +_, blur);
blur.width = _ =>
_ === undefined ? width : (width = Math.round(+_), blur);
blur.value = _ =>
typeof _ === "function" ? (value = _, blur) : value;
return blur;
}