Sharkey/packages/backend/src/misc/gen-identicon.ts
2023-02-09 11:02:37 +09:00

100 lines
2.4 KiB
TypeScript

/**
* Identicon generator
* https://en.wikipedia.org/wiki/Identicon
*/
import * as p from 'pureimage';
import gen from 'random-seed';
import type { WriteStream } from 'node:fs';
const size = 128; // px
const n = 5; // resolution
const margin = (size / 4);
const colors = [
['#FF512F', '#DD2476'],
['#FF61D2', '#FE9090'],
['#72FFB6', '#10D164'],
['#FD8451', '#FFBD6F'],
['#305170', '#6DFC6B'],
['#00C0FF', '#4218B8'],
['#009245', '#FCEE21'],
['#0100EC', '#FB36F4'],
['#FDABDD', '#374A5A'],
['#38A2D7', '#561139'],
['#121C84', '#8278DA'],
['#5761B2', '#1FC5A8'],
['#FFDB01', '#0E197D'],
['#FF3E9D', '#0E1F40'],
['#766eff', '#00d4ff'],
['#9bff6e', '#00d4ff'],
['#ff6e94', '#00d4ff'],
['#ffa96e', '#00d4ff'],
['#ffa96e', '#ff009d'],
['#ffdd6e', '#ff009d'],
];
const actualSize = size - (margin * 2);
const cellSize = actualSize / n;
const sideN = Math.floor(n / 2);
/**
* Generate buffer of an identicon by seed
*/
export function genIdenticon(seed: string, stream: WriteStream): Promise<void> {
const rand = gen.create(seed);
const canvas = p.make(size, size, undefined);
const ctx = canvas.getContext('2d');
const bgColors = colors[rand(colors.length)];
const bg = ctx.createLinearGradient(0, 0, size, size);
bg.addColorStop(0, bgColors[0]);
bg.addColorStop(1, bgColors[1]);
ctx.fillStyle = bg as any;
ctx.beginPath();
ctx.fillRect(0, 0, size, size);
ctx.fillStyle = '#ffffff';
// side bitmap (filled by false)
const side: boolean[][] = new Array(sideN);
for (let i = 0; i < side.length; i++) {
side[i] = new Array(n).fill(false);
}
// 1*n (filled by false)
const center: boolean[] = new Array(n).fill(false);
// eslint:disable-next-line:prefer-for-of
for (let x = 0; x < side.length; x++) {
for (let y = 0; y < side[x].length; y++) {
side[x][y] = rand(3) === 0;
}
}
for (let i = 0; i < center.length; i++) {
center[i] = rand(3) === 0;
}
// Draw
for (let x = 0; x < n; x++) {
for (let y = 0; y < n; y++) {
const isXCenter = x === ((n - 1) / 2);
if (isXCenter && !center[y]) continue;
const isLeftSide = x < ((n - 1) / 2);
if (isLeftSide && !side[x][y]) continue;
const isRightSide = x > ((n - 1) / 2);
if (isRightSide && !side[sideN - (x - sideN)][y]) continue;
const actualX = margin + (cellSize * x);
const actualY = margin + (cellSize * y);
ctx.beginPath();
ctx.fillRect(actualX, actualY, cellSize, cellSize);
}
}
return p.encodePNGToStream(canvas, stream);
}