44 lines
1.9 KiB
JavaScript
44 lines
1.9 KiB
JavaScript
// Writes public/icon-192.png and icon-512.png (teal square with two white waves) with no dependencies.
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import { deflateSync } from 'node:zlib';
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import { writeFileSync } from 'node:fs';
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import { fileURLToPath } from 'node:url';
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const crcTable = Array.from({ length: 256 }, (_, n) => {
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let c = n;
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for (let k = 0; k < 8; k++) c = c & 1 ? 0xedb88320 ^ (c >>> 1) : c >>> 1;
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return c >>> 0;
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});
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const crc = (b) => {
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let c = 0xffffffff;
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for (const x of b) c = crcTable[(c ^ x) & 255] ^ (c >>> 8);
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return (c ^ 0xffffffff) >>> 0;
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};
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const chunk = (type, data) => {
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const len = Buffer.alloc(4); len.writeUInt32BE(data.length);
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const td = Buffer.concat([Buffer.from(type), data]);
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const c = Buffer.alloc(4); c.writeUInt32BE(crc(td));
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return Buffer.concat([len, td, c]);
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};
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function png(size) {
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const raw = Buffer.alloc((size * 4 + 1) * size);
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for (let y = 0; y < size; y++) {
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raw[y * (size * 4 + 1)] = 0;
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for (let x = 0; x < size; x++) {
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const u = x / size, v = y / size; // 0..1
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const wave = (off) => 0.5 + off + 0.06 * Math.sin((u - 0.19) * Math.PI * 6);
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const body = v > wave(0.0) + 0.06 && v < 0.85 && u > 0.19 && u < 0.81; // lower filled wave
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const line = Math.abs(v - wave(-0.1)) < 0.03 && u > 0.19 && u < 0.81;
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const i = y * (size * 4 + 1) + 1 + x * 4;
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const on = body || line;
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raw[i] = on ? 255 : 0x1f; raw[i + 1] = on ? 255 : 0x5c; raw[i + 2] = on ? 255 : 0x5c; raw[i + 3] = 255;
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}
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}
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const ihdr = Buffer.alloc(13);
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ihdr.writeUInt32BE(size, 0); ihdr.writeUInt32BE(size, 4); ihdr[8] = 8; ihdr[9] = 6;
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return Buffer.concat([Buffer.from([137, 80, 78, 71, 13, 10, 26, 10]), chunk('IHDR', ihdr), chunk('IDAT', deflateSync(raw)), chunk('IEND', Buffer.alloc(0))]);
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}
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for (const s of [192, 512]) writeFileSync(fileURLToPath(new URL(`../public/icon-${s}.png`, import.meta.url)), png(s));
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console.log('icons written');
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