| 1 | // QR code encoder — byte mode, versions 1-10, error correction level L. |
| 2 | // |
| 3 | // Zero-dependency, so the Weixin bridge keeps its no-npm-deps property. The |
| 4 | // login URL is ASCII (~70 bytes), which fits version 4-5 at ECC L; versions up |
| 5 | // to 10 are supported for headroom. |
| 6 | // |
| 7 | // Rendered the same way the Rust side does it |
| 8 | // (`qrcode::render::unicode::Dense1x2` in crates/tui/src/runtime_api.rs): |
| 9 | // two QR rows per text row using half-block glyphs. |
| 10 | |
| 11 | // --- Galois field GF(256) tables for Reed-Solomon ------------------------- |
| 12 | |
| 13 | const EXP = new Uint8Array(512); |
| 14 | const LOG = new Uint8Array(256); |
| 15 | (() => { |
| 16 | let x = 1; |
| 17 | for (let i = 0; i < 255; i++) { |
| 18 | EXP[i] = x; |
| 19 | LOG[x] = i; |
| 20 | x <<= 1; |
| 21 | if (x & 0x100) x ^= 0x11d; |
| 22 | } |
| 23 | for (let i = 255; i < 512; i++) EXP[i] = EXP[i - 255]; |
| 24 | })(); |
| 25 | |
| 26 | function gfMul(a, b) { |
| 27 | if (a === 0 || b === 0) return 0; |
| 28 | return EXP[LOG[a] + LOG[b]]; |
| 29 | } |
| 30 | |
| 31 | /** Reed-Solomon generator polynomial of the given degree. */ |
| 32 | function rsGenerator(degree) { |
| 33 | let poly = [1]; |
| 34 | for (let i = 0; i < degree; i++) { |
| 35 | const next = new Array(poly.length + 1).fill(0); |
| 36 | for (let j = 0; j < poly.length; j++) { |
| 37 | next[j] ^= gfMul(poly[j], 1); |
| 38 | next[j + 1] ^= gfMul(poly[j], EXP[i]); |
| 39 | } |
| 40 | poly = next; |
| 41 | } |
| 42 | return poly; |
| 43 | } |
| 44 | |
| 45 | /** Compute `ecLength` Reed-Solomon error correction bytes for `data`. */ |
| 46 | function rsEncode(data, ecLength) { |
| 47 | const gen = rsGenerator(ecLength); |
| 48 | const result = new Array(ecLength).fill(0); |
| 49 | for (const byte of data) { |
| 50 | const factor = byte ^ result[0]; |
| 51 | result.shift(); |
| 52 | result.push(0); |
| 53 | for (let i = 0; i < ecLength; i++) { |
| 54 | result[i] ^= gfMul(gen[i + 1], factor); |
| 55 | } |
| 56 | } |
| 57 | return result; |
| 58 | } |
| 59 | |
| 60 | // --- Version tables -------------------------------------------------------- |
| 61 | |
| 62 | // [ecCodewordsPerBlock, [[blockCount, dataCodewordsPerBlock], ...]] |
| 63 | // Error correction level L only. |
| 64 | const VERSION_TABLE = { |
| 65 | 1: [7, [[1, 19]]], |
| 66 | 2: [10, [[1, 34]]], |
| 67 | 3: [15, [[1, 55]]], |
| 68 | 4: [20, [[1, 80]]], |
| 69 | 5: [26, [[1, 108]]], |
| 70 | 6: [18, [[2, 68]]], |
| 71 | 7: [20, [[2, 78]]], |
| 72 | 8: [24, [[2, 97]]], |
| 73 | 9: [30, [[2, 116]]], |
| 74 | 10: [18, [[2, 68], [2, 69]]], |
| 75 | }; |
| 76 | |
| 77 | const ALIGNMENT_POSITIONS = { |
| 78 | 1: [], |
| 79 | 2: [6, 18], |
| 80 | 3: [6, 22], |
| 81 | 4: [6, 26], |
| 82 | 5: [6, 30], |
| 83 | 6: [6, 34], |
| 84 | 7: [6, 22, 38], |
| 85 | 8: [6, 24, 42], |
| 86 | 9: [6, 26, 46], |
| 87 | 10: [6, 28, 50], |
| 88 | }; |
| 89 | |
| 90 | /** Total data codewords available at level L for a version. */ |
| 91 | function dataCapacity(version) { |
| 92 | const [, blocks] = VERSION_TABLE[version]; |
| 93 | return blocks.reduce((sum, [count, size]) => sum + count * size, 0); |
| 94 | } |
| 95 | |
| 96 | // --- Bit buffer ------------------------------------------------------------ |
| 97 | |
| 98 | class BitBuffer { |
| 99 | constructor() { |
| 100 | this.bits = []; |
| 101 | } |
| 102 | put(value, length) { |
| 103 | for (let i = length - 1; i >= 0; i--) { |
| 104 | this.bits.push((value >>> i) & 1); |
| 105 | } |
| 106 | } |
| 107 | get length() { |
| 108 | return this.bits.length; |
| 109 | } |
| 110 | } |
| 111 | |
| 112 | // --- Encoding -------------------------------------------------------------- |
| 113 | |
| 114 | function chooseVersion(byteLength) { |
| 115 | for (const version of Object.keys(VERSION_TABLE).map(Number).sort((a, b) => a - b)) { |
| 116 | // 4 bits mode + 8 or 16 bits length + payload, then terminator headroom. |
| 117 | const lengthBits = version < 10 ? 8 : 16; |
| 118 | const needed = 4 + lengthBits + byteLength * 8; |
| 119 | if (needed <= dataCapacity(version) * 8) return version; |
| 120 | } |
| 121 | throw new Error(`qr: payload too long for supported versions (${byteLength} bytes)`); |
| 122 | } |
| 123 | |
| 124 | function buildCodewords(bytes, version) { |
| 125 | const capacity = dataCapacity(version); |
| 126 | const buf = new BitBuffer(); |
| 127 | buf.put(0b0100, 4); // byte mode |
| 128 | buf.put(bytes.length, version < 10 ? 8 : 16); |
| 129 | for (const byte of bytes) buf.put(byte, 8); |
| 130 | |
| 131 | // Terminator, then pad to a byte boundary. |
| 132 | const maxBits = capacity * 8; |
| 133 | buf.put(0, Math.min(4, maxBits - buf.length)); |
| 134 | while (buf.length % 8 !== 0) buf.bits.push(0); |
| 135 | |
| 136 | const data = []; |
| 137 | for (let i = 0; i < buf.length; i += 8) { |
| 138 | let byte = 0; |
| 139 | for (let j = 0; j < 8; j++) byte = (byte << 1) | buf.bits[i + j]; |
| 140 | data.push(byte); |
| 141 | } |
| 142 | // Alternating pad bytes. |
| 143 | const pads = [0xec, 0x11]; |
| 144 | for (let i = 0; data.length < capacity; i++) data.push(pads[i % 2]); |
| 145 | |
| 146 | // Split into blocks, add EC, then interleave. |
| 147 | const [ecPerBlock, blockSpec] = VERSION_TABLE[version]; |
| 148 | const dataBlocks = []; |
| 149 | const ecBlocks = []; |
| 150 | let offset = 0; |
| 151 | for (const [count, size] of blockSpec) { |
| 152 | for (let b = 0; b < count; b++) { |
| 153 | const block = data.slice(offset, offset + size); |
| 154 | offset += size; |
| 155 | dataBlocks.push(block); |
| 156 | ecBlocks.push(rsEncode(block, ecPerBlock)); |
| 157 | } |
| 158 | } |
| 159 | |
| 160 | const out = []; |
| 161 | const maxData = Math.max(...dataBlocks.map((b) => b.length)); |
| 162 | for (let i = 0; i < maxData; i++) { |
| 163 | for (const block of dataBlocks) if (i < block.length) out.push(block[i]); |
| 164 | } |
| 165 | for (let i = 0; i < ecPerBlock; i++) { |
| 166 | for (const block of ecBlocks) out.push(block[i]); |
| 167 | } |
| 168 | return out; |
| 169 | } |
| 170 | |
| 171 | // --- Matrix construction --------------------------------------------------- |
| 172 | |
| 173 | function makeMatrix(version) { |
| 174 | const size = version * 4 + 17; |
| 175 | const modules = Array.from({ length: size }, () => new Array(size).fill(null)); |
| 176 | const reserved = Array.from({ length: size }, () => new Array(size).fill(false)); |
| 177 | |
| 178 | const setFinder = (row, col) => { |
| 179 | for (let r = -1; r <= 7; r++) { |
| 180 | for (let c = -1; c <= 7; c++) { |
| 181 | const rr = row + r; |
| 182 | const cc = col + c; |
| 183 | if (rr < 0 || rr >= size || cc < 0 || cc >= size) continue; |
| 184 | const inRing = r >= 0 && r <= 6 && c >= 0 && c <= 6; |
| 185 | const dark = |
| 186 | inRing && (r === 0 || r === 6 || c === 0 || c === 6 || (r >= 2 && r <= 4 && c >= 2 && c <= 4)); |
| 187 | modules[rr][cc] = dark ? 1 : 0; |
| 188 | reserved[rr][cc] = true; |
| 189 | } |
| 190 | } |
| 191 | }; |
| 192 | |
| 193 | setFinder(0, 0); |
| 194 | setFinder(0, size - 7); |
| 195 | setFinder(size - 7, 0); |
| 196 | |
| 197 | // Alignment patterns. |
| 198 | const positions = ALIGNMENT_POSITIONS[version]; |
| 199 | for (const row of positions) { |
| 200 | for (const col of positions) { |
| 201 | // Skip the three finder corners. |
| 202 | const nearFinder = |
| 203 | (row <= 8 && col <= 8) || |
| 204 | (row <= 8 && col >= size - 9) || |
| 205 | (row >= size - 9 && col <= 8); |
| 206 | if (nearFinder) continue; |
| 207 | for (let r = -2; r <= 2; r++) { |
| 208 | for (let c = -2; c <= 2; c++) { |
| 209 | const dark = Math.max(Math.abs(r), Math.abs(c)) !== 1; |
| 210 | modules[row + r][col + c] = dark ? 1 : 0; |
| 211 | reserved[row + r][col + c] = true; |
| 212 | } |
| 213 | } |
| 214 | } |
| 215 | } |
| 216 | |
| 217 | // Timing patterns. |
| 218 | for (let i = 8; i < size - 8; i++) { |
| 219 | if (!reserved[6][i]) { |
| 220 | modules[6][i] = i % 2 === 0 ? 1 : 0; |
| 221 | reserved[6][i] = true; |
| 222 | } |
| 223 | if (!reserved[i][6]) { |
| 224 | modules[i][6] = i % 2 === 0 ? 1 : 0; |
| 225 | reserved[i][6] = true; |
| 226 | } |
| 227 | } |
| 228 | |
| 229 | // Dark module + reserve format areas. |
| 230 | modules[size - 8][8] = 1; |
| 231 | reserved[size - 8][8] = true; |
| 232 | for (let i = 0; i < 9; i++) { |
| 233 | if (!reserved[8][i]) reserved[8][i] = true; |
| 234 | if (!reserved[i][8]) reserved[i][8] = true; |
| 235 | } |
| 236 | for (let i = 0; i < 8; i++) { |
| 237 | reserved[8][size - 1 - i] = true; |
| 238 | reserved[size - 1 - i][8] = true; |
| 239 | } |
| 240 | |
| 241 | // Reserve version info for version >= 7. |
| 242 | if (version >= 7) { |
| 243 | for (let i = 0; i < 6; i++) { |
| 244 | for (let j = 0; j < 3; j++) { |
| 245 | reserved[size - 11 + j][i] = true; |
| 246 | reserved[i][size - 11 + j] = true; |
| 247 | } |
| 248 | } |
| 249 | } |
| 250 | |
| 251 | return { size, modules, reserved }; |
| 252 | } |
| 253 | |
| 254 | function placeData(matrix, codewords) { |
| 255 | const { size, modules, reserved } = matrix; |
| 256 | let bitIndex = 0; |
| 257 | const totalBits = codewords.length * 8; |
| 258 | const nextBit = () => { |
| 259 | if (bitIndex >= totalBits) return 0; |
| 260 | const byte = codewords[bitIndex >> 3]; |
| 261 | const bit = (byte >>> (7 - (bitIndex & 7))) & 1; |
| 262 | bitIndex++; |
| 263 | return bit; |
| 264 | }; |
| 265 | |
| 266 | // Two-module-wide columns, right to left, alternating up/down. The vertical |
| 267 | // timing column (6) is skipped by shifting the whole pair left by one, which |
| 268 | // is why the guard is `<= 6` rather than `=== 6`: once the pair straddles the |
| 269 | // timing column every subsequent column is offset. |
| 270 | let upward = true; |
| 271 | for (let col = size - 1; col > 0; col -= 2) { |
| 272 | if (col <= 6) col -= 1; |
| 273 | for (let i = 0; i < size; i++) { |
| 274 | const row = upward ? size - 1 - i : i; |
| 275 | for (const c of [col, col - 1]) { |
| 276 | if (reserved[row][c]) continue; |
| 277 | modules[row][c] = nextBit(); |
| 278 | } |
| 279 | } |
| 280 | upward = !upward; |
| 281 | } |
| 282 | } |
| 283 | |
| 284 | function applyMask(modules, reserved, maskId) { |
| 285 | const size = modules.length; |
| 286 | return modules.map((row, r) => |
| 287 | row.map((value, c) => { |
| 288 | if (reserved[r][c]) return value; |
| 289 | let invert; |
| 290 | switch (maskId) { |
| 291 | case 0: invert = (r + c) % 2 === 0; break; |
| 292 | case 1: invert = r % 2 === 0; break; |
| 293 | case 2: invert = c % 3 === 0; break; |
| 294 | case 3: invert = (r + c) % 3 === 0; break; |
| 295 | case 4: invert = (Math.floor(r / 2) + Math.floor(c / 3)) % 2 === 0; break; |
| 296 | case 5: invert = ((r * c) % 2) + ((r * c) % 3) === 0; break; |
| 297 | case 6: invert = (((r * c) % 2) + ((r * c) % 3)) % 2 === 0; break; |
| 298 | default: invert = (((r + c) % 2) + ((r * c) % 3)) % 2 === 0; break; |
| 299 | } |
| 300 | return invert ? value ^ 1 : value; |
| 301 | }) |
| 302 | ); |
| 303 | } |
| 304 | |
| 305 | function penalty(modules) { |
| 306 | const size = modules.length; |
| 307 | let score = 0; |
| 308 | // Rule 1: runs of 5+ same-colour modules. |
| 309 | for (let r = 0; r < size; r++) { |
| 310 | for (const dir of ["row", "col"]) { |
| 311 | let run = 1; |
| 312 | for (let i = 1; i < size; i++) { |
| 313 | const prev = dir === "row" ? modules[r][i - 1] : modules[i - 1][r]; |
| 314 | const cur = dir === "row" ? modules[r][i] : modules[i][r]; |
| 315 | if (cur === prev) { |
| 316 | run++; |
| 317 | } else { |
| 318 | if (run >= 5) score += 3 + (run - 5); |
| 319 | run = 1; |
| 320 | } |
| 321 | } |
| 322 | if (run >= 5) score += 3 + (run - 5); |
| 323 | } |
| 324 | } |
| 325 | // Rule 2: 2x2 blocks. |
| 326 | for (let r = 0; r < size - 1; r++) { |
| 327 | for (let c = 0; c < size - 1; c++) { |
| 328 | const v = modules[r][c]; |
| 329 | if (v === modules[r][c + 1] && v === modules[r + 1][c] && v === modules[r + 1][c + 1]) { |
| 330 | score += 3; |
| 331 | } |
| 332 | } |
| 333 | } |
| 334 | // Rule 3: the two ISO/IEC 18004 finder-like patterns, each 11 modules long: |
| 335 | // pattern1: 10111010000 |
| 336 | // pattern2: 00001011101 |
| 337 | // Matching these exactly matters — a looser check selects a different mask |
| 338 | // than reference encoders, producing a valid-looking but different matrix. |
| 339 | const PATTERN1 = [1, 0, 1, 1, 1, 0, 1, 0, 0, 0, 0]; |
| 340 | const PATTERN2 = [0, 0, 0, 0, 1, 0, 1, 1, 1, 0, 1]; |
| 341 | const scanForFinderLike = (get) => { |
| 342 | let hits = 0; |
| 343 | for (let start = 0; start + 11 <= size; start++) { |
| 344 | let p1 = true; |
| 345 | let p2 = true; |
| 346 | for (let i = 0; i < 11; i++) { |
| 347 | const v = get(start + i); |
| 348 | if (v !== PATTERN1[i]) p1 = false; |
| 349 | if (v !== PATTERN2[i]) p2 = false; |
| 350 | if (!p1 && !p2) break; |
| 351 | } |
| 352 | if (p1 || p2) hits++; |
| 353 | } |
| 354 | return hits; |
| 355 | }; |
| 356 | for (let r = 0; r < size; r++) { |
| 357 | score += 40 * scanForFinderLike((i) => modules[r][i]); |
| 358 | } |
| 359 | for (let c = 0; c < size; c++) { |
| 360 | score += 40 * scanForFinderLike((i) => modules[i][c]); |
| 361 | } |
| 362 | // Rule 4: dark-module balance. |
| 363 | let dark = 0; |
| 364 | for (const row of modules) for (const v of row) dark += v; |
| 365 | const percent = (dark * 100) / (size * size); |
| 366 | score += Math.floor(Math.abs(percent - 50) / 5) * 10; |
| 367 | return score; |
| 368 | } |
| 369 | |
| 370 | function formatBits(maskId) { |
| 371 | // ECC level L (0b01) + mask, BCH(15,5) with the standard generator. |
| 372 | let data = (0b01 << 3) | maskId; |
| 373 | let rem = data << 10; |
| 374 | for (let i = 14; i >= 10; i--) { |
| 375 | if ((rem >>> i) & 1) rem ^= 0b10100110111 << (i - 10); |
| 376 | } |
| 377 | return ((data << 10) | rem) ^ 0b101010000010010; |
| 378 | } |
| 379 | |
| 380 | function placeFormat(matrix, maskId) { |
| 381 | const { size, modules } = matrix; |
| 382 | const bits = formatBits(maskId); |
| 383 | for (let i = 0; i < 15; i++) { |
| 384 | const bit = (bits >>> i) & 1; |
| 385 | // First copy: bits 0-5 down the left of the top-left finder (column 8), |
| 386 | // bit 6 at (8,7), bits 7-8 at (8,5)-(8,6)... then along row 8 to the right. |
| 387 | if (i < 6) { |
| 388 | modules[i][8] = bit; |
| 389 | } else if (i < 8) { |
| 390 | modules[i + 1][8] = bit; |
| 391 | } else if (i === 8) { |
| 392 | modules[8][7] = bit; |
| 393 | } else { |
| 394 | modules[8][14 - i] = bit; |
| 395 | } |
| 396 | // Second copy: bits 0-7 along the bottom of the top-right finder, |
| 397 | // bits 8-14 down the right of the bottom-left finder. |
| 398 | if (i < 8) { |
| 399 | modules[8][size - 1 - i] = bit; |
| 400 | } else { |
| 401 | modules[size - 15 + i][8] = bit; |
| 402 | } |
| 403 | } |
| 404 | modules[size - 8][8] = 1; |
| 405 | } |
| 406 | |
| 407 | function versionBits(version) { |
| 408 | let rem = version << 12; |
| 409 | for (let i = 17; i >= 12; i--) { |
| 410 | if ((rem >>> i) & 1) rem ^= 0b1111100100101 << (i - 12); |
| 411 | } |
| 412 | return (version << 12) | rem; |
| 413 | } |
| 414 | |
| 415 | function placeVersion(matrix, version) { |
| 416 | if (version < 7) return; |
| 417 | const { size, modules } = matrix; |
| 418 | const bits = versionBits(version); |
| 419 | for (let i = 0; i < 18; i++) { |
| 420 | const bit = (bits >>> i) & 1; |
| 421 | const row = Math.floor(i / 3); |
| 422 | const col = i % 3; |
| 423 | modules[size - 11 + col][row] = bit; |
| 424 | modules[row][size - 11 + col] = bit; |
| 425 | } |
| 426 | } |
| 427 | |
| 428 | // --- Public API ------------------------------------------------------------ |
| 429 | |
| 430 | /** |
| 431 | * Encode `text` as a QR module matrix (1 = dark). |
| 432 | * @param {string} text |
| 433 | * @returns {number[][]} |
| 434 | */ |
| 435 | export function encodeQr(text) { |
| 436 | const bytes = [...Buffer.from(text, "utf8")]; |
| 437 | const version = chooseVersion(bytes.length); |
| 438 | const codewords = buildCodewords(bytes, version); |
| 439 | const matrix = makeMatrix(version); |
| 440 | placeData(matrix, codewords); |
| 441 | |
| 442 | let best = null; |
| 443 | for (let maskId = 0; maskId < 8; maskId++) { |
| 444 | const masked = applyMask(matrix.modules, matrix.reserved, maskId); |
| 445 | const score = penalty(masked); |
| 446 | if (!best || score < best.score) best = { score, masked, maskId }; |
| 447 | } |
| 448 | placeFormat({ size: matrix.size, modules: best.masked }, best.maskId); |
| 449 | placeVersion({ size: matrix.size, modules: best.masked }, version); |
| 450 | return best.masked; |
| 451 | } |
| 452 | |
| 453 | /** |
| 454 | * Render `text` as a terminal QR code using half-block glyphs, matching the |
| 455 | * Rust side's `Dense1x2` renderer. |
| 456 | * |
| 457 | * @param {string} text |
| 458 | * @param {{invert?: boolean, quietZone?: number}} [options] |
| 459 | * @returns {string} |
| 460 | */ |
| 461 | export function renderQrToText(text, options = {}) { |
| 462 | const { invert = false, quietZone = 2 } = options; |
| 463 | const matrix = encodeQr(text); |
| 464 | const size = matrix.length; |
| 465 | const padded = size + quietZone * 2; |
| 466 | |
| 467 | // Pad so the matrix has an even number of rows for half-block pairing. |
| 468 | const totalRows = padded % 2 === 0 ? padded : padded + 1; |
| 469 | |
| 470 | const dark = (r, c) => { |
| 471 | const rr = r - quietZone; |
| 472 | const cc = c - quietZone; |
| 473 | if (rr < 0 || rr >= size || cc < 0 || cc >= size) return false; |
| 474 | return matrix[rr][cc] === 1; |
| 475 | }; |
| 476 | |
| 477 | const lines = []; |
| 478 | for (let r = 0; r < totalRows; r += 2) { |
| 479 | let line = ""; |
| 480 | for (let c = 0; c < padded; c++) { |
| 481 | const top = dark(r, c); |
| 482 | const bottom = dark(r + 1, c); |
| 483 | // Half-block glyphs: each text cell covers two module rows. |
| 484 | if (top && bottom) line += "\u2588"; // █ |
| 485 | else if (top) line += "\u2580"; // ▀ |
| 486 | else if (bottom) line += "\u2584"; // ▄ |
| 487 | else line += " "; |
| 488 | } |
| 489 | // Dark modules must be dark ink; when the terminal draws light-on-dark this |
| 490 | // is already correct, but allow the caller to flip for dark-on-light. |
| 491 | lines.push(invert ? line.replace(/[\u2580\u2584\u2588 ]/g, (ch) => |
| 492 | ch === " " ? "\u2588" : " ") : line); |
| 493 | } |
| 494 | return lines.join("\n"); |
| 495 | } |
| 496 |