@akamfoad/qr/src/lib/QRCode.ts

Fully typed QRCode encoding implementation in JavaScript with no dependencies!

import BitByte from './8BitByte';
import RSBlock from './RSBlock';
import BitBuffer from './BitBuffer';
import util from './util';
import Polynomial from './Polynomial';

export default class QRCode {
  typeNumber: number;
  errorCorrectLevel: number;
  modules: (number | boolean | null)[][] | null;
  moduleCount: number;
  dataCache: number[] | null;
  dataList: BitByte[];
  constructor(typeNumber: number, errorCorrectLevel: number) {
    this.typeNumber = typeNumber;
    this.errorCorrectLevel = errorCorrectLevel;
    this.modules = null;
    this.moduleCount = 0;
    this.dataCache = null;
    this.dataList = [];
  }

  // TODO  data may be anything, but we start with string
  addData(data: string) {
    const newData = new BitByte(data);
    this.dataList.push(newData);
    this.dataCache = null;
  }

  isDark(row: number, col: number) {
    if (
      row < 0 ||
      this.moduleCount <= row ||
      col < 0 ||
      this.moduleCount <= col
    ) {
      throw new Error(row + ',' + col);
    }

    if (this.modules === null) {
      throw new Error('this.modules is null');
    }

    return this.modules[row][col];
  }

  getModuleCount() {
    return this.moduleCount;
  }

  make() {
    // Calculate automatically typeNumber if provided is < 1
    if (this.typeNumber < 1) {
      let typeNumber = 1;
      for (typeNumber = 1; typeNumber < 40; typeNumber++) {
        const rsBlocks = RSBlock.getRSBlocks(
          typeNumber,
          this.errorCorrectLevel,
        );

        const buffer = new BitBuffer();
        let totalDataCount = 0;
        for (let i = 0; i < rsBlocks.length; i++) {
          totalDataCount += rsBlocks[i].dataCount;
        }

        for (let i = 0; i < this.dataList.length; i++) {
          const data = this.dataList[i];
          buffer.put(data.mode, 4);
          buffer.put(
            data.getLength(),
            util.getLengthInBits(data.mode, typeNumber),
          );
          data.write(buffer);
        }
        if (buffer.getLengthInBits() <= totalDataCount * 8) break;
      }
      this.typeNumber = typeNumber;
    }
    this.makeImpl(false, this.getBestMaskPattern());
  }

  makeImpl(test: boolean, maskPattern: number) {
    this.moduleCount = this.typeNumber * 4 + 17;
    this.modules = new Array(this.moduleCount);

    for (let row = 0; row < this.moduleCount; row++) {
      this.modules[row] = new Array(this.moduleCount);

      for (let col = 0; col < this.moduleCount; col++) {
        this.modules[row][col] = null; //(col + row) % 3;
      }
    }

    this.setupPositionProbePattern(0, 0);
    this.setupPositionProbePattern(this.moduleCount - 7, 0);
    this.setupPositionProbePattern(0, this.moduleCount - 7);
    this.setupPositionAdjustPattern();
    this.setupTimingPattern();
    this.setupTypeInfo(test, maskPattern);

    if (this.typeNumber >= 7) {
      this.setupTypeNumber(test);
    }

    if (this.dataCache == null) {
      this.dataCache = QRCode.createData(
        this.typeNumber,
        this.errorCorrectLevel,
        this.dataList,
      );
    }

    this.mapData(this.dataCache, maskPattern);
  }

  setupPositionProbePattern(row: number, col: number) {
    for (let r = -1; r <= 7; r++) {
      if (row + r <= -1 || this.moduleCount <= row + r) continue;

      for (let c = -1; c <= 7; c++) {
        if (col + c <= -1 || this.moduleCount <= col + c) continue;

        if (
          (0 <= r && r <= 6 && (c == 0 || c == 6)) ||
          (0 <= c && c <= 6 && (r == 0 || r == 6)) ||
          (2 <= r && r <= 4 && 2 <= c && c <= 4)
        ) {
          if (this.modules === null) {
            throw new Error('this.modules is null');
          }
          this.modules[row + r][col + c] = true;
        } else {
          if (this.modules === null) {
            throw new Error('this.modules is null');
          }
          this.modules[row + r][col + c] = false;
        }
      }
    }
  }

  getBestMaskPattern() {
    let minLostPoint = 0;
    let pattern = 0;

    for (let i = 0; i < 8; i++) {
      this.makeImpl(true, i);

      const lostPoint = util.getLostPoint(this);

      if (i == 0 || minLostPoint > lostPoint) {
        minLostPoint = lostPoint;
        pattern = i;
      }
    }

    return pattern;
  }

  setupTimingPattern() {
    if (this.modules === null) {
      throw new Error('this.modules is null');
    }

    for (let r = 8; r < this.moduleCount - 8; r++) {
      if (this.modules[r][6] != null) {
        continue;
      }
      this.modules[r][6] = r % 2 == 0;
    }

    for (let c = 8; c < this.moduleCount - 8; c++) {
      if (this.modules[6][c] != null) {
        continue;
      }
      this.modules[6][c] = c % 2 == 0;
    }
  }

  setupPositionAdjustPattern() {
    if (this.modules === null) {
      throw new Error('this.modules is null');
    }

    const pos = util.getPatternPosition(this.typeNumber);

    for (let i = 0; i < pos.length; i++) {
      for (let j = 0; j < pos.length; j++) {
        const row = pos[i];
        const col = pos[j];

        if (this.modules[row][col] != null) {
          continue;
        }

        for (let r = -2; r <= 2; r++) {
          for (let c = -2; c <= 2; c++) {
            if (r == -2 || r == 2 || c == -2 || c == 2 || (r == 0 && c == 0)) {
              this.modules[row + r][col + c] = true;
            } else {
              this.modules[row + r][col + c] = false;
            }
          }
        }
      }
    }
  }

  setupTypeNumber(test: boolean) {
    if (this.modules === null) {
      throw new Error('this.modules is null');
    }

    const bits = util.getBCHTypeNumber(this.typeNumber);

    for (let i = 0; i < 18; i++) {
      const mod = !test && ((bits >> i) & 1) == 1;
      this.modules[Math.floor(i / 3)][(i % 3) + this.moduleCount - 8 - 3] = mod;
    }

    for (let i = 0; i < 18; i++) {
      const mod = !test && ((bits >> i) & 1) == 1;
      this.modules[(i % 3) + this.moduleCount - 8 - 3][Math.floor(i / 3)] = mod;
    }
  }

  setupTypeInfo(test: boolean, maskPattern: number) {
    if (this.modules === null) {
      throw new Error('this.modules is null');
    }

    const data = (this.errorCorrectLevel << 3) | maskPattern;
    const bits = util.getBCHTypeInfo(data);

    // vertical
    for (let i = 0; i < 15; i++) {
      const mod = !test && ((bits >> i) & 1) == 1;

      if (i < 6) {
        this.modules[i][8] = mod;
      } else if (i < 8) {
        this.modules[i + 1][8] = mod;
      } else {
        this.modules[this.moduleCount - 15 + i][8] = mod;
      }
    }

    // horizontal
    for (let i = 0; i < 15; i++) {
      const mod = !test && ((bits >> i) & 1) == 1;

      if (i < 8) {
        this.modules[8][this.moduleCount - i - 1] = mod;
      } else if (i < 9) {
        this.modules[8][15 - i - 1 + 1] = mod;
      } else {
        this.modules[8][15 - i - 1] = mod;
      }
    }

    // fixed module
    this.modules[this.moduleCount - 8][8] = !test;
  }

  mapData(data: number[], maskPattern: number) {
    if (this.modules === null) {
      throw new Error('this.modules is null');
    }

    let inc = -1;
    let row = this.moduleCount - 1;
    let bitIndex = 7;
    let byteIndex = 0;

    for (let col = this.moduleCount - 1; col > 0; col -= 2) {
      if (col == 6) col--;

      // eslint-disable-next-line no-constant-condition
      while (true) {
        for (let c = 0; c < 2; c++) {
          if (this.modules[row][col - c] == null) {
            let dark = false;

            if (byteIndex < data.length) {
              dark = ((data[byteIndex] >>> bitIndex) & 1) == 1;
            }

            const mask = util.getMask(maskPattern, row, col - c);

            if (mask) {
              dark = !dark;
            }

            this.modules[row][col - c] = dark;
            bitIndex--;

            if (bitIndex == -1) {
              byteIndex++;
              bitIndex = 7;
            }
          }
        }

        row += inc;

        if (row < 0 || this.moduleCount <= row) {
          row -= inc;
          inc = -inc;
          break;
        }
      }
    }
  }

  static PAD0 = 0xec;
  static PAD1 = 0x11;

  static createData(
    typeNumber: number,
    errorCorrectLevel: number,
    dataList: BitByte[],
  ) {
    const rsBlocks = RSBlock.getRSBlocks(typeNumber, errorCorrectLevel);

    const buffer = new BitBuffer();

    for (let i = 0; i < dataList.length; i++) {
      const data = dataList[i];
      buffer.put(data.mode, 4);
      buffer.put(data.getLength(), util.getLengthInBits(data.mode, typeNumber));
      data.write(buffer);
    }

    // calc num max data.
    let totalDataCount = 0;
    for (let i = 0; i < rsBlocks.length; i++) {
      totalDataCount += rsBlocks[i].dataCount;
    }

    if (buffer.getLengthInBits() > totalDataCount * 8) {
      throw new Error(
        'code length overflow. (' +
          buffer.getLengthInBits() +
          '>' +
          totalDataCount * 8 +
          ')',
      );
    }

    // end code
    if (buffer.getLengthInBits() + 4 <= totalDataCount * 8) {
      buffer.put(0, 4);
    }

    // padding
    while (buffer.getLengthInBits() % 8 != 0) {
      buffer.putBit(false);
    }

    // padding
    // eslint-disable-next-line no-constant-condition
    while (true) {
      if (buffer.getLengthInBits() >= totalDataCount * 8) {
        break;
      }
      buffer.put(QRCode.PAD0, 8);

      if (buffer.getLengthInBits() >= totalDataCount * 8) {
        break;
      }
      buffer.put(QRCode.PAD1, 8);
    }

    return QRCode.createBytes(buffer, rsBlocks);
  }

  static createBytes(buffer: BitBuffer, rsBlocks: RSBlock[]): number[] {
    let offset = 0;

    let maxDcCount = 0;
    let maxEcCount = 0;

    const dcdata = new Array<number[]>(rsBlocks.length);
    const ecdata = new Array<number[]>(rsBlocks.length);

    for (let r = 0; r < rsBlocks.length; r++) {
      const dcCount = rsBlocks[r].dataCount;
      const ecCount = rsBlocks[r].totalCount - dcCount;

      maxDcCount = Math.max(maxDcCount, dcCount);
      maxEcCount = Math.max(maxEcCount, ecCount);

      dcdata[r] = new Array<number>(dcCount);

      for (let i = 0; i < dcdata[r].length; i++) {
        dcdata[r][i] = 0xff & buffer.buffer[i + offset];
      }
      offset += dcCount;

      const rsPoly = util.getErrorCorrectPolynomial(ecCount);
      const rawPoly = new Polynomial(dcdata[r], rsPoly.getLength() - 1);

      const modPoly = rawPoly.mod(rsPoly);
      ecdata[r] = new Array(rsPoly.getLength() - 1);
      for (let i = 0; i < ecdata[r].length; i++) {
        const modIndex = i + modPoly.getLength() - ecdata[r].length;
        ecdata[r][i] = modIndex >= 0 ? modPoly.get(modIndex) : 0;
      }
    }

    let totalCodeCount = 0;
    for (let i = 0; i < rsBlocks.length; i++) {
      totalCodeCount += rsBlocks[i].totalCount;
    }

    const data = new Array<number>(totalCodeCount);
    let index = 0;

    for (let i = 0; i < maxDcCount; i++) {
      for (let r = 0; r < rsBlocks.length; r++) {
        if (i < dcdata[r].length) {
          data[index++] = dcdata[r][i];
        }
      }
    }

    for (let i = 0; i < maxEcCount; i++) {
      for (let r = 0; r < rsBlocks.length; r++) {
        if (i < ecdata[r].length) {
          data[index++] = ecdata[r][i];
        }
      }
    }

    return data;
  }
}