@nuintun/qrcode/cjs/detector/utils/pattern.cjs

A pure JavaScript QRCode encode and decode library.

/**
 * @module QRCode
 * @package @nuintun/qrcode
 * @license MIT
 * @version 5.0.3
 * @author nuintun <nuintun@qq.com>
 * @description A pure JavaScript QRCode encode and decode library.
 * @see https://github.com/nuintun/qrcode#readme
 */

'use strict';

const utils = require('../../common/utils.cjs');
const constants = require('./constants.cjs');
const scanline = require('./scanline.cjs');

/**
 * @module pattern
 */
function isDiagonalScanlineCheckPassed(slash, backslash, ratios, strict) {
  return strict
    ? isMatchPattern(slash, ratios) && isMatchPattern(backslash, ratios)
    : isMatchPattern(slash, ratios) || isMatchPattern(backslash, ratios);
}
function alignCrossPattern(matrix, x, y, overscan, ratios, isVertical) {
  const [scanline$1, end] = scanline.getCrossScanline(matrix, x, y, overscan, isVertical);
  return [isMatchPattern(scanline$1, ratios) ? scanline.centerFromScanlineEnd(scanline$1, end) : NaN, scanline$1];
}
function isEqualsSize(size1, size2, ratio) {
  if (size1 > size2) {
    [size1, size2] = [size2, size1];
  }
  return size2 - size1 <= size2 * ratio;
}
function isMatchPattern(scanline$1, { ratios, modules }) {
  const { length } = scanline$1;
  const scanlineTotal = scanline.sumScanlineNonzero(scanline$1);
  if (scanlineTotal >= modules) {
    const moduleSize = scanlineTotal / modules;
    const threshold = moduleSize * constants.DIFF_PATTERN_RATIO + constants.DIFF_PATTERN_ALLOWANCE;
    // Allow less than DIFF_PATTERN_RATIO variance from 1-1-3-1-1 or 1-1-1-1-1 proportions.
    for (let i = 0; i < length; i++) {
      const ratio = ratios[i];
      const count = scanline$1[i];
      const countDiff = Math.abs(count - moduleSize * ratio);
      if (countDiff > threshold) {
        return false;
      }
    }
    return true;
  }
  return false;
}
function calculatePatternNoise(ratios, ...scanlines) {
  let noises = 0;
  let averageNoises = 0;
  const { length } = scanlines;
  const averages = [];
  // scanline length must be equals ratios length.
  for (const scanline$1 of scanlines) {
    const [noise, average] = scanline.calculateScanlineNoise(scanline$1, ratios);
    noises += noise;
    averages.push(average);
  }
  const total = utils.accumulate(averages);
  const averagesAvg = total / length;
  for (const average of averages) {
    averageNoises += Math.abs(average - averagesAvg);
  }
  return noises + averageNoises / total;
}

exports.alignCrossPattern = alignCrossPattern;
exports.calculatePatternNoise = calculatePatternNoise;
exports.isDiagonalScanlineCheckPassed = isDiagonalScanlineCheckPassed;
exports.isEqualsSize = isEqualsSize;
exports.isMatchPattern = isMatchPattern;