小程序动态生成二维码，并点击保存到手机

//---------------------------------------------------------------------
//
// QR Code Generator for JavaScript
//
// Copyright (c) 2009 Kazuhiko Arase
//
// URL: http://www.d-project.com/
//
// Licensed under the MIT license:
//	http://www.opensource.org/licenses/mit-license.php
//
// The word ‘QR Code‘ is registered trademark of
// DENSO WAVE INCORPORATED
//	http://www.denso-wave.com/qrcode/faqpatent-e.html
//
//---------------------------------------------------------------------

//---------------微信小程序基于base64生成二维码插件修改-------------------
/*
 * @Modified: Pudon
 * @demoURL: https://github.com/Pudon/weapp-qrcode
 * @Date: 2018-09-11 14:00:05 
 * @Last Modified by: Pudon
 * @Last Modified time: 2018-09-12 16:33:19
 */
//---------------------------------------------------------------------

/**
 * qrcode
 * @param typeNumber 1 to 40
 * @param errorCorrectLevel ‘L‘,‘M‘,‘Q‘,‘H‘
 */
var qrcode = function (typeNumber, errorCorrectLevel) {

  var PAD0 = 0xEC;
  var PAD1 = 0x11;

  var _typeNumber = typeNumber;
  var _errorCorrectLevel = QRErrorCorrectLevel[errorCorrectLevel];
  var _modules = null;
  var _moduleCount = 0;
  var _dataCache = null;
  var _dataList = new Array();

  var _this = {};

  var makeImpl = function (test, maskPattern) {

    _moduleCount = _typeNumber * 4 + 17;
    _modules = function (moduleCount) {
      var modules = new Array(moduleCount);
      for (var row = 0; row < moduleCount; row += 1) {
        modules[row] = new Array(moduleCount);
        for (var col = 0; col < moduleCount; col += 1) {
          modules[row][col] = null;
        }
      }
      return modules;
    }(_moduleCount);

    setupPositionProbePattern(0, 0);
    setupPositionProbePattern(_moduleCount - 7, 0);
    setupPositionProbePattern(0, _moduleCount - 7);
    setupPositionAdjustPattern();
    setupTimingPattern();
    setupTypeInfo(test, maskPattern);

    if (_typeNumber >= 7) {
      setupTypeNumber(test);
    }

    if (_dataCache == null) {
      _dataCache = createData(_typeNumber, _errorCorrectLevel, _dataList);
    }

    mapData(_dataCache, maskPattern);
  };

  var setupPositionProbePattern = function (row, col) {

    for (var r = -1; r <= 7; r += 1) {

      if (row + r <= -1 || _moduleCount <= row + r) continue;

      for (var c = -1; c <= 7; c += 1) {

        if (col + c <= -1 || _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)) {
          _modules[row + r][col + c] = true;
        } else {
          _modules[row + r][col + c] = false;
        }
      }
    }
  };

  var getBestMaskPattern = function () {

    var minLostPoint = 0;
    var pattern = 0;

    for (var i = 0; i < 8; i += 1) {

      makeImpl(true, i);

      var lostPoint = QRUtil.getLostPoint(_this);

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

    return pattern;
  };

  var setupTimingPattern = function () {

    for (var r = 8; r < _moduleCount - 8; r += 1) {
      if (_modules[r][6] != null) {
        continue;
      }
      _modules[r][6] = (r % 2 == 0);
    }

    for (var c = 8; c < _moduleCount - 8; c += 1) {
      if (_modules[6][c] != null) {
        continue;
      }
      _modules[6][c] = (c % 2 == 0);
    }
  };

  var setupPositionAdjustPattern = function () {

    var pos = QRUtil.getPatternPosition(_typeNumber);

    for (var i = 0; i < pos.length; i += 1) {

      for (var j = 0; j < pos.length; j += 1) {

        var row = pos[i];
        var col = pos[j];

        if (_modules[row][col] != null) {
          continue;
        }

        for (var r = -2; r <= 2; r += 1) {

          for (var c = -2; c <= 2; c += 1) {

            if (r == -2 || r == 2 || c == -2 || c == 2
              || (r == 0 && c == 0)) {
              _modules[row + r][col + c] = true;
            } else {
              _modules[row + r][col + c] = false;
            }
          }
        }
      }
    }
  };

  var setupTypeNumber = function (test) {

    var bits = QRUtil.getBCHTypeNumber(_typeNumber);

    for (var i = 0; i < 18; i += 1) {
      var mod = (!test && ((bits >> i) & 1) == 1);
      _modules[Math.floor(i / 3)][i % 3 + _moduleCount - 8 - 3] = mod;
    }

    for (var i = 0; i < 18; i += 1) {
      var mod = (!test && ((bits >> i) & 1) == 1);
      _modules[i % 3 + _moduleCount - 8 - 3][Math.floor(i / 3)] = mod;
    }
  };

  var setupTypeInfo = function (test, maskPattern) {

    var data = (_errorCorrectLevel << 3) | maskPattern;
    var bits = QRUtil.getBCHTypeInfo(data);

    // vertical
    for (var i = 0; i < 15; i += 1) {

      var mod = (!test && ((bits >> i) & 1) == 1);

      if (i < 6) {
        _modules[i][8] = mod;
      } else if (i < 8) {
        _modules[i + 1][8] = mod;
      } else {
        _modules[_moduleCount - 15 + i][8] = mod;
      }
    }

    // horizontal
    for (var i = 0; i < 15; i += 1) {

      var mod = (!test && ((bits >> i) & 1) == 1);

      if (i < 8) {
        _modules[8][_moduleCount - i - 1] = mod;
      } else if (i < 9) {
        _modules[8][15 - i - 1 + 1] = mod;
      } else {
        _modules[8][15 - i - 1] = mod;
      }
    }

    // fixed module
    _modules[_moduleCount - 8][8] = (!test);
  };

  var mapData = function (data, maskPattern) {

    var inc = -1;
    var row = _moduleCount - 1;
    var bitIndex = 7;
    var byteIndex = 0;
    var maskFunc = QRUtil.getMaskFunction(maskPattern);

    for (var col = _moduleCount - 1; col > 0; col -= 2) {

      if (col == 6) col -= 1;

      while (true) {

        for (var c = 0; c < 2; c += 1) {

          if (_modules[row][col - c] == null) {

            var dark = false;

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

            var mask = maskFunc(row, col - c);

            if (mask) {
              dark = !dark;
            }

            _modules[row][col - c] = dark;
            bitIndex -= 1;

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

        row += inc;

        if (row < 0 || _moduleCount <= row) {
          row -= inc;
          inc = -inc;
          break;
        }
      }
    }
  };

  var createBytes = function (buffer, rsBlocks) {

    var offset = 0;

    var maxDcCount = 0;
    var maxEcCount = 0;

    var dcdata = new Array(rsBlocks.length);
    var ecdata = new Array(rsBlocks.length);

    for (var r = 0; r < rsBlocks.length; r += 1) {

      var dcCount = rsBlocks[r].dataCount;
      var ecCount = rsBlocks[r].totalCount - dcCount;

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

      dcdata[r] = new Array(dcCount);

      for (var i = 0; i < dcdata[r].length; i += 1) {
        dcdata[r][i] = 0xff & buffer.getBuffer()[i + offset];
      }
      offset += dcCount;

      var rsPoly = QRUtil.getErrorCorrectPolynomial(ecCount);
      var rawPoly = qrPolynomial(dcdata[r], rsPoly.getLength() - 1);

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

    var totalCodeCount = 0;
    for (var i = 0; i < rsBlocks.length; i += 1) {
      totalCodeCount += rsBlocks[i].totalCount;
    }

    var data = new Array(totalCodeCount);
    var index = 0;

    for (var i = 0; i < maxDcCount; i += 1) {
      for (var r = 0; r < rsBlocks.length; r += 1) {
        if (i < dcdata[r].length) {
          data[index] = dcdata[r][i];
          index += 1;
        }
      }
    }

    for (var i = 0; i < maxEcCount; i += 1) {
      for (var r = 0; r < rsBlocks.length; r += 1) {
        if (i < ecdata[r].length) {
          data[index] = ecdata[r][i];
          index += 1;
        }
      }
    }

    return data;
  };

  var createData = function (typeNumber, errorCorrectLevel, dataList) {

    var rsBlocks = QRRSBlock.getRSBlocks(typeNumber, errorCorrectLevel);

    var buffer = qrBitBuffer();

    for (var i = 0; i < dataList.length; i += 1) {
      var data = dataList[i];
      buffer.put(data.getMode(), 4);
      buffer.put(data.getLength(), QRUtil.getLengthInBits(data.getMode(), typeNumber));
      data.write(buffer);
    }

    // calc num max data.
    var totalDataCount = 0;
    for (var i = 0; i < rsBlocks.length; i += 1) {
      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
    while (true) {

      if (buffer.getLengthInBits() >= totalDataCount * 8) {
        break;
      }
      buffer.put(PAD0, 8);

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

    return createBytes(buffer, rsBlocks);
  };

  _this.addData = function (data) {
    var newData = qr8BitByte(data);
    _dataList.push(newData);
    _dataCache = null;
  };

  _this.isDark = function (row, col) {
    if (row < 0 || _moduleCount <= row || col < 0 || _moduleCount <= col) {
      throw new Error(row + ‘,‘ + col);
    }
    return _modules[row][col];
  };

  _this.getModuleCount = function () {
    return _moduleCount;
  };

  _this.make = function () {
    makeImpl(false, getBestMaskPattern());
  };

  _this.createTableTag = function (cellSize, margin) {

    cellSize = cellSize || 2;
    margin = (typeof margin == ‘undefined‘) ? cellSize * 4 : margin;

    var qrHtml = ‘‘;

    qrHtml += ‘<table style="‘;
    qrHtml += ‘ border-width: 0px; border-style: none;‘;
    qrHtml += ‘ border-collapse: collapse;‘;
    qrHtml += ‘ padding: 0px; margin: ‘ + margin + ‘px;‘;
    qrHtml += ‘">‘;
    qrHtml += ‘<tbody>‘;

    for (var r = 0; r < _this.getModuleCount(); r += 1) {

      qrHtml += ‘<tr>‘;

      for (var c = 0; c < _this.getModuleCount(); c += 1) {
        qrHtml += ‘<td style="‘;
        qrHtml += ‘ border-width: 0px; border-style: none;‘;
        qrHtml += ‘ border-collapse: collapse;‘;
        qrHtml += ‘ padding: 0px; margin: 0px;‘;
        qrHtml += ‘ width: ‘ + cellSize + ‘px;‘;
        qrHtml += ‘ height: ‘ + cellSize + ‘px;‘;
        qrHtml += ‘ background-color: ‘;
        qrHtml += _this.isDark(r, c) ? ‘#000000‘ : ‘#ffffff‘;
        qrHtml += ‘;‘;
        qrHtml += ‘"/>‘;
      }

      qrHtml += ‘</tr>‘;
    }

    qrHtml += ‘</tbody>‘;
    qrHtml += ‘</table>‘;

    return qrHtml;
  };

  _this.createImgTag = function (cellSize, margin, size) {

    cellSize = cellSize || 2;
    margin = (typeof margin == ‘undefined‘) ? cellSize * 4 : margin;

    var min = margin;
    var max = _this.getModuleCount() * cellSize + margin;

    return createImgTag(size, size, function (x, y) {
      if (min <= x && x < max && min <= y && y < max) {
        var c = Math.floor((x - min) / cellSize);
        var r = Math.floor((y - min) / cellSize);
        return _this.isDark(r, c) ? 0 : 1;
      } else {
        return 1;
      }
    });
  };

  return _this;
};

//---------------------------------------------------------------------
// qrcode.stringToBytes
//---------------------------------------------------------------------

qrcode.stringToBytes = function (s) {
  var bytes = new Array();
  for (var i = 0; i < s.length; i += 1) {
    var c = s.charCodeAt(i);
    bytes.push(c & 0xff);
  }
  return bytes;
};

//---------------------------------------------------------------------
// qrcode.createStringToBytes
//---------------------------------------------------------------------

/**
 * @param unicodeData base64 string of byte array.
 * [16bit Unicode],[16bit Bytes], ...
 * @param numChars
 */
qrcode.createStringToBytes = function (unicodeData, numChars) {

  // create conversion map.

  var unicodeMap = function () {

    var bin = base64DecodeInputStream(unicodeData);
    var read = function () {
      var b = bin.read();
      if (b == -1) throw new Error();
      return b;
    };

    var count = 0;
    var unicodeMap = {};
    while (true) {
      var b0 = bin.read();
      if (b0 == -1) break;
      var b1 = read();
      var b2 = read();
      var b3 = read();
      var k = String.fromCharCode((b0 << 8) | b1);
      var v = (b2 << 8) | b3;
      unicodeMap[k] = v;
      count += 1;
    }
    if (count != numChars) {
      throw new Error(count + ‘ != ‘ + numChars);
    }

    return unicodeMap;
  }();

  var unknownChar = ‘?‘.charCodeAt(0);

  return function (s) {
    var bytes = new Array();
    for (var i = 0; i < s.length; i += 1) {
      var c = s.charCodeAt(i);
      if (c < 128) {
        bytes.push(c);
      } else {
        var b = unicodeMap[s.charAt(i)];
        if (typeof b == ‘number‘) {
          if ((b & 0xff) == b) {
            // 1byte
            bytes.push(b);
          } else {
            // 2bytes
            bytes.push(b >>> 8);
            bytes.push(b & 0xff);
          }
        } else {
          bytes.push(unknownChar);
        }
      }
    }
    return bytes;
  };
};

//---------------------------------------------------------------------
// QRMode
//---------------------------------------------------------------------

var QRMode = {
  MODE_NUMBER: 1 << 0,
  MODE_ALPHA_NUM: 1 << 1,
  MODE_8BIT_BYTE: 1 << 2,
  MODE_KANJI: 1 << 3
};

//---------------------------------------------------------------------
// QRErrorCorrectLevel
//---------------------------------------------------------------------

var QRErrorCorrectLevel = {
  L: 1,
  M: 0,
  Q: 3,
  H: 2
};

//---------------------------------------------------------------------
// QRMaskPattern
//---------------------------------------------------------------------

var QRMaskPattern = {
  PATTERN000: 0,
  PATTERN001: 1,
  PATTERN010: 2,
  PATTERN011: 3,
  PATTERN100: 4,
  PATTERN101: 5,
  PATTERN110: 6,
  PATTERN111: 7
};

//---------------------------------------------------------------------
// QRUtil
//---------------------------------------------------------------------

var QRUtil = function () {

  var PATTERN_POSITION_TABLE = [
    [],
    [6, 18],
    [6, 22],
    [6, 26],
    [6, 30],
    [6, 34],
    [6, 22, 38],
    [6, 24, 42],
    [6, 26, 46],
    [6, 28, 50],
    [6, 30, 54],
    [6, 32, 58],
    [6, 34, 62],
    [6, 26, 46, 66],
    [6, 26, 48, 70],
    [6, 26, 50, 74],
    [6, 30, 54, 78],
    [6, 30, 56, 82],
    [6, 30, 58, 86],
    [6, 34, 62, 90],
    [6, 28, 50, 72, 94],
    [6, 26, 50, 74, 98],
    [6, 30, 54, 78, 102],
    [6, 28, 54, 80, 106],
    [6, 32, 58, 84, 110],
    [6, 30, 58, 86, 114],
    [6, 34, 62, 90, 118],
    [6, 26, 50, 74, 98, 122],
    [6, 30, 54, 78, 102, 126],
    [6, 26, 52, 78, 104, 130],
    [6, 30, 56, 82, 108, 134],
    [6, 34, 60, 86, 112, 138],
    [6, 30, 58, 86, 114, 142],
    [6, 34, 62, 90, 118, 146],
    [6, 30, 54, 78, 102, 126, 150],
    [6, 24, 50, 76, 102, 128, 154],
    [6, 28, 54, 80, 106, 132, 158],
    [6, 32, 58, 84, 110, 136, 162],
    [6, 26, 54, 82, 110, 138, 166],
    [6, 30, 58, 86, 114, 142, 170]
  ];
  var G15 = (1 << 10) | (1 << 8) | (1 << 5) | (1 << 4) | (1 << 2) | (1 << 1) | (1 << 0);
  var G18 = (1 << 12) | (1 << 11) | (1 << 10) | (1 << 9) | (1 << 8) | (1 << 5) | (1 << 2) | (1 << 0);
  var G15_MASK = (1 << 14) | (1 << 12) | (1 << 10) | (1 << 4) | (1 << 1);

  var _this = {};

  var getBCHDigit = function (data) {
    var digit = 0;
    while (data != 0) {
      digit += 1;
      data >>>= 1;
    }
    return digit;
  };

  _this.getBCHTypeInfo = function (data) {
    var d = data << 10;
    while (getBCHDigit(d) - getBCHDigit(G15) >= 0) {
      d ^= (G15 << (getBCHDigit(d) - getBCHDigit(G15)));
    }
    return ((data << 10) | d) ^ G15_MASK;
  };

  _this.getBCHTypeNumber = function (data) {
    var d = data << 12;
    while (getBCHDigit(d) - getBCHDigit(G18) >= 0) {
      d ^= (G18 << (getBCHDigit(d) - getBCHDigit(G18)));
    }
    return (data << 12) | d;
  };

  _this.getPatternPosition = function (typeNumber) {
    return PATTERN_POSITION_TABLE[typeNumber - 1];
  };

  _this.getMaskFunction = function (maskPattern) {

    switch (maskPattern) {

      case QRMaskPattern.PATTERN000:
        return function (i, j) { return (i + j) % 2 == 0; };
      case QRMaskPattern.PATTERN001:
        return function (i, j) { return i % 2 == 0; };
      case QRMaskPattern.PATTERN010:
        return function (i, j) { return j % 3 == 0; };
      case QRMaskPattern.PATTERN011:
        return function (i, j) { return (i + j) % 3 == 0; };
      case QRMaskPattern.PATTERN100:
        return function (i, j) { return (Math.floor(i / 2) + Math.floor(j / 3)) % 2 == 0; };
      case QRMaskPattern.PATTERN101:
        return function (i, j) { return (i * j) % 2 + (i * j) % 3 == 0; };
      case QRMaskPattern.PATTERN110:
        return function (i, j) { return ((i * j) % 2 + (i * j) % 3) % 2 == 0; };
      case QRMaskPattern.PATTERN111:
        return function (i, j) { return ((i * j) % 3 + (i + j) % 2) % 2 == 0; };

      default:
        throw new Error(‘bad maskPattern:‘ + maskPattern);
    }
  };

  _this.getErrorCorrectPolynomial = function (errorCorrectLength) {
    var a = qrPolynomial([1], 0);
    for (var i = 0; i < errorCorrectLength; i += 1) {
      a = a.multiply(qrPolynomial([1, QRMath.gexp(i)], 0));
    }
    return a;
  };

  _this.getLengthInBits = function (mode, type) {

    if (1 <= type && type < 10) {

      // 1 - 9

      switch (mode) {
        case QRMode.MODE_NUMBER: return 10;
        case QRMode.MODE_ALPHA_NUM: return 9;
        case QRMode.MODE_8BIT_BYTE: return 8;
        case QRMode.MODE_KANJI: return 8;
        default:
          throw new Error(‘mode:‘ + mode);
      }

    } else if (type < 27) {

      // 10 - 26

      switch (mode) {
        case QRMode.MODE_NUMBER: return 12;
        case QRMode.MODE_ALPHA_NUM: return 11;
        case QRMode.MODE_8BIT_BYTE: return 16;
        case QRMode.MODE_KANJI: return 10;
        default:
          throw new Error(‘mode:‘ + mode);
      }

    } else if (type < 41) {

      // 27 - 40

      switch (mode) {
        case QRMode.MODE_NUMBER: return 14;
        case QRMode.MODE_ALPHA_NUM: return 13;
        case QRMode.MODE_8BIT_BYTE: return 16;
        case QRMode.MODE_KANJI: return 12;
        default:
          throw new Error(‘mode:‘ + mode);
      }

    } else {
      throw new Error(‘type:‘ + type);
    }
  };

  _this.getLostPoint = function (qrcode) {

    var moduleCount = qrcode.getModuleCount();

    var lostPoint = 0;

    // LEVEL1

    for (var row = 0; row < moduleCount; row += 1) {
      for (var col = 0; col < moduleCount; col += 1) {

        var sameCount = 0;
        var dark = qrcode.isDark(row, col);

        for (var r = -1; r <= 1; r += 1) {

          if (row + r < 0 || moduleCount <= row + r) {
            continue;
          }

          for (var c = -1; c <= 1; c += 1) {

            if (col + c < 0 || moduleCount <= col + c) {
              continue;
            }

            if (r == 0 && c == 0) {
              continue;
            }

            if (dark == qrcode.isDark(row + r, col + c)) {
              sameCount += 1;
            }
          }
        }

        if (sameCount > 5) {
          lostPoint += (3 + sameCount - 5);
        }
      }
    };

    // LEVEL2

    for (var row = 0; row < moduleCount - 1; row += 1) {
      for (var col = 0; col < moduleCount - 1; col += 1) {
        var count = 0;
        if (qrcode.isDark(row, col)) count += 1;
        if (qrcode.isDark(row + 1, col)) count += 1;
        if (qrcode.isDark(row, col + 1)) count += 1;
        if (qrcode.isDark(row + 1, col + 1)) count += 1;
        if (count == 0 || count == 4) {
          lostPoint += 3;
        }
      }
    }

    // LEVEL3

    for (var row = 0; row < moduleCount; row += 1) {
      for (var col = 0; col < moduleCount - 6; col += 1) {
        if (qrcode.isDark(row, col)
          && !qrcode.isDark(row, col + 1)
          && qrcode.isDark(row, col + 2)
          && qrcode.isDark(row, col + 3)
          && qrcode.isDark(row, col + 4)
          && !qrcode.isDark(row, col + 5)
          && qrcode.isDark(row, col + 6)) {
          lostPoint += 40;
        }
      }
    }

    for (var col = 0; col < moduleCount; col += 1) {
      for (var row = 0; row < moduleCount - 6; row += 1) {
        if (qrcode.isDark(row, col)
          && !qrcode.isDark(row + 1, col)
          && qrcode.isDark(row + 2, col)
          && qrcode.isDark(row + 3, col)
          && qrcode.isDark(row + 4, col)
          && !qrcode.isDark(row + 5, col)
          && qrcode.isDark(row + 6, col)) {
          lostPoint += 40;
        }
      }
    }

    // LEVEL4

    var darkCount = 0;

    for (var col = 0; col < moduleCount; col += 1) {
      for (var row = 0; row < moduleCount; row += 1) {
        if (qrcode.isDark(row, col)) {
          darkCount += 1;
        }
      }
    }

    var ratio = Math.abs(100 * darkCount / moduleCount / moduleCount - 50) / 5;
    lostPoint += ratio * 10;

    return lostPoint;
  };

  return _this;
}();

//---------------------------------------------------------------------
// QRMath
//---------------------------------------------------------------------

var QRMath = function () {

  var EXP_TABLE = new Array(256);
  var LOG_TABLE = new Array(256);

  // initialize tables
  for (var i = 0; i < 8; i += 1) {
    EXP_TABLE[i] = 1 << i;
  }
  for (var i = 8; i < 256; i += 1) {
    EXP_TABLE[i] = EXP_TABLE[i - 4]
      ^ EXP_TABLE[i - 5]
      ^ EXP_TABLE[i - 6]
      ^ EXP_TABLE[i - 8];
  }
  for (var i = 0; i < 255; i += 1) {
    LOG_TABLE[EXP_TABLE[i]] = i;
  }

  var _this = {};

  _this.glog = function (n) {

    if (n < 1) {
      throw new Error(‘glog(‘ + n + ‘)‘);
    }

    return LOG_TABLE[n];
  };

  _this.gexp = function (n) {

    while (n < 0) {
      n += 255;
    }

    while (n >= 256) {
      n -= 255;
    }

    return EXP_TABLE[n];
  };

  return _this;
}();

//---------------------------------------------------------------------
// qrPolynomial
//---------------------------------------------------------------------

function qrPolynomial(num, shift) {

  if (typeof num.length == ‘undefined‘) {
    throw new Error(num.length + ‘/‘ + shift);
  }

  var _num = function () {
    var offset = 0;
    while (offset < num.length && num[offset] == 0) {
      offset += 1;
    }
    var _num = new Array(num.length - offset + shift);
    for (var i = 0; i < num.length - offset; i += 1) {
      _num[i] = num[i + offset];
    }
    return _num;
  }();

  var _this = {};

  _this.getAt = function (index) {
    return _num[index];
  };

  _this.getLength = function () {
    return _num.length;
  };

  _this.multiply = function (e) {

    var num = new Array(_this.getLength() + e.getLength() - 1);

    for (var i = 0; i < _this.getLength(); i += 1) {
      for (var j = 0; j < e.getLength(); j += 1) {
        num[i + j] ^= QRMath.gexp(QRMath.glog(_this.getAt(i)) + QRMath.glog(e.getAt(j)));
      }
    }

    return qrPolynomial(num, 0);
  };

  _this.mod = function (e) {

    if (_this.getLength() - e.getLength() < 0) {
      return _this;
    }

    var ratio = QRMath.glog(_this.getAt(0)) - QRMath.glog(e.getAt(0));

    var num = new Array(_this.getLength());
    for (var i = 0; i < _this.getLength(); i += 1) {
      num[i] = _this.getAt(i);
    }

    for (var i = 0; i < e.getLength(); i += 1) {
      num[i] ^= QRMath.gexp(QRMath.glog(e.getAt(i)) + ratio);
    }

    // recursive call
    return qrPolynomial(num, 0).mod(e);
  };

  return _this;
};

//---------------------------------------------------------------------
// QRRSBlock
//---------------------------------------------------------------------

var QRRSBlock = function () {


  // [1: [L, M, Q, H], ..]
  var RS_BLOCK_TABLE = [[1, 26, 19], [1, 26, 16], [1, 26, 13], [1, 26, 9], [1, 44, 34], [1, 44, 28], [1, 44, 22], [1, 44, 16], [1, 70, 55], [1, 70, 44], [2, 35, 17], [2, 35, 13], [1, 100, 80], [2, 50, 32], [2, 50, 24], [4, 25, 9], [1, 134, 108], [2, 67, 43], [2, 33, 15, 2, 34, 16], [2, 33, 11, 2, 34, 12], [2, 86, 68], [4, 43, 27], [4, 43, 19], [4, 43, 15], [2, 98, 78], [4, 49, 31], [2, 32, 14, 4, 33, 15], [4, 39, 13, 1, 40, 14], [2, 121, 97], [2, 60, 38, 2, 61, 39], [4, 40, 18, 2, 41, 19], [4, 40, 14, 2, 41, 15], [2, 146, 116], [3, 58, 36, 2, 59, 37], [4, 36, 16, 4, 37, 17], [4, 36, 12, 4, 37, 13], [2, 86, 68, 2, 87, 69], [4, 69, 43, 1, 70, 44], [6, 43, 19, 2, 44, 20], [6, 43, 15, 2, 44, 16], [4, 101, 81], [1, 80, 50, 4, 81, 51], [4, 50, 22, 4, 51, 23], [3, 36, 12, 8, 37, 13], [2, 116, 92, 2, 117, 93], [6, 58, 36, 2, 59, 37], [4, 46, 20, 6, 47, 21], [7, 42, 14, 4, 43, 15], [4, 133, 107], [8, 59, 37, 1, 60, 38], [8, 44, 20, 4, 45, 21], [12, 33, 11, 4, 34, 12], [3, 145, 115, 1, 146, 116], [4, 64, 40, 5, 65, 41], [11, 36, 16, 5, 37, 17], [11, 36, 12, 5, 37, 13], [5, 109, 87, 1, 110, 88], [5, 65, 41, 5, 66, 42], [5, 54, 24, 7, 55, 25], [11, 36, 12], [5, 122, 98, 1, 123, 99], [7, 73, 45, 3, 74, 46], [15, 43, 19, 2, 44, 20], [3, 45, 15, 13, 46, 16], [1, 135, 107, 5, 136, 108], [10, 74, 46, 1, 75, 47], [1, 50, 22, 15, 51, 23], [2, 42, 14, 17, 43, 15], [5, 150, 120, 1, 151, 121], [9, 69, 43, 4, 70, 44], [17, 50, 22, 1, 51, 23], [2, 42, 14, 19, 43, 15], [3, 141, 113, 4, 142, 114], [3, 70, 44, 11, 71, 45], [17, 47, 21, 4, 48, 22], [9, 39, 13, 16, 40, 14], [3, 135, 107, 5, 136, 108], [3, 67, 41, 13, 68, 42], [15, 54, 24, 5, 55, 25], [15, 43, 15, 10, 44, 16], [4, 144, 116, 4, 145, 117], [17, 68, 42], [17, 50, 22, 6, 51, 23], [19, 46, 16, 6, 47, 17], [2, 139, 111, 7, 140, 112], [17, 74, 46], [7, 54, 24, 16, 55, 25], [34, 37, 13], [4, 151, 121, 5, 152, 122], [4, 75, 47, 14, 76, 48], [11, 54, 24, 14, 55, 25], [16, 45, 15, 14, 46, 16], [6, 147, 117, 4, 148, 118], [6, 73, 45, 14, 74, 46], [11, 54, 24, 16, 55, 25], [30, 46, 16, 2, 47, 17], [8, 132, 106, 4, 133, 107], [8, 75, 47, 13, 76, 48], [7, 54, 24, 22, 55, 25], [22, 45, 15, 13, 46, 16], [10, 142, 114, 2, 143, 115], [19, 74, 46, 4, 75, 47], [28, 50, 22, 6, 51, 23], [33, 46, 16, 4, 47, 17], [8, 152, 122, 4, 153, 123], [22, 73, 45, 3, 74, 46], [8, 53, 23, 26, 54, 24], [12, 45, 15, 28, 46, 16], [3, 147, 117, 10, 148, 118], [3, 73, 45, 23, 74, 46], [4, 54, 24, 31, 55, 25], [11, 45, 15, 31, 46, 16], [7, 146, 116, 7, 147, 117], [21, 73, 45, 7, 74, 46], [1, 53, 23, 37, 54, 24], [19, 45, 15, 26, 46, 16], [5, 145, 115, 10, 146, 116], [19, 75, 47, 10, 76, 48], [15, 54, 24, 25, 55, 25], [23, 45, 15, 25, 46, 16], [13, 145, 115, 3, 146, 116], [2, 74, 46, 29, 75, 47], [42, 54, 24, 1, 55, 25], [23, 45, 15, 28, 46, 16], [17, 145, 115], [10, 74, 46, 23, 75, 47], [10, 54, 24, 35, 55, 25], [19, 45, 15, 35, 46, 16], [17, 145, 115, 1, 146, 116], [14, 74, 46, 21, 75, 47], [29, 54, 24, 19, 55, 25], [11, 45, 15, 46, 46, 16], [13, 145, 115, 6, 146, 116], [14, 74, 46, 23, 75, 47], [44, 54, 24, 7, 55, 25], [59, 46, 16, 1, 47, 17], [12, 151, 121, 7, 152, 122], [12, 75, 47, 26, 76, 48], [39, 54, 24, 14, 55, 25], [22, 45, 15, 41, 46, 16], [6, 151, 121, 14, 152, 122], [6, 75, 47, 34, 76, 48], [46, 54, 24, 10, 55, 25], [2, 45, 15, 64, 46, 16], [17, 152, 122, 4, 153, 123], [29, 74, 46, 14, 75, 47], [49, 54, 24, 10, 55, 25], [24, 45, 15, 46, 46, 16], [4, 152, 122, 18, 153, 123], [13, 74, 46, 32, 75, 47], [48, 54, 24, 14, 55, 25], [42, 45, 15, 32, 46, 16], [20, 147, 117, 4, 148, 118], [40, 75, 47, 7, 76, 48], [43, 54, 24, 22, 55, 25], [10, 45, 15, 67, 46, 16], [19, 148, 118, 6, 149, 119], [18, 75, 47, 31, 76, 48], [34, 54, 24, 34, 55, 25], [20, 45, 15, 61, 46, 16]];

  var qrRSBlock = function (totalCount, dataCount) {
    var _this = {};
    _this.totalCount = totalCount;
    _this.dataCount = dataCount;
    return _this;
  };

  var _this = {};

  var getRsBlockTable = function (typeNumber, errorCorrectLevel) {

    switch (errorCorrectLevel) {
      case QRErrorCorrectLevel.L:
        return RS_BLOCK_TABLE[(typeNumber - 1) * 4 + 0];
      case QRErrorCorrectLevel.M:
        return RS_BLOCK_TABLE[(typeNumber - 1) * 4 + 1];
      case QRErrorCorrectLevel.Q:
        return RS_BLOCK_TABLE[(typeNumber - 1) * 4 + 2];
      case QRErrorCorrectLevel.H:
        return RS_BLOCK_TABLE[(typeNumber - 1) * 4 + 3];
      default:
        return undefined;
    }
  };

  _this.getRSBlocks = function (typeNumber, errorCorrectLevel) {

    var rsBlock = getRsBlockTable(typeNumber, errorCorrectLevel);

    if (typeof rsBlock == ‘undefined‘) {
      throw new Error(‘bad rs block @ typeNumber:‘ + typeNumber +
        ‘/errorCorrectLevel:‘ + errorCorrectLevel);
    }

    var length = rsBlock.length / 3;

    var list = new Array();

    for (var i = 0; i < length; i += 1) {

      var count = rsBlock[i * 3 + 0];
      var totalCount = rsBlock[i * 3 + 1];
      var dataCount = rsBlock[i * 3 + 2];

      for (var j = 0; j < count; j += 1) {
        list.push(qrRSBlock(totalCount, dataCount));
      }
    }

    return list;
  };

  return _this;
}();

//---------------------------------------------------------------------
// qrBitBuffer
//---------------------------------------------------------------------

var qrBitBuffer = function () {

  var _buffer = new Array();
  var _length = 0;

  var _this = {};

  _this.getBuffer = function () {
    return _buffer;
  };

  _this.getAt = function (index) {
    var bufIndex = Math.floor(index / 8);
    return ((_buffer[bufIndex] >>> (7 - index % 8)) & 1) == 1;
  };

  _this.put = function (num, length) {
    for (var i = 0; i < length; i += 1) {
      _this.putBit(((num >>> (length - i - 1)) & 1) == 1);
    }
  };

  _this.getLengthInBits = function () {
    return _length;
  };

  _this.putBit = function (bit) {

    var bufIndex = Math.floor(_length / 8);
    if (_buffer.length <= bufIndex) {
      _buffer.push(0);
    }

    if (bit) {
      _buffer[bufIndex] |= (0x80 >>> (_length % 8));
    }

    _length += 1;
  };

  return _this;
};

//---------------------------------------------------------------------
// qr8BitByte
//---------------------------------------------------------------------

var qr8BitByte = function (data) {

  var _mode = QRMode.MODE_8BIT_BYTE;
  var _data = data;
  var _parsedData = [];

  var _this = {};


  // Added to support UTF-8 Characters
  for (var i = 0, l = _data.length; i < l; i++) {
    var byteArray = [];
    var code = _data.charCodeAt(i);

    if (code > 0x10000) {
      byteArray[0] = 0xF0 | ((code & 0x1C0000) >>> 18);
      byteArray[1] = 0x80 | ((code & 0x3F000) >>> 12);
      byteArray[2] = 0x80 | ((code & 0xFC0) >>> 6);
      byteArray[3] = 0x80 | (code & 0x3F);
    } else if (code > 0x800) {
      byteArray[0] = 0xE0 | ((code & 0xF000) >>> 12);
      byteArray[1] = 0x80 | ((code & 0xFC0) >>> 6);
      byteArray[2] = 0x80 | (code & 0x3F);
    } else if (code > 0x80) {
      byteArray[0] = 0xC0 | ((code & 0x7C0) >>> 6);
      byteArray[1] = 0x80 | (code & 0x3F);
    } else {
      byteArray[0] = code;
    }

    // Fix Unicode corruption bug
    _parsedData.push(byteArray);
  }

  _parsedData = Array.prototype.concat.apply([], _parsedData);

  if (_parsedData.length != _data.length) {
    _parsedData.unshift(191);
    _parsedData.unshift(187);
    _parsedData.unshift(239);
  }

  var _bytes = _parsedData;

  _this.getMode = function () {
    return _mode;
  };

  _this.getLength = function (buffer) {
    return _bytes.length;
  };

  _this.write = function (buffer) {
    for (var i = 0; i < _bytes.length; i += 1) {
      buffer.put(_bytes[i], 8);
    }
  };

  return _this;
};

//=====================================================================
// GIF Support etc.
//

//---------------------------------------------------------------------
// byteArrayOutputStream
//---------------------------------------------------------------------

var byteArrayOutputStream = function () {

  var _bytes = new Array();

  var _this = {};

  _this.writeByte = function (b) {
    _bytes.push(b & 0xff);
  };

  _this.writeShort = function (i) {
    _this.writeByte(i);
    _this.writeByte(i >>> 8);
  };

  _this.writeBytes = function (b, off, len) {
    off = off || 0;
    len = len || b.length;
    for (var i = 0; i < len; i += 1) {
      _this.writeByte(b[i + off]);
    }
  };

  _this.writeString = function (s) {
    for (var i = 0; i < s.length; i += 1) {
      _this.writeByte(s.charCodeAt(i));
    }
  };

  _this.toByteArray = function () {
    return _bytes;
  };

  _this.toString = function () {
    var s = ‘‘;
    s += ‘[‘;
    for (var i = 0; i < _bytes.length; i += 1) {
      if (i > 0) {
        s += ‘,‘;
      }
      s += _bytes[i];
    }
    s += ‘]‘;
    return s;
  };

  return _this;
};

//---------------------------------------------------------------------
// base64EncodeOutputStream
//---------------------------------------------------------------------

var base64EncodeOutputStream = function () {

  var _buffer = 0;
  var _buflen = 0;
  var _length = 0;
  var _base64 = ‘‘;

  var _this = {};

  var writeEncoded = function (b) {
    _base64 += String.fromCharCode(encode(b & 0x3f));
  };

  var encode = function (n) {
    if (n < 0) {
      // error.
    } else if (n < 26) {
      return 0x41 + n;
    } else if (n < 52) {
      return 0x61 + (n - 26);
    } else if (n < 62) {
      return 0x30 + (n - 52);
    } else if (n == 62) {
      return 0x2b;
    } else if (n == 63) {
      return 0x2f;
    }
    throw new Error(‘n:‘ + n);
  };

  _this.writeByte = function (n) {

    _buffer = (_buffer << 8) | (n & 0xff);
    _buflen += 8;
    _length += 1;

    while (_buflen >= 6) {
      writeEncoded(_buffer >>> (_buflen - 6));
      _buflen -= 6;
    }
  };

  _this.flush = function () {

    if (_buflen > 0) {
      writeEncoded(_buffer << (6 - _buflen));
      _buffer = 0;
      _buflen = 0;
    }

    if (_length % 3 != 0) {
      // padding
      var padlen = 3 - _length % 3;
      for (var i = 0; i < padlen; i += 1) {
        _base64 += ‘=‘;
      }
    }
  };

  _this.toString = function () {
    return _base64;
  };

  return _this;
};

//---------------------------------------------------------------------
// base64DecodeInputStream
//---------------------------------------------------------------------

var base64DecodeInputStream = function (str) {

  var _str = str;
  var _pos = 0;
  var _buffer = 0;
  var _buflen = 0;

  var _this = {};

  _this.read = function () {

    while (_buflen < 8) {

      if (_pos >= _str.length) {
        if (_buflen == 0) {
          return -1;
        }
        throw new Error(‘unexpected end of file./‘ + _buflen);
      }

      var c = _str.charAt(_pos);
      _pos += 1;

      if (c == ‘=‘) {
        _buflen = 0;
        return -1;
      } else if (c.match(/^\s$/)) {
        // ignore if whitespace.
        continue;
      }

      _buffer = (_buffer << 6) | decode(c.charCodeAt(0));
      _buflen += 6;
    }

    var n = (_buffer >>> (_buflen - 8)) & 0xff;
    _buflen -= 8;
    return n;
  };

  var decode = function (c) {
    if (0x41 <= c && c <= 0x5a) {
      return c - 0x41;
    } else if (0x61 <= c && c <= 0x7a) {
      return c - 0x61 + 26;
    } else if (0x30 <= c && c <= 0x39) {
      return c - 0x30 + 52;
    } else if (c == 0x2b) {
      return 62;
    } else if (c == 0x2f) {
      return 63;
    } else {
      throw new Error(‘c:‘ + c);
    }
  };

  return _this;
};

//---------------------------------------------------------------------
// gifImage (B/W)
//---------------------------------------------------------------------

var gifImage = function (width, height) {

  var _width = width;
  var _height = height;
  var _data = new Array(width * height);

  var _this = {};

  _this.setPixel = function (x, y, pixel) {
    _data[y * _width + x] = pixel;
  };

  _this.write = function (out) {

    //---------------------------------
    // GIF Signature

    out.writeString(‘GIF87a‘);

    //---------------------------------
    // Screen Descriptor

    out.writeShort(_width);
    out.writeShort(_height);

    out.writeByte(0x80); // 2bit
    out.writeByte(0);
    out.writeByte(0);

    //---------------------------------
    // Global Color Map

    // black
    out.writeByte(0x00);
    out.writeByte(0x00);
    out.writeByte(0x00);

    // white
    out.writeByte(0xff);
    out.writeByte(0xff);
    out.writeByte(0xff);

    //---------------------------------
    // Image Descriptor

    out.writeString(‘,‘);
    out.writeShort(0);
    out.writeShort(0);
    out.writeShort(_width);
    out.writeShort(_height);
    out.writeByte(0);

    //---------------------------------
    // Local Color Map

    //---------------------------------
    // Raster Data

    var lzwMinCodeSize = 2;
    var raster = getLZWRaster(lzwMinCodeSize);

    out.writeByte(lzwMinCodeSize);

    var offset = 0;

    while (raster.length - offset > 255) {
      out.writeByte(255);
      out.writeBytes(raster, offset, 255);
      offset += 255;
    }

    out.writeByte(raster.length - offset);
    out.writeBytes(raster, offset, raster.length - offset);
    out.writeByte(0x00);

    //---------------------------------
    // GIF Terminator
    out.writeString(‘;‘);
  };

  var bitOutputStream = function (out) {

    var _out = out;
    var _bitLength = 0;
    var _bitBuffer = 0;

    var _this = {};

    _this.write = function (data, length) {

      if ((data >>> length) != 0) {
        throw new Error(‘length over‘);
      }

      while (_bitLength + length >= 8) {
        _out.writeByte(0xff & ((data << _bitLength) | _bitBuffer));
        length -= (8 - _bitLength);
        data >>>= (8 - _bitLength);
        _bitBuffer = 0;
        _bitLength = 0;
      }

      _bitBuffer = (data << _bitLength) | _bitBuffer;
      _bitLength = _bitLength + length;
    };

    _this.flush = function () {
      if (_bitLength > 0) {
        _out.writeByte(_bitBuffer);
      }
    };

    return _this;
  };

  var getLZWRaster = function (lzwMinCodeSize) {

    var clearCode = 1 << lzwMinCodeSize;
    var endCode = (1 << lzwMinCodeSize) + 1;
    var bitLength = lzwMinCodeSize + 1;

    // Setup LZWTable
    var table = lzwTable();

    for (var i = 0; i < clearCode; i += 1) {
      table.add(String.fromCharCode(i));
    }
    table.add(String.fromCharCode(clearCode));
    table.add(String.fromCharCode(endCode));

    var byteOut = byteArrayOutputStream();
    var bitOut = bitOutputStream(byteOut);

    // clear code
    bitOut.write(clearCode, bitLength);

    var dataIndex = 0;

    var s = String.fromCharCode(_data[dataIndex]);
    dataIndex += 1;

    while (dataIndex < _data.length) {

      var c = String.fromCharCode(_data[dataIndex]);
      dataIndex += 1;

      if (table.contains(s + c)) {

        s = s + c;

      } else {

        bitOut.write(table.indexOf(s), bitLength);

        if (table.size() < 0xfff) {

          if (table.size() == (1 << bitLength)) {
            bitLength += 1;
          }

          table.add(s + c);
        }

        s = c;
      }
    }

    bitOut.write(table.indexOf(s), bitLength);

    // end code
    bitOut.write(endCode, bitLength);

    bitOut.flush();

    return byteOut.toByteArray();
  };

  var lzwTable = function () {

    var _map = {};
    var _size = 0;

    var _this = {};

    _this.add = function (key) {
      if (_this.contains(key)) {
        throw new Error(‘dup key:‘ + key);
      }
      _map[key] = _size;
      _size += 1;
    };

    _this.size = function () {
      return _size;
    };

    _this.indexOf = function (key) {
      return _map[key];
    };

    _this.contains = function (key) {
      return typeof _map[key] != ‘undefined‘;
    };

    return _this;
  };

  return _this;
};

var createImgTag = function (width, height, getPixel, alt) {

  var gif = gifImage(width, height);
  for (var y = 0; y < height; y += 1) {
    for (var x = 0; x < width; x += 1) {
      gif.setPixel(x, y, getPixel(x, y));
    }
  }

  var b = byteArrayOutputStream();
  gif.write(b);

  var base64 = base64EncodeOutputStream();
  var bytes = b.toByteArray();
  for (var i = 0; i < bytes.length; i += 1) {
    base64.writeByte(bytes[i]);
  }
  base64.flush();

  var img = ‘‘;
  img += ‘data:image/png;base64,‘;
  img += base64;

  return img;
};

//---------------------------------------------------------------------
// returns qrcode function.

var drawImg = function (text, options) {
  options = options || {};
  var typeNumber = options.typeNumber || 4;
  var errorCorrectLevel = options.errorCorrectLevel || ‘M‘;
  var size = options.size || 500;

  var qr;

  try {
    qr = qrcode(typeNumber, errorCorrectLevel || ‘M‘);
    qr.addData(text);
    qr.make();
  } catch (e) {
    if (typeNumber >= 40) {
      throw new Error(‘Text too long to encode‘);
    } else {
      return drawImg(text, {
        size: size,
        errorCorrectLevel: errorCorrectLevel,
        typeNumber: typeNumber + 1
      });
    }
  }

  // calc cellsize and margin
  var cellsize = parseInt(size / qr.getModuleCount());
  var margin = parseInt((size - qr.getModuleCount() * cellsize) / 2);

  return qr.createImgTag(cellsize, margin, size);
};
module.exports = {
  drawImg: drawImg
};