js生成带有logo的二维码并保存成图片下载

生成二维码，需要依赖jquery，先引入一个jquery，然后需要一个插件改变过了jquery-qrcode.js

插件代码（需要的自己打开看）：

/*! jquery-qrcode v0.14.0 - https://larsjung.de/jquery-qrcode/ */
(function (vendor_qrcode) {
    'use strict';

    var jq = window.jQuery;

    // Check if canvas is available in the browser (as Modernizr does)
    var hasCanvas = (function () {
        var elem = document.createElement('canvas');
        return !!(elem.getContext && elem.getContext('2d'));
    }());

    // Wrapper for the original QR code generator.
    function createQRCode(text, level, version, quiet) {
        var qr = {};

        var vqr = vendor_qrcode(version, level);
        vqr.addData(text);
        vqr.make();

        quiet = quiet || 0;

        var qrModuleCount = vqr.getModuleCount();
        var quietModuleCount = vqr.getModuleCount() + 2 * quiet;

        function isDark(row, col) {
            row -= quiet;
            col -= quiet;

            if (row < 0 || row >= qrModuleCount || col < 0 || col >= qrModuleCount) {
                return false;
            }
            return vqr.isDark(row, col);
        }

        function addBlank(l, t, r, b) {
            var prevIsDark = qr.isDark;
            var moduleSize = 1 / quietModuleCount;

            qr.isDark = function (row, col) {
                var ml = col * moduleSize;
                var mt = row * moduleSize;
                var mr = ml + moduleSize;
                var mb = mt + moduleSize;

                return prevIsDark(row, col) && (l > mr || ml > r || t > mb || mt > b);
            };
        }

        qr.text = text;
        qr.level = level;
        qr.version = version;
        qr.moduleCount = quietModuleCount;
        qr.isDark = isDark;
        qr.addBlank = addBlank;

        return qr;
    }

    // Returns a minimal QR code for the given text starting with version `minVersion`.
    // Returns `undefined` if `text` is too long to be encoded in `maxVersion`.
    function createMinQRCode(text, level, minVersion, maxVersion, quiet) {
        minVersion = Math.max(1, minVersion || 1);
        maxVersion = Math.min(40, maxVersion || 40);
        for (var version = minVersion; version <= maxVersion; version += 1) {
            try {
                return createQRCode(text, level, version, quiet);
            } catch (err) {/* empty */}
        }
        return undefined;
    }

    function drawBackgroundLabel(qr, context, settings) {
        var size = settings.size;
        var font = 'bold ' + settings.mSize * size + 'px ' + settings.fontname;
        var ctx = jq('<canvas/>')[0].getContext('2d');

        ctx.font = font;

        var w = ctx.measureText(settings.label).width;
        var sh = settings.mSize;
        var sw = w / size;
        var sl = (1 - sw) * settings.mPosX;
        var st = (1 - sh) * settings.mPosY;
        var sr = sl + sw;
        var sb = st + sh;
        var pad = 0.01;

        if (settings.mode === 1) {
            // Strip
            qr.addBlank(0, st - pad, size, sb + pad);
        } else {
            // Box
            qr.addBlank(sl - pad, st - pad, sr + pad, sb + pad);
        }

        context.fillStyle = settings.fontcolor;
        context.font = font;
        context.fillText(settings.label, sl * size, st * size + 0.75 * settings.mSize * size);
    }

    function drawBackgroundImage(qr, context, settings) {
        var size = settings.size;
        var w = settings.image.naturalWidth || 1;
        var h = settings.image.naturalHeight || 1;
        var sh = settings.mSize;
        var sw = sh * w / h;
        var sl = (1 - sw) * settings.mPosX;
        var st = (1 - sh) * settings.mPosY;
        var sr = sl + sw;
        var sb = st + sh;
        var pad = 0.01;

        if (settings.mode === 3) {
            // Strip
            qr.addBlank(0, st - pad, size, sb + pad);
        } else {
            // Box
            qr.addBlank(sl - pad, st - pad, sr + pad, sb + pad);
        }

        context.drawImage(settings.image, sl * size, st * size, sw * size, sh * size);
    }

    function drawBackground(qr, context, settings) {
        if (jq(settings.background).is('img')) {
            context.drawImage(settings.background, 0, 0, settings.size, settings.size);
        } else if (settings.background) {
            context.fillStyle = settings.background;
            context.fillRect(settings.left, settings.top, settings.size, settings.size);
        }

        var mode = settings.mode;
        if (mode === 1 || mode === 2) {
            drawBackgroundLabel(qr, context, settings);
        } else if (mode === 3 || mode === 4) {
            drawBackgroundImage(qr, context, settings);
        }
    }

    function drawModuleDefault(qr, context, settings, left, top, width, row, col) {
        if (qr.isDark(row, col)) {
            context.rect(left, top, width, width);
        }
    }

    function drawModuleRoundedDark(ctx, l, t, r, b, rad, nw, ne, se, sw) {
        if (nw) {
            ctx.moveTo(l + rad, t);
        } else {
            ctx.moveTo(l, t);
        }

        if (ne) {
            ctx.lineTo(r - rad, t);
            ctx.arcTo(r, t, r, b, rad);
        } else {
            ctx.lineTo(r, t);
        }

        if (se) {
            ctx.lineTo(r, b - rad);
            ctx.arcTo(r, b, l, b, rad);
        } else {
            ctx.lineTo(r, b);
        }

        if (sw) {
            ctx.lineTo(l + rad, b);
            ctx.arcTo(l, b, l, t, rad);
        } else {
            ctx.lineTo(l, b);
        }

        if (nw) {
            ctx.lineTo(l, t + rad);
            ctx.arcTo(l, t, r, t, rad);
        } else {
            ctx.lineTo(l, t);
        }
    }

    function drawModuleRoundendLight(ctx, l, t, r, b, rad, nw, ne, se, sw) {
        if (nw) {
            ctx.moveTo(l + rad, t);
            ctx.lineTo(l, t);
            ctx.lineTo(l, t + rad);
            ctx.arcTo(l, t, l + rad, t, rad);
        }

        if (ne) {
            ctx.moveTo(r - rad, t);
            ctx.lineTo(r, t);
            ctx.lineTo(r, t + rad);
            ctx.arcTo(r, t, r - rad, t, rad);
        }

        if (se) {
            ctx.moveTo(r - rad, b);
            ctx.lineTo(r, b);
            ctx.lineTo(r, b - rad);
            ctx.arcTo(r, b, r - rad, b, rad);
        }

        if (sw) {
            ctx.moveTo(l + rad, b);
            ctx.lineTo(l, b);
            ctx.lineTo(l, b - rad);
            ctx.arcTo(l, b, l + rad, b, rad);
        }
    }

    function drawModuleRounded(qr, context, settings, left, top, width, row, col) {
        var isDark = qr.isDark;
        var right = left + width;
        var bottom = top + width;
        var radius = settings.radius * width;
        var rowT = row - 1;
        var rowB = row + 1;
        var colL = col - 1;
        var colR = col + 1;
        var center = isDark(row, col);
        var northwest = isDark(rowT, colL);
        var north = isDark(rowT, col);
        var northeast = isDark(rowT, colR);
        var east = isDark(row, colR);
        var southeast = isDark(rowB, colR);
        var south = isDark(rowB, col);
        var southwest = isDark(rowB, colL);
        var west = isDark(row, colL);

        if (center) {
            drawModuleRoundedDark(context, left, top, right, bottom, radius, !north && !west, !north && !east, !south && !east, !south && !west);
        } else {
            drawModuleRoundendLight(context, left, top, right, bottom, radius, north && west && northwest, north && east && northeast, south && east && southeast, south && west && southwest);
        }
    }

    function drawModules(qr, context, settings) {
        var moduleCount = qr.moduleCount;
        var moduleSize = settings.size / moduleCount;
        var fn = drawModuleDefault;
        var row;
        var col;

        if (settings.radius > 0 && settings.radius <= 0.5) {
            fn = drawModuleRounded;
        }

        context.beginPath();
        for (row = 0; row < moduleCount; row += 1) {
            for (col = 0; col < moduleCount; col += 1) {
                var l = settings.left + col * moduleSize;
                var t = settings.top + row * moduleSize;
                var w = moduleSize;

                fn(qr, context, settings, l, t, w, row, col);
            }
        }
        if (jq(settings.fill).is('img')) {
            context.strokeStyle = 'rgba(0,0,0,0.5)';
            context.lineWidth = 2;
            context.stroke();
            var prev = context.globalCompositeOperation;
            context.globalCompositeOperation = 'destination-out';
            context.fill();
            context.globalCompositeOperation = prev;

            context.clip();
            context.drawImage(settings.fill, 0, 0, settings.size, settings.size);
            context.restore();
        } else {
            context.fillStyle = settings.fill;
            context.fill();
        }
    }

    // Draws QR code to the given `canvas` and returns it.
    function drawOnCanvas(canvas, settings) {
        var qr = createMinQRCode(settings.text, settings.ecLevel, settings.minVersion, settings.maxVersion, settings.quiet);
        if (!qr) {
            return null;
        }

        var $canvas = jq(canvas).data('qrcode', qr);
        var context = $canvas[0].getContext('2d');

        drawBackground(qr, context, settings);
        drawModules(qr, context, settings);

        return $canvas;
    }

    // Returns a `canvas` element representing the QR code for the given settings.
    function createCanvas(settings) {
        var $canvas = jq('<canvas/>').attr('width', settings.size).attr('height', settings.size);
        return drawOnCanvas($canvas, settings);
    }

    // Returns an `image` element representing the QR code for the given settings.
    function createImage(settings) {
        return jq('<img/>').attr('src', createCanvas(settings)[0].toDataURL('image/png'));
    }

    // Returns a `div` element representing the QR code for the given settings.
    function createDiv(settings) {
        var qr = createMinQRCode(settings.text, settings.ecLevel, settings.minVersion, settings.maxVersion, settings.quiet);
        if (!qr) {
            return null;
        }

        // some shortcuts to improve compression
        var settings_size = settings.size;
        var settings_bgColor = settings.background;
        var math_floor = Math.floor;

        var moduleCount = qr.moduleCount;
        var moduleSize = math_floor(settings_size / moduleCount);
        var offset = math_floor(0.5 * (settings_size - moduleSize * moduleCount));

        var row;
        var col;

        var containerCSS = {
            position: 'relative',
            left: 0,
            top: 0,
            padding: 0,
            margin: 0,
            width: settings_size,
            height: settings_size
        };
        var darkCSS = {
            position: 'absolute',
            padding: 0,
            margin: 0,
            width: moduleSize,
            height: moduleSize,
            'background-color': settings.fill
        };

        var $div = jq('<div/>').data('qrcode', qr).css(containerCSS);

        if (settings_bgColor) {
            $div.css('background-color', settings_bgColor);
        }

        for (row = 0; row < moduleCount; row += 1) {
            for (col = 0; col < moduleCount; col += 1) {
                if (qr.isDark(row, col)) {
                    jq('<div/>')
                        .css(darkCSS)
                        .css({
                            left: offset + col * moduleSize,
                            top: offset + row * moduleSize
                        })
                        .appendTo($div);
                }
            }
        }

        return $div;
    }

    function createHTML(settings) {
        if (hasCanvas && settings.render === 'canvas') {
            return createCanvas(settings);
        } else if (hasCanvas && settings.render === 'image') {
            return createImage(settings);
        }

        return createDiv(settings);
    }

    // Plugin
    // ======

    // Default settings
    // ----------------
    var defaults = {
        // render method: `'canvas'`, `'image'` or `'div'`
        render: 'canvas',

        // version range somewhere in 1 .. 40
        minVersion: 1,
        maxVersion: 40,

        // error correction level: `'L'`, `'M'`, `'Q'` or `'H'`
        ecLevel: 'L',

        // offset in pixel if drawn onto existing canvas
        left: 0,
        top: 0,

        // size in pixel
        size: 200,

        // code color or image element
        fill: '#000',

        // background color or image element, `null` for transparent background
        background: null,

        // content
        text: 'no text',

        // corner radius relative to module width: 0.0 .. 0.5
        radius: 0,

        // quiet zone in modules
        quiet: 0,

        // modes
        // 0: normal
        // 1: label strip
        // 2: label box
        // 3: image strip
        // 4: image box
        mode: 0,

        mSize: 0.1,
        mPosX: 0.5,
        mPosY: 0.5,

        label: 'no label',
        fontname: 'sans',
        fontcolor: '#000',

        image: null
    };

    // Register the plugin
    // -------------------
    jq.fn.qrcode = function (options) {
        var settings = jq.extend({}, defaults, options);

        return this.each(function (idx, el) {
            if (el.nodeName.toLowerCase() === 'canvas') {
                drawOnCanvas(el, settings);
            } else {
                jq(el).append(createHTML(settings));
            }
        });
    };
}(function () {
    // `qrcode` is the single public function defined by the `QR Code Generator`
    //---------------------------------------------------------------------
    //
    // 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
    //
    //---------------------------------------------------------------------

    var qrcode = function() {

      //---------------------------------------------------------------------
      // qrcode
      //---------------------------------------------------------------------

      /**
       * 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) {

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

          var size = _this.getModuleCount() * cellSize + margin * 2;
          var min = margin;
          var max = size - 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() {

        var RS_BLOCK_TABLE = [

          // L
          // M
          // Q
          // H

          //
          [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, 7, 37, 13],

          //
          [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 _bytes = qrcode.stringToBytes(data);

        var _this = {};

        _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 += '<img';
        img += '\u0020src="';
        img += 'data:image/gif;base64,';
        img += base64;
        img += '"';
        img += '\u0020width="';
        img += width;
        img += '"';
        img += '\u0020height="';
        img += height;
        img += '"';
        if (alt) {
          img += '\u0020alt="';
          img += alt;
          img += '"';
        }
        img += '/>';

        return img;
      };

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

      return qrcode;
    }();

    (function (factory) {
      if (typeof define === 'function' && define.amd) {
          define([], factory);
      } else if (typeof exports === 'object') {
          module.exports = factory();
      }
    }(function () {
        return qrcode;
    }));
    //---------------------------------------------------------------------
    //
    // QR Code Generator for JavaScript UTF8 Support (optional)
    //
    // Copyright (c) 2011 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
    //
    //---------------------------------------------------------------------

    !function(qrcode) {

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

      qrcode.stringToBytes = function(s) {
        // http://*.com/questions/18729405/how-to-convert-utf8-string-to-byte-array
        function toUTF8Array(str) {
          var utf8 = [];
          for (var i=0; i < str.length; i++) {
            var charcode = str.charCodeAt(i);
            if (charcode < 0x80) utf8.push(charcode);
            else if (charcode < 0x800) {
              utf8.push(0xc0 | (charcode >> 6),
                  0x80 | (charcode & 0x3f));
            }
            else if (charcode < 0xd800 || charcode >= 0xe000) {
              utf8.push(0xe0 | (charcode >> 12),
                  0x80 | ((charcode>>6) & 0x3f),
                  0x80 | (charcode & 0x3f));
            }
            // surrogate pair
            else {
              i++;
              // UTF-16 encodes 0x10000-0x10FFFF by
              // subtracting 0x10000 and splitting the
              // 20 bits of 0x0-0xFFFFF into two halves
              charcode = 0x10000 + (((charcode & 0x3ff)<<10)
                | (str.charCodeAt(i) & 0x3ff));
              utf8.push(0xf0 | (charcode >>18),
                  0x80 | ((charcode>>12) & 0x3f),
                  0x80 | ((charcode>>6) & 0x3f),
                  0x80 | (charcode & 0x3f));
            }
          }
          return utf8;
        }
        return toUTF8Array(s);
      };

    }(qrcode);

    return qrcode; // eslint-disable-line no-undef
}()));

html代码：

　　注意：下面放的img图片logo只能是相对路径，绝对路径生成是二维码没有logo（尤其是连接引用的图片地址，个人认为是加载顺序的问题，有兴趣的小伙伴可以研究一下）

<div id="qrcode"></div>
<img src="./img/m.png" alt="" id="qrcode-logo">

<button type="button" onclick="downloadClick()">下载</button>

css代码（仅做参考，用到自己再调）：

  #qrcode{
            margin: 50px;
            width: 200px;
        }
        #qrcode img{
            width: 100%;
        }
        #qrcode-logo{
            opacity:;
        }

js代码：

 var url = 'https://www.baidu.com';

        var options = {};
        options.url = url; //二维码的链接
        options.dom = "#qrcode"; //二维码生成的位置
        options.image = document.getElementById('qrcode-logo'); //图片id
        options.render = "image"; //设置生成的二维码是canvas格式，也有image、div格式
        xyqrcode(options);
function xyqrcode(options) {
        var settings = {
            dom: '',
            render: 'canvas', //生成二维码的格式还有image、div
            ecLevel: "H",
            text: "",
            background: "#ffffff",
            fill: "#333333", //二维码纹路的颜色
            fontcolor: "#ff9818",
            fontname: "Ubuntu",
            image: {},
            label: "",
            mPosX: 0.5, //图片在X轴的位置
            mPosY: 0.5, //图片在X轴的位置
            mSize: 0.27, //图片大小
            minVersion: 10,
            mode: 4,
            quiet: 1,
            radius: 1,
            size: 500
        };
        if (options) {
            $.extend(settings, options); //options对象跟settings比较，相同的就替换，没有的就添加

        }
        if (settings.dom.length == 0) {
            window.console.log("Error: dom empty!");
            return;
        }
        if (settings.url.length == 0) {
            window.console.log("Error: url empty!");
            return;
        }
        settings.text = settings.url; //在qrcode生成二维码的地址是text。这里就把url赋值给text
        $(settings.dom).qrcode(settings);

    }

downloadClick = function() {
            var imgData = $("#qrcode").find("img").attr("src");
            downloadFile('测试.png', imgData);
        }
        //下载
        function downloadFile(fileName, content) {
            let aLink = document.createElement('a');
            let blob = base64ToBlob(content); //new Blob([content]);

            let evt = document.createEvent("HTMLEvents");
            evt.initEvent("click", true, true);//initEvent 不加后两个参数在FF下会报错  事件类型，是否冒泡，是否阻止浏览器的默认行为
            aLink.download = fileName;
            aLink.href = URL.createObjectURL(blob);

            // aLink.dispatchEvent(evt);
            //aLink.click()
            aLink.dispatchEvent(new MouseEvent('click', {bubbles: true, cancelable: true, view: window}));//兼容火狐
        }
        //base64转blob
        function base64ToBlob(code) {
            let parts = code.split(';base64,');
            let contentType = parts[0].split(':')[1];
            let raw = window.atob(parts[1]);
            let rawLength = raw.length;

            let uInt8Array = new Uint8Array(rawLength);

            for (let i = 0; i < rawLength; ++i) {
                uInt8Array[i] = raw.charCodeAt(i);
            }
            return new Blob([uInt8Array], {type: contentType});
        }

以上代码仅做参考，样式有点小问题，调试一下都能解决，希望有所帮助，大家相互学习