绘制二维码添加中间头像Logo

  onLoad: function (options) {
/**
 * 绘制带logo二维码
 * @param url 二维码字符串 如 https://github.com/xlsn0w
 * @param canvas-id 画布ID 如 logoQRCode
 * @param width 二维码宽度 如 275
 * @param height 二维码高度 如 275
 * @param logo 二维码logo 如 /images/xlsn0w.png
 */
    QRCodeJS.qrApi.draw('https://github.com/xlsn0w', "logoQRCode", 275, 275, null, '/images/xlsn0w.png');
  }

代码

image

var drawImg = function (src, width,ctx) {
var imgSize = width / 5;
var imgPos = width / 10 * 4;
var imgPosFix = width / 120;
    ctx.strokeStyle = '#fff';
    ctx.lineWidth = 1;
    ctx.globalAlpha = 0.8;
    ctx.lineCap = "round";
    ctx.lineJoin = "round";

    ctx.beginPath();
    ctx.moveTo(imgPos - imgPosFix, imgPos - imgPosFix);

    ctx.lineTo(imgPos + imgSize + imgPosFix, imgPos - imgPosFix);
    ctx.lineTo(imgPos + imgSize + imgPosFix, imgPos + imgSize + imgPosFix);
    ctx.lineTo(imgPos - imgPosFix, imgPos + imgSize + imgPosFix);
    ctx.lineTo(imgPos - imgPosFix, imgPos - imgPosFix);

    ctx.stroke();
    ctx.closePath();

    ctx.drawImage(src, imgPos, imgPos, imgSize, imgSize);
    ctx.beginPath();
  }

var _canvas = null;

var api = {

    get ecclevel() {
return ecclevel;
    },

    set ecclevel(val) {
      ecclevel = val;
    },

    get size() {
return _size;
    },

    set size(val) {
      _size = val
    },

    get canvas() {
return _canvas;
    },

    set canvas(el) {
      _canvas = el;
    },

getFrame: function (string) {
return genframe(string);
    },
//这里的utf16to8(str)是对Text中的字符串进行转码，让其支持中文
    utf16to8: function (str) {
var out, i, len, c;

      out = "";
      len = str.length;
for (i = 0; i < len; i++) {
        c = str.charCodeAt(i);
if ((c >= 0x0001) && (c <= 0x007F)) {
          out += str.charAt(i);
        } else if (c > 0x07FF) {
          out += String.fromCharCode(0xE0 | ((c >> 12) & 0x0F));
          out += String.fromCharCode(0x80 | ((c >> 6) & 0x3F));
          out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
        } else {
          out += String.fromCharCode(0xC0 | ((c >> 6) & 0x1F));
          out += String.fromCharCode(0x80 | ((c >> 0) & 0x3F));
        }
      }
return out;
    },
draw: function (str, canvas, cavW, cavH, ecc,src) {
      ecclevel = ecc || ecclevel;
      canvas = canvas || _canvas;
if (!canvas) {
console.warn('No canvas provided to draw QR code in!')
return;
      }
var size = Math.min(cavW, cavH);
      str = this.utf16to8(str);//增加中文显示
//console.log(str)
var frame = this.getFrame(str),
        ctx = wx.createCanvasContext(canvas),
        px = Math.round(size / (width + 8));
var roundedSize = px * (width + 8),
        offset = Math.floor((size - roundedSize) / 2);
      size = roundedSize;
      ctx.clearRect(0, 0, cavW, cavW);
      ctx.setFillStyle('#000000');
for (var i = 0; i < width; i++) {
for (var j = 0; j < width; j++) {
if (frame[j * width + i]) {
            ctx.fillRect(px * (4 + i) + offset, px * (4 + j) + offset, px, px);
          }
        }
      }
      drawImg(src, cavW,ctx);
      ctx.draw();
    }
  }

本文作者：XLsn0w
项目地址：http://www.wxapp-union.com/portal.php?mod=view&aid=3649