绘制二维码添加中间头像Logo
发布时间：2018-05-05 14:37 所属栏目：小程序开发教程
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
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();
}
}
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