jquery canvas生成带有二维码的海报

//jquery.js<script type="text/javascript" src="https://apps.bdimg.com/libs/jquery/2.1.4/jquery.min.js"></script>//解决生成的图片模糊、不清晰问题<script src="/images/202010/hidpi-canvas.min.js"></script>

<script>    // 执行代码    $(function () {        //  像素密度 如果没这段代码生成的图片可能会模糊        function getPixelRatio(context) {            var backingStore = context.backingStorePixelRatio ||                context.webkitBackingStorePixelRatio ||                context.mozBackingStorePixelRatio ||                context.msBackingStorePixelRatio ||                context.oBackingStorePixelRatio ||                context.backingStorePixelRatio || 1;            return (window.devicePixelRatio || 1) / backingStore;        };        //点击事件        $(".myImg").click(function () {            $(".dialog").fadeIn();            var dialogSrc = $(this).attr("src")            var csrfToken = document.querySelector('meta[name="csrf-token"]').getAttribute('content');            //2.发送请求            $.ajax({                url: "xxxx",                type: "post",                dataType: 'json',                headers: {                    'X-CSRF-TOKEN': csrfToken                }, //设置请求头                success: function (res) {                    var canvas = document.createElement("canvas");                    var context = canvas.getContext("2d");                    var ratio = getPixelRatio(context)                    canvas.width = 262 * ratio;                    canvas.height = 450 * ratio;                    context.rect(0, 0, canvas.width * ratio, canvas.height * ratio);                    context.fillStyle = "#fff";                    context.fill();                    var myImage2 = new Image();                    //背景图                    myImage2.src = dialogSrc                    //获取终端                    var u = navigator.userAgent;                    var isAndroid = u.indexOf('Android') > -1 || u.indexOf('Adr') > -1; //android终端                    var isiOS = !!u.match(//(i[^;]+;( U;)? CPU.+Mac OS X/); //ios终端                    myImage2.onload = function () {                        context.drawImage(myImage2, 0, 0, 262 * ratio, 450 * ratio);                        //文本                        var text = res.data.company + ',' + res.data.sales;                        var str = new Array();                        str = text.split(",");                        var uphight = 0                        //解决苹果手机和安卓手机 文字位置和字体大小显示差异问题                        for (var i = 0; i < str.length; i++) {                            if (isAndroid) {                                context.font = "12px Calibri";                                context.fillText(str[i], 70, 390 + uphight)        uphight += 20                            }                            if (isiOS) {                                context.font = "20px Calibri";                                context.fillText(str[i], 140, 450 * ratio - 120 + uphight)        uphight += 40                            }                        }                        var myImage = new Image();                        //二维码图片                        myImage.src = res.data.wxcode                        myImage.crossOrigin = 'Anonymous';                        myImage.onload = function () {                            context.drawImage(myImage, 30, 380 * ratio, 48 * ratio, 50 * ratio);                            var base64 = canvas.toDataURL("image/jpeg", 1.0);                            var img = document.getElementById('myPoster');                            img.setAttribute('src', base64);                        }                    }                },                error: function (e) {                    console.log('ajax请求异常，异常信息如下：', e);                }            });        });        //关闭弹窗        $(".close").click(function () {            $(".dialog").fadeOut();        })    });</script>