http://www.bootcdn.cn/（可以搜索html2canvans）

1.选择html2canvas版本（这个版本可以放大倍数保证图片清晰）

默认生成的 canvas 图片在 retina 设备上显示很模糊，处理成 2 倍图能解决这个问题：

var w = $("#code").width();
var h = $("#code").height();

//要将 canvas 的宽高设置成容器宽高的 2 倍
var canvas = document.createElement("canvas");
canvas.width = w * 2;
canvas.height = h * 2;
canvas.style.width = w + "px";
canvas.style.height = h + "px";
var context = canvas.getContext("2d");
//然后将画布缩放，将图像放大两倍画到画布上
context.scale(2,2);

html2canvas(document.querySelector("#code"), {
 canvas: canvas,
 onrendered: function(canvas) {
 ...
 }
});

下载方法：

.on('click','.download',function(){
 $('#mycanvas').remove();
 var _height=$('.skinReport').height();
 //滚到顶部
 $('html, body').animate({scrollTop:0});

 if(confirm('是否下载肌肤检测报告？'))
 {

 setTimeout(function(){
 var canvas = document.createElement("canvas"),
 w=$('#skinReport').width(),
 h=$('#skinReport').height();
 canvas.width = w * 2;
 canvas.height = h * 2;
 canvas.style.width = w + "px";
 canvas.style.height = h + "px";
 var context = canvas.getContext("2d");
//然后将画布缩放，将图像放大两倍画到画布上
 context.scale(2,2);
 html2canvas(document.getElementById('skinReport'), {
 allowTaint: false,
 taintTest: true,
 canvas: canvas,
 onrendered: function(canvas) {
 canvas.id = "mycanvas";
 canvas.style.display = 'none';
 document.body.appendChild(canvas);
 //生成base图片数据

 imgData = canvas.toDataURL(type);
 //var newImg = document.createElement("img");
 //newImg.src = dataUrl;
 //document.body.appendChild(newImg);
 //console.log(imgData);

 var _fixType = function(type) {
 type = type.toLowerCase().replace(/jpg/i, 'jpeg');
 var r = type.match(/png|jpeg|bmp|gif/)[0];
 return 'image/' + r;
 };
 // 加工image data，替换mime type
 imgData = imgData.replace(_fixType(type),'image/octet-stream');
 /**
 * 在本地进行文件保存
 * @param {String} data 要保存到本地的图片数据
 * @param {String} filename 文件名
 */
 var saveFile = function(data, filename){
 var save_link = document.createElementNS('http://www.w3.org/1999/xhtml', 'a');
 save_link.href = data;
 save_link.download = filename;

 var event = document.createEvent('MouseEvents');
 event.initMouseEvent('click', true, false, window, 0, 0, 0, 0, 0, false, false, false, false, 0, null);
 save_link.dispatchEvent(event);
 };

 // 下载后的问题名
 var filename = aname+'肌肤检测报告' + (new Date()).getTime() + '.' + type;
 // download
 saveFile(imgData,filename);
 },
 width:1512,
 height:15000
 })
 },2500)
 }
 else
 {
 return;
 }

 })