详解使用canvas保存网页为pdf文件支持跨域

<script type="text/javascript" src="js/html2canvas.js"></script>
<script type="text/javascript" src="js/html2canvas.min.js"></script>
<script type="text/javascript" src="js/jspdf.debug.js"></script>

 <div id="down_pdf">导出为PDF按钮</div>
 <div class="sta-main">需要获取为PDF的div</div>

<script type="text/javascript">
/ var downPdf = document.getElementById("down_pdf"); /
var downPdf = document.getElementById("down_pdf");
$("#down_pdf").on("click", function() {
 var canvas2 = document.createElement("canvas");
 let _canvas = document.querySelector('.sta-main');
 //获取宽高
 var w = parseInt(window.getComputedStyle(_canvas).width);
 var h = parseInt(window.getComputedStyle(_canvas) .height);
 //将canvas画布放大2倍，然后盛放在小的容器内，处理模糊
 canvas2.width = w  2;
 canvas2.height = h  2;
 canvas2.style.width = w + "px";
 canvas2.style.height = h + "px";
 var context = canvas2.getContext("2d");
 //处理偏移
 context.scale(1.5, 1.5);
 //修改背景颜色，默认是黑色
 $('.sta-main').css("background", "#fff")
 html2canvas( _canvas, {
 //处理pdf跨域获取不到跨域信息问题
 taintTest : false,
 useCORS : true,
 allowTaint : false, 
 canvas : canvas2,
 dpi: 172,//导出pdf清晰度
 onrendered: function (canvas) {
 var contentWidth = canvas.width;
 var contentHeight = canvas.height;
 //一页pdf显示html页面生成的canvas高度;
 var pageHeight = contentWidth / 592.28  841.89;
 //未生成pdf的html页面高度
 var leftHeight = contentHeight;
 //pdf页面偏移
 var position = 0;
 //html页面生成的canvas在pdf中图片的宽高（a4纸的尺寸[595.28,841.89]）
 var imgWidth = 595.28;
 var imgHeight = 592.28 / contentWidth  contentHeight;
 var pageData = canvas.toDataURL('image/jpeg', 1.0);
 var pdf = new jsPDF('', 'pt', 'a4');
 //有两个高度需要区分，一个是html页面的实际高度，和生成pdf的页面高度(841.89)
 //当内容未超过pdf一页显示的范围，无需分页
 if (leftHeight < pageHeight) {
 pdf.addImage(pageData, 'JPEG', 0, 0, imgWidth, imgHeight);
 } else {
 while (leftHeight > 0) {
 pdf.addImage(pageData, 'JPEG', 0, position, imgWidth, imgHeight)
 leftHeight -= pageHeight;
 position -= 841.89;
 //避免添加空白页
 if (leftHeight > 0) {
 pdf.addPage();
 }
 }
 }
 pdf.save('PDF的名字.pdf');
 }
 })
 $('.sta-main').css("background", "")
})
</script>