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Generate pdf report using jspdf_jquery

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May 16, 2016 pm 03:51 PM

jspdf

Since the frontend html has dynamically generated reports, and the frontend has a function, a date range component, when you drag it, the report will change dynamically without being submitted to the background.
Therefore, js needs to be used to generate reports:

Components used:

jquery.js
jspdf.js
canvg.js
html2canvas.js
jspdf.plugin.autotable.js

Charts dynamically generated by the front desk usually use HTML5 canvas or svg. Unfortunately, I encountered svg. If it is flash, I have not studied it.

Since the report still needs to maintain the appearance of the original html page, but it is not the entire html, what really needs to be converted into a pdf report is: html svg

Premise: jsPDF supports HTML, but the support is not very good. When you use an HTML to directly generate a PDF, in fact, it only retains the text, style, and structure in the HTML and is lost.
For example: the table is lost.
jsPDF does not support svg import.

Idea: Convert svg to canvas, then convert html canvas to canvas, then use html2canvas to convert canvas to picture, and finally write the picture to pdf.
For table, use: jspdf.plugin.autotable.js

firefox: html2canvas cannot directly convert svg html to canvas --> Convert svg elements to canvas first --> Convert html canvas to canvas
chrome: html2canvas can directly convert svg html into canvas

//将指定节点下面的所有svg转换成canvas
//这里需要:canvg.js
function svg2canvas (targetElem) {
  var nodesToRecover = [];
  var nodesToRemove = [];

  var svgElem = targetElem.find('svg');

  svgElem.each(function(index, node) {
    var parentNode = node.parentNode;
    
    var svg = node.outerHTML;

    var canvas = document.createElement('canvas');
    
    canvg(canvas, svg);
    
    nodesToRecover.push({
      parent: parentNode,
      child: node
    });
    parentNode.removeChild(node);
    
    nodesToRemove.push({
      parent: parentNode,
      child: canvas
    });
    
    parentNode.appendChild(canvas);
  });
  
}

//这里是将html(文本)在一个iframe里面打开
//主要是排除其它元素的干扰导致不成功，之前是一直输出不成功，所示才使用iframe
//这段代码是官网抠下来的。
//还有个问题就是：如果将页面的chart转换成canvas了，那web页面报表动态变化的功能将丢失。
function openWithIframe(html){
    
  var iframe = document.createElement('iframe');
  iframe.setAttribute("id", "myFrmame");
  
  var $iframe = $(iframe);
  $iframe.css({
   'visibility': 'hidden', 'position':'static', 'z-index':'4'
  }).width($(window).width()).height($(window).height());

  $('body').append(iframe);
  
  
  var ifDoc = iframe.contentWindow.document;
  
　　//这里做是将报表使用到的css重新写入到iframe中，根据自身的需要
  var style = "<link href='/javax.faces.resource/css/auth.css.jsf' rel='stylesheet' type='text/css'>";
  style+="<link href='/javax.faces.resource/css/common.css.jsf' rel='stylesheet' type='text/css'>";
  style+="<link href='/javax.faces.resource/css/dc.css.jsf' rel='stylesheet' type='text/css'>";
  
  html = "<!DOCTYPE html><html><head>"+style+"</head><body>"+html+"</body></html>"
  
  ifDoc.open();    
  ifDoc.write(html);    
  ifDoc.close();
  
  /*
  //这里做一些微调，根据自身的需要
  var fbody = $iframe.contents().find("body");
  
  fbody.find("#chart-center").removeAttr("width");
  
  fbody.find(".page-container").css("width", "370px");
  fbody.find(".center-container").css("width", "600px");
  
  fbody.find("#severity-chart svg").attr("width", "370");
  fbody.find("#status-chart svg").attr("width", "300");
  */
  return fbody;
}

//导出pdf
function exportAsPDF(){
  //得到要导出pdf的html根节点  
  var chartCenter = document.getElementById("chart-center").outerHTML;
  
  var fbody = openWithIframe(chartCenter);
  svg2canvas(fbody);
  
  //html2canvas官网的标准方法
  html2canvas(fbody, {
    onrendered: function(canvas) {
      //var myImage = canvas.toDataURL("image/png");
      //alert(myImage);
      //window.open(myImage);
      
      /*
      canvas.toBlob(function(blob) {
        saveAs(blob, "report.png");
      }, "image/png");
      */
      
      //将图片转换成：base64编码的jpg图片。
      var imgData = canvas.toDataURL('image/jpeg');
      //alert(imgData);
            
      //l:横向， p：纵向
      var doc = new jsPDF('l', 'pt', 'a3');
      //var doc = new jsPDF('p', 'mm', [290, 210]);
      //var doc = new jsPDF();//默认是A4，由于我的报表比较大，所以专门设置了尺寸。
      doc.setFontSize(22);
      doc.setFontType("bolditalic");
      doc.text(500, 30, "Ticket Report"); //x:500, y:30
      
      doc.addImage(imgData, 'jpeg', 10, 60); //写入位置：x:10, y:60
      
      doc.addPage();  //新建一页
      
      //这里就是把将table写入到pdf里面。
      var res = doc.autoTableHtmlToJson(document.getElementById("tickets-summary-table"), true);
      doc.autoTable(res.columns, res.data);
      
      doc.save('ticket.report_'+new Date().getTime()+'.pdf');
      $('#myFrmame').remove(); //最后将iframe删除
    },
    background:"#fff", //这里给生成的图片默认背景，不然的话，如果你的html根节点没有设置背景的话，会用黑色填充。
    allowTaint: true  //避免一些不识别的图片干扰，默认为false，遇到不识别的图片干扰则会停止处理html2canvas
  });
  
};

The above is the entire content of this article, I hope you all like it.

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