html,vue转换成PDF

大地飞鸿 2019-11-08

1,先看html的,直接上代码

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <title>Document</title>
  <style>
    #demo{
      background-color: yellow;
      width: 1000px;
      height: 2000px;
      /* margin: auto; */
    }
    .red{
      background-color: red;
      width: 50px;
      height: 50px;
    }
  </style>
</head>
<body>
  <div class="demo-container">
    <div id="demo">
      <div class="red"></div>
    </div>    
  </div>
  <button>
    下载简历
  </button>
</body>
<script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/jspdf/1.0.272/jspdf.debug.js"></script>
<script src="https://cdn.bootcss.com/html2canvas/0.5.0-beta4/html2canvas.js"></script>
<script>
   function download(){
     window.scrollTo(0,0);   //解决有滚动条的情况图片或者pdf展示不完全
     var element = $("#demo");    // 这个dom元素是要导出pdf的div容器
     var w = element.width();    // 获得该容器的宽
     var h = element.height();    // 获得该容器的高
     var offsetTop = element.offset().top;    // 获得该容器到文档顶部的距离
     var offsetLeft = element.offset().left;    // 获得该容器到文档最左的距离
     var canvas = document.createElement("canvas");
     var abs = 0;
     var win_i = $(window).width();    // 获得当前可视窗口的宽度(不包含滚动条)
     var win_o = window.innerWidth;    // 获得当前窗口的宽度(包含滚动条)
     if(win_o>win_i){
       abs = (win_o - win_i)/2;    // 获得滚动条长度的一半
     }
     canvas.width = w * 2;    // 将画布宽&&高放大两倍
     canvas.height = h * 2;
     var context = canvas.getContext("2d");
     context.scale(2, 2);
     context.translate(-offsetLeft-abs,-offsetTop);    
     // 这里默认横向没有滚动条的情况,因为offset.left(),有无滚动条的时候存在差值,因此        
     // translate的时候,要把这个差值去掉
     html2canvas(element).then(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;
      //页面偏移
      var position = 0;
      //a4纸的尺寸[595.28,841.89],html页面生成的canvas在pdf中图片的宽高
      var imgWidth = 595.28;
      var imgHeight = 592.28/contentWidth * contentHeight;
      var pageData = canvas.toDataURL(‘image/jpeg‘, 1.0);
      console.log(pageData);
      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 {    // 分页
          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(‘我的简历.pdf‘);        
    })
  }
  $("button").click(function(){
    download();
  })
</script>
</html>

2,vue项目中使用

①先安装依赖

第一个.将页面html转换成图片
npm install --save html2canvas 
第二个.将图片生成pdf
npm install jspdf --save

②定义工具文件

/* eslint-disable */
//不使用JQuery版的
import html2canvas from ‘html2canvas‘;
import JsPDF from ‘jspdf‘;

/**
 * @param  ele          要生成 pdf 的DOM元素(容器)
 * @param  padfName     PDF文件生成后的文件名字
 * */

function downloadPDF(ele, pdfName) {
  window.scrollTo(0, 0);
  let eleW = ele.offsetWidth;// 获得该容器的宽
  let eleH = ele.offsetHeight;// 获得该容器的高
  let eleOffsetTop = ele.offsetTop;  // 获得该容器到文档顶部的距离
  let eleOffsetLeft = ele.offsetLeft; // 获得该容器到文档最左的距离

  var canvas = document.createElement("canvas");
  var abs = 0;

  let win_in = document.documentElement.clientWidth || document.body.clientWidth; // 获得当前可视窗口的宽度(不包含滚动条)
  let win_out = window.innerWidth; // 获得当前窗口的宽度(包含滚动条)

  if (win_out > win_in) {
    // abs = (win_o - win_i)/2;    // 获得滚动条长度的一半
    abs = (win_out - win_in) / 2;    // 获得滚动条宽度的一半
    // console.log(a, ‘新abs‘);
  }
  canvas.width = eleW * 2;    // 将画布宽&&高放大两倍
  canvas.height = eleH * 2;

  var context = canvas.getContext("2d");
  context.scale(2, 2);
  context.translate(-eleOffsetLeft - abs, -eleOffsetTop);
  // 这里默认横向没有滚动条的情况,因为offset.left(),有无滚动条的时候存在差值,因此
  // translate的时候,要把这个差值去掉

  // html2canvas(element).then( (canvas)=>{ //报错
  // html2canvas(element[0]).then( (canvas)=>{
  html2canvas(ele, {
    dpi: 300,
    // allowTaint: true,  //允许 canvas 污染, allowTaint参数要去掉,否则是无法通过toDataURL导出canvas数据的
    useCORS: true  //允许canvas画布内 可以跨域请求外部链接图片, 允许跨域请求。
  }).then((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;
    //页面偏移
    var position = 0;
    //a4纸的尺寸[595.28,841.89],html页面生成的canvas在pdf中图片的宽高
    var imgWidth = 595.28;
    var imgHeight = 595.28 / 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) {
      //在pdf.addImage(pageData, ‘JPEG‘, 左,上,宽度,高度)设置在pdf中显示;
      pdf.addImage(pageData, ‘JPEG‘, 0, 0, imgWidth, imgHeight);
      // pdf.addImage(pageData, ‘JPEG‘, 20, 40, imgWidth, imgHeight);
    } else {    // 分页
      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();
        }
      }
    }
    //可动态生成
    pdf.save(pdfName);
  })
}

async function previewImg(ele) { // 返回图片base64格式
  window.scrollTo(0, 0);
  let eleW = ele.offsetWidth;// 获得该容器的宽
  let eleH = ele.offsetHeight;// 获得该容器的高
  let eleOffsetTop = ele.offsetTop;  // 获得该容器到文档顶部的距离
  let eleOffsetLeft = ele.offsetLeft; // 获得该容器到文档最左的距离

  var canvas = document.createElement("canvas");
  var abs = 0;

  let win_in = document.documentElement.clientWidth || document.body.clientWidth; // 获得当前可视窗口的宽度(不包含滚动条)
  let win_out = window.innerWidth; // 获得当前窗口的宽度(包含滚动条)

  if (win_out > win_in) {
    abs = (win_out - win_in) / 2;    // 获得滚动条宽度的一半
  }
  canvas.width = eleW * 2;
  canvas.height = eleH * 2;

  var context = canvas.getContext("2d");
  context.scale(2, 2);
  context.translate(-eleOffsetLeft - abs, -eleOffsetTop);
  var baseSrc = ‘‘
  await html2canvas(ele, { //等待函数执行完成
    dpi: 300,
    useCORS: true  //允许canvas画布内 可以跨域请求外部链接图片, 允许跨域请求。
  }).then((canvas) => {
    var pageData = canvas.toDataURL(‘image/jpeg‘, 1.0);
    baseSrc = pageData
  })

  return baseSrc;
}

export default {
  downloadPDF,
  previewImg
}

③在项目中使用

<div style="padding: 10px;">
     <el-button type="primary" @click="handlePreview()">预览</el-button>
     <el-button type="primary" @click="handleDown()">下载</el-button>
</div>
import htmlToPdf from ‘@/assets/js/toPdf‘
export default {
  methods: {
     handleDown () {       htmlToPdf.downloadPDF(document.querySelector(‘#demo‘), ‘离职申请表‘)     },     handlePreview () {       htmlToPdf.previewImg(document.querySelector(‘#demo‘)).then( res => {        this.previewUrl = res       })     }
  }
}

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