Article directory
1. Install dependencies
The following two dependencies are mainly used:
html2canvas: By obtaining an element of HTML and then generating a Canvas, users can save it as a picture.
jspdf: HTML5-based client-side solution for generating PDF documents for various purposes.
npm i html2canvas jspdf --save
package.json
"dependencies": {
"html2canvas": "^1.4.1",
"jspdf": "^2.5.1",
"vue": "^3.2.37"
}
2. Create htmlToPdf.js
/* 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 js_getDPI() {
var arrDPI = new Array();
if (window.screen.deviceXDPI != undefined) {
arrDPI[0] = window.screen.deviceXDPI;
arrDPI[1] = window.screen.deviceYDPI;
}
else {
var tmpNode = document.createElement("DIV");
tmpNode.style.cssText = "width:1in;height:1in;position:absolute;left:0px;top:0px;z-index:99;visibility:hidden";
document.body.appendChild(tmpNode);
arrDPI[0] = parseInt(tmpNode.offsetWidth);
arrDPI[1] = parseInt(tmpNode.offsetHeight);
tmpNode.parentNode.removeChild(tmpNode);
}
return arrDPI;
}
export function getPdfUrl(ele, pdfName,callback){
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
}
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,
width:eleW+135,
height:eleH,
// 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 = 30;
//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', 30, 30, imgWidth, imgHeight);
// pdf.addImage(pageData, 'JPEG', 20, 40, imgWidth, imgHeight);
} else {
// 分页
while(leftHeight > 0) {
pdf.addImage(pageData, 'JPEG', 30, 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);
var buffer = pdf.output("datauristring");
callback(buffer)
})
}
export function downloadPDF2(ele, pdfName,callback){
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,
width:eleW+135,
height:eleH,
// 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 = 30;
//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', 30, 30, imgWidth, imgHeight);
// pdf.addImage(pageData, 'JPEG', 20, 40, imgWidth, imgHeight);
} else {
// 分页
while(leftHeight > 0) {
pdf.addImage(pageData, 'JPEG', 30, 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 + '.pdf');
callback()
})
}
3. How to use htmlToPdf.js
Take App.vue as an example. In this way, the base64Url of the PDF within the scope of pdf-con can be obtained, which can be converted into a file object for uploading and submitted to the backend parameters. After calling this method, the browser will directly
download the PDF
