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本文章介绍 Uni-app 项目中 PDF 批注插件库 ElasticPDF 在线版 API 示例教程，API 包含 ① 导出批注后PDF数据；② 导出纯批注 json 数据；③ 加载旧批注；④ 切换文档；⑤ 切换用户；⑥ 清空批注 等数据处理功能，可满足通常业务需求。本教程可用于月付许可和在线测试版，欢迎 联系我们 咨询和获取接入 key。

0 ElasticPDF 产品介绍

ElasticPDF基于开源pdf.js，增加了多种开箱即用的 PDF 批注功能。代码包延续了 pdf.js-dist 独立且完全离线的结构风格，仅增加了用于支持批注的离线 Javascript 代码，可以快速完美集成到任何可以运行Javascript, HTML, CSS 的项目环境中，在公网及内网环境都可以完美的运行。

根据不同的功能及预算需求，有两个版本的产品可供选择，两者仅在最终的批注保存阶段有区别，产品 Demo 地址如下：

① 批注合成版: https://demos.libertynlp.com/#/pdfjs-annotation
② 专业批注版: https://www.elasticpdf.com/demo

1 导入页面 HTML 及初始化

首先将以下代码导入到目标页面，其中包含了初始化代码 initialPDFEditor() 和接收所有回报信息的函数 listenPDFEditorMessage()，所有导出的 PDF数据，批注数据 都在函数listenPDFEditorMessage() 下，可以与后续的业务融合。

<template><view class="content"><div v-if='language=="zh-cn"' class='project-title'><img src="https://elasticpdf.com/elasticpdf-image/logo-no-back.png" alt="" /><h2> Uni-app 项目在线版 API 示例教程</h2><a style="cursor: pointer;text-decoration: none;" href='https://www.elasticpdf.com/contact-us.html'target="_blank"><div title='联系我们获取测试 key' class='message-div info-message'><i class="fa fa-info-circle" aria-hidden="true"></i><span>获取测试 key</span></div></a><button class='theme-btn btn-outline-warning'@click="getPDFData()">获取PDF数据</button><button class='theme-btn btn-outline-help' @click="outputAnnotation()">导出批注</button><button class='theme-btn btn-outline-success' @click="changeFile()">切换文档</button><button class='theme-btn btn-outline-warning' @click="setMember()">切换用户</button><button class='theme-btn btn-outline-danger' @click="clearAnnotation()">清空批注</button><button class='theme-btn btn-outline-info' @click="reloadOldAnnotationData()">加载旧批注</button></div><web-view id='elasticpdf-iframe'src="https://pdfmaster.libertynlp.com/web/viewer.html?file=tutorial.pdf"style="position: relative; width: 100%; height: 660px;"></web-view></view>
</template><script>export default {data() {return {title: 'Hello',language:'en',}},onLoad() {var that = this;let count = 0;const userLang = navigator.languages;// alert('userLang'+userLang);if (userLang[0].toLowerCase().includes('zh')) {this.language='zh-cn';}const timer = setInterval(function() {const iframe = document.getElementById('elasticpdf-iframe');if (iframe) {clearInterval(timer);that.initialPDFEditor();} else {count++;if (count >= 30) { // 最多尝试 10 次clearInterval(timer);console.warn('未检测到 iframe，已停止尝试');}}}, 1000);},methods: {initialPDFEditor() {// Listen for callbacks of various information about PDF editing// 监听 pdf 编辑各种信息的回调this.listenPDFEditorMessage();var elasticpdf_viewer = document.getElementById('elasticpdf-iframe').contentWindow;// The online version only supports opening online documents// 在线版只支持打开在线文档var pdf_url = 'tutorial.pdf';elasticpdf_viewer.postMessage({"source": "test-elasticpdf","function_name": "initialApp","content": {'language': this.language, // 交互语言'pdf_url': pdf_url,'member_info': { //用户信息'id': 'elasticpdf_id','name': 'elasticpdf',},}}, '*');},// For security reasons, console output has been disabled by the test website and cannot use console.log to print out content// Please use alert to print content// 出于安全考虑, 控制台输出已被测试网站禁用无法使用 console.log 打印出内容// 请用 alert 打印内容listenPDFEditorMessage() {window.addEventListener('message', (e) => {if (e.data.source != 'elasticpdf') {return;}// PDF loading completed callback, you can import the annotation file stored on the server here// pdf 加载结束的回调，可以在此处导入服务器上储存的批注文件if (e.data.function_name == 'pdfLoaded') {// console.log is invalid, please use alert to print content// console.log 无效，请使用 alert 打印内容// alert('PDF loaded successfully PDF加载成功');this.reloadData();}// PDF annotation editing callback, where annotations can be exported and transferred to the server// pdf 批注编辑回调，可以在此处导出批注并传输到服务器if (e.data.function_name == 'annotationsModified') {// Only get the PDF annotation data, do not write it into the PDF// 仅获取 pdf 批注文件，不写入到 pdf 中let this_data = e.data.content;let annotation_content = JSON.stringify(this_data['file_annotation']);let file_name = this_data['file_name'];// console.log is invalid, please use alert to print content// alert('annotation modified 批注被修改');this.postService('upload-annotation-data', {'file_name': file_name,'file_id': '123ddasfsdffads','file_annotation': annotation_content,});}// PDF annotation export callback, where annotations can be exported and transferred to the server// pdf 批注导出回调，可以在此处导出批注并传输到服务器if (e.data.function_name == 'outputAnnotation') {// Only get the PDF annotation data, do not write it into the PDF// 仅获取 pdf 批注文件，不写入到 pdf 中let this_data = e.data.content;let annotation_content = JSON.stringify(this_data['file_annotation']);let file_name = this_data['file_name'];// console.log is invalid, please use alert to print content// console.log 无效，请使用 alert 打印内容// alert('Annotation data 批注数据\n'+annotation_content);}// Receive the edited PDF data, and the annotations are written into the PDF// 接收编辑后的pdf数据，批注被写入 PDF 中if (e.data.function_name == 'downloadPDF') {let file_name = e.data.content['file_name'];let pdf_blob = e.data.content['pdf_blob'];let pdf_base64 = e.data.content['pdf_base64'];// If the document has not been edited, pdf_base64 is still the file name or file url// Receive pdf data, where pdf_base64 can be quickly uploaded to the server// 如果文档没有被编辑过，则 pdf_base64 仍然是文件名或文件链接// 接收到 pdf 数据，其中 pdf_base64 可以快捷上传到服务器this.postService('upload-pdf-data', {'file_name': file_name,'file_id': '123ddasfsdffads','file_data': pdf_base64,});alert('Get the pdf base64 data. Please go to postService function to add the subsequent function.\n\n获取到 pdf base64 数据，如有需要请到postService中增加业务函数');}});}}}
</script>

2 调用 API

① 导出批注数据

导出 pdf 批注的 json 数据，可以用于后续的筛选、合并、入库保存等业务流程，非常适用于在线批注流程，因为只需要保存一个原 pdf 文档，然后从数据库中仅加载和回显批注，可以节省很多的服务器性能、流量和带宽费用。

// export annotations data 导出可保存的批注对象
outputAnnotation() {var elasticpdf_viewer = document.getElementById('elasticpdf-iframe').contentWindow;elasticpdf_viewer.postMessage({"source": "test-elasticpdf","function_name": "outputAnnotation","content": ""}, '*');
},

② 导入旧批注

从服务器中依据文件 ID 或 PDF 链接加载 ① 中导出的批注数据并回显至文档上，支持再次操作编辑，以此来实现批注数据的云端同步。

// reload old annotation data
// 加载旧批注
reloadOldAnnotationData() {var elasticpdf_viewer = document.getElementById('elasticpdf-iframe').contentWindow;var old_annotation = this.getOldAnnotation();elasticpdf_viewer.postMessage({"source": "test-elasticpdf","function_name": "setFileAnnotation","content": old_annotation}, '*');
},// Generate simulated old annotation data
// 生成模拟旧批注数据
getOldAnnotation() {var old_annotation = {"annos-for-page-1": {"page_id": "annos-for-page-1","page_canvas_container": {},"page_annotations": [],"page_canvas": {"fabric_canvas": {"version": "5.2.0","objects": [{"type": "rect","version": "5.2.0","left": 64.38,"top": 159.99,"width": 608.27,"height": 290.3,"fill": "rgba(255,237,0,0.3)","stroke": "rgba(17,153,158,1)","erasable": true}],"background": "rgba(255, 255, 255, 0)"},"width": 994,"height": 1407,"fabric_canvas_json": {"version": "5.2.0","objects": [{"type": "rect","version": "5.2.0","left": 64.38,"top": 159.99,"width": 608.27,"height": 290.3,"fill": "rgba(255,237,0,0.3)","stroke": "rgba(17,153,158,1)","erasable": true,"id": "1742436474916_1","hasControls": true,"hasBorders": true,"selectable": true,"lockMovementX": false,"lockMovementY": false,"member_id": "elasticpdf_id","member_name": "elasticpdf","my_type": "rectangle","comment": "添加批注","backup_opacity": 1,"lockRotation": false}],"background": "rgba(255, 255, 255, 0)"}}}}return JSON.stringify(old_annotation);
},

③ 导出 PDF 文件

将批注合并到批注文件并导出批注后 PDF 文档 base64 数据，可以直接入库保存。

// export edited pdf data
// 导出批注编辑后pdf数据
getPDFData() {var elasticpdf_viewer = document.getElementById('elasticpdf-iframe').contentWindow;elasticpdf_viewer.postMessage({"source": "test-elasticpdf","function_name": "getPDFData","content": ""}, '*');
},

④ 切换和打开文档

打开在线文档，其中文件服务器或站点需要允许 CORS 跨域，否则加载文档会失败。

// You can change test_pdf with any online pdf url
// The file server needs to be configured to allow cross-domain
// 切换打开的文档，可以把 test_pdf 换成任意在线pdf链接
// 文件服务器需要配置允许跨域
changeFile() {var elasticpdf_viewer = document.getElementById('elasticpdf-iframe').contentWindow;var test_pdf = 'https://mozilla.github.io/pdf.js/web/compressed.tracemonkey-pldi-09.pdf';elasticpdf_viewer.postMessage({"source": "test-elasticpdf","function_name": "openFile","content": test_pdf}, '*');
},

⑤ 设置用户信息

设置插件内当前操作用户的 ID 和用户名，这些信息会被记录到每个批注中，后续可以用于做权限差异设置，例如是否允许当前用户操作他人批注。

// set member info including id and name
// 设置用户的 id 和 name
setMember(id) {var elasticpdf_viewer = document.getElementById('elasticpdf-iframe').contentWindow;var this_member = {'id': 'test-id','name': 'test-name',};elasticpdf_viewer.postMessage({"source": "test-elasticpdf","function_name": "setMember","content": this_member}, '*');
},

⑥ 清空批注数据

将当前文档对应的操作批注完全清空。

// clear all annotations
// 清空批注
clearAnnotation() {var elasticpdf_viewer = document.getElementById('elasticpdf-iframe').contentWindow;elasticpdf_viewer.postMessage({"source": "test-elasticpdf","function_name": "clearFileAnnotation","content": ""}, '*');
},

总结

至此，elasticpdf 在线测试版集成于 Uni-app 项目并调用数据业务 API 的代码介绍完毕，测试代码文件已上传至 Github(网址：https://github.com/ElasticPDF/uniapp-use-pdf.js-elasticpdf)，欢迎联系我们咨询和获取 Key。

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