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本文章介绍 Angular 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 HTML页面，此处为 app.component.html

<div *ngIf='language==="zh-cn"' class='project-title'><img src="https://elasticpdf.com/elasticpdf-image/logo-no-back.png" alt="" /><h2>Angular 项目在线 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 style="margin-left: 20px;" 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('test_id')">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>
<div style="width: 100%;height: auto;"><iframe src="https://pdfmaster.libertynlp.com/web/viewer.html?file=tutorial.pdf" id='elasticpdf-iframe' (load)='initialPDFEditor()' width="100%" height="680px" frameborder="0"></iframe>
</div>

再将以下逻辑代码导入到 app.component.html 对应的 ts 页面中，此处为 app.component.ts，其中包含了初始化代码 initialPDFEditor() 和接收所有回报信息的函数，所有导出的 PDF数据，批注数据 都在函数 @HostListener 下，可以与后续的业务融合。

import { Component } from '@angular/core';
import { CommonModule } from '@angular/common';
import { RouterOutlet } from '@angular/router';
import { HostListener } from '@angular/core';@Component({selector: 'app-root',standalone: true,imports: [CommonModule, RouterOutlet],templateUrl: './app.component.html',styleUrls: ['./app.component.css']
})export class AppComponent {language:any = 'en';elasticpdf_viewer:any = null;elasticpdf_iframe:any = null;initialPDFEditor() {let languages = navigator.languages as string[];		if (languages[0].toLowerCase().includes('zh')) {this.language = 'zh-cn';// alert(languages);}this.elasticpdf_iframe = document.getElementById('elasticpdf-iframe') as HTMLIFrameElement;// The online version only supports opening online documents// 在线版只支持打开在线文档let pdf_url = "tutorial.pdf";if (this.elasticpdf_iframe && this.elasticpdf_iframe.contentWindow) {this.elasticpdf_viewer = this.elasticpdf_iframe?.contentWindow as any;this.elasticpdf_viewer.postMessage({"source": "test-elasticpdf","function_name": "initialApp","content": {'language': this.language, // GUI language 交互语言'pdf_url': pdf_url,'member_info': { //Member Info  用户信息'id': 'elasticpdf_id','name': 'elasticpdf',},}}, '*');}}// Listen for callbacks of various information about PDF editing// 监听 pdf 编辑各种信息的回调@HostListener('window:message', ['$event'])onMessage(event : Event) : void {const e : any = event;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 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);}// 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,});}// 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');}}
}

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() {this.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 old_annotation = this.getOldAnnotation();this.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() {this.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 test_pdf = 'https://mozilla.github.io/pdf.js/web/compressed.tracemonkey-pldi-09.pdf';this.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:string) {var this_member = {'id': 'test-id','name': 'test-name',};this.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() {this.elasticpdf_viewer.postMessage({"source": "test-elasticpdf","function_name": "clearFileAnnotation","content": ""}, '*');
}

总结

至此，elasticpdf 在线测试版集成于 Angular 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/Angular-use-pdf.js-elasticpdf)，欢迎联系我们咨询和获取 Key。

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