如何使用nodejs在pdf中添加水印？答案

【问题标题】：How to add watermark in pdf using nodejs?如何使用nodejs在pdf中添加水印？
【发布时间】：2018-08-29 10:30:54
【问题描述】：

我通过nodejs生成了pdf。我想在这个生成的 pdf 中添加水印。我在代码中使用了 dynamic-html-pdf 插件。如果有在 dynamic-html-pdf 中添加水印的任何选项。我在这里展示我的示例代码。

var path=require('path');
var pdf = require('dynamic-html-pdf');
var html='<!DOCTYPE html><html><head><style>';
html=html+'</style>';
html=html+'</head>';
html=html+'<body>';
html=html+'<div class="divstyle1" id="content">A computer is a device that can be instructed to carry out sequences of arithmetic or logical operations automatically via computer programming. </div>';
html=html+'</body></html>';
var options = {
    format: "A4",
    orientation: "portrait",
    border: "10mm",
    base: 'file://' + path.resolve('./public/graph') + '/'
};
var document = {
    type: 'file', 
    template: html,
    context: {
        img:'./public/graph/logo.jpg'
    },
    path: "./public/graph/mypdf.pdf"    
};
pdf.create(document, options)
.then(res => {
    res.status(200).json({
        message: 'pdf created'
    });  
})
.catch(error => {
    res.status(200).json({
        message: 'error'
    });

});

【问题讨论】：

标签： javascript node.js node-html-pdf

【解决方案1】：

保存您的 pdf 文档后。使用 image-watermark 模块将水印附加到您生成的 pdf 中。

var watermark = require('image-watermark'); 
watermark.embedWatermark('/path/to/your/generated/pdf', {'text' : 'sample watermark'});

【讨论】：

/usr/local/lib/node_modules/image-watermark/watermark.js:196 throw new Error('Image-Watermark::embedWatermark : Unable to process image file : ' + err);
它仅适用于图像文件。当我将 pdf 作为输入时，它会显示上述错误

【解决方案2】：

在PDF文档中添加文本水印的另一种解决方案是Aspose.PDF Cloud SDK for Node.js。它是一个商业产品，但每月提供 150 次免费 API 调用。

目前，它支持来自云存储的 PDF 文件处理：Aspose 内部存储、Amazon S3、DropBox、Google Drive Storage、Google Cloud Storage、Windows Azure Storage 和 FTP Storage。但是，我们计划添加支持以处理来自请求正文（流）的 PDF 文档。

P.S：我是 Aspose 的开发者传道者。

const { PdfApi } = require("asposepdfcloud");
const { TextStamp }= require("asposepdfcloud/src/models/textStamp");
const { TextState }= require("asposepdfcloud/src/models/textState");
const { HorizontalAlignment }= require("asposepdfcloud/src/models/horizontalAlignment");
const { VerticalAlignment }= require("asposepdfcloud/src/models/verticalAlignment");
const { Rotation }= require("asposepdfcloud/src/models/rotation");


// Get Client Id and Client Secret from https://dashboard.aspose.cloud/
pdfApi = new PdfApi("xxxxx-xxxx-xxxx-xxxx-xxxxxxxxxx", "xxxxxxxxxxxxxxxxxxxxxxx");
var fs = require('fs');

const name = "Test.pdf";
const pageNumber = 1;
const remoteTempFolder = "Temp";
const localTestDataFolder = "C:\\Temp";
const path = remoteTempFolder + "\\" + name;
var data = fs.readFileSync(localTestDataFolder + "\\" + name);

// Upload File
pdfApi.uploadFile(path, data).then((result) => {  
                     console.log("Uploaded File");    
                    }).catch(function(err) {
    // Deal with an error
    console.log(err);
});

// Add Text Stamp
const textState = new TextState();
textState.fontSize = 14;
textState.font = 'Arial';

const stamp = new TextStamp();
stamp.background = true;
stamp.leftMargin = 1;
stamp.rightMargin = 2;
stamp.topMargin = 3;
stamp.bottomMargin = 4;
stamp.horizontalAlignment = HorizontalAlignment.Center;
stamp.verticalAlignment = VerticalAlignment.Center;
stamp.opacity = 1;
stamp.rotate = Rotation.None;
stamp.rotateAngle = 0;
stamp.xIndent = 0;
stamp.yIndent = 0;
stamp.zoom = 1;
stamp.textAlignment = HorizontalAlignment.Center;
stamp.value = "Aspose.PDF Cloud";
stamp.textState = textState;

pdfApi.postPageTextStamps(name, pageNumber,[stamp], null, remoteTempFolder).then((result) => {    
    console.log(result.body.code);                  
}).catch(function(err) {
    // Deal with an error
    console.log(err);
});
//Download file
const localPath = "C:/Temp/textstamp.pdf";

pdfApi.downloadFile(path).then((result) => {    
    console.log(result.response.statusCode);    
    console.log(result.body.byteLength);    
    fs.writeFileSync(localPath, result.body);
    console.log("File Downloaded");    
}).catch(function(err) {
    // Deal with an error
    console.log(err);
});

【讨论】：