How to merge different files into a single PDF document using C#/VB.NET?

14 mins read

Syncfusion® PDF is a feature-rich and high-performance .NET PDF library used to create, read, and edit PDF documents programmatically without Adobe dependencies. This library also offers functionality to merge, split, stamp, add forms, compress, and secure PDF files.

Using this library, you can merge documents of different file formats into a single PDF document. This sample merges an image file, a PDF document, a Word document, and an Excel file into a single PDF document.

Steps to merge files of different file formats into a PDF document programmatically in C#:

Create a new C# console application project. Caption
Install the following NuGet packages as references to your .NET Framework application from NuGet.org:

The Syncfusion.Pdf.WinForms NuGet to package for working with PDF files.
The Syncfusion.DocIO.WinForms and Syncfusion.DocToPdfConverter.WinForms packages for working with Word documents and converting them into PDF documents.
The Syncfusion.XlsIO.WinForms and Syncfusion.ExcelToPdfConverter.WinForms packages for working with Excel documents and converting them into PDF documents.

The files of different file formats can be merged into a single PDF document only after converting each file to a PDF document.
Include the following namespaces in the Program.cs file.

using Syncfusion.DocIO;
using Syncfusion.DocIO.DLS;
using Syncfusion.DocToPDFConverter;
using Syncfusion.Pdf;
using Syncfusion.Pdf.Graphics;
using Syncfusion.Pdf.Parsing;
using Syncfusion.XlsIO;
using Syncfusion.ExcelToPdfConverter;
using System;
using System.Drawing;
using System.IO;

VB.NET

Imports Syncfusion.DocIO
Imports Syncfusion.DocIO.DLS
Imports Syncfusion.DocToPDFConverter
Imports Syncfusion.Pdf
Imports Syncfusion.Pdf.Graphics
Imports Syncfusion.Pdf.Parsing
Imports Syncfusion.XlsIO
Imports Syncfusion.ExcelToPdfConverter
Imports System.Drawing
Imports System.IO

Include the following code snippet in the main method of Program.cs file, to merge the documents of different file formats into a single PDF and add watermark to the merged PDF document.

// Get the path of documents into DirectoryInfo
DirectoryInfo directoryInfo = new DirectoryInfo("../../Documents/");

// Create a new PDF document
PdfDocument document = new PdfDocument();

// Initialize MemoryStream
MemoryStream stream = new MemoryStream();

// Convert the documents to PDF
foreach (FileInfo fileInfo in directoryInfo.GetFiles())
{
    // Import pages from PDF document and store them into the stream
    if (fileInfo.Extension == ".pdf")
        stream = ImportPagesFromPDF(fileInfo.FullName);

    // Convert the Excel document into PDF and store it in the stream
    if (fileInfo.Extension == ".xls" || fileInfo.Extension == ".xlsx")
        stream = ConvertExcelToPDF(fileInfo.FullName);

    // Convert the Word document into PDF and store it in the stream
    if (fileInfo.Extension == ".doc" || fileInfo.Extension == ".docx")
        stream = ConvertWordToPDF(fileInfo.FullName);

    // Convert the image file into PDF and store it in the stream
    if (fileInfo.Extension == ".jpg" || fileInfo.Extension == ".png" || fileInfo.Extension == ".jpeg")
        stream = ImageToPDF(fileInfo.FullName);

    // Load the stream into PdfLoadedDocument
    PdfLoadedDocument loadedDocument = new PdfLoadedDocument(stream);

    // Add the watermark
    AddWatermark(loadedDocument, document);
}

// Save the PDF document
document.Save("MergedPDF.pdf");

// Close the instance of PdfDocument
document.Close(true);

VB.NET

' Get the path of documents into DirectoryInfo
Dim directoryInfo As DirectoryInfo = New DirectoryInfo("../../Documents/")

' Create a new PDF document
Dim document As PdfDocument = New PdfDocument

' Initialize MemoryStream
Dim stream As MemoryStream = New MemoryStream

' Convert the documents to PDF
For Each fileInfo As FileInfo In directoryInfo.GetFiles
    ' Import pages from PDF document and store them into the stream
    If (fileInfo.Extension = ".pdf") Then
        stream = ImportPagesFromPDF(fileInfo.FullName)
    End If

    ' Convert the Excel document into PDF and store it in the stream
    If ((fileInfo.Extension = ".xls") OrElse (fileInfo.Extension = ".xlsx")) Then
        stream = ConvertExcelToPDF(fileInfo.FullName)
    End If

    ' Convert the Word document into PDF and store it in the stream
    If ((fileInfo.Extension = ".doc") OrElse (fileInfo.Extension = ".docx")) Then
        stream = ConvertWordToPDF(fileInfo.FullName)
    End If

    ' Convert the image file into PDF and store it in the stream
    If ((fileInfo.Extension = ".jpg") OrElse ((fileInfo.Extension = ".png") OrElse (fileInfo.Extension = ".jpeg"))) Then
        stream = ImageToPDF(fileInfo.FullName)
    End If

    ' Load the stream into PdfLoadedDocument
    Dim loadedDocument As PdfLoadedDocument = New PdfLoadedDocument(stream)

    ' Add the watermark
    AddWatermark(loadedDocument, document)
Next

' Save the PDF document
document.Save("MergedPDF.pdf")

' Close the instance of PdfDocument
document.Close(True)

The code snippet given above has static methods declared for the conversion of files of different file formats to PDF documents and the addition of a watermark.
Define the ImportPagesFromPDF static method with the following code snippet to import pages from one PDF document into another PDF document.

// Load the PDF document into PdfLoadedDocument
PdfLoadedDocument loadedDocument = new PdfLoadedDocument(filePath);

// Create a new PDF document
PdfDocument document = new PdfDocument();

// Import all the pages in PdfLoadedDocument into PdfDocument
document.ImportPageRange(loadedDocument, 0, loadedDocument.Pages.Count - 1);

// Save the PDF document as a stream
MemoryStream stream = new MemoryStream();
document.Save(stream);

// Close the instances of PdfLoadedDocument and PdfDocument
loadedDocument.Close(true);
document.Close(true);

// Return the stream
return stream;

VB.NET

' Load the PDF document into PdfLoadedDocument
Dim loadedDocument As PdfLoadedDocument = New PdfLoadedDocument(filePath)

' Create a new PDF document
Dim document As PdfDocument = New PdfDocument

' Import all the pages in PdfLoadedDocument into PdfDocument
document.ImportPageRange(loadedDocument, 0, loadedDocument.Pages.Count - 1)

' Save the PDF document as a stream
Dim stream As MemoryStream = New MemoryStream
document.Save(stream)

' Close the instances of PdfLoadedDocument and PdfDocument
loadedDocument.Close(True)
document.Close(True)

' Return the stream
Return stream

An Excel document can be converted to PDF by using the Convert method of ExcelToPdfConverter. Define the ConvertExcelToPDF static method with the following code snippet to convert an Excel document to PDF.

// Create an instance of ExcelEngine
ExcelEngine excelEngine = new ExcelEngine();

// Initialize IApplication and set the default application version
IApplication application = excelEngine.Excel;
application.DefaultVersion = ExcelVersion.Excel2016;

// Load the Excel document into IWorkbook
IWorkbook workbook = application.Workbooks.Open(filePath, ExcelOpenType.Automatic);

// Initialize ExcelToPdfConverter for the workbook
ExcelToPdfConverter converter = new ExcelToPdfConverter(workbook);

// Initialize ExcelToPdfConverterSettings and set the layout
ExcelToPdfConverterSettings settings = new ExcelToPdfConverterSettings();
settings.LayoutOptions = LayoutOptions.FitAllColumnsOnOnePage;

// Convert the Excel document to PDF with converter settings
PdfDocument document = converter.Convert(settings);

// Save the PDF document as a stream
MemoryStream stream = new MemoryStream();
document.Save(stream);

// Close the instances of PdfDocument, IWorkbook, and dispose of ExcelEngine
document.Close(true);
workbook.Close();
excelEngine.Dispose();

// Return the stream
return stream;

VB.NET

' Create an instance of ExcelEngine
Dim excelEngine As ExcelEngine = New ExcelEngine

' Initialize IApplication and set the default application version
Dim application As IApplication = excelEngine.Excel
application.DefaultVersion = ExcelVersion.Excel2016

' Load the Excel document into IWorkbook
Dim workbook As IWorkbook = application.Workbooks.Open(filePath, ExcelOpenType.Automatic)

' Initialize ExcelToPdfConverter for the workbook
Dim converter As ExcelToPdfConverter = New ExcelToPdfConverter(workbook)

' Initialize ExcelToPdfConverterSettings and set the layout
Dim settings As ExcelToPdfConverterSettings = New ExcelToPdfConverterSettings
settings.LayoutOptions = LayoutOptions.FitAllColumnsOnOnePage

' Convert the Excel document to PDF with converter settings
Dim document As PdfDocument = converter.Convert(settings)

' Save the PDF document as a stream
Dim stream As MemoryStream = New MemoryStream
document.Save(stream)

' Close the instances of PdfDocument, IWorkbook, and dispose of ExcelEngine
document.Close(True)
workbook.Close
excelEngine.Dispose()

' Return the stream
Return stream

You can convert a word document into PDF using the ConvertToPDF method of DocToPDFConverter. Include the following code snippet in the definition part of the ConvertWordToPDF method.

// Load an existing Word document into WordDocument
WordDocument wordDocument = new WordDocument(filePath, FormatType.Automatic);

// Initialize the DocToPDFConverter
DocToPDFConverter converter = new DocToPDFConverter();

// Convert Word document into PDF document
PdfDocument document = converter.ConvertToPDF(wordDocument);

// Save the PDF document as a stream
MemoryStream stream = new MemoryStream();
document.Save(stream);

// Close the instances of PdfDocument and WordDocument
document.Close(true);
wordDocument.Close();

// Return the stream
return stream;

VB.NET

' Load an existing Word document into WordDocument
Dim wordDocument As WordDocument = New WordDocument(filePath, FormatType.Automatic)

' Initialize the DocToPDFConverter
Dim converter As DocToPDFConverter = New DocToPDFConverter

' Convert Word document into PDF document
Dim document As PdfDocument = converter.ConvertToPDF(wordDocument)

' Save the PDF document as a stream
Dim stream As MemoryStream = New MemoryStream
document.Save(stream)

' Close the instances of PdfDocument and WordDocument
document.Close(True)
wordDocument.Close()

' Return the stream
Return stream

Converting image to PDF is nothing but drawing the image on the PDF document. This can be achieved by using the DrawImage method of PdfGraphics. Define the ImageToPDF static method with the following code snippet to convert an image to PDF.

// Create a new PDF document
PdfDocument document = new PdfDocument();

// Add a page to the document
PdfPage page = document.Pages.Add();

// Load the image into PdfBitmap
PdfBitmap image = new PdfBitmap(imagePath);

// Draw the image on PdfPage
page.Graphics.DrawImage(image, 70, 30);

// Save the PDF document as a stream
MemoryStream stream = new MemoryStream();
document.Save(stream);

// Close the instance of PdfDocument
document.Close(true);

// Return the stream
return stream;

VB.NET

' Create a new PDF document
Dim document As PdfDocument = New PdfDocument

' Add a page to the document
Dim page As PdfPage = document.Pages.Add

' Load the image into PdfBitmap
Dim image As PdfBitmap = New PdfBitmap(imagePath)

' Draw the image on PdfPage
page.Graphics.DrawImage(image, 70, 30)

' Save the PDF document as a stream
Dim stream As MemoryStream = New MemoryStream
document.Save(stream)

' Close the instance of PdfDocument
document.Close(True)

' Return the stream
Return stream

Use the following code snippet in the AddWatermark method to merge and add a watermark to the PDF documents.

for (int i = 0; i < loadedDocument.Pages.Count; i++)
{
    // Set the width, height, and margins for PdfDocument
    document.PageSettings.Margins.All = 0;
    document.PageSettings.Width = 500;
    document.PageSettings.Height = 800;

    // Create a PdfTemplate
    PdfTemplate template = loadedDocument.Pages[i].CreateTemplate();

    // Add a page to the PdfDocument
    PdfPage page = document.Pages.Add();

    // Create PdfGraphics for the page
    PdfGraphics graphics = page.Graphics;

    // Draw the PDF template
    graphics.DrawPdfTemplate(template, new PointF(0, 0), new SizeF(page.GetClientSize().Width, page.GetClientSize().Height));

    // Initialize PdfStandardFont
    PdfFont font = new PdfStandardFont(PdfFontFamily.Helvetica, 14, PdfFontStyle.Bold);

    // Save the graphics of the page
    PdfGraphicsState state = page.Graphics.Save();

    // Draw the watermark on the PDF page
    graphics.SetTransparency(0.5f);
    graphics.DrawString("Page Number : " + document.Pages.Count.ToString(), font, PdfBrushes.Red, new PointF(350, 400));
}

VB.NET

For i As Integer = 0 To loadedDocument.Pages.Count - 1 Step 1
    ' Set the width, height, and margins for PdfDocument
    document.PageSettings.Margins.All = 0
    document.PageSettings.Width = 500
    document.PageSettings.Height = 800

    ' Create a PdfTemplate
    Dim template As PdfTemplate = loadedDocument.Pages(i).CreateTemplate

    ' Add a page to the PdfDocument
    Dim page As PdfPage = document.Pages.Add

    ' Create PdfGraphics for the page
    Dim graphics As PdfGraphics = page.Graphics

    ' Draw the PDF template
    graphics.DrawPdfTemplate(template, New PointF(0, 0), New SizeF(page.GetClientSize.Width, page.GetClientSize.Height))

    ' Initialize PdfStandardFont
    Dim font As PdfFont = New PdfStandardFont(PdfFontFamily.Helvetica, 14, PdfFontStyle.Bold)

    ' Save the graphics of the page
    Dim state As PdfGraphicsState = page.Graphics.Save

    ' Draw the watermark on the PDF page
    graphics.SetTransparency(0.5!)
    graphics.DrawString("Page Number : " + document.Pages.Count.ToString(), font, PdfBrushes.Red, New PointF(350, 400))
Next