Splitting and Merging PDFs with PDFEdit

Requirements: Secure PDF or PDF SDK

Introduction

Reorganizing PDF documents – breaking a large file into smaller pieces, or combining several files into one – is one of the most common document management tasks developers are asked to automate. Whether you are separating a scanned batch of invoices into individual files, extracting a single page from a signed contract, or assembling a set of reports into a single deliverable, the PDFEdit component in Secure PDF and PDF SDK provides a straightforward, page-level API for doing so.

This guide covers how to use PDFEdit to split a document into multiple files and merge multiple documents into one.

Overview

Both splitting and merging are built on the same small set of page-level methods:

• SelectPage selects a page from an open document, populating the SelectedPage property with a PDFPage object.
• NewPage accepts a PDFPage object to be committed to a document.
• AppendPage adds the page in NewPage to the end of the document.
• InsertPage adds the page in NewPage at a specific position in the document.
• RemovePage and RemovePages remove one or more pages from a document.

Splitting PDFs

Splitting is handled by removing the unwanted pages from a copy of the document and saving the rest. Because RemovePages operates on the document currently loaded in a PDFEdit object, the simplest approach is to open the source document once per output file, remove the pages that do not belong in that output, and save.

Splitting a Document into Two Parts

The following example splits a 4-page document into two 2-page documents:

pdfedit.InputFile = "input_4_pages.pdf"; pdfedit.Open();
// Remove the pages after page 1, and save the first part (pages 0-1) pdfedit.OutputFile = "input_first.pdf"; pdfedit.RemovePages(2, 2); pdfedit.Close();
// Remove the pages up to and including page 1, and save the second part (pages 2-3) pdfedit.OutputFile = "input_second.pdf"; pdfedit.Open(); pdfedit.RemovePages(0, 2); pdfedit.Close();

RemovePages takes a starting index and a count, so RemovePages(2, 2) removes two pages beginning at index 2 (i.e., pages 3 and 4), leaving pages 1 and 2 in the output.

Splitting a Document into One File per Page

The same pattern extends naturally to splitting every page of a document into its own file. Reopen the source document for each page, remove every page except the one you want to keep, and save it under a unique name:

int pageCount = 0; pdfedit.OnDocumentInfo += (s, e) => { pageCount = e.PageCount; };
pdfedit.InputFile = "input.pdf"; pdfedit.Open();
for (int i = 0; i < pageCount; i++) { pdfedit.Reset(); pdfedit.InputFile = "input.pdf"; pdfedit.OutputFile = $"page_{i + 1}.pdf"; pdfedit.Open();
if (i < pageCount - 1) { pdfedit.RemovePages(i + 1, pageCount - (i + 1)); // remove trailing pages } if (i > 0) { pdfedit.RemovePages(0, i); // remove leading pages }
pdfedit.Close(); }

Extracting a Specific Page

To pull a single page out of a larger document without discarding the rest, remove every page except the one you want to extract, in two operations – one for the pages before it, and one for the pages after:

pdfedit.InputFile = "report.pdf"; pdfedit.OutputFile = "report_page3.pdf"; pdfedit.Open();
pdfedit.RemovePages(3, pageCount - 3); // remove everything after page 3 pdfedit.RemovePages(0, 2); // remove pages 1-2
pdfedit.Close();

Merging PDFs

Merging works in the opposite direction: rather than removing pages, you copy pages from one or more source documents into a destination document. Since PDFEdit operates on a single open document at a time, merging requires a separate PDFEdit object for each document involved – one for the destination, and one for each source you are pulling pages from.

Merging Two Documents

To copy pages from a source document into a destination document, open both documents, then use SelectPage on the source to populate SelectedPage, assign that page to the destination's NewPage property, and commit it with AppendPage:

dest.InputFile = "recipient.pdf"; dest.Open();
src.InputFile = "donor.pdf"; src.Open();
src.SelectPage(0); dest.NewPage = src.SelectedPage; dest.AppendPage();
dest.OutputFile = "merged.pdf"; dest.Close(); src.Close();

AppendPage adds the page to the end of the destination document. If you need the page inserted at a specific position instead (e.g., to interleave pages from two sources), use InsertPage with the target index in place of AppendPage.

Merging Entire Documents

To merge every page of a source document rather than a single page, loop over each page in the source, selecting and appending it in turn:

dest.InputFile = "recipient.pdf"; dest.Open();
src.InputFile = "donor.pdf"; src.Open();
for (int i = 0; i < donorPageCount; i++) { src.SelectPage(i); dest.NewPage = src.SelectedPage; dest.AppendPage(); }
dest.OutputFile = "merged.pdf"; dest.Close(); src.Close();

Merging More than Two Documents

Because merging is just repeated appending or inserting, combining any number of documents into one is a matter of looping over your list of source files and repeating the copy step for each:

dest.CreateNew();
foreach (string file in new[] { "part1.pdf", "part2.pdf", "part3.pdf" }) { src.InputFile = file; src.Open();
for (int i = 0; i < pageCount; i++) { src.SelectPage(i); dest.NewPage = src.SelectedPage; dest.AppendPage(); }
src.Close(); }
dest.RemovePage(0); // remove the empty page created by CreateNew() dest.OutputFile = "combined.pdf"; dest.Close();

Creating the destination document with CreateNew instead of opening an existing file lets you build the combined document entirely from the source pages rather than starting from one of them.