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Using PdfFormatProvider in RadPdfProcessing

Updated on Jun 11, 2026

Use PdfFormatProvider to import a PDF file into a RadFixedDocument or export a RadFixedDocument to PDF. This article explains the required packages, the stream requirements for import and export, and the common points to verify before you integrate the provider into your application.

PdfFormatProvider preserves the document structure and formatting that RadPdfProcessing supports. After import, you work with the resulting RadFixedDocument in the same way as a code-generated document.

To use the format provider, add references to these packages:

Telerik.Windows.Documents.Core
Telerik.Windows.Documents.Fixed

The PdfFormatProvider class is in the Telerik.Windows.Documents.Fixed.FormatProviders.Pdf namespace.

Use this article when you need to:

Open an existing PDF file as a RadFixedDocument.
Save a RadFixedDocument to a PDF stream or file.
Understand which stream capabilities the import and export APIs require.
Avoid common issues such as disposing a stream too early.

Starting with Q2 2025, the Document Processing libraries use System.IO.Compression instead of the Telerik Zip Library as an internal dependency. The Telerik Zip Library continues to ship as a standalone library for separate use.

Import

Use the Import() method of PdfFormatProvider to load a PDF document.

Example 1 shows how to import a PDF document from a file.

Before you call Import(), verify these requirements:

The input stream supports both read and seek operations.
If the original stream supports only read operations, copy it to a MemoryStream first.
If the document contains images, keep the stream open for as long as the RadFixedDocument needs access to those image resources.

When the imported document contains images, keep the stream open instead of disposing it immediately. The ImageSource API can continue to use the stream while the RadFixedDocument works with those images.

Example 1: Import a PDF File

PdfFormatProvider provider = new PdfFormatProvider();
RadFixedDocument document;
using (Stream stream = File.OpenRead("sample.pdf"))
{
    document = provider.Import(stream, TimeSpan.FromSeconds(10));

    //Do your work with the document inside the using statement.
}

The result of Import() is a RadFixedDocument that you can inspect, modify, render, or export again.

Import support is limited to the PDF features that RadPdfProcessing can export, so some custom PDF constructs might not be imported exactly as they appear in the original file.

Complete import and export examples are available in the Document Processing SDK repository on GitHub.

Export

Use the Export() method to serialize a RadFixedDocument to PDF.

Example 2 shows how to export a RadFixedDocument to a file.

Before you call Export(), verify these points:

The output stream is writable.
The destination file path exists or can be created by your application.
If the document is digitally signed, the stream supports both reading and writing.

Example 2: Export a PDF File

PdfFormatProvider pdf_provider = new PdfFormatProvider();
using (Stream output = File.OpenWrite("sample.pdf"))
{
    pdf_provider.Export(document, output, TimeSpan.FromSeconds(10));
}

When you export a digitally signed document, pass a stream that supports both reading and writing. Otherwise, the export throws NotSupportedException with the message Stream does not support reading. For example, create the output stream with new FileStream("signed.pdf", FileMode.OpenOrCreate, FileAccess.ReadWrite).

After export, you can open the resulting document in any application that supports PDF files.

In most applications, the PdfFormatProvider workflow looks like this:

Create a PdfFormatProvider instance.
Open a readable and seekable stream to import a PDF file, or prepare a writable stream to export one.
Import the PDF to a RadFixedDocument, or export an existing RadFixedDocument to PDF.
Keep the stream open when the imported document still depends on image resources from that stream.
Validate the result by opening the exported PDF in a PDF viewer or by inspecting the imported document in code.

Troubleshooting

Check these common issues if import or export does not behave as expected:

Import fails on stream access: Confirm that the input stream supports read and seek operations.
Imported images are missing later: Make sure that you do not dispose the underlying stream too early.
Export of signed PDFs fails: Use a stream with both read and write access.
Imported content differs from the original file: Confirm whether the source PDF uses features outside the supported RadPdfProcessing export surface.