Draw a PDF Page Background Using RadPdfProcessing

Environment

Version	Product	Author
2025.4.1104	RadPdfProcessing	Yoan Karamanov

Description

To draw a page background, you can create a colored rectangle and insert it at the beginning of the page's content collection so that it renders behind the rest of the content.

Solution

The approach is to import the PDF, create a rectangle path sized to the page, and insert it into the page content at index 0 (first position).

Key Points

• PDF pages don't have a built-in background property. Draw a rectangle to create a background.
• Backgrounds are typically the first element in the page content, subsequent elements render above earlier ones.
• Insert at index 0 to draw a background behind all content.
• Size the rectangle to match firstPage.Size for full-page coverage.

RadFixedDocument inputDocument;
PdfFormatProvider pdfFormatProvider = new PdfFormatProvider();

using (System.IO.Stream input = System.IO.File.OpenRead("input.pdf"))
{
    inputDocument = pdfFormatProvider.Import(input);
}

RadFixedPage firstPage = inputDocument.Pages.First();

// Create the background
RectangleGeometry rectangleGeometry = new RectangleGeometry();
rectangleGeometry.Rect = new Rect(1, 1, firstPage.Size.Width, firstPage.Size.Height);

Telerik.Windows.Documents.Fixed.Model.Graphics.Path path = new Telerik.Windows.Documents.Fixed.Model.Graphics.Path();
path.Geometry = rectangleGeometry;

path.IsFilled = true;
path.Fill = new RgbColor(100, 150, 0, 0);

// Insert the background (at position 1) into the first page
firstPage.Content.Insert(0, path); // Use index '1' if the document already has a set background

string pdfOutputPath = "output.pdf";

System.IO.File.Delete(pdfOutputPath);
using (System.IO.Stream output = System.IO.File.OpenWrite(pdfOutputPath))
{
    pdfFormatProvider.Export(inputDocument, output, TimeSpan.FromSeconds(10));
}

See Also

• RadPdfProcessing Overview