Replace Text Content With Image | Telerik Document Processing

Updated on Feb 19, 2026

Product Version	Product	Author
2021.1.118	RadPdfProcessing	Tanya Dimitrova

Description

A common scenario is to replace a temporary page content (a placeholder text) with an image. This allows already created PDF documents to be modified by adding an image on a position defined by the existing content of the document.

Solution

The following example demonstrates the approach of iterating the page content and finding TextFragment elements matching the $ImagePlaceholder text. For each match, an Image instance is created and the TextFragment is replaced with it. The Position property is used to correctly position the image on the page.

csharp

    foreach (RadFixedPage page in pdfDocument.Pages)
    {
    	List<TextFragment> contentToRemove = new List<TextFragment>();
    
    	for (int i = 0; i < page.Content.Count; i++)
    	{
    		ContentElementBase contentElement = page.Content[i];
    		if (contentElement is TextFragment textFragment)
    		{
    			int count = contentToRemove.Sum(f => f.Text.Length);
       
                // Find a TextFragment exactly matching or be part of the $ImagePlaceholder text  
    			if (count == 0 && textToRemove.StartsWith(textFragment.Text))
    			{
    				contentToRemove.Add(textFragment);
    			}
    			else if (count > 0)
    			{
    				string oldValueRemainings = textToRemove.Substring(count);
    
    				if (oldValueRemainings.StartsWith(textFragment.Text))
    				{
    					contentToRemove.Add(textFragment);
    				}
    				else
    				{
    					contentToRemove.Clear();
    					return;
    				}
    			}
    
    			count = contentToRemove.Sum(f => f.Text.Length);
    
    			if (count == textToRemove.Length)
    			{
    				// Create and add an image 
    				ImageSource source = new ImageSource(File.OpenRead(imagePath));
    				Image image = page.Content.AddImage(source);
    
    				// Set the desired size to the image 
    				image.Width = 300;
    				image.Height = 50;
    				TextFragment firstFragment = contentToRemove[0];
    
    				// Position the image 
    				image.Position = firstFragment.Position;
    				image.Position.Translate(0, -firstFragment.FontSize);
    
    				// Indicate the TextFragment to be removed  
    				for (int j = 0; j < contentToRemove.Count; j++)
    				{
    					TextFragment fragment = contentToRemove[j];
    					page.Content.Remove(fragment);
    				}
    			}
    		}
    	}
    }