Spire.PDF for .NET is a PDF library which enables users to handle the whole PDF document with wide range of tasks in C#, VB.NET. Spire.PDF supports to create PDF links, extract PDF links, update PDF links and remove PDF links from a PDF file. This article mainly shows how to extract and update link from a PDF file in C#.
Before the steps and codes, please check the original PDF file at first:
Firstly we need to create a new Document object and load a PDF file which needs to extract and update the links. The links are represented as annotations in a PDF file. Before extract and update the link from a PDF file, we need to extract all the AnnotationsWidget objects.
The following code snippet shows you how to extract links from the PDF file.
//Load an existing PDF file PdfDocument document = new PdfDocument(); document.LoadFromFile(@"..\..\output.pdf"); //Get the first page PdfPageBase page = document.Pages[0]; //Get the annotation collection PdfAnnotationCollection widgetCollection = page.AnnotationsWidget; //Verify whether widgetCollection is not null or not if (widgetCollection.Count > 0) { foreach (var obj in widgetCollection) { //Get the TextWebLink Annotation if (obj is PdfTextWebLinkAnnotationWidget) { PdfTextWebLinkAnnotationWidget link = obj as PdfTextWebLinkAnnotationWidget;
The following code snippet shows you how to update the link in PDF file
//Change the url of TextWebLink Annotation link.Url = "http://www.e-iceblue.com/Introduce/pdf-for-net-introduce.html"; //Saves PDF document to file. document.SaveToFile("sample.pdf");
This picture will show you the link has been updated in the PDF file.