Tagging Links

This guide demonstrates how to create accessible links in PDF documents following best practices for PDF/UA compliance using UniPDF.

Before you begin #

You should get your API key from your UniCloud account.

If this is your first time using UniPDF SDK, follow this guide to set up a local development environment.

Clone the project repository #

In your terminal, clone the examples repository. It contains the Go code we will be using for this guide.

git clone https://github.com/unidoc/unipdf-examples.git

Navigate to the accessibility folder in the unipdf-examples directory.

cd unipdf-examples/accessibility

How it works #

The following example code shows how to create different types of accessible links.

Code Explanation #

The code begins by initializing the metered license API key in the init function (lines 21-28). A StructTreeRoot and a base KDictionary of type Document are created (lines 41-47) to form the document’s structure tree. The example then demonstrates creating various types of accessible links.

First, a link with descriptive text (“Download PDF Specification”) is created (lines 61-71). Since the text itself is descriptive, no AltText is needed, but a Tooltip is set to the URL. The AddExternalLinkWithTag method is used to add the link and automatically generate the corresponding structure element. Next, a link with generic text (“Click here”) is created (lines 79-91). In this case, AltText is set to “Download PDF Specification” to provide necessary context for screen readers. The example also shows how to create an email link (mailto:) with a descriptive tooltip (“Send email to…”) (lines 94-106) and an internal link to another page, where the tooltip explains the destination (lines 109-121).

Run the code #

Run this command to generate the PDF with accessible links.

go run pdf_tag_link_annot.go

Sample output #

The output file will contain links that are properly tagged and have appropriate alternate text and tooltips.