WebLink property

WebLink returns a TWebLink record for the URL detected at the specified 1-based PageNumber and 0-based Index. The record contains the Url string (typically http://, https://, or mailto:) and a Rectangles array of TPdfRectangle bounding boxes — one rectangle per visual line, since PDFium reports separate rectangles when a single URL wraps onto multiple lines.

Index ranges from 0 to WebLinkCount[PageNumber] - 1. Outside that range PDFium returns an empty record (Url is empty, Rectangles is nil). Web link detection runs lazily on the first read for a given page and is cached until the page is reloaded; reading WebLink itself is O(1) after the scan completes.

WebLink complements LinkAnnotation, which surfaces explicit /Link annotations declared by the PDF author. Use the rectangles to build click-through overlays on a custom renderer, or to highlight URLs in extracted text. The data is read-only — PDFiumVCL exposes detection results, not modification primitives. To insert real link annotations, use the FPDFPage_CreateAnnot path on the underlying Page handle.

• The rectangle coordinates are in PDF user space — transform through TPdfView.PageToScreen to overlay HTML or other widgets.
• Only text-based URLs are detected. Images that visually depict a URL do not register unless their underlying text has been OCR’d into the page.
• For unified click handling (annotations + auto-detected URLs), wire both TPdfView.OnAnnotationLinkClick and TPdfView.OnWebLinkClick.