Outlines

Outlines are what a PDF viewer shows as bookmarks: a tree of titles, each pointing at a place in the document. UniPDF models them at two levels. PdfOutlineTreeNode is the PDF structure itself, a doubly linked list of siblings with parent and child pointers. model.Outline and model.OutlineItem are the high-level view: a slice of entries, each with a title, a destination, and its own entries. Work with the high-level types and let ToOutlineTree build the linked list.

outline := model.NewOutline()
outline.Add(model.NewOutlineItem("Chapter 1", model.NewOutlineDest(0, 0, 792)))

pdfWriter.AddOutlineTree(outline.ToOutlineTree())

The Outline container holds only its top level entries. Everything else belongs to the item: its title, its destination, and its children. There is no separate node type for a nested bookmark, so the structure is uniform however deep it goes.

A destination is an OutlineDest with a page index, a mode and up to three coordinates. The page index is zero-based. The mode is the PDF destination type, XYZ for an explicit position and the Fit variants for viewer-chosen zoom, and it determines which coordinates are used.

Both types carry JSON tags, which is what makes the outlines of a document portable: read them, marshal to a file, edit it, apply it to another document. That round trip is what the two guides below cover.

Where to look

An outline is navigation metadata and is not drawn on the page. If you want a visible, clickable table of contents in the page content, that is the creator package’s table of contents rather than an outline.