Navigating the document

HtkPDF offers two dedicated tools for moving quickly through a long document: the Outline (the PDF table of contents) and Bookmarks (page markers specific to HtkPDF). Both modules are available from the Reading category of the Dashboard.

The document Outline

The Outline module displays the table of contents embedded in the PDF, as defined by the author of the document. The structure is presented as a hierarchical tree: main chapters can be expanded to reveal their subsections.

Navigating the outline

Click a heading to take the document straight to the corresponding page;
The page number of each entry is shown on the right;
The disclosure arrows control the display depth;
Scrolling the document visually highlights the destination page.

If the PDF contains no outline, a "No table of contents found" message is shown with an explicit icon. You can then generate an outline automatically from the document content.

Generating a structure automatically

The Generate structure (Auto) button runs a twofold analysis of the document:

a heuristic analysis based on formatting (font sizes, styles, visual hierarchy) to reconstruct a hypothetical outline;
a Page titles analysis: it extracts the document's text (with OCR if needed) and keeps, for each page, the first meaningful line as the title, discarding headers that repeat from page to page. It yields one flat entry per page. Neither analysis involves an artificial-intelligence model, and nothing leaves your Mac.

Once generation is finished, the application switches to a comparison view showing both proposals side by side. You can then:

examine each of the proposed structures;
enable the Merge with existing option to add the new headings without erasing the outline already present (if there is one), or leave the option off to replace the current outline entirely;
click Apply Heuristic or Apply page titles to confirm your choice.

The button matching an empty analysis (for example a document with no text, even after OCR) is automatically disabled. Like any editing operation, the new table of contents is recorded as a checkpoint in the history and is only made permanent once the document is saved.

Document Bookmarks

Document bookmarks are personal markers you place on the pages you want to find again quickly. Unlike the Outline, which is defined by the PDF author, bookmarks are specific to HtkPDF and attached to your copy of the document. They do not modify the PDF file itself: they are kept in the application's internal database.

Adding or removing a bookmark

The Bookmarks module shows first an Add Bookmark / Remove Bookmark button, which acts on the page currently being viewed. The button updates automatically according to the state:

empty bookmark icon → the page is not bookmarked: a click adds it;
filled bookmark icon → the page is already bookmarked: a click removes it.

To bookmark another page, navigate to it first (from the control bar, the Outline, or the sidebar), then come back to this module.

Bookmark list

The Your Bookmarks section lists every marker saved for the current document, sorted by ascending page number. Two actions are available for each entry:

Blue arrow: takes the reader straight to the page concerned;
Red bin: deletes that bookmark.

If no bookmark has been saved yet, a "No bookmarks for this document" message is shown.

Bookmark persistence

Bookmarks are stored in each document's record in HtkPDF (the same record that feeds the Recents tab). This means that:

bookmarks persist from one session to the next as long as the document remains in HtkPDF;
they are independent of the original PDF: opening the same file from another location will create a new record without the previous bookmarks;
deleting the document from the Recents tab also deletes its bookmarks.

Note: to export your markers durably into the PDF itself, use the Outline module instead to add those pages to the document's table of contents — that one is embedded in the PDF file and therefore visible to any third-party reader.

Screenshots

2 screenshots — click to enlarge