Links module: adding and managing hyperlinks

The Link module lets you turn a portion of text into a clickable area that opens either a web page or another page of the document. Like ordinary annotations, links are stored in the standard PDF format and will keep working in any third-party reader. The module is available from the Editing category of the Dashboard.

How to use it

Creating a link always follows the same sequence:

1. Select text directly in the PDF view on the left, by dragging the cursor. The clickable area will follow the selection line by line;
2. Choose the link type (external URL or internal page);
3. Fill in the destination;
4. Choose the border color (optional);
5. Click Create link.

The Create link button is disabled as long as no selection is active or the destination entered is not valid. When no selection is in progress, a "No active selection" message is shown in orange under the button.

Link type

The Link type segmented selector offers two choices:

Website

To point to an external URL (web page, hosted document, online file, mailto: email address, and so on). An URL address field appears, with the example https://example.com.

HtkPDF completes the prefix automatically: if you type example.com without http:// or https://, the application adds https:// at creation time. For mailto: URLs or particular protocols, enter the complete address.

Document page

To point to another page of the same PDF. A Page number field appears, along with an indication of the total number of pages available. The link takes the reader to the top of the requested page.

The destination is limited to existing pages: an out-of-bounds number triggers an "Invalid page number" message at creation time.

Border color

Four border choices are offered:

• Blue (default);
• Red;
• Green;
• Transparent: the clickable area stays invisible — useful so as not to disturb the layout of an elegant document while keeping the interactivity.

The colored border frames each line of the selection. For text spanning several lines, several distinct frames are created so as to respect the text layout.

Behaviour and storage

• The link is attached to the geometric area of the selected text, not to the text itself. If the text is later modified or the page cropped, the link may end up offset from its visual target;
• Several links can coexist on the same page; they do not interfere with each other;
• Links already present in the PDF (for example generated from a word processor) are kept intact.

Confirming and history

Like the other annotations, each link creation:

• can be undone immediately through the Undo button at the top of the sidebar;
• creates a checkpoint in the History when you confirm with Apply — Back discards the links you created;
• stays in pending changes until it is explicitly saved from the Dashboard (⌘S).

Editing or deleting a link

The module does not (for now) offer an editable list of existing links. To remove a link:

1. Click the link's border in the PDF view to select it;
2. Press the Delete key to remove it.

To change the destination of an existing link, delete it and then create a new one at the same position.

Tip: to create a purely informative link ("click here to open the official site") without changing the appearance of the text, use the Transparent border and keep the original formatting. The cursor will still turn into a hand on hover — the user will know it is a link.

Known limitations

• Internal links always point to the top of the destination page, and not to a precise location within the page. For fine cross-references (to a figure, to a specific section), consider using the table of contents through the Outline module instead.
• Editing existing links (changing the destination) is not exposed in the interface: they have to be deleted and recreated.

Screenshots

1 screenshot — click to enlarge

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