PDFs are a very common format, from academia and online bill payments to equipment manuals. Fortunately, they are first-class citizens that can be viewed and annotated within DEVONthink. The annotation tools should be familiar and include options like arrows, text, and link annotations. While DEVONthink may not have some options found in specialized PDF applications, it is still a very capable PDF tool.

Beyond importing and indexing, PDF files can also be created by capturing web content, directly in DEVONthink or via our browser extension, Clip to DEVONthink. You can also print a paginated PDF with the Save PDF to DEVONthink in the PDF dropdown of the print dialogs of most macOS applications.

PDFs often come directly from text sources, like word processing or page layout applications. The content of these files should be indexed and searchable when added to your database. But there are also times when a PDF only contains pages of images, e.g., PDFs made from scans of old books. In a process similar to Apple's Live Text, DEVONthink will detect and index the text transparently, allowing you to search for these documents. However, you will not be able to use the Search inspector and see occurrences of search terms in the found documents as there is no actual text layer present.

Pro

OCR: Even if PDF text is detected internally, we strongly recommend you use OCR to create properly searchable documents. OCR adds a text layer to the document, allowing search hits to be shown in the Search inspector. That text layer is a permanent part of the document, so it is preserved when using it outside of our application, or even across platforms. For scanned PDFs without a text layer, you can do OCR directly in DEVONthink when needed.

Viewing PDFs: When you view a PDF it will display as single or two side-by-side pages. Choose the desired option in the View > PDF Display options. When the document opens, the pages are viewed as the entire page or magnified to the width of the view/edit pane. You can choose how the document is displayed in the View > Zoom submenu. If you'd like to always view PDFs with a specific Zoom option, you can set a default in the Files > Multimedia > PDF Display preferences. Enable Automatically resize then choose a single or double page option. The Zoom option used is controlled as shown below:

- Continuous: Zoom to Width
- Non-Continuous: Zoom to Fit

## Interface

Navigation Bar: Not only containing the typical properties like word count, with PDFs the Navigation bar shows the current page folio along side the total number of pages in the document. Clicking on this navigation bar item opens a Go to page function so you can quickly jump to a specific page. In addition, there are buttons to move to the first, previous, next, or last page. Also, you will see an icon if the document is encrypted. Also, if the document is read-only and cannot be edited, for whatever reason, you will see this icon.

Editing Bar: The navigation bar for PDF files includes the Editing Bar, providing access to editing and annotation tools. Click this and the editing bar will replace the navigation bar. You can also access them in the Tools > Annotate menu. The available tools are:

- Select text for copy or highlighting.
- Select annotations on the page. Double-click an annotation to edit its properties. Press the `⌦︎` Delete key to remove the annotation.
- Move or scroll the current page.
- Underline selected text in the document.
- Strike through selected text in the document.
- Apply or remove highlighting on selected text. The highlight color will be the color selected in Format > Highlight Color. Alternately, click and hold to select another color.
- Add a link to a selected area. Click and drag over an area to establish a hotspot for the link to be active. For the Link Type, choose Link within PDF, navigate to another page and click Set to create a link between pages within the same PDF. Alternatively, choose URL and enter a URL to an external item. This can be a web site address, or drag files from the Finder or your DEVONthink databases into this field.
- Add a rectangle annotation.
- Add an oval annotation.
- Add a line annotation.
- Add a note annotation.
- Add a text annotation. Drag to create a text box. To change the font, choose Format > Font > Show Fonts.. Note only one font can apply to each text annotation.
- Rotate the current page left (counter-clockwise).
- Rotate the current page right (clockwise).
- Add a new blank page before the current page.
- Delete the current page.
- Reverse the page order of the document.

When using certain annotation tools, e.g., Note or Link annotations, the Annotations panel will open. You can set type-specific properties in this panel. The settings here will be retained for subsequent uses of each type of annotation.

Context Menu: In addition to many common context menu items, there are also a few PDF-specific commands:

- Add to Reading List/Favorites: Add the current page to the Reading List sidebar or the Favorites section of the Navigate sidebar.
- Add to Table of Contents: Adds the current page as a bookmark to the Table of Contents. This command is also available in the Document > Thumbnails inspector.
- Automatically Resize: When checked, the zoom factor adjusts to the width of the view/edit pane or document window.
- Delete Annotation: Deletes the selected annotations.
- Single Page/Two Page (Continuous): Displays the PDF as single or double pages. Use the Continuous option to allow quick scrolling through the pages as one continuous document.
- Previous/Next Page: Jumps to the previous or next page.
- Rotate Left/Right: Rotates the current page 90 degrees in the selected direction.
- Insert Blank Page: Insert a new blank page before the current page.
- Delete Page: Delete the current page.
- Reverse Page Order: Reverses the order of the pages in the entire document.

Inspectors: There are a few inspector panes with information specifically pertaining to PDF documents: Info > Properties, Content inspectors, and Document > Annotations.

- Properties: The Properties inspector displays PDF metadata from some third-party applications, e.g., Adobe Acrobat. It will display things like a title, copyright, author, and keywords, if available.
- Content: The Table of Contents inspector displays a PDF's table of contents, if one exists. You can navigate through the document with the section markers in it. The Thumbnails inspector displays page thumbnails of the PDF currently displayed in the view/edit pane. You can navigate the document via the thumbnails. You can also drag to rearrange the pages or even drag them out of the inspector to export them. Alternately, drag other PDFs into the inspector to merge one document into another. Commands for deleting or inserting blank pages are found in the Tools > PDF submenu. And the Split Document command becomes available in the Tools and context menus when you've selected a page thumbnail.
- Document: If you are annotating your PDFs, the Document > Annotations inspector is where you can see and manage the document's annotations. Edits made with the annotation tools mentioned above will appear here. You can also selectively delete annotations in this inspector. While not specific to just PDFs, the Document > Links inspector displays links detected in the content.

## Item Linking

In addition to the document's standard item link, PDF documents support these alternative item links:

- Page Link: Links to the current page.
- Selection Link: Links to selected text.
- Annotation Link: Links to a selected annotation.

Alternate item links are available in the context menu in the view/edit pane or the Thumbnails inspector. The alternate links are also accessible when holding the `⇧︎` Shift key while viewing the Edit menu.