This is a dynamic module for Emacs, built with Rust using the emacs crate. The objective of this module is to allow one to open specific pages of a PDF from a link in Org-mode.
First make sure your Emacs was built with dynamic module support.
You can compile the shared object library from source using cargo build --release, in which case it will be located in ./target/release with the name libemacs_open_pdf.so. Because the module name exposed to Emacs is actually open-pdf, if you want Emacs to auto-discover the file from a loaded path you can either create a symlink (e.g. ln -s libemacs_open_pdf.so open-pdf.so) or simply rename the file to the correct name (e.g. mv libemacs_open_pdf.so open-pdf.so).
Alternatively you may download a pre-compiled binary from releases.
When attempting to load the module, make sure Org-mode loads before it, as this module uses an Org-mode specific function ('org-open-file). For example, you can simply (require 'org) before loading this module as shown below.
Then you may load the module, wrap it with an interactive function, and bind that to some key combination (e.g. C-c f) as shown below:
(require 'open-pdf "/absolute/path/to/file/open-pdf.so")
(defun open-pdf-wrapper ()
(interactive)
(open-pdf-from "/absolute/path/to/storage/dir" (thing-at-point 'line)))
(define-key org-mode-map "\C-cf" 'open-pdf-wrapper)where the given storage directory is assumed to contain a directory called bibtex-pdfs, where your PDFs are contained, and a directory called tmp, where a temporary PDF file will be created with only the requested pages (see example).
It is necessary to wrap the module function open-pdf-from into another function because it is not interactive and would not have access to calls to thing-at-point, which is desirable for opening links at the cursor.
Example notes.org:
* recipes
** favorites
*** [[#my_recipe_book][p53+4]], dumplings, [[https://www.sauce.com][sauce to go with]]
where our desired link is [[#my_recipe_book][p53+4]] and my_recipe_book.pdf is in bibtex-pdfs.
When you press the configured key combination (e.g. C-c f) on the line containing the desired link, a PDF with the specified pages (e.g. page 53 plus 4 pages) should open with whatever program was configured for opening PDF files in Org.