qpdf.el

Installation

qpdf.el is a transient Emacs wrapper for qpdf.

To use it you hence need Emacs, transient, and qpdf. Transient may be installed from ELPA or its Github repo, but you likely already have it as it comes as a Magit dependency. Linux and Windows binaries for qpdf are available here; a homebrew formula for macOS is here.

To install qpdf.el itself and set it up with straight.el the following can be used:

(use-package qpdf.el
  :straight (:host github :repo "orgtre/qpdf.el")
  :commands qpdf)

Features

qpdf.el provides the Emacs command qpdf, which brings up a transient menu through which arguments in a call to the powerful qpdf shell command can be quickly specified.

Examples of what is possible:

• Through the --pages argument, pages from one pdf file can be flexibly removed or reordered, and pages from several different pdf files can be merged in any order.
• The --flatten-annotations argument gives control over which annotations are visible in the output.
• Any qpdf command-line arguments not specifically exposed through qpdf.el can be entered via the --custom argument. Note that transient automatically saves per-argument (infix) history, so anything entered here will by default be saved. This is especially useful when combined with a completion framework.

See the qpdf documentation, which can be shown by using the qpdf-docs command, for a list of all available arguments and syntax details.

When the command qpdf is invoked from a buffer in doc-view-mode or pdf-tools’ pdf-view-mode, the default infile is set to the current file, the default outfile is set based on the current file, presets for pages are shown based on the current page, and the outfile is opened in Emacs.

Customization

Flexible customization options exist – see the source code or customization group qpdf.el. For example, to change key bindings and control which commands are shown in the qpdf transient, qpdf-prefix-groups can be edited.

It is also possible to make use of transients built-in customization methods. When the qpdf transient is active, C-x l (transient-set-level) can be used to set the level of each argument/command. By default only those with level 4 or larger are shown. See this section of the transient manual.

Transient also provides several functions to modify existing transients non-interactively. For example, (transient-insert-suffix 'qpdf "c" '("l" "" "--linearize")) inserts the --linearize argument before the --custom argument, while the following inserts a group of “Transformation” options after the second group in the qpdf transient and hides this group unless t is pressed:

(transient-append-suffix 'qpdf '(1)
  ["Transformation"
   :hide (lambda ()
           (not (eq (car transient--redisplay-key)
                    ?t)))
   ("t l" "" "--linearize")
   ("t r" "" "--remove-unreferenced-resources")])

The command qpdf passes the arguments it receives through the transient menu on to the command qpdf-run. By passing suitable arguments directly to qpdf-run, even more convenient custom commands to for example delete the current page, rotate the current page, en/decrypt a file, etc. can quickly be created. See the docstring of qpdf-run. An example is:

(defun qpdf-delete-current-page ()
  "Delete the current page of pdf file."
  (interactive)
  (unless (or (equal major-mode 'doc-view-mode)
	      (equal major-mode 'pdf-view-mode))
    (error "Buffer should visit a pdf file in doc-view-mode or pdf-view-mode."))
  (qpdf-run (list
	     (concat "--pages="
		     (qpdf--read-pages-with-presets nil nil nil
						    'except-current))
	     (concat "--infile="
		     (buffer-file-name))
	     "--replace-input")))