Image tooltips with pdf

Question

I want the image tooltip code also make work for pdf format, thus I added the pdf keyword to the file extension list of the original code (http://kitchingroup.cheme.cmu.edu/blog/2016/03/21/Displaying-image-overlays-on-image-filenames-in-Emacs/#sec-1)). However it doesn't work with pdf. How can I make this work?

(defvar image-tooltip-re (concat  "\\(?3:'\\|\"\\)\\(?1:.*\\."
                                  (regexp-opt '("png" "PNG" "JPG" "jpeg"
                                                "jpg" "JPEG" "eps" "EPS" "pdf"))
                                  "\\)\\(?:\\3\\)")
  "Regexp to match image filenames in quotes")

(defun image-tooltip (window object position)
  (save-excursion
    (goto-char position)
    (let (beg end imgfile img s)
      (while (not (looking-at image-tooltip-re))
        (forward-char -1))
      (setq imgfile (match-string-no-properties 1))
      (when (file-exists-p imgfile)
        (setq img (create-image (expand-file-name imgfile)
                                'imagemagick nil :width 200))
        (propertize "Look in the minibuffer"
                    'display img)))))

(font-lock-add-keywords
 nil
 `((,image-tooltip-re
    0 '(face font-lock-keyword-face
             help-echo image-tooltip))))

(font-lock-fontify-buffer)
(setq x-gtk-use-system-tooltips nil)

"tikz-standalone.pdf"

I think the imagemagick backend should support it, for example I can do display file.pdf from command line.

Answer 1

Imagemagick seems to be able to render PDF files, though apparently it is very slow.

Also, hovering the mouse over a filename calls the original image-tooltip about a dozen times, making things even worse. A solution could be to immediately put the image as a help-echo property, see below.

(defvar image-tooltip-regexp (concat  "\\(?3:'\\|\"\\)\\(?1:.*\\.\\(?2:"
                                      (regexp-opt '("png" "jpeg" "jpg" "eps" "pdf"))
                                      "\\)\\)\\(?:\\3\\)"))

(defvar image-tooltip-width 200)

(defun image-tooltip-fontify (&optional limit)
  (while (re-search-forward image-tooltip-regexp nil t)
    (let* ((imgfile (expand-file-name (match-string-no-properties 1)))
           (imgtype (intern (downcase (match-string-no-properties 2))))
           (data-p (and (eq imgtype 'pdf)
                        (require 'pdf-tools nil t)))
           (data-or-file (if data-p
                             (pdf-info-renderpage 1 image-tooltip-width imgfile)
                           imgfile)))
      (when (file-exists-p imgfile)
        (with-silent-modifications
          (put-text-property
           (match-beginning 0)
           (match-end 0)
           'help-echo
           (propertize " " 'display
                       (create-image
                        data-or-file
                        'imagemagick
                        data-p
                        :width image-tooltip-width))))))))

(font-lock-add-keywords nil
  `((image-tooltip-fontify)))

(font-lock-fontify-buffer)
(setq x-gtk-use-system-tooltips nil)

Answer 2

pdf is probably not a supported image type for create-image. You probably have to run a command to convert the pdf to a temporary png file (eg. convert some.pdf temp.png), and use the temporary png file in the create-image function.