Feature Request: Allow customization to open images in external viewer.

[michelk]

Images associated with image links may be displayed inline in the buffer. This is not possible when not using a GUI (emacsclient). C-c C-0 then opens a useless text version.

It should be possible to define an external program like eog to open the image. In org-mode this is done by defining (add-to-list 'org-file-apps '("\\.png\\'" . "eog %s"))

It would be great, if this would also be possible in markdown-mode.

Issue first raised in syl20bnr/spacemacs#11973

[saf-dmitry]

@michelk For the time being you can delegate opening external Markdown links to Org mode by using the following command, which you can bind to C-c C-o or another suitable key combination:

(defun markdown-org-follow-link-at-point ()
  "Open external Markdown link as if it was in Org mode.
See variable `org-file-apps' for setting external applications
for opening links in a document."
  (interactive)
  (if (and (markdown-link-p)
           (not (string-prefix-p "#" (markdown-link-url))))
      (org-open-link-from-string (format "[[%s]]" (markdown-link-url)))
    (user-error "Point is not at an external Markdown link or URL")))

[syohex]

I have merged #467. Please check latest version and set markdown-open-image-command customize variable