This is already the second request I know of for displaying images without files on hard-disk.
So maybe it is really time for a feature request at the org-mode mailing list (org-submit-bug-report).
In the question about youtube links user Adam already asked about displaying the preview images of youtube® videos.
I wrote up the package org-yt for the previous request.
Please see my answer to the youtube question for comments about the org-mode internals.
For answering this question I generalized that solution to allow customized data images.
One registers the function that generates the image data from the link as :image-data-fun in org-link-properties.
The registered function takes three arguments:
- the protocol type, e.g.,
img
- the link, e.g., the byte64 encoded data
- the link description
If you are willing to use the new version of package org-yt the following code for your special case is quite short and clear.
(require 'org-yt)
(defun org-inline-data-image (_protocol link _description)
"Interpret LINK as base64-encoded image data."
(base64-decode-string link))
(org-link-set-parameters
"img"
:image-data-fun #'org-inline-data-image)
You can easily add exporters to the link parameters of img with the :export property in the variable org-link-parameters (see the doc of that variable). An example would be an html exporter which just prepends data:image/png;base64, to the image data and embeds that stuff into an img tag.
Avoiding citations as solutions I also post a self-contained solution here. You can avoid pulling in the youtube stuff by using the following code.
UPDATE: The full code contains now a function org-download-screenshot-img for yanking image files from the clipboard. It is bases on org-download.el. So you need that package to make it work.
The function org-download-screenshot-img is bound to S-C-y in org-mode at the end of the code.
(require 'org)
(require 'org-element)
(require 'subr-x) ;; for when-let
(defun org-image-update-overlay (file link &optional data-p refresh)
"Create image overlay for FILE associtated with org-element LINK.
If DATA-P is non-nil FILE is not a file name but a string with the image data.
If REFRESH is non-nil don't download the file but refresh the image.
See also `create-image'.
This function is almost a duplicate of a part of `org-display-inline-images'."
(when (or data-p (file-exists-p file))
(let ((width
;; Apply `org-image-actual-width' specifications.
(cond
((not (image-type-available-p 'imagemagick)) nil)
((eq org-image-actual-width t) nil)
((listp org-image-actual-width)
(or
;; First try to find a width among
;; attributes associated to the paragraph
;; containing link.
(let ((paragraph
(let ((e link))
(while (and (setq e (org-element-property
:parent e))
(not (eq (org-element-type e)
'paragraph))))
e)))
(when paragraph
(save-excursion
(goto-char (org-element-property :begin paragraph))
(when
(re-search-forward
"^[ \t]*#\\+attr_.*?: +.*?:width +\\(\\S-+\\)"
(org-element-property
:post-affiliated paragraph)
t)
(string-to-number (match-string 1))))))
;; Otherwise, fall-back to provided number.
(car org-image-actual-width)))
((numberp org-image-actual-width)
org-image-actual-width)))
(old (get-char-property-and-overlay
(org-element-property :begin link)
'org-image-overlay)))
(if (and (car-safe old) refresh)
(image-refresh (overlay-get (cdr old) 'display))
(let ((image (create-image file
(and width 'imagemagick)
data-p
:width width)))
(when image
(let* ((link
;; If inline image is the description
;; of another link, be sure to
;; consider the latter as the one to
;; apply the overlay on.
(let ((parent
(org-element-property :parent link)))
(if (eq (org-element-type parent) 'link)
parent
link)))
(ov (make-overlay
(org-element-property :begin link)
(progn
(goto-char
(org-element-property :end link))
(skip-chars-backward " \t")
(point)))))
(overlay-put ov 'display image)
(overlay-put ov 'face 'default)
(overlay-put ov 'org-image-overlay t)
(overlay-put
ov 'modification-hooks
(list 'org-display-inline-remove-overlay))
(push ov org-inline-image-overlays)
ov)))))))
(defun org-display-user-inline-images (&optional _include-linked _refresh beg end)
"Like `org-display-inline-images' but for image data links.
_INCLUDE-LINKED and _REFRESH are ignored.
Restrict to region between BEG and END if both are non-nil.
Image data links have a :image-data-fun parameter.
\(See `org-link-set-parameters'.)
The value of the :image-data-fun parameter is a function
taking the PROTOCOL, the LINK, and the DESCRIPTION as arguments.
If that function returns nil the link is not interpreted as image.
Otherwise the return value is the image data string to be displayed.
Note that only bracket links are allowed as image data links
with one of the formats [[PROTOCOL:LINK]] or [[PROTOCOL:LINK][DESCRIPTION]] are recognized."
(interactive)
(when (and (called-interactively-p 'any)
(use-region-p))
(setq beg (region-beginning)
end (region-end)))
(when (display-graphic-p)
(org-with-wide-buffer
(goto-char (or beg (point-min)))
(when-let ((image-data-link-parameters
(cl-loop for link-par-entry in org-link-parameters
with fun
when (setq fun (plist-get (cdr link-par-entry) :image-data-fun))
collect (cons (car link-par-entry) fun)))
(image-data-link-re (regexp-opt (mapcar 'car image-data-link-parameters)))
(re (format "\\[\\[\\(%s\\):\\([^]]+\\)\\]\\(?:\\[\\([^]]+\\)\\]\\)?\\]"
image-data-link-re)))
(while (re-search-forward re end t)
(let* ((protocol (match-string-no-properties 1))
(link (match-string-no-properties 2))
(description (match-string-no-properties 3))
(image-data-link (assoc-string protocol image-data-link-parameters))
(el (save-excursion (goto-char (match-beginning 1)) (org-element-context)))
image-data)
(when (and el
(eq (org-element-type el) 'link))
(setq image-data
(or (let ((old (get-char-property-and-overlay
(org-element-property :begin el)
'org-image-overlay)))
(and old
(car-safe old)
(overlay-get (cdr old) 'display)))
(funcall (cdr image-data-link) protocol link description)))
(when image-data
(let ((ol (org-image-update-overlay image-data el t t)))
(when (and ol description)
(overlay-put ol 'after-string description)))))))))))
(advice-add #'org-display-inline-images :after #'org-display-user-inline-images)
(defun org-inline-data-image (_protocol link _description)
"Interpret LINK as base64-encoded image data."
(base64-decode-string link))
(org-link-set-parameters
"img"
:image-data-fun #'org-inline-data-image)
(require 'org-download)
(defun org-download-screenshot-img ()
"Capture screenshot and insert img link with base64 encoded data."
(interactive)
(let ((file (expand-file-name org-download-screenshot-file)))
(shell-command (format org-download-screenshot-method file))
(insert "[[img:"
(with-temp-buffer
(let ((coding-system-for-read 'no-conversion))
(insert-file-contents file)
(base64-encode-region (point-min) (point-max) t)
(buffer-string)))
"]]"))
(org-display-user-inline-images))
(defun org-activate-yank-img-links ()
"Activate keybinding S-C-y for yanking [[img:...]] links in function `org-mode'.
Hook this function into `org-mode-hook'."
(org-defkey org-mode-map (kbd "S-C-y") #'org-download-screenshot-img))
(add-hook 'org-mode-hook #'org-activate-yank-img-links)
I've tested the code with
emacs -q avoiding other customizationpackage-initialize to use the newer org-version 9.1.6 installed on my computeremacs-version 25.1.50.2
Next there follows an example org-mode file that works for me with the above Lisp code.
#+ATTR_ORG: :width 100
[[img:iVBORw0KGgoAAAANSUhEUgAAACUAAAAuCAAAAACKMo8cAAACmElEQVR4nIXUW0iUQRjG8f+uq2ZK
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1RkGC9pmQeZ+VYfFNc6G9B8xtL2tqj3MQgAAAABJRU5ErkJggg==]]
