Re: Displaying remote images

[Jack Kamm <jackkamm@gmail.com>]

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I've attached a patch which implements displaying remote images.

> This is a longstanding problem, and there was an attempt to patch it in
> 2014, but the patch was never accepted:
> https://lists.gnu.org/archive/html/emacs-orgmode/2014-11/msg00583.html

Compared to the previous attempt from 2014, I think my patch is simpler
-- it doesn't require creating any temp files.

> The fault might be with image.el rather than with org-mode itself --
> for example, when I execute the following elisp, I get the same blank
> box:

After doing some reading, I learned that image.el doesn't really create
the image. Instead, create-image simply creates a blank string with a
text property pointing to the image file location, and the rendering of
the image gets handled later by the C code (for example, png_load_body()
in image.c), which doesn't know how to read remote image files.

Since I wasn't comfortable trying to get the C code to read the remote
file, I instead took the approach used by image-mode.el, which reads the
remote image file and passes its contents directly to create-image,
instead of just passing the filename.


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From 47120666dad6eb0b6ca716325d7de86924e1d28e Mon Sep 17 00:00:00 2001
From: Jack Kamm <jackkamm@gmail.com>
Date: Thu, 28 Nov 2019 17:45:56 -0800
Subject: [PATCH] org: display remote images

---
 lisp/org.el | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/lisp/org.el b/lisp/org.el
index 90f222c8b..dc7bcc7aa 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -16754,13 +16754,20 @@ buffer boundaries with possible narrowing."
 			    (t nil)))
 			  (old (get-char-property-and-overlay
 				(org-element-property :begin link)
-				'org-image-overlay)))
+				'org-image-overlay))
+			  (remote-p (file-remote-p file)))
 		      (if (and (car-safe old) refresh)
 			  (image-refresh (overlay-get (cdr old) 'display))
-			(let ((image (create-image file
+			(let ((image (create-image (if (not remote-p)
+						       file
+						     (with-temp-buffer
+						       (insert-file-contents file)
+						       (string-make-unibyte
+							(buffer-substring-no-properties
+							 (point-min) (point-max)))))
 						   (and (image-type-available-p 'imagemagick)
 							width 'imagemagick)
-						   nil
+						   remote-p
 						   :width width)))
 			  (when image
 			    (let ((ov (make-overlay
-- 
2.24.0