[PATCH]

[Timothy <tecosaur@gmail.com>]

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Hi Everyone,

I’ve recently been wondering why it is that for sensibly sized images in a
LaTeX-export-oriented document I need to do both:
┌────
│ #+attr_org: :width 400
│ #+attr_latex: :width 0.4\linewidth
└────

When in HTML, just
┌────
│ #+attr_html: :width 400px
└────
is fine.

This has lead me to have a look at `org-display-inline-images', and I’ve realised
that the `#+attr_latex' width of `0.4\linewidth' is actually picked up, and
interpreted as a width of `0.4' pixels. I think it would make much more sense for
fractional values between zero and one to be interpreted as that portion of the
text width in the buffer. On second thoughts, given that the document width can
be slightly larger than the text width, perhaps an upper bound just a bit higher
— say 2, could be better.

I’ve prepared a patch which implements this logic, by converting extracted
widths that are:
⁃ floats, and
⁃ within the range [0,2]
and sizes them as that proportion of the text width in the buffer, which is
determined by checking
1. `visual-fill-column-width', when that package is installed and the mode active
2. `fill-column', when auto fill is active
3. `(window-text-width)', if neither of the above two cases hold

Please let me know what you think 🙂.

All the best,
Timothy

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From bc8aa862f513946599efe4a9bb420e54c504ab3b Mon Sep 17 00:00:00 2001
From: TEC <tec@tecosaur.com>
Date: Fri, 24 Sep 2021 01:39:31 +0800
Subject: [PATCH] org: Display proportional image widths

* lisp/org.el (org-display-inline-images): When the image width is given
as a float less than 2, interpret the value as that portion of the text
area width.  This works well with cases such as "#+attr_latex: :width
0.6\linewidth" as this will now be interpreted as 60% of the text area
width.  The upper bound is set to 2 not 1, as more than 100% of the text
width can be realistic, e.g. "1.2\linewidth" in LaTeX, but more than
200% seems unrealistic.
---
 lisp/org.el | 47 +++++++++++++++++++++++++++++++----------------
 1 file changed, 31 insertions(+), 16 deletions(-)

diff --git a/lisp/org.el b/lisp/org.el
index 66ca73d5e..ce2ac7404 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -16622,22 +16622,37 @@ (defun org-display-inline-images (&optional include-linked refresh beg end)
 			   (cond
 			    ((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.
-			      (pcase (org-element-lineage link '(paragraph))
-				(`nil nil)
-				(p
-				 (let* ((case-fold-search t)
-					(end (org-element-property :post-affiliated p))
-					(re "^[ \t]*#\\+attr_.*?: +.*?:width +\\(\\S-+\\)"))
-				   (when (org-with-point-at
-					     (org-element-property :begin p)
-					   (re-search-forward re end t))
-				     (string-to-number (match-string 1))))))
-			      ;; Otherwise, fall-back to provided number.
-			      (car org-image-actual-width)))
+                             (let ((width
+                                    (or
+                                     ;; First try to find a width among
+                                     ;; attributes associated to the paragraph
+                                     ;; containing link.
+                                     (pcase (org-element-lineage link '(paragraph))
+                                       (`nil nil)
+                                       (par (let* ((case-fold-search t)
+                                                   (end (org-element-property :post-affiliated par))
+                                                   (re "^[ \t]*#\\+attr_.*?: +.*?:width +\\(\\S-+\\)"))
+                                              (when (org-with-point-at
+                                                        (org-element-property :begin par)
+                                                      (re-search-forward re end t))
+                                                (string-to-number (match-string 1)))))))
+                                    ;; Otherwise, fall-back to provided number.
+                                    (car org-image-actual-width))))
+                               (when width
+                                 (if (and (floatp width) (<= 0 width 2.0))
+                                     ;; A float in [0,2] should be interpereted as this portion of
+                                     ;; the text width in the window.  This works well with cases like
+                                     ;; #+attr_latex: :width 0.X\{line,page,column,etc.}width,
+                                     ;; as the "0.X" is pulled out as a float.  We use 2 as the upper
+                                     ;; bound as cases such as 1.2\linewidth are feasible.
+                                     (round (* width
+                                               (window-pixel-width)
+                                               (/ (or (and (bound-and-true-p visual-fill-column-mode)
+                                                           (or visual-fill-column-width auto-fill-function))
+                                                      (when auto-fill-function fill-column)
+                                                      (window-text-width))
+                                                  (float (window-total-width)))))
+                                   width))))
 			    ((numberp org-image-actual-width)
 			     org-image-actual-width)
 			    (t nil)))
-- 
2.33.0