Re: [PATCH] Fix regex for determining image width from attribute

[Matt Huszagh <huszaghmatt@gmail.com>]

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Max Nikulin <manikulin@gmail.com> writes:

> This is related solely to docscring.
>
>> +that is not found, use the first #+ATTR_.*:width specification.
>
> I am unsure how to make this phrase more clear, maybe something like
> "use :width value from the first #+ATTR_,*" or even "#+ATTR_xxx" to 
> avoid ".*".
>
>> +                                 (re-search-forward (funcall attr-re "[a-z]*?")
>> +                                                    par-end t))))
>
> https://orgmode.org/worg/dev/org-syntax.html#Keywords
> has no requirement that it may be letter only. I expect it to be more 
> coherent with
> http://git.savannah.gnu.org/cgit/emacs/org-mode.git/tree/lisp/org-element.el#n2387
> that uses "\\S-" non-space character.

Better?

Matt


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From 73f6d6d0c16d9b3312737463361cefe08b01d35c Mon Sep 17 00:00:00 2001
From: Matt Huszagh <huszaghmatt@gmail.com>
Date: Mon, 22 Nov 2021 23:28:48 -0800
Subject: [PATCH 1/2] org.el: Prioritize attr_org when computing image width

	* lisp/org.el (org-display-inline-image--width): First look
	for attr_org: :width and then look for another attr_.* :width
	when that isn't specified.
---
 lisp/org.el | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/lisp/org.el b/lisp/org.el
index 308bb7d51..3718d3118 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -16853,13 +16853,20 @@ buffer boundaries with possible narrowing."
    ((listp org-image-actual-width)
     (let* ((case-fold-search t)
            (par (org-element-lineage link '(paragraph)))
-           (attr-re "^[ \t]*#\\+attr_.*?: +.*?:width +\\(\\S-+\\)")
+           (attr-re (lambda (backend)
+                      (concat "^[ \t]*#\\+attr_"
+                              backend
+                              ":+.*? :width +\\(\\S-+\\)")))
            (par-end (org-element-property :post-affiliated par))
-           ;; Try to find an attribute providing a :width.
+           ;; If an attr_org provides a :width, use that. Otherwise,
+           ;; use the first attribute that provides it, if any.
            (attr-width
             (when (and par (org-with-point-at
                                (org-element-property :begin par)
-                             (re-search-forward attr-re par-end t)))
+                             (or (re-search-forward (funcall attr-re "org")
+                                                    par-end t)
+                                 (re-search-forward (funcall attr-re "\\S-+?")
+                                                    par-end t))))
               (match-string 1)))
            (width
             (cond
-- 
2.31.1


From 76e92428716f2dcde0fbd281f71739c44a9be9d3 Mon Sep 17 00:00:00 2001
From: Matt Huszagh <huszaghmatt@gmail.com>
Date: Mon, 22 Nov 2021 23:30:11 -0800
Subject: [PATCH 2/2] org.el: Clarify documentation for computing image width

	* lisp/org.el (org-display-inline-image--width)
	(org-image-actual-width): Specify documentation for computing
	an inline image width in org-image-actual-width and remove the
	redundant documentation from org-display-inline-image--width.
---
 lisp/org.el | 38 ++++++++++++++++++++++++--------------
 1 file changed, 24 insertions(+), 14 deletions(-)

diff --git a/lisp/org.el b/lisp/org.el
index 3718d3118..b050cb0dd 100644
--- a/lisp/org.el
+++ b/lisp/org.el
@@ -15529,10 +15529,29 @@ When set to a number in a list, try to get the width from any
 
 and fall back on that number if none is found.
 
-When set to nil, try to get the width from an #+ATTR.* keyword
-and fall back on the original width if none is found.
-
-When set to any other non-nil value, always use the image width.
+When set to nil, first try to get the width from #+ATTR_ORG.  If
+that is not found, use the first #+ATTR_xxx :width specification.
+If that is also not found, fall back on the original image width.
+
+Finally, org is quite flexible in the width specifications it
+supports and intelligently interprets width specifications for
+other backends when rendering an image in an org buffer.  This
+behavior is described presently.
+
+1. A floating point value is interpreted as the percentage of the text
+   area that should be taken up by the image.
+2. A number followed by a percent sign is divided by 100 and then
+   interpreted as a floating point value.
+3. If a number is followed by other text, extract the number and
+   discard the remaining text.  That number is then interpreted as a
+   floating-point value.  For example,
+
+   #+ATTR_LATEX: :width 0.7\\linewidth
+
+   would be interpreted as 70% of the text width.
+4. If t is provided the original image width is used.  This is useful
+   when you want to specify a width for a backend, but still want to
+   use the original image width in the org buffer.
 
 This requires Emacs >= 24.1, built with imagemagick support."
   :group 'org-appearance
@@ -16838,16 +16857,7 @@ buffer boundaries with possible narrowing."
 (defvar visual-fill-column-width) ; Silence compiler warning
 (defun org-display-inline-image--width (link)
   "Determine the display width of the image LINK, in pixels.
-- When `org-image-actual-width' is t, the image's pixel width is used.
-- When `org-image-actual-width' is a number, that value will is used.
-- When `org-image-actual-width' is nil or a list, the first :width attribute
-  set (if it exists) is used to set the image width.  A width of X% is
-  divided by 100.
-  If no :width attribute is given and `org-image-actual-width' is a list with
-  a number as the car, then that number is used as the default value.
-  If the value is a float between 0 and 2, it interpreted as that proportion
-  of the text width in the buffer."
-  ;; Apply `org-image-actual-width' specifications.
+See `org-image-actual-width' for how the image width is computed."
   (cond
    ((eq org-image-actual-width t) nil)
    ((listp org-image-actual-width)
-- 
2.31.1