Recognize :trim-pre and :trim-post in the org special block plist

`("mark" . (:trim-pre t :trim-post t))` is added to the default value
of `org-hugo-special-block-type-properties` (ref
#540).

doc/ox-hugo-manual.org

@@ -3404,14 +3404,19 @@ Then simply put /tikz/ snippets in the Org source like so:
 
 {{{test-search(tikzjax)}}}
 **** Whitespace Trimming
-Whitespace trimming around exported Org Special Blocks is supported
-with the help of ~#+header:~ keywords above those blocks.
+The default whitespace trimming around exported Org Special Blocks can
+be configured by setting the ~:trim-pre~ and ~:trim-post~ properties
+for specific special block types in the
+~org-hugo-special-block-type-properties~ defcustom.
 
-- If the header has ~:trim-pre t~, whitespace is removed before the
+- If ~:trim-pre~ is set to ~t~, whitespace is removed before the
   block.
-- If the header has ~:trim-post t~, whitespace is removed after the
+- If ~:trim-post~ is set to ~t~, whitespace is removed after the
   block.
 
+The default values of these properties can be overridden by using the
+~#+header:~ keywords above the special blocks.
+
 #+begin_note
 If a special block tag is not recognized as an HTML block or inline
 element, or as a Hugo shortcode, it defaults to exporting [[#special-blocks--div-tags][with ~<div>~

ox-hugo.el

@@ -517,6 +517,7 @@ HTML element."
 
 (defcustom org-hugo-special-block-type-properties '(("audio" . (:raw t))
                                                     ("katex" . (:raw t))
+                                                    ("mark" . (:trim-pre t :trim-post t))
                                                     ("tikzjax" . (:raw t))
                                                     ("video" . (:raw t)))
   "Alist for storing default properties for special block types.
@@ -531,12 +532,18 @@ string.
 
 Properties recognized in the PLIST:
 
-- :raw :: When set to `t', the contents of the special block as exported raw
-          i.e. as typed in the Org buffer.
+- :raw :: When set to `t', the contents of the special block as
+          exported raw i.e. as typed in the Org buffer.
+
+- :trim-pre :: When set to `t', the whitespace before the special
+               block is removed.
+
+- :trim-pre :: When set to `t', the whitespace after the special
+               block is removed.
 
 For the special block types not specified in this variable, the
-default behavior is same as if (:raw nil) plist were associated
-with them."
+default behavior is same as if (:raw nil :trim-pre nil :trim-post
+nil) plist were associated with them."
   :group 'org-export-hugo
   :type '(list (cons string (plist :key-type symbol :value-type boolean))))
 
@@ -2841,10 +2848,12 @@ INFO is a plist holding export options."
          (block-type-plist (cdr (assoc block-type org-hugo-special-block-type-properties)))
          (header (org-babel-parse-header-arguments
                   (car (org-element-property :header special-block))))
-         (trim-pre (alist-get :trim-pre header))
-         (trim-pre-tag (or (and trim-pre org-hugo--trim-pre-marker) ""))
-         (trim-post (alist-get :trim-post header))
-         (trim-post-tag (or (and trim-post org-hugo--trim-post-marker) ""))
+         (trim-pre (or (alist-get :trim-pre header) ;`:trim-pre' in #+header has higher precedence.
+                       (plist-get block-type-plist :trim-pre)))
+         (trim-pre-tag (if trim-pre org-hugo--trim-pre-marker ""))
+         (trim-post (or (alist-get :trim-post header) ;`:trim-post' in #+header has higher precedence.
+                        (plist-get block-type-plist :trim-pre)))
+         (trim-post-tag (if trim-post org-hugo--trim-post-marker ""))
          (paired-shortcodes (let* ((str (plist-get info :hugo-paired-shortcodes))
                                    (str-list (when (org-string-nw-p str)
                                                (split-string str " "))))

test/site/content-org/all-posts.org

@@ -4732,8 +4732,9 @@ Here's a link to the [[circle][Circle]].
 :EXPORT_FILE_NAME: ws-trimming-around-special-blocks
 :EXPORT_DESCRIPTION: Whitespace trimming using ~#+header: :trim-pre t :trim-post t~ before special blocks.
 :END:
-**** No trimming
+**** Whitespace trimmed before and after the ~mark~ special block (default)
 Below Org block:
+
 #+begin_src org
 line 1
 ,#+begin_mark
@@ -4749,12 +4750,12 @@ line 1
 abc def
 #+end_mark
 line 2
-**** Whitespace trimmed before and after the ~mark~ special block
+**** Whitespace trimmed only before the ~mark~ special block
 Below Org block:
 
 #+begin_src org
 line 1
-,#+header: :trim-pre t :trim-post t
+,#+header: :trim-post nil
 ,#+begin_mark
 abc def
 ,#+end_mark
@@ -4764,17 +4765,17 @@ line 2
 exports and renders as:
 
 line 1
-#+header: :trim-pre t :trim-post t
+#+header: :trim-post nil
 #+begin_mark
 abc def
 #+end_mark
 line 2
-**** Whitespace trimmed only before the ~mark~ special block
+**** Whitespace trimmed only after the ~mark~ special block
 Below Org block:
 
 #+begin_src org
 line 1
-,#+header: :trim-pre t
+,#+header: :trim-pre nil
 ,#+begin_mark
 abc def
 ,#+end_mark
@@ -4784,17 +4785,16 @@ line 2
 exports and renders as:
 
 line 1
-#+header: :trim-pre t
+#+header: :trim-pre nil
 #+begin_mark
 abc def
 #+end_mark
 line 2
-**** Whitespace trimmed only after the ~mark~ special block
+**** No trimming
 Below Org block:
-
 #+begin_src org
 line 1
-,#+header: :trim-post t
+,#+header: :trim-pre nil :trim-post nil
 ,#+begin_mark
 abc def
 ,#+end_mark
@@ -4804,7 +4804,7 @@ line 2
 exports and renders as:
 
 line 1
-#+header: :trim-post t
+#+header: :trim-pre nil :trim-post nil
 #+begin_mark
 abc def
 #+end_mark

test/site/content/posts/ws-trimming-around-special-blocks.md

@@ -5,7 +5,7 @@ tags = ["special-block", "whitespace", "trimming"]
 draft = false
 +++
 
-## No trimming {#no-trimming}
+## Whitespace trimmed before and after the `mark` special block (default) {#whitespace-trimmed-before-and-after-the-mark-special-block--default}
 
 Below Org block:
 
@@ -19,20 +19,16 @@ line 2
 
 exports and renders as:
 
-line 1
-
-<mark>abc def</mark>
-
-line 2
+line 1 <mark>abc def</mark> line 2
 
 
-## Whitespace trimmed before and after the `mark` special block {#whitespace-trimmed-before-and-after-the-mark-special-block}
+## Whitespace trimmed only before the `mark` special block {#whitespace-trimmed-only-before-the-mark-special-block}
 
 Below Org block:
 
 ```org
 line 1
-#+header: :trim-pre t :trim-post t
+#+header: :trim-post nil
 #+begin_mark
 abc def
 #+end_mark
@@ -44,13 +40,13 @@ exports and renders as:
 line 1 <mark>abc def</mark> line 2
 
 
-## Whitespace trimmed only before the `mark` special block {#whitespace-trimmed-only-before-the-mark-special-block}
+## Whitespace trimmed only after the `mark` special block {#whitespace-trimmed-only-after-the-mark-special-block}
 
 Below Org block:
 
 ```org
 line 1
-#+header: :trim-pre t
+#+header: :trim-pre nil
 #+begin_mark
 abc def
 #+end_mark
@@ -59,18 +55,16 @@ line 2
 
 exports and renders as:
 
-line 1 <mark>abc def</mark>
-
-line 2
+line 1 <mark>abc def</mark> line 2
 
 
-## Whitespace trimmed only after the `mark` special block {#whitespace-trimmed-only-after-the-mark-special-block}
+## No trimming {#no-trimming}
 
 Below Org block:
 
 ```org
 line 1
-#+header: :trim-post t
+#+header: :trim-pre nil :trim-post nil
 #+begin_mark
 abc def
 #+end_mark
@@ -79,9 +73,7 @@ line 2
 
 exports and renders as:
 
-line 1
-
-<mark>abc def</mark> line 2
+line 1 <mark>abc def</mark> line 2
 
 
 ## Use `<span>` tag if trimming detected {#use-span-tag-if-trimming-detected}