Support internal linking to images by their block names

http://orgmode.org/manual/Images-and-tables.html

Fixes https://github.com/kaushalmodi/ox-hugo/issues/29

ox-hugo.el

@@ -1054,9 +1054,15 @@ and rewrite link paths to make blogging more seamless."
              ;; case.
              (grand-parent (when (eq parent-type 'link)
                              (org-export-get-parent parent)))
-             (attr (if grand-parent
-                       (org-export-read-attribute :attr_html grand-parent)
-                     (org-export-read-attribute :attr_html parent)))
+             (useful-parent (if grand-parent
+                                grand-parent
+                              parent))
+             (label (let ((lbl (and (org-element-property :name useful-parent)
+                                    (org-export-get-reference useful-parent info))))
+                      (if lbl
+                          (format "<a id=\"%s\"></a>\n" lbl)
+                        "")))
+             (attr (org-export-read-attribute :attr_html useful-parent))
              ;; Hugo `figure' shortcode named parameters
              ;; https://gohugo.io/content-management/shortcodes/#figure
              (caption (org-string-nw-p
@@ -1087,7 +1093,7 @@ and rewrite link paths to make blogging more seamless."
                                              (format "%s=\"%s\" "
                                                      name val))))))
         ;; (message "[org-hugo-link DBG] figure params: %s" figure-param-str)
-        (format "{{<figure %s>}}" (org-trim figure-param-str))))
+        (format "%s{{<figure %s>}}" label (org-trim figure-param-str))))
      ((string= type "coderef")
       (let ((ref (org-element-property :path link)))
         (format (org-export-get-coderef-format ref contents)

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

@@ -1608,6 +1608,43 @@ link./
 #+INCLUDE: "./all-posts.org::#lorem-ipsum" :only-contents t
 
 *Here we refer to table [[tab__simple]].*
+*** Links to images                                                :noexport:
+:PROPERTIES:
+:EXPORT_FILE_NAME: links-to-images
+:END:
+*Note*: This test is marked as =noexport= because the Org generated
+ link IDs are random and thus would fail the tests. So let this test
+ serve just as an example and not as a part of the automated test
+ suite.
+
+To export this test, you'll need to temporarily remove the =noexport=
+tag.
+-----
+From  [[http://orgmode.org/manual/Images-and-tables.html][(org) Images and tables]],
+
+*Note*: When targeting a =#+NAME= keyword, =#+CAPTION= keyword is
+mandatory in order to get proper numbering for images and images.
+
+#+BEGIN_SRC org
+,#+CAPTION: Org Logo
+,#+NAME: img__org_logo
+[[/images/org-mode-unicorn-logo.png]]
+Here we refer to image [[img__org_logo]].
+#+END_SRC
+
+will output below (/lorem-ipsum/ added to increase page content so
+that the link jump is evident):
+
+#+CAPTION: Org Logo
+#+NAME: img__org_logo
+[[/images/org-mode-unicorn-logo.png]]
+
+/Scroll to the end of the below 'lorem-ipsum' block to find the test
+link./
+
+#+INCLUDE: "./all-posts.org::#lorem-ipsum" :only-contents t
+
+*Here we refer to image [[img__org_logo]].*
 * Equations                                                       :equations:
 ** Inline equations
 :PROPERTIES:

test/site/content/posts/links-to-images.md

@@ -0,0 +1,90 @@
++++
+title = "Links to images"
+tags = ["links", "internal-links"]
+draft = false
++++
+
+**Note**: This test is marked as `noexport` because the Org generated
+ link IDs are random and thus would fail the tests. So let this test
+ serve just as an example and not as a part of the automated test
+ suite.
+
+To export this test, you'll need to temporarily remove the `noexport`
+tag.
+
+---
+
+From  [(org) Images and tables](http://orgmode.org/manual/Images-and-tables.html),
+
+**Note**: When targeting a `#+NAME` keyword, `#+CAPTION` keyword is
+mandatory in order to get proper numbering for images and images.
+
+```org
+#+CAPTION: Org Logo
+#+NAME: img__org_logo
+[[/images/org-mode-unicorn-logo.png]]
+Here we refer to image [[img__org_logo]].
+```
+
+will output below (_lorem-ipsum_ added to increase page content so
+that the link jump is evident):
+
+<a id="org22e708b"></a>
+{{<figure src="/images/org-mode-unicorn-logo.png" caption="Org Logo">}}
+
+_Scroll to the end of the below 'lorem-ipsum' block to find the test
+link._
+
+Lorem ipsum dolor sit amet, consectetur adipiscing elit. Quisque et
+quam metus. Etiam in iaculis mi, sit amet pretium magna. Donec ut dui
+mi. Maecenas pharetra sapien nunc, ut mollis enim aliquam quis. Nam at
+ultricies metus. Nulla tempor augue in vestibulum tristique. Phasellus
+volutpat pharetra metus quis suscipit. Morbi maximus sem dolor, id
+accumsan ipsum commodo non.
+
+Fusce quam ligula, gravida ac dui venenatis, bibendum commodo
+lorem. Duis id elit turpis. Integer sed diam nibh. Donec tempus
+lacinia odio, a laoreet velit dictum id. Suspendisse efficitur euismod
+purus et porttitor. Aliquam sit amet tellus mauris. Mauris semper
+dignissim nibh, faucibus vestibulum purus varius quis. Suspendisse
+potenti. Cras at ligula sit amet nunc vehicula condimentum quis nec
+est. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices
+posuere cubilia Curae; Donec iaculis, neque sit amet maximus rhoncus,
+nisl tortor convallis ante, ut mollis purus augue ut justo. Praesent
+felis urna, volutpat sit amet posuere dictum, luctus quis nibh. Proin
+et tristique ipsum, in aliquam ante.
+
+Aenean eget ex mauris. Cras ut tempor quam. Curabitur eget nulla
+laoreet, bibendum neque porta, tempus nulla. Ut tellus nisi, semper eu
+ligula pretium, aliquam accumsan dolor. Nunc fermentum cursus arcu eu
+suscipit. Nam dolor tellus, efficitur sed condimentum at, fringilla
+eget nisi. Nulla luctus metus felis. Suspendisse potenti. Cras lacinia
+orci nec dui sodales commodo. Donec tellus arcu, congue porta ultrices
+non, pretium et sapien. Proin mattis risus dignissim feugiat
+tristique. Donec nibh lorem, facilisis id posuere ut, varius ac
+urna. Etiam ultrices dignissim mauris, quis venenatis ex semper ut.
+
+Curabitur id fermentum erat, rhoncus scelerisque est. Sed pulvinar,
+nulla sed sollicitudin scelerisque, ipsum erat sollicitudin dolor, ut
+commodo arcu justo vel libero. Curabitur turpis dolor, fermentum ut
+elit a, vehicula commodo nunc. Sed sit amet blandit nulla, quis
+sodales massa. Donec lobortis, urna vel volutpat ullamcorper, mauris
+est efficitur nulla, et suscipit velit dui at metus. Aliquam id sem
+sed metus tristique scelerisque nec vitae odio. Phasellus a
+pellentesque libero, vel convallis metus. Sed nec fringilla magna, non
+varius ex. Sed interdum eleifend ligula, quis porta enim ultrices
+a. Donec hendrerit diam ac elementum tincidunt.
+
+Pellentesque eget nisl rhoncus, malesuada justo nec, suscipit
+quam. Nam sodales mauris eu bibendum suscipit. Vivamus sodales dui
+lorem, scelerisque pellentesque diam fermentum sed. Etiam fermentum
+nisl id nisl blandit, sit amet semper erat ultricies. Nulla tincidunt
+nulla metus, eu imperdiet lorem malesuada sagittis. Maecenas accumsan
+risus sed ante eleifend, vitae pretium leo porta. Suspendisse vitae
+eros vitae dui ornare condimentum id sit amet mauris. Etiam tincidunt
+consequat risus, eu posuere mi. Donec ut nunc eu massa porttitor
+suscipit nec nec neque. Suspendisse vitae tincidunt justo, sed
+molestie velit. Nullam pellentesque convallis ante, vel posuere libero
+blandit in.
+
+**Here we refer to image [6](#org22e708b).**