7

Github has a convenient way to show some lines as highlighted in the code, like so.

I'd like to know if there's a way to setup something similar with org-mode code blocks when exporting (in my use case, to HTML), so I can show a longer code block for context yet point the reader quickly towards the lines that were added or modified.

I haven't found anything obvious in the documentation. I don't know where I would start the research to implement this myself.

Can this be done? Has it already been implemented? If not, can I implement this myself? Where would I start?

I have found that org-mode exports to HTML and provides a .code-highlighted class, but that seems to be only for the (ref:xx) tools: hover over a reference, the corresponding code gets highlighted.

  • There is no way without writing some code I think. You probably need to mark up your code block with something that looks like a comment, and then use an org-filter to modify the output with the html markup required for highlighting. – John Kitchin Feb 23 '16 at 0:10
2

Based on the coderef label syntax I use a (hl:line) pseudo label that gets replaced by an org-export-filter afunction. Referenced lines are wrapped in a div with a style attribute:

(defun org-html-hl-line (src backend info)
  (when (org-export-derived-backend-p backend 'html)
    (replace-regexp-in-string
     "\\([^\n]+\\)(hl:line)\n"
     "<div style=\"background-color: rgb(248, 238, 199);\">\\1\n</div>" src)))

(add-to-list 'org-export-filter-src-block-functions
             'org-html-hl-line)

Note that labels have to be at the end of the line as shown in the following example:

(functionp &rest form)           (hl:line)

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