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I've been using EWW and I noticed that it displays inline LaTeX expressions ($ ... $) but it fails to display those that have their own line ($$ ... $$). I'm attaching a print below. Have a look the blank space after the sentence "Symbolically, ".

I'm very new to Emacs, EWW, and text-based browsers so I have the following questions:

  • Is it possible to display those $$ ... $$ LaTeX formulas?
  • Can I choose whether I want to see the LaTeX code or the rendered version?

enter image description here

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    Neither Firefox nor EWW is rendering TeX. The inline expressions are pure HTML (e.g. <b>A</b><sup>1</sup> for A^1) and the standalone expressions are images. – Basil Oct 24 '18 at 13:40
  • I see. So why aren't all the standalone formulas displayed in eww as images? – aadcg Oct 24 '18 at 13:41
  • I'm not sure, can you reproduce from emacs -Q? Some causes off the top of my head are 0) running Emacs under a text terminal; 1) disabling HTML image rendering via variables like shr-inhibit-images/shr-blocked-images; 2) omitting some images by calling eww-readable; 3) image foreground is same colour as buffer background; 4) something else in your configuration or installed packages is somehow interfering; 5) Emacs is built without image support or has a bug; 6) etc. FWIW, I can't reproduce on latest Emacs development snapshot. – Basil Oct 24 '18 at 13:54
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    Looks like it's some variant of option 5 (lack of image support or bug), the image loads fine for me on Emacs 26 and 27 but not in 25. – Basil Oct 24 '18 at 13:58
  • I'm running version 25.2.2 so that's it... Thanks! – aadcg Oct 24 '18 at 14:02
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Looks like this is bug#24111, which was fixed for Emacs 26 in "Fix rendering of some complex SVG images" of 2017-01-24.

It is always recommended to use the latest Emacs version possible, especially in the context of browsing the web, but in the meantime I think you can hack around this issue on Emacs 25 with the following advice:

(define-advice shr-parse-image-data (:around (fn &rest args) my-emacs-25-patch)
  "Hackaround for bug#24111 in Emacs 25."
  (if shr-blocked-images
      (apply fn args)
    (cl-letf (((symbol-function 'libxml-parse-xml-region) #'buffer-substring)
              ((symbol-function 'shr-dom-to-xml)          #'identity))
      (apply fn args))))

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