bug#50958: 27.2; Very blurry svg rendering on Retina screen

[Carlos Pita]

> SVG rendering on HiDPI screens has been improved in Emacs 28 -- could
> you try that instead to see whether it fixes the problem?

Sure Lars, I was going to do it anyway because of other issues with pdf-tools.

It indeed fixes part of the problem:

* LaTeX previews in org-mode are high resolution now.
* Also adds the frame-scale-factor function that’s used by the fix to pdf-tools 
[1] blurry rendering.

But other related issues remain:

* doc-view still renders low-resolution svg.
* doc-view still renders low-resolution pdf (which is not the topic of this 
issue but may be relevant).

Best regards,
Carlos

---

[1] 
https://github.com/vedang/pdf-tools/commit/f771c93781b3135200cae6dbc8e45dbb887f77b1