bug#10895: Quirky behaviours with Arabic text

[Stefan Kangas <stefan@marxist.se>]

sergei karhof <karhof21@gmail.com> writes:

> I want to report some quirky behaviours of Emacs (devel 24.0.93 version,
> running under Windows 7), when dealing with Arabic text:
>
> 1) in some fonts (e.g. courier New), the vowel marks (harakaat) are
> not displayed, despite the fact that the texts contains them. However,
> if the cursor passes over the relevant text, moving in the
> right-to-left direction, the vowel marks become visible. Curiously, if
> the cursor passes back on the text, moving in the left-to-right
> direction, the vowel marks disappear.
> This problem manifests itself in different ways according to the font used.
> With other fonts, the problem is only partial: only part of the
> diacritic signs is visible, and by passing over them with the cursor
> (from right to left), they become fully visible. When passing over the
> text in the opposite direction, they again become half-visible.
>
> 2) the rendering of the vowel marks is poor even when they are
> displayed. For instance, vowel marks partially overlap some of the
> letters, e.g. the kasrah sign overlaps the two dots of the letter yaa.
>
> 3) vowel marks are not always in synch with the main text, so that
> they sometimes appear in a displaced position (e.g. on the previous
> letter). This is totally unacceptable, of course.
>
> Bottomline: there are multiple problems with the visual rendering of
> the diacritics.

(That was 8 years ago.)

Do you still see this on a recent version of Emacs, such as the recently
released version 27.1?

Would this have been fixed by the recent addition of harfbuzz support?

Best regards,
Stefan Kangas