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bug#50951: Fwd: bug#50951: 28.0.50; Urdu text is not displayed correctly
From: |
Eli Zaretskii |
Subject: |
bug#50951: Fwd: bug#50951: 28.0.50; Urdu text is not displayed correctly |
Date: |
Sat, 02 Oct 2021 15:18:28 +0300 |
> From: Rah Guzar <aikrahguzar@gmail.com>
> Date: Sat, 2 Oct 2021 13:43:47 +0200
>
> Let us consider the word نہیں
>
> It is composed of four letters. I will use character field from
> `describe-char` for each of them below
> 1) ن (displayed as ن) (codepoint 1606, #o3106, #x646)
> 2) ہ (displayed as ہ) (codepoint 1729, #o3301, #x6c1)
> 3) ی (displayed as ی) (codepoint 1740, #o3314, #x6cc)
> 4) ں (displayed as ں) (codepoint 1722, #o3272, #x6ba)
>
> It should be displayed with all 4 characters joined together, instead they
> are all displayed individually.
What font displays them individually? You should be able to tell that
if you type "C-u C-x =" on one of these characters.
For me, they display joined together.
> If I change to `NotoNastaliqUrdu` this word is displayed correctly. But there
> is problem with حرف
>
> It consist of three letters,
> 1) ح (displayed as ح) (codepoint 1581, #o3055, #x62d)
> 2) ر (displayed as ر) (codepoint 1585, #o3061, #x631)
> 3) ف (displayed as ف) (codepoint 1601, #o3101, #x641)
>
> The first two characters should be joined and the last one should be on its
> own. This seems to be the case.
> But the two groups are rendered on top of each other making it illegible.
>
> So isn't this a matter of finding a proper font, in particularly given
> the "Nastaliq vs Naskh" issues? NotoNastaliqUrdu is not the only font
> supporting Nastaliq, so perhaps other fonts fare better?
>
> My knowledge here is very deficient but my impression is Nastaliq and Naskh
> are styles and shouldn't affect
> composition.
> NotoNastaliqUrdu was the only Urdu font available from my distro.
> Libreoffice which also uses harfbuzz
> renders it
> correctly so I didn't try another font at first. Like emacs libreoffice also
> uses a Naskh font by default but all the
> characters are joined properly.
>
> I did try some fonts from https://urdufonts.net/ after your suggestions and
> they render correctly. Specifically
> the font I tried
> were:
> Jameel Noori Nastaleeq Regular
> Alvi Nastaleeq
> Zohra Unicode
> Manzor Unicode
>
> I didn't notice a problem with any of them except a very minor one for the
> last two which have visible
> boundaries where glyphs
> are joined.
So would it be correct to say that using a proper font solves the
problem?
> Since Urdu uses the Arabic characters, Emacs uses character
> composition rules for Arabic when displaying this text. Do you know
> if the composition rules for Urdu are different?
>
> I think using Arabic composition rules might be part of the problem. Urdu
> alphabet is a superset of Arabic
> alphabet and if I
> don't set a font specifically designed for Urdu, the words where some
> characters should be joined but aren't
> always seem to
> include a character like ہ which is in Urdu alphabet but not in Arabic.
I don't think the problem is with compositions, because in the 2
examples you described above, there are no character compositions.
Moreover, our pattern for asking HarfBuzz to shape Arabic text is
this:
"[\u0600-\u074F\u200C\u200D]+"
which includes all of the characters, including U+06C1 which you say
causes problems.
You could try setting current-iso639-language to the symbol 'ur'
(without the quotes), that should tell HarfBuzz to shape the text as
appropriate for Urdu. But I think the real problem is with the font,
not with shaping.
- bug#50951: 28.0.50; Urdu text is not displayed correctly, Rah Guzar, 2021/10/01
- bug#50951: 28.0.50; Urdu text is not displayed correctly, Eli Zaretskii, 2021/10/02
- Message not available
- bug#50951: Fwd: bug#50951: 28.0.50; Urdu text is not displayed correctly, Rah Guzar, 2021/10/02
- bug#50951: Fwd: bug#50951: 28.0.50; Urdu text is not displayed correctly,
Eli Zaretskii <=
- bug#50951: Fwd: bug#50951: 28.0.50; Urdu text is not displayed correctly, Rah Guzar, 2021/10/02
- bug#50951: Fwd: bug#50951: 28.0.50; Urdu text is not displayed correctly, Eli Zaretskii, 2021/10/02
- bug#50951: Fwd: bug#50951: 28.0.50; Urdu text is not displayed correctly, Rah Guzar, 2021/10/02
- bug#50951: Fwd: bug#50951: 28.0.50; Urdu text is not displayed correctly, Eli Zaretskii, 2021/10/02
- Message not available
- bug#50951: Fwd: bug#50951: 28.0.50; Urdu text is not displayed correctly, Eli Zaretskii, 2021/10/02
- bug#50951: Fwd: bug#50951: 28.0.50; Urdu text is not displayed correctly, Rah Guzar, 2021/10/02
- bug#50951: Fwd: bug#50951: 28.0.50; Urdu text is not displayed correctly, Andreas Schwab, 2021/10/02
- bug#50951: Fwd: bug#50951: 28.0.50; Urdu text is not displayed correctly, Eli Zaretskii, 2021/10/02
- bug#50951: Fwd: bug#50951: 28.0.50; Urdu text is not displayed correctly, Rah Guzar, 2021/10/02
- bug#50951: Fwd: bug#50951: 28.0.50; Urdu text is not displayed correctly, Eli Zaretskii, 2021/10/02