Syloti is poorly hinted in W10/GDI

[Mercury13]

Defect Report

Title

Several letters of Syloti (e.g. Ko U+A807) are poorly hinted in Windows 10 (GDI rendering).

Font

NotoSansSylotiNagari.ttf
I also tried unhinted font, but no pixel was changed.

Where the font came from, and when

Site: this repo
Date: 2021-07-20

Font Version

2.001

OS name and version

Windows 10 20H2

Application name and version

Probably all applications with GDI rendering. Specially seen in Qt 6.1.2, default Tahoma font, <font size='+2'>

Issue

1. Disable ClearType. Put a label to a Qt Creator form, content is <font face='Noto Sans Syloti Nagri' size='+2'>ꠇ</font>
2. Legs are both 1 and 2 px
3. Strokes should be either 1px or 2px. I’d prefer 1px.
4. Char ꠇ A807. I also tried unhinted font, but no pixel was changed.

Character data

Char ꠇ A807

Screenshot

There’s mostly Russian/Tahoma here, so you see problems in Syloti letters that are bigger than Russian ones.

(If you wonder what’s written here: Ordinary Brahmic abugida with inherent vowel “o” and virama (hasanta): K=ko, KA=ka, K^=k. Other variant of virama exists, K=k, like in other Brahmic scripts. Starting vowels are different letters. Doubled consonants and some conjuncts form ligatures: KK=kko, KT=kto. Typing these ligatures is standard: 1st letter, virama, 2nd letter. Text hangs from a common line, but, unlike [Devanagari], “holds” it tightly. // Text is written LTR, but Syloti books, as a tribute to Islam, are bound RTL.)

[fitojb]

I don’t think anybody making fonts nowadays is pursuing that kind of monochromatic, pixel-snapping rendering as the old W95 fonts did. You should enable ClearType.

[Mercury13]

Here’s ClearType — bad hinting is still here!

[simoncozens]

I think the problem here is that ttfautohint doesn't support Syloti. It shouldn't be too hard to add it, but I need to learn how...