juliamono Add Anchors to U+25CC DOTTED CIRCLE for Proper Rendering of Combining Diacritical Marks.

Add Anchors to U+25CC DOTTED CIRCLE for Proper Rendering of Combining Diacritical Marks.

Open AlexpFr opened this issue 1 year ago • 8 comments

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The character U+25CC DOTTED CIRCLE (Wikipedia - Dotted circle) is often used as a neutral character to represent combining diacritical marks (Wikipedia - Combining character). The Unicode standard allows, for example, writing U+25CCU+0327, which should render [image].

However, no anchor is currently present on the DOTTED CIRCLE to achieve a correct rendering. An ugly hack that works in VS Code is to type, for example, U+0327U+025CC, but the result depends on the editor...

Is it possible/desirable to add anchors to the DOTTED CIRCLE character to properly render the combined diacritical marks alone?

Thanks.

Jun 06 '24 08:06 AlexpFr

I'd like to see the [image] in your comment.

This is what I see:

Jun 06 '24 09:06 cormullion

In VSCode :

In Kwrite:

In Word:

In LibreOffice:

Jun 06 '24 09:06 AlexpFr

Noto Sans Mono have anchors on the dotted circle:

Jun 06 '24 09:06 AlexpFr

Yes, it's very variable depending on environment. On my Mac:

works OK	doesn’t work
BBEdit	Kitty
Jupyter Notebook	Wezterm
Terminal	Alacritty
iTerm	VS-Code
Pages

I can add anchors easily, although I can't say if this will fix it in all these applications.

Jun 06 '24 09:06 cormullion

I can add anchors easily, although I can't say if this will fix it in all these applications.

Yes... At least with anchors, it will work consistently across applications that correctly implement Unicode.

If you need more information or want to test the behavior, feel free to reach out, I'm available to assist!

Jun 06 '24 09:06 AlexpFr

I'm not an expert in font creation, but the issue lies in the different interpretations of text editors when a combining character is displayed alone. For example, VS Code combines it with the preceding character by adding a space, which is confusing.

There may be rules to introduce directly into the GPOS table of the font to make the behavior more predictable without needing to add anchors to characters that shouldn't have them. ??

Edit: Another observation, "Noto Sans Mono" has chosen to use zero width for diacritical characters, I'm not sure if it's a good practice. For instance, they have chosen a double advance width for a certain arrow, which is not always desirable for a Mono font...