I'm curious how this relates to the "old" way of doing superscript.
If I understand correctly (and I might not!), then
x<span style="font-variant-position: super">2</span>
will render as "x²", somehow finding the "super" variant of 2 in the font?
The old way of doing this would be with
x<span style="vertical-align: super; font-size: 0.83em">2</span>
which will use the normal glyph for 2, but smaller and differently
positioned?
/Daniel
On 2023-02-14 22:26, Manuel Rego Casasnovas wrote:
Is there a way to feature detect the synthesis functionality or not? How
a web author will be able to differentiate between Gecko vs
Chromium/WebKit behaviors? Would the lack of this feature confuse
authors? Maybe having some console message information when
font-variant-position doesn't have any effect due to missing synthesis
functionality, dunno if that makes sense.
Do we have an use counter for the cases where we're not using
synthesized glyphs due to lack of functionality? So we can track how
common is that situation and understand the priority of such feature in
the future.
Cheers,
Rego
On 14/02/2023 17:08, Philip Jägenstedt wrote:
I will recuse myself from this one since I have an interest in the
success of Interop 2022 (and 2023), but I think shipping this makes
sense. Chrome is the last browser to not support it at all, and we've
seen with other features that the time it becomes available in all
browsers can be an inflection point in usage.
On Tue, Feb 14, 2023 at 4:56 PM 'Munira Tursunova' via blink-dev
<blink-dev@chromium.org <mailto:blink-dev@chromium.org>> wrote:
Contact emails
moon...@google.com <mailto:moon...@google.com>, dr...@google.com
<mailto:dr...@google.com>
Explainer
https://developer.mozilla.org/en-US/docs/Web/CSS/font-variant-position
<https://developer.mozilla.org/en-US/docs/Web/CSS/font-variant-position>
Specification
https://drafts.csswg.org/css-fonts-4/#propdef-font-variant-position
<https://drafts.csswg.org/css-fonts-4/#propdef-font-variant-position>
Summary
The font-variant-position CSS property controls the use of
alternate, smaller glyphs that are positioned as superscript or
subscript.
Motivation
Font-variant-position property allows users to control usage of
typographic superscript and subscript glyphs.
Currently font-variant-position is implemented without synthesis
functionality and affects only fonts that have superscript or
subscript glyphs (“sups”/”subs” opentype feature); i.e. if the font
doesn’t have superscript/subscript then setting
font-variant-position to “super”/“sub” won’t synthesize superscript
and subscript glyphs, therefore won’t change anything.
Subscript and superscript glyphs can be also activated using the
font-feature-settings property, however using font-variant-position
property might be more reasonable since it cascades like a regular
CSS property and with the font-feature-settings, if the element
inherits the “sups” or “subs” value, users need to
activate/deactivate other features that were also defined in
font-feature-settings of the parent element.
Implementing the synthesis part would be complex and it is
questionable if it is worth the cost since synthesized glyphs may
look unnatural and synthesis of the font-variant-position property
is at risk in the spec
<https://drafts.csswg.org/css-fonts-4/#:~:text=The%20following%20features,variant%2Dposition%20property>.
Also Safari supports font-variant-position property without synthesis functionality
as well.
This feature is implemented behind the ‘experimental’ flag and is
part of Interop 2022. Shipping this feature will provide a higher
stable score for Interop and will decrease the stable vs.
experimental score difference.Since Chrome is the last browser to
ship this, this will enable broader usage of the feature on the web.
Blink component
Blink>Fonts
<https://bugs.chromium.org/p/chromium/issues/list?q=component:Blink%3EFonts>
Search tags
font-variant-position
<https://chromestatus.com/features#tags:font-variant-position>,
subscript glyphs
<https://chromestatus.com/features#tags:subscript%20glyphs>,
superscript glyphs
<https://chromestatus.com/features#tags:superscript%20glyphs>, sub
<https://chromestatus.com/features#tags:sub>, super
<https://chromestatus.com/features#tags:super>
TAG review
Already shipped in other browsers, see below, no TAG review required.
TAG review status
Not applicable, existing standard, shipped in other UAs
Risks
Interoperability and Compatibility
Gecko: Shipped/Shipping
https://bugzilla.mozilla.org/show_bug.cgi?id=1024804
<https://bugzilla.mozilla.org/show_bug.cgi?id=1024804>Gecko has
implemented the feature with the synthesis functionality.
WebKit: Shipped/Shipping
https://bugs.webkit.org/show_bug.cgi?id=148413
<https://bugs.webkit.org/show_bug.cgi?id=148413>WebKit has
implemented the feature without the synthesis functionality.
Web developers: No signals
Other signals: -
Activation
None expected; Feature already implemented in other browsers.
Debuggability
Same as any other CSS property, css_properties.json will be rolled
to DevTools during development.
Will this feature be supported on all six Blink platforms
(Windows, Mac, Linux, Chrome OS, Android, and Android WebView)?
Yes
Is this feature fully tested by web-platform-tests
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?
Yes, following tests are testing property implementation:
https://wpt.fyi/results/css/css-fonts/font-variant-position.html
<https://wpt.fyi/results/css/css-fonts/font-variant-position.html>
https://wpt.fyi/results/css/css-fonts/font-variant-position-01.html
<https://wpt.fyi/results/css/css-fonts/font-variant-position-01.html>
https://wpt.fyi/results/css/css-fonts/font-variant-position-02.html
<https://wpt.fyi/results/css/css-fonts/font-variant-position-02.html>
https://wpt.fyi/results/css/css-fonts/font-variant-position-03.html
<https://wpt.fyi/results/css/css-fonts/font-variant-position-03.html>
https://wpt.fyi/results/css/css-fonts/parsing/font-variant-position-valid.html
<https://wpt.fyi/results/css/css-fonts/parsing/font-variant-position-valid.html>
https://wpt.fyi/results/css/css-fonts/parsing/font-variant-position-computed.html
<https://wpt.fyi/results/css/css-fonts/parsing/font-variant-position-computed.html>
https://wpt.fyi/results/css/css-fonts/parsing/font-variant-valid.html
<https://wpt.fyi/results/css/css-fonts/parsing/font-variant-valid.html>
Flag name
FontVariantPosition
Requires code in //chrome?
False
Tracking bug
https://bugs.chromium.org/p/chromium/issues/detail?id=1212668
<https://bugs.chromium.org/p/chromium/issues/detail?id=1212668>
Estimated milestones
No milestones specified
Anticipated spec changes
None expected
Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/5067180721307648
<https://chromestatus.com/feature/5067180721307648>
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