LGTM3
On 3/25/26 7:07 a.m., Yoav Weiss (@Shopify) wrote:
LGTM2
On Wed, Mar 25, 2026 at 11:26 AM Philip Jägenstedt
<[email protected]> wrote:
LGTM1, I think this is a very straightforward case given that it's
already supported in Firefox and Safari. Thank you for verifying
that locally and adding the tests to WPT!
On Wed, Mar 25, 2026 at 10:45 AM Dominik Röttsches
<[email protected]> wrote:
Philip asked me a few questions, here are the details:
Tests:
The new WPT tests are in the CL: https://crrev.com/c/7692195
These are newly added to WPT, but have been manually verified
in Firefox on Linux and Safari on Mac and confirmed to show
behavior that indicates full support for Avar2.
Signals:
/Web developers/: Positive
This should be "Neutral" instead. I filled this field
initially, but then moved to comment on
Google Fonts as an internal stake holder is keen on having
this feature available on the web for optimising future fonts.
To "Other Signals", as we would not count Google Fonts under
"Web Developers".
On Tue, Mar 24, 2026 at 4:27 PM Dominik Röttsches
<[email protected]> wrote:
*> Specification*
> https://www.iso.org/standard/87621.html
As for specification details, avar2 is part of the draft
of the 5th edition draft, ISO/IEC FDIS 14496-22 .
https://www.iso.org/standard/87621.html
<https://www.iso.org/standard/87621.html> in Section
7.3.1. avar.
On Tuesday, March 24, 2026 at 3:57:03 PM UTC+2
[email protected] wrote:
*Contact emails*
[email protected]
*Explainer*
https://github.com/harfbuzz/boring-expansion-spec/blob/main/avar2.md
*Specification*
https://www.iso.org/standard/87621.html
*Summary*
Version 2 of the avar (Axis Variations) table enables
font designers to create variable fonts with better
control over interpolation. While the original
variable font spec handles axes independently, avar2
allows axes to influence one another.
This leads to fonts that are easier to use for content
authors to use, and enable compact storage.
Support for this feature in Blink means at the core,
activating a compile flag in HarfBuzz that processes
the version 2 additional fields of the avar table to
extend axis variations processing.
Avar2 works by using the same familiar concepts of
font variations, but applying the variable delta
values to the design axis specifications itself. Plus,
it allows doing this over a range of multiple axes.
As anexample, it allows the creation of "meta sliders"
which control multiple variation axes at once,
alleviating the user from fine-tuning and finding a
useful corner of the font's design space.
Avar2 gives font designers better control over the
usable variation space of their font, and allows
coordinating the adjustment of design axes across
several axes. By defining the relationships between
axes mathematically within the avar version 2 table,
fonts can achieve complex designs with fewer masters,
leading to smaller file sizes, because the
interpolation is stored more efficiently.
*Blink component*
Blink>Fonts
<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EFonts%22>
*Web Feature ID*
font-variation-settings
<https://webstatus.dev/features/font-variation-settings>
*Motivation*
Provide interoperability for this new feature of the
of the Open Font Format font standard.
*Initial public proposal*
/No information provided/
*TAG review*
Not needed, as it is not a W3C spec, but ISO/OFF spec.
*TAG review status*
Not applicable
*Goals for experimentation*
None
*Risks*
*Interoperability and Compatibility*
Low, Safari and FireFox have shipped the feature. The
change to add this feature adds WPT tests that perform
basic interop tests which Safari and FireFox seem to
handle correctly.
/Gecko/: Shipped/Shipping Tests show that avar2
support is present in FireFox. Shaping and glyph
variations work (tested on Linux).
/WebKit/: Shipped/Shipping Tests show that Safari
ships avar2 by means of support in the OS' CoreText
libraries. Avar2 shaping and glyph variations work.
/Web developers/: Positive
/Other signals/: Google Fonts as an internal stake
holder is keen on having this feature available on the
web for optimising future fonts.
*Activation*
With the avar2 font-tech feature definition in
https://drafts.csswg.org/css-fonts-5/#font-technologies-formats
it
is possible for authors to implement graceful
degradation. Only if the UA understands the
technology(avar2) attribute, it would load and use
such a font.
*Security*
We pass all avar2 web fonts to Fontations, which
actually increases security over using system rasterizers.
*WebView application risks*
Does this intent deprecate or change behavior of
existing APIs, such that it has potentially high risk
for Android WebView-based applications?
No specific WebView risks.
*Debuggability*
Not applicable here, DevTools does not descend into
sub features of Open Font Format or OpenType fonts and
their activation.
*Will this feature be supported on all six Blink
platforms (Windows, Mac, Linux, ChromeOS, 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
Covered by several WPT tests added as part of enabling
avar2.
*Flag name on about://flags*
/No information provided/
*Finch feature name*
/No information provided/
*Non-finch justification*
It is not possible to have a cleanly isolating
RuntimeEnabledFeature flag for the launch of this
feature. The tech(avar2) support can be gated, which
controls whether the UA selects an avar2 font if it is
tagged as such.
HarfBuzz (where shaping support for avar2 is
implemented) only allows this as a compile time
feature. Fontations (where glyph rendering support for
avar2 is implemented) has no switch and we were
already shipping glyhph variant support for this
feature when switching to Fontations.
*Rollout plan*
Will ship enabled for all users
*Requires code in //chrome?*
False
*Tracking bug*
https://crbug.com/40246300
*Measurement*
Blink.Fonts.VariableFontsRatio metric measures
different font format's instantiation ratios. This
covers avar2 and shows the proportion of avar2 fonts
among all web fonts.
*Availability expectation*
Across browsers.
*Estimated milestones*
Shipping on desktop 148
Shipping on Android 148
Shipping on WebView 148
*Anticipated spec changes*
Open questions about a feature may be a source of
future web compat or interop issues. Please list open
issues (e.g. links to known github issues in the
project for the feature specification) whose
resolution may introduce web compat/interop risk
(e.g., changing to naming or structure of the API in a
non-backward-compatible way).
/No information provided/
*Link to entry on the Chrome Platform Status*
https://chromestatus.com/feature/5169590743203840?gate=6513397493530624
This intent message was generated by Chrome Platform
Status <https://chromestatus.com/>.
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