1430632 - DirectWrite support for OpenType Font Variations

Status: RESOLVED FIXED

(Core :: Graphics: Text, enhancement)

Description

[Jonathan Kew [:jfkthame]]

As of the Win10 Fall Creators Update, there is support for variation fonts via new DirectWrite APIs. So we should be able to implement CSS variation-font support on current Win10 systems fairly easily via the DWrite backend.

This will not work on earlier Windows systems (we'll need to test API availability at runtime), so if we want variation-font support on older systems we'll need to take another approach, e.g. based on bug 1403299.

Comment 1

[Jonathan Kew [:jfkthame]]

Attachment: Support OpenType variation fonts in the DirectWrite font back-end

This seems to be sufficient to make things work nicely on the axis-praxis test page, for example (with the exception of the Winner font; that looks like a DWrite bug). A followup bug will be needed to hook it all up to webrender, as I didn't tackle that yet.

Comment 2

[Jonathan Kew [:jfkthame]]

https://treeherder.mozilla.org/#/jobs?repo=try&revision=7aed061a4163801d02943cce066c0464b68d066f

Comment 3

[Jonathan Kew [:jfkthame]]

Note that the patch here won't currently build on tryserver (or inbound/central), because it depends on bug 1430634 and bug 1430638. Here's a try build where I just hacked in a bunch of the new DirectWrite declarations in a temporary extra header file, to work around this: https://treeherder.mozilla.org/#/jobs?repo=try&revision=bcac12062637ac8d453c558a905560627f3908c1.

Comment 4

[Jonathan Kew [:jfkthame]]

Attachment: Copy declarations of new DirectWrite interfaces into our code so it will build against the current Windows SDK and WINVER settings

AFAICT, this allows us to build successfully with the current toolchains etc., until we're ready to bump the SDK and WINVER settings (at which point it should harmlessly stop getting included, even if we don't remember to rip it out right away). The resulting build still runs happily on Win7, it just won't actually support font variations.

Comment 5

[Nathan Froyd [:froydnj]]

Comment on attachment 8943665 [details] [diff] [review]
Copy declarations of new DirectWrite interfaces into our code so it will build against the current Windows SDK and WINVER settings

Review of attachment 8943665 [details] [diff] [review]:
-----------------------------------------------------------------

Thank you!

Comment 6

[Jonathan Kew [:jfkthame]]

So just FTR, with the additional patch, this no longer depends on bug 1430638 and bug 1430634; but when we're ready to move forward on those issues, we'll be able to remove the extra header here.

Comment 7

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/794abd47aa0c
Support OpenType variation fonts in the DirectWrite font back-end (on Win10 Fall Creators Update). r=lsalzman
https://hg.mozilla.org/integration/mozilla-inbound/rev/6d97ae42700e
Copy declarations of new DirectWrite interfaces into our code so it will build against the current Windows SDK and WINVER settings. r=lsalzman,froydnj

Comment 8

[Raul Gurzau (:RaulG)]

:jfkthame windows-mingw32-32 debug build-win32-mingw32/debug (B) job got busted on this push:
https://treeherder.mozilla.org/#/jobs?repo=mozilla-inbound&revision=6d97ae42700e4086584d74cde222fa2f870780dd&filter-platform=windows-mingw32-32%20debug&selectedJob=157551905
It's tier2 job but is there any chance you can take a look? Thank you.

Comment 9

[Jonathan Kew [:jfkthame]]

Ugh, looks like it must be using an older (pre-Win10?) SDK, and doesn't have the dwrite_3.h header at all. I guess we can work around that by copying the necessary declarations into our code, but it may take some trial and error to determine exactly what needs to be included.

Or is it possible to update the SDK those builds are using, so that it matches what we use in the tier-1 builds?

Comment 10

[Bogdan Tara[:bogdan_tara | bogdant]]

https://hg.mozilla.org/mozilla-central/rev/794abd47aa0c
https://hg.mozilla.org/mozilla-central/rev/6d97ae42700e

Comment 11

[Gregor]

Works pretty good on Windows 10...but the print-function don't work.
The print-preview shows the variable font, but if you print it out, the printer prints without the font-variable-settings..