Jeff Muizelaar [:jrmuizel] Reporter
	Description • 6 years ago

Now that harfbuzz supports AAT layout it seems like we should be able to drop support for shaping with CoreText.

	Jonathan Kew [:jfkthame] Assignee
	Comment 1 • 6 years ago

In principle, yes, though we should plan to do a fair bit of testing before we make that jump; this is very new (and not very extensively tested yet) on the harfbuzz side, so I don't want to rush things here.

	ebrahim
	Comment 2 • 6 years ago

Chrome is switched https://chromium-review.googlesource.com/c/chromium/src/+/1275945

	ebrahim
	Comment 3 • 6 years ago

Is it possible to see which tests needs to be rebaselined after the switch on Firefox also? That may help HarfBuzz development also.

	Jonathan Kew [:jfkthame] Assignee
	Comment 4 • 6 years ago

Here's a patch to make us use harfbuzz native AAT support rather than Core Text for shaping; let's see how it fares on try: https://treeherder.mozilla.org/#/jobs?repo=try&revision=a1311b6661a30c824554d387b4b300d07322e320.

	Jonathan Kew [:jfkthame] Assignee
	Comment 5 • 6 years ago

Oops - the pref was set backwards in that patch, so the try push didn't really test anything... here goes, with the pref flipped so we'll really test the harfbuzz version. https://treeherder.mozilla.org/#/jobs?repo=try&revision=d983a399d6f17c2716ba49fce641cb41a43f5d48

	Jonathan Kew [:jfkthame] Assignee
	Comment 6 • 6 years ago

The test failures on try look pretty insignificant, but OTOH I've noticed a number of cases where the harfbuzz AAT support doesn't match Core Text rendering. Filed some issues upstream:

  https://github.com/harfbuzz/harfbuzz/issues/1528
  https://github.com/harfbuzz/harfbuzz/issues/1529
  https://github.com/harfbuzz/harfbuzz/issues/1530
  https://github.com/harfbuzz/harfbuzz/issues/1531
  https://github.com/harfbuzz/harfbuzz/issues/1532

We should probably see what happens with these before moving forward here.

	Jonathan Kew [:jfkthame] Assignee
	Comment 7 • 6 years ago

Try run after harfbuzz 2.3.1 (bug 1524102) landed. The test failures look insignificant (typically tiny subpixel antialiasing issues), but there are still some Indic rendering issues with a few Apple fonts; e.g. the first line of the main text at https://www.unicode.org/standard/translations/telugu.html has a cluster that shapes incorrectly.

	Pulsebot
	Comment 11 • 5 years ago

Pushed by jkew@mozilla.com:
https://hg.mozilla.org/integration/autoland/rev/7bab77eee333
Disable the gfxCoreText backend and use native HarfBuzz shaping for AAT fonts. r=jrmuizel
https://hg.mozilla.org/integration/autoland/rev/6df30b02e311
Test/manifest updates to account for minor rendering differences between HarfBuzz and Core Text. r=jrmuizel

	Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)
	Comment 12 • 5 years ago

Created web-platform-tests PR https://github.com/web-platform-tests/wpt/pull/16919 for changes under testing/web-platform/tests

	Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)
	Comment 13 • 5 years ago

Upstream web-platform-tests status checks passed, PR will merge once commit reaches central.

	Web Platform Test Sync Bot (Matrix: #interop:mozilla.org)
	Comment 15 • 5 years ago

Upstream PR merged