1262774 - broken support for mark filter sets in OpenType lookups

Status: RESOLVED FIXED

(Core :: Graphics: Text, defect)

Description

[Jonathan Kew [:jfkthame]]

See discussion beginning at https://lists.freedesktop.org/archives/harfbuzz/2016-April/005533.html.

This was broken in harfbuzz 1.2.2, which we took in bug 1249861, and can disrupt the rendering of fonts with complex mark handling -- e.g. some Arabic-script fonts.

The fix is trivial, so we should cherry-pick it and uplift to FF47 so as to avoid shipping a release with the bug present.

Comment 1

[Jonathan Kew [:jfkthame]]

Attachment: Cherry-pick upstream fix for broken mark filter set support in harfbuzz

We'll take a new harfbuzz version in bug 1251203 shortly, but as this is a regression with a trivial fix, I think we should cherry-pick it and uplift to FF47 rather than waiting for the new version to ride the train.

Comment 2

[Jonathan Kew [:jfkthame]]

I tested (manually) that we currently have bad rendering of the Hussaini Nastaleeq font in Nightly, and this patch fixes it. I don't think we can readily add a reftest here (not without considerable effort to create a custom font, etc), but upstream now has a unit test so it shouldn't get regressed again.

Comment 3

[Jonathan Kew [:jfkthame]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/556ead25fa217327f8d116b4390db1f459704636
Bug 1262774 - Cherry-pick upstream fix for broken mark filter set support in harfbuzz. r=jrmuizel

Comment 4

[Jonathan Kew [:jfkthame]]

Comment on attachment 8738943 [details] [diff] [review]
Cherry-pick upstream fix for broken mark filter set support in harfbuzz

Approval Request Comment
[Feature/regressing bug #]: 1249861 (upstream regression, now fixed)

[User impact if declined]: some complex OpenType fonts will render incorrectly (some mark-handling lookups will fail)

[Describe test coverage new/current, TreeHerder]: upstream now has unit test covering this; patch tested manually with an affected Arabic font

[Risks and why]: minimal: trivial one-line fix for an obvious mistake

[String/UUID change made/needed]: none

Comment 5

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/556ead25fa21

Comment 6

[Ritu Kothari (:ritu) (Inactive, please n-i to RyanVM, jcristau, or pascal)]

Comment on attachment 8738943 [details] [diff] [review]
Cherry-pick upstream fix for broken mark filter set support in harfbuzz

Low risk, was manually tested, Aurora47+

Comment 7

[Jonathan Kew [:jfkthame]]

https://hg.mozilla.org/releases/mozilla-aurora/rev/e6cf7714ab97