1395926 - GPOS doesn't work for vertical text with upright orientation

Status: RESOLVED FIXED

(Core :: Graphics: Text, enhancement, P3)

Description

[Jonathan Kew [:jfkthame]]

The vertical-writing-mode rendering of attachment 8610505 [details] from bug 1148660 was fixed by the patch there, but subsequently broken again by bug 729993. (Unfortunately, we didn't have a reftest in place to detect this immediately.)

See also bug 1395774, although fixing this issue is not sufficient by itself to render the bopomofo example properly.

Comment 1

[Jonathan Kew [:jfkthame]]

Attachment: Reftest for GPOS glyph positioning adjustments in vertical-upright mode

Here's a reftest based on the testcase from bug 1148660, which currently fails on trunk -- many of the diacritics are misplaced to the left. (The GPOS-related fix we landed in bug 1376231 at least got the diacritics to the proper vertical positions, but we also handle the horizontal offsets incorrectly.) If we'd had this test in the tree already when we originally fixed bug 1148660, we wouldn't have promptly re-broken it in the next release (or at least, we'd have been aware that we did so...) :\

Comment 2

[Jonathan Kew [:jfkthame]]

Attachment: Fix up handling of glyph offsets for text shaped in vertical mode

And this fixes the rendering (again), so that the test passes. With this in place, and covered by reftests, we can then consider revising how the glyph offsets are stored, so as to remove the vertical-shaping swap from the DrawGlyphs loop as per bug 1408612 comment 21; I'll file a fresh bug for that.

Comment 3

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/2182bb31daa6
Reftest for GPOS glyph positioning adjustments in vertical-upright mode. r=jrmuizel
https://hg.mozilla.org/integration/mozilla-inbound/rev/f31841220317
Fix up handling of glyph offsets for text shaped in vertical mode. r=jrmuizel

Comment 4

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

https://hg.mozilla.org/mozilla-central/rev/2182bb31daa6
https://hg.mozilla.org/mozilla-central/rev/f31841220317