427659 - some combining marks (for accents) are invisible

Status: RESOLVED FIXED

(Core :: MathML, defect)

Description

[Karl Tomlinson (:karlt)]

Attachment: testcase

Combining marks in many fonts have zero advance width (and sometimes very negative leftbearing), but these marks are often used alone in text frames for MathML accents.

In the testcase, the spacing character U+005E CIRCUMFLEX ACCENT (above the right "a") renders fine, but U+0302 COMBINING CIRCUMFLEX ACCENT (above the left "a") is not rendered.  For some accents there is only the combining character (no spacing character).

Comment 1

[Karl Tomlinson (:karlt)]

Attachment: use text-rendering:optimizeLegibility

This fixes the MathML use cases.

Comment 2

[Robert O'Callahan (:roc) (email my personal email if necessary)]

Comment on attachment 314220 [details] [diff] [review]
use text-rendering:optimizeLegibility

good call!

Comment 3

[Damon Sicore (:damons)]

Not a blocker, but would take the patch.

Comment 4

[Karl Tomlinson (:karlt)]

Comment on attachment 314220 [details] [diff] [review]
use text-rendering:optimizeLegibility

(In reply to comment #3)
> but would take the patch.

Should I interpret that as approval1.9?

The patch only affects MathML.  The only risk I can imagine is that it uses
some different code paths and thus might show some bugs that would otherwise
have only shown at larger font sizes.

Re testing: we could check something is displayed for the accents in a reftest
by comparing an accent against a blank or by comparing the same base char with
two different color accents and make sure they render differently.  (I could
do that after code freeze.)

Comment 5

[Damon Sicore (:damons)]

Ok, approving, but need to get that test in ASAP (i.e., < 24 hours after freeze).

Comment 6

[Damon Sicore (:damons)]

Comment on attachment 314220 [details] [diff] [review]
use text-rendering:optimizeLegibility

a1.9+=damons

Comment 7

[Karl Tomlinson (:karlt)]

http://bonsai.mozilla.org/cvsquery.cgi?module=PhoenixTinderbox&branch=HEAD&cvsroot=%2Fcvsroot&date=explicit&mindate=1207719000&maxdate=1207719124&who=karlt%2B%25karlt.net

Comment 8

[Karl Tomlinson (:karlt)]

test checked in (with 2h25 to spare)
http://bonsai.mozilla.org/cvsquery.cgi?module=PhoenixTinderbox&branch=HEAD&cvsroot=%2Fcvsroot&date=explicit&mindate=1207801922&maxdate=1207802117&who=karlt%2B%25karlt.net