387170 - Disable ligatures in uniscribe path if the text has spacing

Status: RESOLVED WORKSFORME

(Core :: Graphics, defect)

Description

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

Attachment: fix

we should disable ligatures also in uniscribe path if the text has spacing.

see also css2.1 spec:
http://www.w3.org/TR/CSS21/text.html#propdef-letter-spacing

> When the resultant space between two characters is not the same as the default space, user agents should not use ligatures.

roc:

should we use this patch after finding the way for disabling the ligatures on linux?

Comment 1

[Simon Montagu :smontagu]

This section of CSS2.1 is very unaware of international issues. http://www.w3.org/TR/css3-text/#letter-spacing is better.

Comment 2

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

     const PRBool mIsRTL;
+    const PRBool mDisableLigatures;

Make these PRPackedBool.

I guess we should be disabling optional ligatures only and allowing compulsory ligatures to still happen. Right Simon? If so then I'll submit a patch that changes DISABLE_LIGATURES to DISABLE_OPTIONAL_LIGATURES and fixes that for ATSUI. I'm not sure how you can do that for Uniscribe...

Comment 3

[Stuart Parmenter]

Without moving to the OpenType Uniscribe APIs (Vista only), I'm not sure how we can specify to only use required ligatures ('rlig' vs 'liga').

We should probably turn off discretionary ligatures ('dlig') on the mac though in all cases though.

Comment 4

[Stuart Parmenter]

either way, i don't think this patch is right for windows

Comment 5

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

You mean you want to turn off all discretionary ligatures on Mac, always? Why?

Comment 6

[Simon Montagu :smontagu]

(In reply to comment #2)
> I guess we should be disabling optional ligatures only and allowing compulsory
> ligatures to still happen. Right Simon?

That sounds right in theory.

Comment 7

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

Filed bug 387867 on that, with a patch.

Comment 8

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

I'm resetting bugs which are assigned to me but I'm not working on them and I don't have plan for fixing them in near future.

Comment 9

[Michael Kohler [:mkohler]]

This is a mass change. Every comment has "assigned-to-new" in it.

I didn't look through the bugs, so I'm sorry if I change a bug which shouldn't be changed. But I guess these bugs are just bugs that were once assigned and people forgot to change the Status back when unassigning.

Comment 10

[Masayuki Nakano [:masayuki] (he/him)(JST, +0900)]

This must have been already fixed by something. I cannot reproduce this.

Comment 11

[Jonathan Kew [:jfkthame]]

(In reply to Masayuki Nakano (:masayuki) (Mozilla Japan) from comment #10)
> This must have been already fixed by something. I cannot reproduce this.

We no longer have a uniscribe text rendering path; it's been replaced by harfbuzz. And yes, we handle this issue when shaping via harfbuzz.