Improvement for ja-jp conf (69-language-selector-ja-jp.conf): measure for ttf-unfonts-core side-effects

[Fumihito YOSHIDA]

Improvement for ja-jp conf(69-language-selector-ja-jp.conf),

Dear language-support/selector maintainers,

[Problem description]
In Japanese language environments, ttf-unfonts-core breaks Qt apps/web browsers font selection.

- If ttf-unfonts-core is installed, their application will neglect the 69-language-selector-ja-jp.conf.
- 'ttf-unfonts-core' is installed by task dependency(ubuntu-desktop,kubuntu-desktop,xubuntu-desktop and so on).

Root problem is fontconfig or Unicode specification("CJK overlapping"), but fontconfig-configuration could mitigate that.
So, 69-language-selector-ja-jp.conf patch is here.

[Background]
ttf-unfonts-core package's fontconfig has higher priority than 69-language-selector-ja-jp.conf's, but that is not root-problem. By historical reason, unicode specification has overlapped CJK range, but 69-language-selector-ja-jp is not robust for CJK overlapping. So, CJK fontconfig is nonpredictable minefield, any CJK related configuration has potential risk like that. ttf-unfonts-core is not guilty.

Mechanism:
1) 69-(snip)-ja-jp.conf is constrained by { <test name="lang" compare="contains"><string>ja</string></test> } COND. That COND limit the CJK settings. That mean: "this font use for CJK at lang=ja is provided".

2) ttf-unfonts-core(and some font packages, microhei may include) has not these COND, this configuration mean "this font use for CJK at anytime".

3) Qt apps are not use lang contains (Notes: That contains are optional, not Qt bug).

These configuration mean: "In Qt apps(and any apps with similar implementation), you have to use ttf-unfonts-core".

So, our measures are:

a) Fix Qt and any others : Unrealistic...

b) Fix ttf-unfonts-core and any others : Unrealistic, better than a).

c) Fix 69-language-selector-ja-jp.conf : Reasonable.

Yes, c) is not fundamental solution, real solution is fontconfig refactoring. But that is too difficult to fix:(

And,
- This approach had included at many CJK settings, that COND use at only ja-jp.
- This fix is widely well-tested. In "Ubuntu Japanese Remix 11.10"(released at Oct 16) include the lang-deleted config, and not reported any side-effects.

<test name="lang">.. COND deletion is only extrication at the moment.

[Fumihito YOSHIDA (hito)]

Additionally, focus of this "font rendering" problem, see attached.

- Glyph of ttf-unfonts-core are not valid in Japanese (please compare blue / green squares)
- To put it in perspective, that like switched U/Umlaut.

[Gunnar Hjalmarsson (gunnarhj)]

Thanks for reporting this issue and for the patch!

[Ubuntu Foundations Team Bug Bot (crichton)]

The attachment "New configuration file of 69-language-selector-ja-jp.conf" of this bug report has been identified as being a patch. The ubuntu-reviewers team has been subscribed to the bug report so that they can review the patch. In the event that this is in fact not a patch you can resolve this situation by removing the tag 'patch' from the bug report and editing the attachment so that it is not flagged as a patch. Additionally, if you are member of the ubuntu-sponsors please also unsubscribe the team from this bug report.

[This is an automated message performed by a Launchpad user owned by Brian Murray. Please contact him regarding any issues with the action taken in this bug report.]

[Launchpad Janitor (janitor)]

This bug was fixed in the package language-selector - 0.57

---------------
language-selector (0.57) precise; urgency=low

  [ Martin Pitt ]
  * data/pkg_depends: Install aspell dictionary for gedit. (LP: #869980)
  * data/pkg_depends: Install ibus-m17n for "te". (LP: #753476)

  [ Gabor Kelemen ]
  * Clean up language-selectors build system (LP: #853501)

  [ Fumihito YOSHIDA ]
  * fontconfig/69-language-selector-ja-jp.conf:
    Handle conflict with ttf-unfonts-core (LP: #884645).
 -- Martin Pitt <email address hidden> Fri, 04 Nov 2011 07:52:38 -0400