Re: master bf0aeaa0d7a: Re-enable displaying `han' characters on Android

[Po Lu <luangruo@yahoo.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Po Lu <luangruo@yahoo.com>
>> Cc: emacs-devel@gnu.org
>> Date: Thu, 01 Aug 2024 17:47:54 +0800
>> 
>> Eli Zaretskii <eliz@gnu.org> writes:
>> 
>> > But users can add a font spec for 'han' to the fontset, cannot they?
>> > And if they do, then the representative characters _are_ important,
>> > aren't they?  So I don't think we should remove those characters.
>> 
>> Such an action would be pointless, as the fontset would not match any
>> CJK font actually in existence, and it would break the Android build to
>> boot.
>
> Then Android users should not do that.  But users of other systems
> could, and we should not prevent them from doing so.

We don't prevent users from modifying script-representative-chars
anywhere, no?

>> If anyone seriously considers non-existent characters important
>> enough to construct a font spec that matches them, he can easily amend
>> script-representative-chars for himself or define another script.  If
>> these pages are opened, for example:
>> 
>>   https://www.compart.com/en/unicode/U+20000
>>   https://www.compart.com/en/unicode/U+2a700
>>   https://www.compart.com/en/unicode/U+2b740
>>   https://www.compart.com/en/unicode/U+2b820
>>   https://www.compart.com/en/unicode/U+2ceb0
>> 
>> in Mozilla (not to mention Emacs) on my GNU/Linux system or on Android,
>> tofu is displayed, and there can hardly be said to exist an OS system
>> that is better internationalized out of the box than is Android.  The
>> remaining characters:
>> 
>>   https://www.compart.com/en/unicode/U+2f804
>>   https://www.compart.com/en/unicode/U+1f210
>> 
>> are displayed correctly, but are barely attested or expected to be
>> present by CJK users in practice, and U+1F210 is arguably rather a
>> symbol than a proper character.
>
> On my Windows 11 system, I see all of them, and I didn't install any
> additional fonts for CJK.  So your assertion is simply not true.
> Maybe your GNU/Linux system is outdated, or maybe GNU/Linux users with
> CJK interests are supposed to install optional packages that you don't
> have installed.

This is an installation of Fedora Workstation 40 that was updated
yesterday, and where all of the Noto font packages that are required for
displaying CJK text are undoubtedly installed.  The reason these
characters are omitted from the suggested set of CJK fonts is that there
is simply insufficient interest in these characters, and probably the
same reasonining holds on Android, where users cannot install fonts at
all, and where the entirety of these pages, save about a dozen, is tofu:

  https://commons.wikimedia.org/wiki/Category:Unicode_20000-2A6DF_CJK_Unified_Ideographs_Extension_B
  https://commons.wikimedia.org/wiki/Category:Unicode_2A700-2B73F_CJK_Unified_Ideographs_Extension_C
  https://commons.wikimedia.org/wiki/Category:Unicode_2B740-2B81F_CJK_Unified_Ideographs_Extension_D
  https://commons.wikimedia.org/wiki/Category:Unicode_2B820-2CEAF_CJK_Unified_Ideographs_Extension_E
  https://commons.wikimedia.org/wiki/Category:Unicode_2CEB0-2EBEF_CJK_Unified_Ideographs_Extension_F

Noto are apparently quite reluctant to support Extension B:

  https://github.com/notofonts/noto-cjk/issues/13

and they are the go-to source of Free CJK fonts nowadays.