F36 Change: Default To Noto Fonts (System-Wide Change proposal)

[Ben Cotton]

https://fedoraproject.org/wiki/Changes/DefaultToNotoFonts

== Summary ==
Changing the default fonts for various languages to Noto Fonts as much
as possible, to make consistency on the text rendering.

== Owner ==
* Name: [[User:Tagoh|Akira TAGOH]]
* Email: <tagoh(a)redhat.com&gt;


== Detailed Description ==
For a long time we have used DejaVu fonts as the default font for
European and other language scripts. On the other hand some language
scripts are not covered by DejaVu and hence have other default fonts.
(A few languages like Chinese, Japanese and Korean, as well as
Gurmukhi, Sinhala, and emoji are already using Noto fonts by default
for some time.)  This situation leads to inconsistencies in text
rendering on applications and desktops, particularly when mixing
different character sets. Further Noto fonts bring some further
advantages: the fonts are generally higher quality and support
variable fonts for most scripts, making them more compact.

This change aims to provide better experience and consistent text
rendering across more languages by replacing DejaVu with Noto as the
general system default set of fonts.

The following packages will be installed by default to replace
DejaVu's coverage:
* google-noto-sans-vf-fonts
* google-noto-serif-vf-fonts
* google-noto-sans-mono-vf-fonts
* google-noto-sans-arabic-vf-fonts
* google-noto-sans-cherokee-vf-fonts
* google-noto-sans-thaana-vf-fonts
* google-noto-sans-hebrew-vf-fonts
* google-noto-rashi-hebrew-vf-fonts
* google-noto-sans-math-vf-fonts
* google-noto-sans-armenian-vf-fonts
* google-noto-serif-armenian-vf-fonts
* google-noto-sans-canadian-aboriginal-vf-fonts
* google-noto-sans-georgian-vf-fonts
* google-noto-serif-georgian-vf-fonts
* google-noto-sans-lao-vf-fonts
* google-noto-serif-lao-vf-fonts
* google-noto-serif-gurmukhi-vf-fonts
* google-noto-serif-sinhala-vf-fonts

And you can check
[https://tagoh.fedorapeople.org/fonts/noto/f36-noto.html the table] to
see what languages will be affected by this change.


== Benefit to Fedora ==
We would get better text rendering on applications and desktops. Also
this change should save about 6MB on the fresh install.

<pre>
$ rpm -qlv dejavu-sans-fonts dejavu-serif-fonts dejavu-sans-mono-fonts
| awk 'BEGIN{a=0}{a+=$5}END{print a}'
10789272</pre>
<pre>
$ rpm -qlv google-noto-sans-vf-fonts google-noto-serif-vf-fonts
google-noto-sans-mono-vf-fonts google-noto-sans-arabic-vf-fonts
google-noto-sans-cherokee-vf-fonts google-noto-sans-thaana-vf-fonts
google-noto
-sans-hebrew-vf-fonts google-noto-rashi-hebrew-vf-fonts
google-noto-sans-math-vf-fonts google-noto-sans-armenian-vf-f
onts google-noto-serif-armenian-vf-fonts
google-noto-sans-canadian-aboriginal-vf-fonts
google-noto-sans-georgian-vf-f
onts google-noto-serif-georgian-vf-fonts google-noto-sans-lao-vf-fonts
google-noto-serif-lao-vf-fonts google-noto-serif-gurmukhi-vf-fonts
google-noto-serif-sinhala-vf-fonts | awk 'BEGIN{a=0}{a+=$5}END{print
a}'
4753340
</pre>

== Scope ==
* Proposal owners:
** Update google-noto-fonts and dejavu-fonts to change the priority
for fontconfig config.
** Update langpacks to update the dependency.
** Update comps to make Noto fonts default.
** Update lorax templates related to DejaVu.
** Update fontconfig to change the order of fonts in the builtin config.

* Other developers:
** Packagers who owns packages implicitly expects DejaVu is installed
by default will needs to update the dependency for them.

* Release engineering: [https://pagure.io/releng/issue/10492 #10492]
* Policies and guidelines: N/A (not needed for this Change)
* Trademark approval: N/A (not needed for this Change)
* Alignment with Objectives:


== Upgrade/compatibility impact ==
The migration will be done by updating langpacks. after upgrading and
rebooting, the default font will be Noto instead of DejaVu.

Since this change aims to switch non-variable fonts to variable fonts,
it may not works with legacy applications as expected such as missing
some variants. in that case, you can install non-variable fonts
packages. the package name will be similar and simply drop `-vf` from
the variable fonts packages.


== How To Test ==
* This change can be simply tested by `fc-match` command like
`fc-match sans:lang=<your langauge>`, `fc-match serif:lang=<your
language>` and `fc-match monospace:lang=<your language>`. You can
check the expected result from
[https://tagoh.fedorapeople.org/fonts/noto/f36-noto.html the table].
* Test the text rendering in your favorite application, which use the
system default font.

== User Experience ==
Users will see the default font is changed to Noto by this change
except for some languages which has much better quality of fonts.

== Dependencies ==
Only dejavu-fonts, langpacks, and fontconfig are required to update.
Other packages which explicitly has a dependency to dejavu-fonts are
basicaly optional to update.

== Contingency Plan ==
* Contingency mechanism:  Revert the relevant packages updated.
* Contingency deadline: Beta freeze
* Blocks release? No

== Documentation ==
None.

== Release Notes ==
The default fonts for most languages will be Google Noto fonts instead
of DejaVu, to keep consistency on the text rendering and to provide
better quality among languages.


-- 
Ben Cotton
He / Him / His
Fedora Program Manager
Red Hat
TZ=America/Indiana/Indianapolis