User:Tagoh/ChangesDraft/FontDependencies

Font Dependencies to Langpacks

Summary

There are font(:lang=...) auto-generated dependency for fonts packages. it is used as a dependency identifier to satisfy a certain language requirement. but this way didn't guarantee qualities because what fonts packages is going to be pulled in is unreliable.

So this proposes to replace it with langpacks instead, which has proper dependencies for fonts and improve the user experience around fonts with applications.

Owner

• Name: Akira TAGOH
• Email: tagoh@redhat.com
• Release notes owner:

Current status

• Targeted release: Fedora 32
• Last updated: 2019-12-27
• Tracker bug: <will be assigned by the Wrangler>

Detailed Description

The language based meta information about font dependency was introduced since Fedora 11. that was helpful to find out a font for missing glyphs through PackageKit and was useful for minority languages because we didn't have fonts packages for them so much. but the user experience wasn't that better under the certain condition.

Users can't predict what fonts will be installed. this may gives us worst result particularly when no fonts for the requested language is installed and/or is majority languages that has too many fonts such as English, because this logic doesn't guarantee the quality of fonts nor preferred fonts we expect to get installed by default. This random dependency sometimes introduces unexpected result too so that it's likely to happen that dependencies may be satisfied from external repositories. this may particularly be a problem when composing ISOs.

So this Changes proposal aims to improve the user experience around font dependencies by replacing it to Langpacks instead. Langpacks contains various dependencies to use for certain languages, including dependencies for default fonts. so it will resolves the above issues.

Specifically speaking, currently font dependency is generated like this:

$ fc-query -f %{=pkgkit}  /usr/share/fonts/dejavu/DejaVuSans.ttf
font(dejavusans)
font(:lang=aa)
font(:lang=ab)
...

and at the build time, it is transformed to:

Provides: font(dejavusans)
Provides: font(:lang=aa)
Provides: font(:lang=ab)
...

After this proposal, the above result will be:

Provides: font(dejavusans)

and then add Provides: font(:lang=...) line to corresponding sub-packages langpacks-core-*.

So asking for a font for a certain language through PackageKit will be achieved by langpacks-core-* instead of a random font package.

Benefit to Fedora

This proposal provides reliable, predictable, and consistencies in dependencies about fonts.

Scope

• Proposal owners:
  • Update fontconfig to drop font(:lang=...) from the alias of the formatter for %{=pkgkit}
  • Add a line of Provides: font(:lang=...) to each langpacks-core-.... for instance, Provides: font(:lang=hi) need to be added to langpacks-core-hi.

• Other developers: N/A

• Release engineering: #Releng issue number all of fonts packages must be rebuilt so that the above change in fontconfig can be reflected to all of fonts packages.
  • List of deliverables: N/A

• Policies and guidelines: N/A

• Trademark approval: N/A

Upgrade/compatibility impact

Some packages may be installed after upgrading if corresponding langpacks-core-* packages isn't yet installed.

How To Test

1. Check dependencies in langpacks-core-*. they must have corresponding Provides: font(:lang=...) line when asking with rpm -q --provides.
2. Check dependencies in fonts packages. they must contain no Provides: font(:lang=...) lines

User Experience

Users may see better fonts for certain language when they need to install a set of fonts for certain language support through PackageKit or package dependencies from others.

Dependencies

• fontconfig
• langpacks

Contingency Plan

• Contingency mechanism: (What to do? Who will do it?) Proposal owners will revert all of changes and rebuild all of fonts packages to add back deps
• Contingency deadline: the beta freeze
• Blocks release? No
• Blocks product? N/A

Documentation

N/A