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= Enable HarfBuzz in FreeType <!-- The name of your change proposal --> =
 
 
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<!-- The actual name of your proposed change page should look something like: Changes/Your_Change_Proposal_Name.  This keeps all change proposals in the same namespace -->
 
 
 
= Change Proposal Name <!-- The name of your change proposal --> =
 
  
 
== Summary ==
 
== Summary ==
<!-- A sentence or two summarizing what this change is and what it will do. This information is used for the overall changeset summary page for each release.
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Goal of this feature is to enable usage of HarfBuzz in FreeType to improve hinting of glyphs of languages which needs more complicated text shaping.
Note that motivation for the change should be in the Benefit to Fedora section below, and this part should answer the question "What?" rather than "Why?". -->
 
  
 
== Owner ==
 
== Owner ==
<!--
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* Name: [[User:mkasik| Marek Kašík]]
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* Email: <mkasik@redhat.com>
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* Name: [[User:tagoh| Akira Tagoh]]
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* Email: <tagoh@redhat.com>
* Name: [[User:FASAcountName| Your Name]]
 
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== Current status ==
 
== Current status ==
 
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[[Category:SelfContainedChange]]
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* Targeted release: [[Releases/<number> | Fedora <number> ]]
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* Targeted release: 34
 
* Last updated: <!-- this is an automatic macro — you don't need to change this line -->  {{REVISIONYEAR}}-{{REVISIONMONTH}}-{{REVISIONDAY2}}  
 
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* Tracker bug: <will be assigned by the Wrangler>
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== Detailed Description ==
 
== Detailed Description ==
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Hinting of glyphs could be complicated due to many different rules of how to render sequence of glyphs. Thanks to enablement of HarfBuzz in FreeType applications will display text with correct hinting of glyphs.
  
<!-- Expand on the summary, if appropriate. A couple sentences suffices to explain the goal, but the more details you can provide the better. -->
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Usage of HarfBuzz helps us to fix some bugs which are not fixable without it. Mainly the bug #1853937.
 +
 
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Freetype upstream has already support for HarfBuzz for almost 6 years.
 +
 
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This change was proposed in the bug #1906714.
  
 
== Feedback ==
 
== Feedback ==
 
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There is the bug #1853937 which can not be solved without this.
<!-- Summarize the feedback from the community and address why you chose not to accept proposed alternatives. This section is optional for all change proposals but is strongly suggested. Incorporating feedback here as it is raised gives FESCo a clearer view of your proposal and leaves a good record for the future. If you get no feedback, that is useful to note in this section as well. For innovative or possibly controversial ideas, consider collecting feedback before you file the change proposal. -->
 
  
 
== Benefit to Fedora ==
 
== Benefit to Fedora ==
 
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Improved user experience for languages for which Unicode does not list all variants of all glyphs. These are determined by different signs or positions in string and their further processing is more difficult.
<!-- What is the benefit to the distribution?  Will the software we generate be improved? How will the process of creating Fedora releases be improved?
 
 
 
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-->
 
  
 
== Scope ==
 
== Scope ==
* Proposal owners:
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* Proposal owners: Enabling usage of HarfBuzz in FreeType means to handle a circular dependency which is needed due to the nature of interconnection of these two packages. Maintainers of FreeType and HarfBuzz will handle this via bootstraping process.
<!-- What work do the feature owners have to accomplish to complete the feature in time for release?  Is it a large change affecting many parts of the distribution or is it a very isolated change? What are those changes?-->
 
  
* Other developers: N/A (not a System Wide Change) <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
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* Other developers: N/A (not needed for this Change)
<!-- What work do other developers have to accomplish to complete the feature in time for release?  Is it a large change affecting many parts of the distribution or is it a very isolated change? What are those changes?-->
 
  
* Release engineering: [https://pagure.io/releng/issues #Releng issue number] (a check of an impact with Release Engineering is needed) <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
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* Release engineering: N/A (not needed for this Change)
<!-- Does this feature require coordination with release engineering (e.g. changes to installer image generation or update package delivery)?  Is a mass rebuild required?  include a link to the releng issue.
 
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* Policies and guidelines: N/A (not a System Wide Change) <!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
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* Policies and guidelines: N/A (not needed for this Change)
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* Trademark approval: N/A (not needed for this Change)
 
* Trademark approval: N/A (not needed for this Change)
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* Alignment with Objectives:  
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* Alignment with Objectives: There will be new dependency of FreeType on HarfBuzz so the footprint will be a little bigger on systems which did not need HarfBuzz before.
<!-- Does your proposal align with the current Fedora Objectives: https://docs.fedoraproject.org/en-US/project/objectives/ ? It's okay if it doesn't, but it's something to consider -->
 
  
 
== Upgrade/compatibility impact ==
 
== Upgrade/compatibility impact ==
<!-- What happens to systems that have had a previous versions of Fedora installed and are updated to the version containing this change? Will anything require manual configuration or data migration? Will any existing functionality be no longer supported? -->
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Updates should go smooth as this change is limited to FreeType and Harfbuzz regarding packaging point of view.
 
 
<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 
N/A (not a System Wide Change)
 
  
 
== How To Test ==
 
== How To Test ==
<!-- This does not need to be a full-fledged document. Describe the dimensions of tests that this change implementation is expected to pass when it is done.  If it needs to be tested with different hardware or software configurations, indicate them.  The more specific you can be, the better the community testing can be.
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Install "pango" and "lato-fonts".
 
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Run 'pango-view --markup -t "<span font_desc='Lato 8'>8pt t ti fi tt</span>  <span font_desc='Lato 9'>9pt t ti fi tt</span>  <span font_desc='Lato 10'>10pt t ti fi tt</span>  <span font_desc='Lato 11'>11pt t ti fi tt</span>  <span font_desc='Lato 14'>14pt t ti fi tt</span>"' and compare the results.
Remember that you are writing this how to for interested testers to use to check out your change implementation - documenting what you do for testing is OK, but it's much better to document what *I* can do to test your change.
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The horizontal stroke over "ti" does not correspond to the one over "fi" for some font sizes for FreeType without HarfBuzz support.
 
 
A good "how to test" should answer these four questions:
 
 
 
0. What special hardware / data / etc. is needed (if any)?
 
1. How do I prepare my system to test this change? What packages
 
need to be installed, config files edited, etc.?
 
2. What specific actions do I perform to check that the change is
 
working like it's supposed to?
 
3. What are the expected results of those actions?
 
-->
 
 
 
<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 
N/A (not a System Wide Change)
 
  
 
== User Experience ==
 
== User Experience ==
<!-- If this change proposal is noticeable by users, how will their experiences change as a result?
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This change improves hinting of glyphs which are composed from multiple characters.
 
 
This section partially overlaps with the Benefit to Fedora section above. This section should be primarily about the User Experience, written in a way that does not assume deep technical knowledge. More detailed technical description should be left for the Benefit to Fedora section.
 
 
 
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-->
 
  
 
== Dependencies ==
 
== Dependencies ==
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This change does not need any involvement other than listed owners.
 
 
<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 
N/A (not a System Wide Change)
 
  
 
== Contingency Plan ==
 
== Contingency Plan ==
 
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This change could be easily reverted if needed.
<!-- If you cannot complete your feature by the final development freeze, what is the backup plan?  This might be as simple as "Revert the shipped configuration". Or it might not (e.g. rebuilding a number of dependent packages).  If you feature is not completed in time we want to assure others that other parts of Fedora will not be in jeopardy.  -->
 
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<!-- Does finishing this feature block the release, or can we ship with the feature in incomplete state? -->
 
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== Documentation ==
 
== Documentation ==
<!-- Is there upstream documentation on this change, or notes you have written yourself?  Link to that material here so other interested developers can get involved. -->
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Not needed as both FreeType and HarfBuzz are already present in Fedora and there will be no change of their code.
 
 
<!-- REQUIRED FOR SYSTEM WIDE CHANGES -->
 
N/A (not a System Wide Change)
 
  
 
== Release Notes ==
 
== Release Notes ==
<!-- The Fedora Release Notes inform end-users about what is new in the release.  Examples of past release notes are here: http://docs.fedoraproject.org/release-notes/ -->
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There is no need for release notes as HarfBuzz is already in Fedora, it was just not used by FreeType.
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Revision as of 17:53, 8 January 2021

Enable HarfBuzz in FreeType

Summary

Goal of this feature is to enable usage of HarfBuzz in FreeType to improve hinting of glyphs of languages which needs more complicated text shaping.

Owner

Current status

  • Targeted release: 34
  • Last updated: 2021-01-08
  • FESCo issue: <will be assigned by the Wrangler>
  • Tracker bug: <will be assigned by the Wrangler>
  • Release notes tracker: <will be assigned by the Wrangler>

Detailed Description

Hinting of glyphs could be complicated due to many different rules of how to render sequence of glyphs. Thanks to enablement of HarfBuzz in FreeType applications will display text with correct hinting of glyphs.

Usage of HarfBuzz helps us to fix some bugs which are not fixable without it. Mainly the bug #1853937.

Freetype upstream has already support for HarfBuzz for almost 6 years.

This change was proposed in the bug #1906714.

Feedback

There is the bug #1853937 which can not be solved without this.

Benefit to Fedora

Improved user experience for languages for which Unicode does not list all variants of all glyphs. These are determined by different signs or positions in string and their further processing is more difficult.

Scope

  • Proposal owners: Enabling usage of HarfBuzz in FreeType means to handle a circular dependency which is needed due to the nature of interconnection of these two packages. Maintainers of FreeType and HarfBuzz will handle this via bootstraping process.
  • Other developers: N/A (not needed for this Change)
  • Release engineering: N/A (not needed for this Change)
  • Policies and guidelines: N/A (not needed for this Change)
  • Trademark approval: N/A (not needed for this Change)
  • Alignment with Objectives: There will be new dependency of FreeType on HarfBuzz so the footprint will be a little bigger on systems which did not need HarfBuzz before.

Upgrade/compatibility impact

Updates should go smooth as this change is limited to FreeType and Harfbuzz regarding packaging point of view.

How To Test

Install "pango" and "lato-fonts". Run 'pango-view --markup -t "8pt t ti fi tt 9pt t ti fi tt 10pt t ti fi tt 11pt t ti fi tt 14pt t ti fi tt"' and compare the results. The horizontal stroke over "ti" does not correspond to the one over "fi" for some font sizes for FreeType without HarfBuzz support.

User Experience

This change improves hinting of glyphs which are composed from multiple characters.

Dependencies

This change does not need any involvement other than listed owners.

Contingency Plan

This change could be easily reverted if needed.

Documentation

Not needed as both FreeType and HarfBuzz are already present in Fedora and there will be no change of their code.

Release Notes

There is no need for release notes as HarfBuzz is already in Fedora, it was just not used by FreeType.