composite emoji shows extra vertical color lines

[Jeremy Bícha]

Impact
------
Composite emoji (such as 🫱🏾 [Rightwards Hand: Medium-Dark Skin Tone]) are not rendered correctly. By "composite emoji", I mean emoji that are made up of multiple Unicode characters joined by "ZWJ". Composite emoji are used for skin tones, gender, flags, and a few other emoji.

The incorrect rendering can be seen in Ubuntu 22.04's default text editor, gedit, as extra vertical red and black lines after the character. Screenshot attached.

Test Case
---------
Install the update
Close Text Editor if it is open
Open Text Editor
Paste this character in Text Editor:
🫱🏾
It should display correctly without any extra vertical lines after it.

Other Info
----------
This was originally noticed while verifying https://launchpad.net/bugs/1990677

What Could Go Wrong
-------------------
This is a one line fix cherry-picked from pango 1.50.8 (plus 30+ lines for a test case).

pango is a text rendering library in GTK. GTK is used for most of the apps in the default install for Ubuntu Desktop and several other Ubuntu desktop flavors. pango is also used by mutter which is a key component of GNOME Shell which provides the basic desktop environment for default Ubuntu. A critical enough bug in pango could make the desktop and apps unusuable because text wouldn't be readable. This is mitigated through build tests and autopkgtests.

[Andreas Hasenack (ahasenack)]

Hello Jeremy, or anyone else affected,

Accepted pango1.0 into jammy-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/pango1.0/1.50.6+ds-2ubuntu1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested, what testing has been performed on the package and change the tag from verification-needed-jammy to verification-done-jammy. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-jammy. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Jeremy Bícha (jbicha)]

Mateusz, if you have tested this package, please also leave a comment mentioning what version you have tested and what testing you have done.

[Jeremy Bícha (jbicha)]

I installed pango 1.50.6+ds-2ubuntu1 on Ubuntu 22.04 LTS and successfully completed the test case.

[Ubuntu SRU Bot (ubuntu-sru-bot)]

All autopkgtests for the newly accepted pango1.0 (1.50.6+ds-2ubuntu1) for jammy have finished running.
The following regressions have been reported in tests triggered by the package:

libreoffice/1:7.3.7-0ubuntu0.22.04.1 (arm64)
libreoffice/unknown (amd64)

Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-migration/jammy/update_excuses.html#pango1.0

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

[Chris Halse Rogers (raof)]

The verification of the Stable Release Update for pango1.0 has completed successfully and the package is now being released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Launchpad Janitor (janitor)]

This bug was fixed in the package pango1.0 - 1.50.6+ds-2ubuntu1

---------------
pango1.0 (1.50.6+ds-2ubuntu1) jammy; urgency=medium

  * Cherry-pick fix for vertical color lines showing with composite emoji
    (LP: #2006756)

 -- Jeremy Bicha <email address hidden> Thu, 09 Feb 2023 11:34:31 -0500