[konsole] [Bug 468465] New: The commit "Draw characters in exact positions" regressed selection of japanese characters.

[Thomas Lindroth]

https://bugs.kde.org/show_bug.cgi?id=468465

            Bug ID: 468465
           Summary: The commit "Draw characters in exact positions"
                    regressed selection of japanese characters.
    Classification: Applications
           Product: konsole
           Version: master
          Platform: Gentoo Packages
                OS: Linux
            Status: REPORTED
          Severity: normal
          Priority: NOR
         Component: font
          Assignee: konsole-devel at kde.org
          Reporter: thomas.lindroth at gmail.com
  Target Milestone: ---

My distribution upgraded konsole from v22.08.3 to v22.12.3 recently and this
introduced some regressions in font handling.

I use the Liberation Mono 9pt font but when displaying japanese characters it
falls back to Arial Unicode MS 1.01 for those characters. This looked correct
in v22.08.3 but when I try to select any japanese text in v22.12.3 only half
the character is selected. This also impacts the new "select mode"
(ctrl+shift+d). The cursor can be placed inside of japanese characters and you
have to press the directional keys twice to move between those characters.

https://i.imgur.com/4ldFigD.png <- v22.08.3 showing the full 二 character
selected
https://i.imgur.com/PoYtSCr.png <- v22.12.3 showing only half of the 二
character selected

The japanese characters are twice as wide as Liberation Mono characters on
screen so if the screen is divided into a strict monospace grid the japanese
characters gets chopped in half but v22.08.3 seem to handle that fine.

There is also a slight change in visual appearance. If konsole is displaying a
mix of Liberation Mono and japanese text on different lines some of the pixels
from the japanese text remains after the screen is cleared.

https://i.imgur.com/DD6CM3I.png <- displaying some mixed text on v22.12.3
https://i.imgur.com/v1tqx6R.png <- after running nano, which clears the screen,
the top row of pixels from the japanese text remains

I've bisected both problems to the following commit:
76f879cd70fb494ab2334d2660b34679546f3d9d is the first bad commit
commit 76f879cd70fb494ab2334d2660b34679546f3d9d
Author: Matan Ziv-Av <matan at svgalib.org>
Date:   Sat Aug 6 19:15:42 2022 +0300

Draw characters in exact positions

The latest git version is also affected.

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