https://bugs.kde.org/show_bug.cgi?id=412267
Bug ID: 412267
Summary: Active fonts should not render fallback glyphs if
missing
Product: kcharselect
Version: 19.08.0
Platform: Manjaro
OS: Linux
Status: REPORTED
Severity: wishlist
Priority: NOR
Component: general
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
SUMMARY
While troubleshooting an emoji rendering setup, I inspected fonts with
KCharSelect but was mislead which fonts had which glyphs as fallbacks were
being deceivingly rendered when the font did not contain the actual glyph.
Installing noto-fonts-emoji
Selecting DejaVu Sans or Bitstream Vera Sans fonts in the dropdown, and then
the sectino/view: `Symbols -> Emoticons`. Both show mostly black/white emoji,
but a few are in colour like 1F624:
1F60E 😎 - "SMILING FACE WITH SUNGLASSES"
1F624 😤 - "FACE WITH LOOK OF TRIUMPH"
When changing font to "Noto Color Emoji", all emoji are rendered in colour,
including 1F60E. 1F624 is the exact same as what was shown in the earlier
mentioned fonts(with my current setup at least), so it has been displayed as a
fallback.
Bitstream Vera fonts should not contain any emoji, so again, this is shown
falling back to both DejaVu, and if not available further back to Noto Color
Emoji.
I have since learned how to identify this fallback order, and that Bitstream
Vera didn't have the black/white emoji that KCharSelect implied it did via
confirming font used with this command:
fc-match serif
VeraSe.ttf: "Bitstream Vera Serif" "Roman"
fc-match serif:charset=1F60E
DejaVuSans.ttf: "DejaVu Sans" "Book"
fc-match serif:charset=1F923
NotoColorEmoji.ttf: "Noto Color Emoji" "Regular"
I assume KCharSelect showed 1F60E correctly when viewing Noto Color Emoji as it
renders the font glyph views with that specific font, thus, no need to render a
fallback.
Perhaps this is out of scope of KCharSelect and it's working as
intended(character selection regardless of how it's rendered by active font),
not for inspecting an actual fonts contents.
I understand that the current implementation is likely rendering the glyphs in
a standard way like regular text with the selected font applied. Thus it's
likely more effort than it's worth to resolve this.
STEPS TO REPRODUCE
1. Select "Bitstream Vera Sans" as font.
2. Enter "1F60E" in search field.
3. A result should appear, but it's not actually from the font but a fallback.
OBSERVED RESULT
Fallback font rendered, no indication of such.
EXPECTED RESULT
No result, does not exist in the selected font. Or should indicate it's
rendering a fallback.
SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Manjaro KDE (up to date), Kernel 4.19.69-1-MANJARO
KDE Plasma Version: 5.16.4
KDE Frameworks Version: 5.61.0
Qt Version: 5.13.0
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