https://bugs.kde.org/show_bug.cgi?id=520874
Bug ID: 520874
Summary: Small toolbar/navigation icons render pixelated under
fractional scaling (Wayland, Plasma 6.6.5)
Classification: Frameworks and Libraries
Product: frameworks-kiconthemes
Version First 6.26.0
Reported In:
Platform: Fedora RPMs
OS: Linux
Status: REPORTED
Severity: normal
Priority: NOR
Component: general
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
## Summary
With a fractional global scale (e.g. 150%) on a Wayland session, small Qt/KDE
icons rendered at
toolbar/navigation sizes (~22px logical) appear pixelated/upscaled — visible
hard, stepped edges — while
text and large icons in the same window are crisp. The clearest example is
Dolphin's breadcrumb Home
button (go-home / user-home). The problem is independent of the icon theme
(reproduces with stock Breeze)
and disappears at integer scale (100% / 200%), confirming it is a
fractional-scaling rendering issue,
not a missing-icon-size or theme issue.
## Environment
- OS: Fedora Linux 44 (kernel 7.0.10-201.fc44.x86_64)
- Session: Wayland, KDE Plasma
- Plasma / KWin: 6.6.5
- Qt: 6.11.1
- KF6 kiconthemes: 6.26.0
- GPU: Intel Raptor Lake-P [UHD Graphics] (iGPU)
- Display: eDP-1, 1920x1080 @ 60 Hz, single monitor
- Global scale: 1.5 (150%)
## Steps to reproduce
1. Wayland Plasma session, single 1080p display.
2. Set Global scale = 150% (System Settings > Display & Monitor). Apply.
3. Open Dolphin.
4. Look at the Home icon in the breadcrumb/URL-navigator (and other small
toolbar icons such as
back/forward).
## Expected result
The small icon is rendered sharply from its vector source at the physical pixel
size implied by the scale
(~33px at 150%), like the text and the large view icons.
## Actual result
The small icon has visibly stepped/pixelated edges — it looks like a ~16-24px
raster scaled up to ~33px —
while everything else in the window is crisp.
## Evidence it is a rendering issue, not the icon theme
third-party theme (tested with Gruvbox-Plus-Dark and Breeze).
- Qt resolves the icon at the correct size on request:
QIcon.fromTheme("go-home") / "user-home" report
actualSize(QSize(33,33)) == 33x33 and non-empty availableSizes(). So the
toolkit can produce a 33px
pixmap — the blur is in how it is rasterised/scaled for display, not in icon
availability.
- Integer scale fixes it: at 100% or 200% the same icon is crisp. Only
fractional factors (125% / 135% /
150%) show the defect.
## Workaround (confirmed working)
Setting QT_SCALE_FACTOR_ROUNDING_POLICY=Round in ~/.config/environment.d makes
the affected icons crisp
again at 150%. At 150% this makes Qt apps render at 2x and the compositor
downscales to 1.5x (effectively
supersampling), which is sharp. This strongly suggests the defect is in the
fractional rasterisation
path rather than the integer one.
## Notes
- Not Fedora-specific; reproducible on any distro shipping Plasma 6.6 / Qt
6.11.
- Related/likely-same root area: KDE bug 491677 (fixed in kiconthemes 6.6 for a
Qt 6.8 scaledPixmap
behaviour change) — but symptom persists on 6.26.0.
--
You are receiving this mail because:
You are watching all bug changes.
