https://bugs.kde.org/show_bug.cgi?id=527496
Bug ID: 527496
Summary: Crash (null CaptureWindow) in region/GUI mode when the
only active output is a replica of a disabled output
Classification: Applications
Product: Spectacle
Version First unspecified
Reported In:
Platform: Kubuntu
OS: Linux
Status: REPORTED
Severity: crash
Priority: NOR
Component: General
Assignee: [email protected]
Reporter: [email protected]
CC: [email protected]
Target Milestone: ---
SUMMARY
Spectacle segfaults immediately after receiving the screenshot from KWin when
the only active output is configured as a replica (mirror) of a disabled
output. This happened on a laptop with the lid closed and only an external
monitor in use. Region mode (spectacle -r) and the GUI full-screen mode
(spectacle -f) crash; background mode (spectacle -b -f -o file.png) works.
STEPS TO REPRODUCE
1. Laptop with an external monitor; close the lid so only the external
monitor is active.
2. KWin ends up with this output configuration (from kscreen-doctor -o):
eDP-1 disabled, connected, replication source: 0, geometry 0,0 1920x1080
DP-2 enabled, connected, replication source: 1, geometry 1920,0
1920x1080
i.e. the only enabled output (DP-2) is a replica of the disabled eDP-1.
System Settings > Display Configuration shows
"All displays are disabled. Enable at least one."
3. Run: spectacle -r
OBSERVED RESULT
Spectacle crashes with SIGSEGV right after startup.
EXPECTED RESULT
Spectacle shows the region-selection overlay on the active monitor, or at
least fails gracefully instead of dereferencing a non-existent capture window.
ADDITIONAL INFORMATION
- Works with the lid open, with or without the external monitor.
- Not related to Tesseract: also crashes with libtesseract removed.
- Same crash with QT_QPA_PLATFORM=xcb.
- Not caused by spectaclerc: also crashes with the config file removed.
- Workaround: choosing "External only" in the display tray applet removes
the replica relationship, after which Spectacle works normally.
Backtrace (with kde-spectacle-dbgsym):
#6 std::__uniq_ptr_impl<CaptureWindow, void (*)(CaptureWindow*)>::_M_ptr
(this=0x0)
at /usr/include/c++/15/bits/unique_ptr.h:192
#7 std::unique_ptr<CaptureWindow, void (*)(CaptureWindow*)>::get (this=0x0)
at /usr/include/c++/15/bits/unique_ptr.h:472
#8 operator() (__closure=<optimised out>, image=<optimised out>)
at src/SpectacleCore.cpp:213
...
#15 QMetaObject::activate<void, QImage> (sender=0x0, mo=<optimised out>,
local_signal_index=3, ret=0x0)
#16 ImagePlatform::newCroppableScreenshotTaken (this=0x62ddf082ab90, _t1=...)
at moc_ImagePlatform.cpp:243
#17 ImagePlatformKWin::trackSource<...>::{lambda(QList<ResultVariant>
const&)#1}::operator()
at src/Platforms/ImagePlatformKWin.cpp:499
SOFTWARE/OS VERSIONS
Spectacle: 6.6.6 (Ubuntu package 4:6.6.6-0ubuntu0.1); also crashes with 6.6.4
KDE Frameworks: 6.24.0
Qt: 6.10.2
Linux: Ubuntu 26.04, kernel 7.0.0-38, Wayland session
Graphics: Intel (i915), Mesa 26.0.8
Hardware: ASUS ZenBook UX325EA + Acer B246HYL via DisplayPort
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