SUMMARY On Wayland, 125% scale, drawing a line in KolourPaint has a significant lag between the cursor and the actual line on the canvas. STEPS TO REPRODUCE 1. Log in to Wayland, and set 125% scale in Display settings. 2. Open KolourPaint 3. Choose "Line" tool and draw something on the canvas OBSERVED RESULT Significant lag EXPECTED RESULT No lag like on X11 SOFTWARE/OS VERSIONS Operating System: openSUSE Tumbleweed 20220210 KDE Plasma Version: 5.24.80 KDE Frameworks Version: 5.91.0 Qt Version: 5.15.2 Kernel Version: 5.16.4-1-default (64-bit) Graphics Platform: X11 Processors: 8 × AMD Ryzen 7 4700U with Radeon Graphics Memory: 15.0 GiB of RAM Graphics Processor: AMD RENOIR ADDITIONAL INFORMATION Information for package kolourpaint: ------------------------------------ Repository : unstable-kde-applications Name : kolourpaint Version : 22.03.70git.20220128T234302~ec495309-ku.7.1 Arch : x86_64 Vendor : obs://build.opensuse.org/KDE:Unstable Installed Size : 1.9 MiB Installed : Yes Status : up-to-date Source package : kolourpaint-22.03.70git.20220128T234302~ec495309-ku.7.1.src Summary : Paint Progra
Can't reproduce on master
I can reproduce it with 22.08.1, which is also current master, under sway window manager (wayland). SOFTWARE/OS VERSIONS sway version: both 1.7 and current master cffb006feba52c318e66f73c3463032fa76782dc reproduce kolourpaint version: 22.08.1 Qt version: 5.15.5 OS: NixOS unstable CPU/GPU: AMD Ryzen 7 5700G with integrated GPU RAM: 16GiB ADDITIONAL INFORMATION 1. 100% scale or 200% scale both work flawlessly. Only 125% scale causes significant redraw lag (500ms to 1s delay) even when selecting "Brush" tool and moving the cursor fast on the canvas, no need to press mouse button. 2. There are also many lines of "QWaylandShmBuffer: mmap failed (Invalid argument)" printed in console.
I'm also encountering this error when using kolourpaint 23.04.1 on opensuse tumbleweed when running my desktop under wayland at 150% scaling. The temporary workaround I use is to force kolourpaint to run via xwayland using 'QT_QPA_PLATFORM=xcb'
Created attachment 159412 [details] video.mp4 Can reproduce with 200% scale
Also an issue for me at 100% scale Operating System: Arch Linux KDE Plasma Version: 5.27.7 KDE Frameworks Version: 5.109.0 Qt Version: 5.15.10 Kernel Version: 6.4.11-arch2-1 (64-bit) Graphics Platform: Wayland
A possibly relevant merge request was started @ https://invent.kde.org/graphics/kolourpaint/-/merge_requests/47
It's an upstream issue which will be fixed in Qt by Kai Uwe Broulik with https://codereview.qt-project.org/c/qt/qtwayland/+/527980.
Not fully fixed. Reopened
According to kbroulik, On X11 AA_CompressHighFrequencyEvents is enabled
This might be fixed with https://invent.kde.org/plasma/kwin/-/merge_requests/5984. Can you re-test with KWin from git master?