| Summary: | KQuickAddons.Plotter skips repaints | ||
|---|---|---|---|
| Product: | [Frameworks and Libraries] frameworks-kdeclarative | Reporter: | Konstantinos Smanis <konstantinos.smanis> |
| Component: | general | Assignee: | Marco Martin <notmart> |
| Status: | RESOLVED INTENTIONAL | ||
| Severity: | normal | CC: | kdelibs-bugs-null, nate |
| Priority: | NOR | ||
| Version First Reported In: | 5.69.0 | ||
| Target Milestone: | --- | ||
| Platform: | Gentoo Packages | ||
| OS: | Linux | ||
| Latest Commit: | Version Fixed/Implemented In: | ||
| Sentry Crash Report: | |||
| Attachments: | Screencast (applet update interval: 1 second) | ||
This component is deprecated in favor of the fancy new hardware-accelerated charts provided by KQuickCharts, and the only things known to be using it have since been ported away. Not worth fixing, since it's a dead man walking. :) |
Created attachment 127986 [details] Screencast (applet update interval: 1 second) SUMMARY The KQuickAddons.Plotter used for the System Monitor applets occasionally skips repaints, leading to jumpy plots. More specifically, the skips occur because the plot itself will not be repainted unless another element in the QML scene changes. According to my understanding, Plotter::addSample() triggers Plotter::update(), which in turn triggers Plotter::updatePaintNode(). However, Plotter::updatePaintNode() only seems to be initializing the paint node, not actually rendering it (why?), therefore relying only on the QQuickWindow::beforeRendering signal to trigger Plotter::render(). As a result, even if you add new samples to the plot, they will be rendered only if another element in the QML scene requires to be repainted. For example, in the CPU load monitoring applet, if the CPU load remains the same across multiple measurements, the applet will not be repainted until a different CPU load measurement comes up. This can be observed in the attached screencast twice: * the first time, the CPU load remains at 14% for two ticks, leading to one missed repaint * the second time, the CPU load remains at 14% for four ticks, leading to three missed repaints STEPS TO REPRODUCE 1. Observe any system monitor applet (preferably in plasmoidviewer or on the desktop, because on a panel other applets will trigger a repaint) 2. Wait for multiple same measurements OBSERVED RESULT The applet is not repainted while the measurement remains the same. It is only updated when a different measurement comes up. EXPECTED RESULT The applet should be repainted for every measurement. SOFTWARE/OS VERSIONS Operating System: Gentoo Linux KDE Plasma Version: 5.18.4 KDE Frameworks Version: 5.69.0 Qt Version: 5.14.1 Kernel Version: 5.6.7-gentoo OS Type: 64-bit