Bug 512338

SUMMARY

When using QML in KWin/Plasma, every frame triggers a full-window repaint, even when only a small region of the UI changes. This results in unnecessary GPU/CPU workload.
I would like to ask whether KWin/Plasma has plans to support QML partial redraw / region-based damage tracking, similar to what Qt Quick can theoretically provide.

STEPS TO REPRODUCE

Create a QML window with a small animated element (e.g. a blinking rectangle).

Run the QML scene under KWin/Plasma Wayland.

Observe with tools such as WAYLAND_DEBUG=1, KWin’s paint debug tools, or GPU profiling.

OBSERVED RESULT

KWin repaints the entire surface every frame, even though only a very small region changes in the QML scene.
This leads to increased GPU usage and unnecessary composition cost.

EXPECTED RESULT

Ideally, QML could provide partial-damage rectangles to the compositor, and KWin would only repaint the regions that actually changed.

This behavior would greatly benefit performance on low-power devices and animations that affect only small portions of the UI.

SOFTWARE/OS VERSIONS

Linux/KDE Plasma: Any recent Plasma Wayland build
KDE Plasma Version: (your version)
KDE Frameworks Version: (your version)
Qt Version: (your Qt version)

ADDITIONAL INFORMATION

I am a developer working on QML scene optimization. I found that Qt Quick Scene Graph is capable of tracking changed dirty regions internally, but currently KWin treats QML surfaces as fully damaged for each frame.

I would like to ask:

Is there an existing plan or ongoing work for supporting partial damage for QML-based windows?

If not, would such a feature be considered for future Plasma releases?