The effect causes KWin to paint the area behind opaque windows, resulting in higher GPU usage

[taj-ny]

With just a few blurred windows in the background, the regions that have to be painted quickly add up, even if all the windows are covered by an opaque window.

I believe this is an accident, as data.setTranslucent() sets data.opaque to an empty region, but just a few lines later you are subtracting from that empty region.
https://github.com/matinlotfali/KDE-Rounded-Corners/blob/master/src/ShapeCornersEffect.cpp#L137-L149
https://github.com/KDE/kwin/blob/v6.0.3/src/effect/effect.cpp#L20-L25

I commented out the data.setTranslucent() line and the GPU usage has dropped in the situation described at the beginning. I haven't noticed any issues with corners, shadows or the outline on Wayland and X11.

Although I should mention that Plasma 6 broke transparent color schemes and the translucent area behind some windows is no longer painted (bug report, video), resulting in artifacts on Wayland. data.setTranslucent() does fix this, so removing it could bring back the issue for some users.

I'm running Plasma 6.0.3 with KDE-Rounded-Corners 0.6.1.

[matinlotfali]

You are absolutely correct. The setTranslucent is there only because of the ugly artifacts. I should have written comments in the code about it.

[matinlotfali]

Sadly, I don't know how else I can prevent the artifact. I am open for suggestions.

[rkunschke]

I have two questions about that:

Is that problem only with semi-transparent and transparent windows?

And would it be a good idea to provide a option to disable that behavier?
Maybe with a warning about artifacts. Maybe on some setups the artifacts seem to be no problem as @taj-ny descried: "I haven't noticed any issues with corners, shadows or the outline on Wayland and X11."

[matinlotfali]

Sure I can make it an option defaulting to false.

[matinlotfali]

@rkunschke Can you test #434?

[taj-ny]

Is that problem only with semi-transparent and transparent windows?

Only windows with opaque areas are affected.

I commented out the data.setTranslucent() line and the GPU usage has dropped in the situation described at the beginning. I haven't noticed any issues with corners, shadows or the outline on Wayland and X11.

After a year of using this I did notice some artifacts in the corners that appear rarely, so that's not the correct solution. I don't have time for testing right now but perhaps try this instead of data.setTranslucent():

data.mask |= Effect::PAINT_WINDOW_TRANSLUCENT;
data.mask &= ~Effect::PAINT_WINDOW_OPAQUE;

This marks the window as translucent but doesn't reset the opaque region (https://github.com/KDE/kwin/blob/580a077e94f35c73417de9e880508f1c0b5d8dbd/src/effect/effect.cpp#L20).

[matinlotfali]

@rkunschke Can you also test #435?

[rkunschke]

@rkunschke Can you also test #435?

I've tested it and felt no difference. Is there a indication if it worked?