blur/rounded-corners: rewrite

[taj-ny]

This is a rewrite of the rounded corners implementation, which has much better-looking corners. There's probably a better way to do it, but for now that's the simplest and most efficient way of doing it that I can implement myself.

The corner radiuses are also now decimal values.

Comparison

The pictures were made in the worst possible situation: maximum blur strength with the corner being on a darker surface right next to a bright one.

Blur only (15px radius)

Before

After

No antialiasing:

0,5 antialiasing:

With window-rounding effects (15px radius)

KDE-Rounded-Corners

17px blur radius with 1 antialiasing

Couldn't get it to match perfectly, but it's definitely better than before.

LightlyShaders

14,75px blur radius with 0,5 antialiasing

Looks perfect.

To do

• Blur is very often painted in the wrong position
• Corners may not be rounded if Blur window decorations as well is disabled
• Don't use the rounded corners shader to paint areas that don't intersect with any of the corners
• Fake blur doesn't work properly
• Very strong artifacts when using the Colorblindness Correction or Invert effects
• Texture behind panels behaves in a weird way when using the Background Contrast effect
• The shader may not work properly with small regions
• Regions behind rounded corners aren't marked as translucent
• Round corners using the blur region mask method when antialiasing is set to 0
• Korners when using scaling on Wayland, caused by the texture size not being multiplied by the screen scale
• Corners aren't rounded when the window is scaled (for example during the closing animation)
• Noise texture doesn't move along the X axis anymore

[talentlessguy]

Sorry for off-topic, but what Window Decoration theme are you using here? I'm using SierraBreezeEnhanced window decoration and Lightly application style and I get artifacts coming from blur:

[taj-ny]

I'm using Breeze with disabled titlebar. In your picture it looks like SierraBreezeEnhanced specifies its own blur region, which needs to be overridden by enabling Blur window decorations as well. The bottom corner appears to be rounded properly, but you'll need an effect that rounds the window as well, such as KDE-Rounded-Corners or LightlyShaders.

[talentlessguy]

@taj-ny what should be border radii in each of the components (LightlyShaders/SierraBreezeEnhanced/Lightly/Force Blur)? Should be all the same (ex. 8px)?

I enabled all of them and I still experience artifacts, but only for window titlebar

also Force blur together with LightlyShaders makes most apps blurry (see a-parhom/LightlyShaders#130)

[taj-ny]

Go to force blur settings, enable Blur window decorations as well and keep adjusting the top corner radius until it looks fine.

Applications becoming blurry when using LightlyShaders/KDE-Rounded-Corners with scaling is a KWin bug.

[talentlessguy]

@taj-ny should I file a bug to KDE? How do I reproduce it properly? I mean without involving desktop effects directly (like via c++ or smth idk)

[taj-ny]

@taj-ny should I file a bug to KDE? How do I reproduce it properly? I mean without involving desktop effects directly (like via c++ or smth idk)

It has already been reported. The bug report is about the Colorblindness Correction effect, but it's the same bug that affects LightlyShaders/KDE-Rounded-Corners.
https://bugs.kde.org/show_bug.cgi?id=482978

[taj-ny]

I've fixed the low texture resolution issue when using scaling on Wayland, but sometimes its position is off by 1 pixel. A similar issue affects many effects, including Blur, Invert, Colorblindness Correction, LightlyShaders and KDE-Rounded-Corners. I guess I'm not going to bother fixing that for now and I'll just let users choose whether they want to use the old or the new rounded corners implementation.

EDIT: The issue described above will not occur when antialiasing is set to 0.

It's also interesting how even on 200% scaling the blur looks fine, even though the texture that's being blurred has a resolution that's two times smaller.

[taj-ny]

There are some minor issues with antialiasing when using scaling on Wayland but other than that everything seems to be working perfectly. I'll probably make a release tomorrow.

Floating panels are now rounded correctly and non-floating panels aren't at all anymore.