`CornerRadius` border radius value semantic and ergonomic improvements by ickshonpe · Pull Request #25050 · bevyengine/bevy

ickshonpe · 2026-07-17T23:26:33Z

Objective

The elliptical border-radius PR was merged with a slightly half baked API.

In particular, a corner given a single radius value should be circular or square. For example, with:

Node {
    width: px(200),
    height: px(100),
    border_radius: px(100),
}

it should clamp the radius on both axes to the min half size (50) so we get circular corners, but on main atm you get an elliptical (100, 50) radius corner.

Solution

Val2 has the wrong semantics. Added a new struct CornerRadius { x: Val, y: Val }.
A CornerRadius created from a single val: Val is mapped to CornerRadius { x: val, y: Val::Auto }.
If either field is zero or both are auto, the corner will be square.
If one field is auto, the resolved radius will be resolved relative to the node's shortest side and clamped to half its length.
BorderRadius's fields are changed from Val2s to CornerRadiuss.
The BorderRadius::px and BorderRadius::percent constructors set circular corners.
BorderRadius::resolve_single_corner is removed, use CornerRadius::resolve instead.

Testing

There is a new test, two doc tests, and an extra example case in the elliptical radius UI testbed.

`CornerRadius` has different semantics to `Val2`: - If one field is auto, the resolved radius will be circular with the radius clamped to max half of the min of the node's width or height. - If either field is zero or both are auto, the node will have square corners.

github-actions · 2026-07-17T23:38:09Z

Your PR caused a change in the graphical output of an example or rendering test. This might be intentional, but it could also mean that something broke!
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github-actions · 2026-07-17T23:38:41Z

Your PR caused a change in the graphical output of an example or rendering test. This might be intentional, but it could also mean that something broke!
You can review it at https://pixel-eagle.com/project/B04F67C0-C054-4A6F-92EC-F599FEC2FD1D?filter=PR-25050

If it's expected, please add the M-Deliberate-Rendering-Change label.

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gagnus

Looks right to me.

gagnus · 2026-07-18T11:03:36Z

@@ -38,8 +38,8 @@ pub enum RoundedCorners {
 impl RoundedCorners {
    /// Convert the `RoundedCorners` to a `BorderRadius` for use in a `Node`.
    pub fn to_border_radius(&self, radius: f32) -> BorderRadius {


It'd be helpful I think if this took Val rather than f32 to standardize it with the underlying API

I agree, but was going to leave it for a follow up PR as it's not directly related to the corner radius impl.

Feathers border radii are always circular, I don't see the need to make the API more complicated.

Feathers is supposed to be opinionated, it's not a goal to expose every option of the underlying engine.

Well we could also give it a generic type parameter so it can take either an f32 or Val. But it's not a priority and I'd definitely yield to you on this.

- Added and improved doc comments. - New consts `MAX` and `MAX_RADIUS` - Renamed `circle` method to `circular`. - New `new` method.

github-actions · 2026-07-18T13:00:29Z

Your PR caused a change in the graphical output of an example or rendering test. This might be intentional, but it could also mean that something broke!
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into border-radius-coords

github-actions · 2026-07-18T13:26:27Z

Your PR caused a change in the graphical output of an example or rendering test. This might be intentional, but it could also mean that something broke!
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github-actions · 2026-07-18T13:33:05Z

Your PR caused a change in the graphical output of an example or rendering test. This might be intentional, but it could also mean that something broke!
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If it's expected, please add the M-Deliberate-Rendering-Change label.

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github-actions · 2026-07-18T13:35:05Z

Your PR caused a change in the graphical output of an example or rendering test. This might be intentional, but it could also mean that something broke!
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…adius` is used instead.

github-actions · 2026-07-18T16:45:58Z

Your PR caused a change in the graphical output of an example or rendering test. This might be intentional, but it could also mean that something broke!
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If it's expected, please add the M-Deliberate-Rendering-Change label.

If this change seems unrelated to your PR, you can consider updating your PR to target the latest main branch, either by rebasing or merging main into it.

github-actions · 2026-07-18T16:47:06Z

Your PR caused a change in the graphical output of an example or rendering test. This might be intentional, but it could also mean that something broke!
You can review it at https://pixel-eagle.com/project/B04F67C0-C054-4A6F-92EC-F599FEC2FD1D?filter=PR-25050

If it's expected, please add the M-Deliberate-Rendering-Change label.

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ickshonpe added 3 commits July 17, 2026 22:51

added another case to elliptical radius testbed

dca11e9

Added new Radius type

147a18d

ickshonpe added A-UI Graphical user interfaces, styles, layouts, and widgets S-Waiting-on-Author The author needs to make changes or address concerns before this can be merged labels Jul 17, 2026

github-project-automation Bot moved this to Needs SME Triage in UI Jul 17, 2026

github-project-automation Bot added this to UI Jul 17, 2026

ickshonpe added D-Straightforward Simple bug fixes and API improvements, docs, test and examples C-Usability A targeted quality-of-life change that makes Bevy easier to use labels Jul 17, 2026

Merge branch 'main' into border-radius-coords

88a6345

gagnus reviewed Jul 18, 2026

View reviewed changes

CornerRadius improvements:

9d0aa74

- Added and improved doc comments. - New consts `MAX` and `MAX_RADIUS` - Renamed `circle` method to `circular`. - New `new` method.

ickshonpe added 5 commits July 18, 2026 14:17

Added some basic doctests

59d9be6

Added some basic doctests

165798a

Added MAX_ELLIPTICAL constant to BorderRadius

3698ab5

Merge branch 'border-radius-coords' of https://github.com/ickshonpe/bevy

79be08c

into border-radius-coords

Further comment edits.

3447456

ickshonpe added 7 commits July 18, 2026 14:43

Clean up, fixed casts and type params.

a6f831a

Updated percent to use circular.

e09dfc1

Another doc comment edit.

500b48c

Removed the resolve_single_corner. The resolve method on `CornerR…

6fbea6f

…adius` is used instead.

Added CornerRadius::ZERO const.

bc97a33

Updated release content.

73a787d

updated migration guide again

21338ce

ickshonpe added 5 commits July 18, 2026 15:32

Removed unused import

d31490e

fixed radius_resolve test, renamed it to corner_radius_resolve

c1c6e26

CI fixes

0fcc8e5

Removed consecutive blank line from migration guide.

224bd1d

Fixed doc test

bf4249c

alice-i-cecile added this to the 0.20 milestone Jul 18, 2026

alice-i-cecile requested review from pcwalton and viridia July 18, 2026 18:24

alice-i-cecile added the M-Deliberate-Rendering-Change An intentional change to how tests and examples are rendered label Jul 18, 2026

alice-i-cecile requested a review from mockersf July 18, 2026 18:24

alice-i-cecile approved these changes Jul 18, 2026

View reviewed changes

alice-i-cecile added D-Modest A "normal" level of difficulty; suitable for simple features or challenging fixes C-Bug An unexpected or incorrect behavior and removed D-Straightforward Simple bug fixes and API improvements, docs, test and examples labels Jul 18, 2026

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Objective

Solution

Testing

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ickshonpe commented Jul 17, 2026 •

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