Add sticky ui nodes #21648
Add sticky ui nodes #21648
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PPakalns
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alice-i-cecile
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A-UI
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alice-i-cecile
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It looks like it should work fine.
I'm not sure about the API and implementation though, but I've been working too much on text and forgotten everything I knew about CSS. I'd like an example, like alice already asked for. It's quite limited compared to position: sticky, we should at least support bottom and right alignment I think.
Probably this is okay for an initial step though and it's simple enough that we can easily replace it completely if it's not possible to extend the implementation to support more features.
| /// Determines which axes of a node are *sticky* during scrolling. | ||
| /// | ||
| /// A **sticky** node maintains its position along the specified axes | ||
| /// instead of moving with its scrolled parent content when [`ScrollPosition`] is applied. | ||
| #[derive(Component, Debug, Clone, Default, Deref, DerefMut, Reflect)] | ||
| #[reflect(Component, Default, Clone)] | ||
| pub struct ScrollSticky(pub BVec2); | ||
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| impl From<BVec2> for ScrollSticky { | ||
| fn from(value: BVec2) -> Self { | ||
| Self(value) | ||
| } | ||
| } |
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I don't like the plain BVec2 here, I'd prefer named fields or some helpers like:
impl ScrollSticky {
fn left() -> Self {
Self(BVec2::new(true, false))
}
// etc..
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I would like to avoid implying in API that ScrollSticky has method left. What does it mean?
Sticky headers can be achieved with this feature only by combining multiple features:
ZIndex, BackgroundColor, ScrollSticky, parent with display Grid.
Users need to carefully mix multiple features to get the final behavior working. So I would like to avoid implying any specific use case in this level of API.
See example: 5ab4c9a
alice-i-cecile
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4 participants
Objective
Add UI nodes that can be used as sticky row, column headers.
Solution
Add ui nodes that ignore parent node scroll position. This approach only allows for row, column headers that are located at the top and at the left side of the parent node. Multiple rows, columns can be used as headers.
Testing
Extended scroll example.
Prior art
Used the same approach to implement sticky elements in egui taffy (sticky)
Showcase
sticky-2025-10-24_23.22.28.mov