Trait Layout 

pub trait Layout: ThemeExt {
    // Provided methods
    fn disclosure(&self, expanded: bool) -> Svg { ... }
    fn collapsible_header(
        &self,
        label: impl Into<SharedString>,
        expanded: bool,
    ) -> Div { ... }
    fn nav_row(
        &self,
        icon: Option<Icon>,
        label: impl Into<SharedString>,
        selected: bool,
        fade: Fade,
    ) -> Div { ... }
    fn split_handle(&self, axis: Axis, style: SplitStyle) -> Div { ... }
    fn tab_bar(&self) -> Div { ... }
    fn tab(&self, label: impl Into<SharedString>, active: bool) -> Div { ... }
}

Provided Methods

fn disclosure(&self, expanded: bool) -> Svg

The disclosure chevron: right when collapsed, down when expanded.

Two assets rather than one rotated: gpui has no transform for divs at the pinned rev, and an SVG rotation would need a transform on the element.

fn collapsible_header( &self, label: impl Into<SharedString>, expanded: bool, ) -> Div

Header row of a collapsible section: chevron plus title. The caller owns expanded and renders the body itself — a container that swallowed its children would have to re-implement layout for them. Hover is caller-owned (gpui panics on a second hover); the default wash is Theme::element_hover.

fn nav_row( &self, icon: Option<Icon>, label: impl Into<SharedString>, selected: bool, fade: Fade, ) -> Div

A navigation row: leading icon, truncating label, and whatever the caller appends — a count, a chevron, a control that shows on hover. shadcn calls it SidebarMenuButton, MUI ListItemButton.

The label is a parameter rather than a child because it carries the truncation, and a caller that has to remember min_w_0().flex_1() forgets it on the first long project name — which pushes the trailing content off the row instead of shortening the label.

fade must be stable across frames. It is also how a trailing control reveals itself on row hover: paint it with motion::hover_blend on this same fade, rather than adding an on_hover of its own — gpui allows only one per element, and this row has claimed it.

fn split_handle(&self, axis: Axis, style: SplitStyle) -> Div

The divider between two panes: a hairline centred in a grab strip, lit while dragged.

The gesture stays with the caller, which owns the fraction — the handle is dragged with gpui’s null-preview drag, and the container reads the pointer:

div()
    .id("split")
    .on_drag_move(cx.listener(|view, event: &DragMoveEvent<SplitDrag>, _, cx| {
        view.fraction = axis_fraction(event.event.position, event.bounds, Axis::Horizontal, 0.15);
        cx.notify();
    }))
    .child(div().w(relative(self.fraction)).child(left))
    .child(
        theme.split_handle(Axis::Horizontal, SplitStyle::Line { dragging: self.dragging })
            .id("split-handle")
            .on_drag(SplitDrag, |_, _, _, cx| cx.new(|_| gpui::Empty)),
    )
    .child(div().flex_1().child(right))

fn tab_bar(&self) -> Div

Tab strip: a hairline-underlined row that tabs sit on.

fn tab(&self, label: impl Into<SharedString>, active: bool) -> Div

One tab. The active tab is marked by the text tone plus a 2px underline that overlaps the bar’s hairline, so switching tabs never changes row height.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementations on Foreign Types

impl Layout for Theme

Implementors