TwistArrow

TwistArrow — a small chevron that indicates and toggles a tree node's expansion.

Renders a right-pointing arrow when collapsed and a down-pointing arrow when expanded; a leaf node (where has_children is false) paints nothing but reserves its slot so the indent column stays aligned across all rows. The glyph flips direction under right-to-left layout. Accessibility-decorative: the chevron hides itself from the AT tree and the parent row's node owns set_expanded.

// TwistArrow is typically instantiated by TreeView row delegates and requires
// an EventContext to wire the tap callback. The snippet below shows the
// construction pattern used inside a custom tree-row build().
let arrow = TwistArrow::new(16.0, true, false)
    .on_click(|ctx| ctx.send_intent(teksilo_core::Intent::new("tree.toggle")));

Touch and pen

A 12 dp chevron is half the 24 dp target floor and cannot grow — the indent column is the tree's own geometry. It declares a Widget::hit_outset instead, which is the one mechanism that can win here: the chevron's neighbour is the row, the row takes presses, and a point inside the row is at distance zero from it, so the miss-only slop pass could never reach the chevron. Zero for a leaf chevron and for a decorative one, which take no press.

Density

The picture above is the widget at TargetDensity::Compact, the mouse-and-keyboard ladder. Below is the same subject on the same canvas with only the ladder changed, so what moves is the density and nothing else — where the subject no longer fits, that is what the denser targets cost it at that size. See docs/density-and-targets.md.

Touch

Builder methods at a glance

color, on_click

API reference

📖 Full rustdoc API for this module

pub struct TwistArrow

Small interactive chevron rendered in the leading indent column of a tree row.

pub struct TwistArrow { /* fields */ }

Methods

pub fn new(size: f32, has_children: bool, expanded: bool) -> Self

Construct a chevron. size is the square side length in logical pixels; has_children determines whether the glyph is painted; expanded determines the glyph direction (down = expanded, right/left = collapsed).

pub fn color(mut self, color: impl Into<ColorProp>) -> Self

Override the glyph colour. Accepts a Color, a TextRole, or a Signal of either.

The default TextRole::Secondary is a muted grey, which is right on every row that is not filled. It is not right on one that is: a design language whose selected row is a solid accent capsule flips its label to TextRole::OnAccent through StandardItemStyle::selected_label_role, and a chevron left behind at Secondary then sits on that capsule at roughly 2.5:1 — under WCAG SC 1.4.11's 3:1 floor, and visibly wrong beside a white label. StandardTreeItem passes the row's own label role here so the two always move together.

pub fn on_click(mut self, f: impl Fn(&mut EventContext) + 'static) -> Self

Install a tap handler. Receives the firing EventContext so consumers can dispatch intents (e.g. lazy-load children on expand) or open dialogs from the chevron toggle.