Spinner

Spinner — a shader-driven circular-arc loading indicator.

Uses the same per-slot uniform-buffer pipeline as ProgressBar::indeterminate (an AnimatedQuadKind variant), so per-frame cost is one queue.write_buffer(64 B) + draw_indexed — the widget's paint() does not re-run between frames and there's no signal-dirty-mark cascade.

# use teksilo_widgets::Spinner;
# use teksilo_tokens::TextRole;
# use teksilo_i18n::lit;
let _s = Spinner::new(24.0)
    .color(TextRole::Secondary)
    .label(lit!("Loading"));

Defaults match the typical CSS spinner: a quarter-circle (90°) arc rotating clockwise from the top, completing one full rotation every 900 ms.

Honours prefers-reduced-motion: registers no animated quad and falls back to a static three-quarter arc — the indicator is still visible (so the user can tell the surface is busy) but doesn't rotate.

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

period, arc_fraction, stroke_fraction, color, label

API reference

📖 Full rustdoc API for this module

pub struct Spinner

A circular-arc loading indicator driven by a GPU shader quad.

Decorative — pair with .label to give screen readers context. Honours prefers-reduced-motion by falling back to a static three-quarter arc.

pub struct Spinner { /* fields */ }

Methods

pub fn new(size: f32) -> Self

Construct a spinner of the given square edge length (logical pixels). Use small sizes (16–24) for inline spinners and larger (32–64) for full-content placeholders.

pub fn period(mut self, period: Duration) -> Self

Override the rotation period. Default: 900 ms (one full rotation per period).

pub fn arc_fraction(mut self, arc_fraction: f32) -> Self

Override the arc length as a fraction of the full circle. Default: 0.25 (a quarter-circle "comet tail" arc).

pub fn stroke_fraction(mut self, stroke_fraction: f32) -> Self

Override the stroke thickness as a fraction of the spinner's edge length. Default: 0.12 (so a 24-px spinner has a ~3-px stroke).

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

Override the arc colour. Default: TextRole::Secondary so the spinner picks up theme-aware text-tier styling.

pub fn label(mut self, text: impl Into<LocalizedString>) -> Self

Accessible name (e.g. "Loading", "Uploading file"). Without this, screen readers announce a bare "progress indicator" with no context.