Pulse

Pulse — a wrapper widget that pulses its child's opacity between a min and max value on a fixed period, sine-shaped.

The classic "blinking red light" / recording-indicator / attention beacon pattern. The wrapped subtree pulses smoothly (sine interpolation), giving a breathing-light feel rather than a hard on/off blink.

ctx.add(
    Pulse::opacity(0.3, 1.0)
        .period(Duration::from_millis(1200))
        .child(RectWidget::new().background(Color::RED)),
);

Layout semantics

Layout-transparent — the child reports its full natural size at all opacity values. Identical layout footprint to Fade.

Reduced motion

Honours prefers-reduced-motion: skips the per-frame driver and pins opacity at the midpoint (min + max) / 2. The subtree stays visible at a steady, non-distracting brightness so the indicator still communicates "active" without animating.

Builder methods at a glance

opacity, period, child, child_id

API reference

📖 Full rustdoc API for this module

pub struct Pulse

Wraps a child and pulses its opacity smoothly between min and max on a fixed period. Useful for recording indicators, notification beacons, and attention-grabbing status icons.

#![allow(unused)]
fn main() {
pub struct Pulse { /* fields */ }
}

Methods

pub fn opacity(min: f32, max: f32) -> Self

Wrap a subtree in an opacity pulse between min and max (both clamped to 0..=1). Uses a sine wave so the transitions at both extremes are smooth, not abrupt.

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

Override the pulse period (full cycle min → max → min). Default: MotionTokens::duration_indeterminate_sweep (~900 ms), the same continuous-loop budget the indeterminate progress bar and spinner use — so a re-themed motion stack stays consistent.

pub fn child(mut self, widget: impl Widget + 'static) -> Self

Inline child widget (deferred insertion).

pub fn child_id(mut self, id: WidgetId) -> Self

Pre-registered child by WidgetId.