Struct Slider

pub struct Slider<Msg: Clone> {
    pub value: f32,
    pub on_change: Option<Arc<dyn Fn(f32) -> Msg>>,
    pub track_surface: &'static str,
    pub fill_surface: &'static str,
    pub accent_thumb: bool,
    pub track_paint: Option<Paint>,
}

A horizontal slider for selecting a value in a range.

The track defaults to a theme-resolved surface; pass Self::track_paint to override with a custom Paint — typically a multi-stop linear gradient for a hue / spectrum picker. When track_paint is set the active-side fill is suppressed (the spectrum already communicates the position visually through colour).

slider( self.brightness )
    .on_change( |v| Msg::SetBrightness( v ) )

Fields

value: f32

Current value in [0.0, 1.0].

on_change: Option<Arc<dyn Fn(f32) -> Msg>>

Callback invoked with the new value when the slider is dragged. Arc (not Box) so the layout pass can clone it into the per-leaf handler snapshot for O(1) dispatch on input events.

track_surface: &'static str

Theme slot id for the track background pill. Defaults to the generic surface-slider-track; override per-instance to opt into the -flat (no per-surface backdrop) variant when the slider already lives inside a panel-wide blur, or any other custom slot.

fill_surface: &'static str

Theme slot id for the rising / leftward fill. Same shape as Self::track_surface but for the active portion.

accent_thumb: bool

Paint the thumb with the active palette’s accent colour and a thicker white border (accent inner pill + 4 px white ring) instead of the default white-on-text-primary thumb.

track_paint: Option<Paint>

Override the track paint with a custom Paint — typically a Paint::Linear for spectrum / hue pickers. When set, the active-side fill is suppressed because a spectrum already conveys position information through colour and the thumb shows where the user is.

Implementations

impl<Msg: Clone> Slider<Msg>

pub fn new(value: f32) -> Self

Create a slider with the given value (clamped to [0.0, 1.0]).

pub fn track_paint(self, paint: Paint) -> Self

Override the track paint with a custom Paint — e.g. a multi-stop linear gradient for a hue / spectrum picker. Disables the active- side fill (the spectrum already encodes the position visually).

pub fn on_change(self, f: impl Fn(f32) -> Msg + 'static) -> Self

Set the callback invoked when the slider value changes.

pub fn track_surface(self, id: &'static str) -> Self

Override the theme slot id used to paint the track background — pass surface-slider-track-flat (or any other surface) to drop the per-instance backdrop blur when the slider already lives inside a panel-wide blur. See crate::widget::vslider::VSlider::track_surface for the use case.

pub fn fill_surface(self, id: &'static str) -> Self

Override the theme slot id used to paint the fill. Mirrors Self::track_surface.

pub fn accent_thumb(self, on: bool) -> Self

Switch the thumb to the accent-pill style: accent-coloured inner

• 4 px white border. Default thumb stays white-on-text-primary for shells that haven’t opted in.

pub fn preferred_size(&self, max_width: f32, _canvas: &Canvas) -> (f32, f32)

Return the preferred (width, height).

pub fn value_from_x(&self, rect: Rect, x: f32) -> f32

Compute the value [0.0, 1.0] from a tap/drag x position within rect.

pub fn paint_bounds(&self, rect: Rect) -> Rect

Thumb border stroke is centered on the thumb edge (which touches the widget’s left/right edges at value 0 / 1), so half the stroke width plus ~1 px of antialiasing sits outside rect.

pub fn draw(&self, canvas: &mut Canvas, rect: Rect, _focused: bool)

Draw the slider into canvas at rect.

Track + fill paint through theme slots (Self::track_surface / Self::fill_surface) when those slots resolve in the active theme — the track pill spans the full inner width and the fill is anchored to the same pill but scissor-clipped to the left band so insets stay positioned against the track rect rather than a shrinking fill rect. Falls back to theme::track_bg() / theme::track_fill() when the active theme has no entry for either slot — a bare-bones third-party theme still paints a usable slider.

Trait Implementations

impl<Msg: Clone + 'static> From<Slider<Msg>> for Element<Msg>

fn from(s: Slider<Msg>) -> Self

Converts to this type from the input type.