Slider

ui.slider(&mut gain, 0.0..=1.0);

The slider is horizontal and binds an &mut of f32 or any Numeric type (f64, i32, u8, ...). Integers step by one and show no decimals without any configuration: ui.slider(&mut count, 0..=10). Integer values pass through f64, so a 64-bit value above 2^53 loses its low bits. Use ui.slider_labeled(&mut gain, 0.0..=1.0, "Gain") for a caption and numeric value.

BuildersCopy Anchor Link

use zaxis::{Slider, SliderStatus};

let response = ui.add(Slider::new(&mut volume, 0.0..=100.0)
    .text("Volume").precision(0).suffix("%")
    .step(5.0)
    .width(280.0)
    .enabled(sound)
    .status(SliderStatus::Success));

Track height is 28 logical pixels; a caption adds spacing and measured text height. The response rectangle covers the interactive track. The track is 6 pixels high and the thumb radius is at most 8 pixels, shrinking for narrow allocations. There is no vertical slider builder.

Invalid ranges, steps and widths never panic: they are normalized and reported as diagnostics.

NormalizationCopy Anchor Link

Enabled sliders normalize the bound value on every UI pass, even without user input:

1. Convert NaN to the minimum; clamp out-of-range values and infinities.
2. If a step is set, snap relative to the range minimum with nearest rounding.
3. Clamp the snapped result to the endpoints.

Both endpoints remain directly selectable when the step does not divide the span. For 0..=10 with step 3, regular ticks are 0, 3, 6, and 9; End and the far-right pointer position can select 10. Home always selects the minimum. An equal-endpoint range normalizes to that single value.

changed() reports whether the final value differs from the value supplied at the start of the pass. Normalization can set it without input. A sequence of adjustments that returns to the original value does not report a net change.

Disabled sliders leave the bound value untouched, including out-of-range values or NaN; their thumb uses a normalized value while the caption shows the unchanged bound value. They cannot focus or capture pointer input. Disabling a captured slider cancels capture when the pass finishes.

Pointer and keyboardCopy Anchor Link

Press anywhere in the control to focus it and select a value. Captured motion and release continue outside the control; values clamp at the endpoints. The thumb's center moves between track endpoints inset by its radius.

Without an explicit step, the keyboard step is 1% of the range span. Key repeats are processed in event order. Enter and Space do not activate sliders.

Response::pressed and has_focus expose interaction state. clicked() remains false; handle numeric updates through changed().

AccentCopy Anchor Link

color overrides these accents while enabled. Disabled sliders use Style::muted_text. The accent affects the filled track and thumb; status does not validate the bound value or change interaction rules.

Sliders at distinct call sites do not share IDs. Repeated calls from one site use an occurrence counter per scope. Inserting ordinary text before them does not change their IDs. For reorderable lists, scope each row with its model key using Ui::push_id. Wrapper functions can propagate their caller location with #[track_caller]. See IDs and retained state.

AccessibilityCopy Anchor Link

Role Slider, named by its caption (text(..)) or .accessible_label(".."). It publishes the formatted value with its suffix, the range and the step, and accepts Increment, Decrement and SetValue; they go through the same clamping and stepping as the keys. See Accessibility.