TimeSpeedRadioButtonGroup

TimeSpeedRadioButtonGroup (from scenerystack/scenery-phet) is a VerticalAquaRadioButtonGroup<TimeSpeed> for choosing a simulation's playback speed. It's driven by the TimeSpeed enumeration — TimeSpeed.SLOW, TimeSpeed.NORMAL, TimeSpeed.FAST — each rendered as a localized text label ("Slow"/"Normal"/"Fast"). It's a subcomponent of TimeControlNode (passed via that component's timeSpeedProperty/timeSpeeds options), but is exported and usable standalone.

import { TimeSpeedRadioButtonGroup, TimeSpeed } from 'scenerystack/scenery-phet';
import { EnumerationProperty } from 'scenerystack/axon';

A minimal example

const timeSpeedProperty = new EnumerationProperty( TimeSpeed.NORMAL );

const timeSpeedRadioButtonGroup = new TimeSpeedRadioButtonGroup(
  timeSpeedProperty,
  [ TimeSpeed.NORMAL, TimeSpeed.SLOW ],
  { tandem: tandem.createTandem( 'timeSpeedRadioButtonGroup' ) }
);

Constructor

new TimeSpeedRadioButtonGroup(
  timeSpeedProperty: EnumerationProperty<TimeSpeed>,
  timeSpeeds: TimeSpeed[],
  providedOptions?: TimeSpeedRadioButtonGroupOptions
)

The timeSpeeds array controls both which speeds get a radio button and the order they're listed in — a sim that only ever runs at normal or slow speed (a common PhET pattern) would pass [ TimeSpeed.NORMAL, TimeSpeed.SLOW ] and omit FAST entirely.

The TimeSpeed enumeration

class TimeSpeed extends EnumerationValue {
  static readonly FAST: TimeSpeed;
  static readonly NORMAL: TimeSpeed;
  static readonly SLOW: TimeSpeed;
  static readonly enumeration: Enumeration<TimeSpeed>;
}

TimeSpeed has exactly three values and carries no numeric multiplier itself — mapping TimeSpeed.SLOW/FAST to an actual time-scale factor (e.g. 0.25, 1, 2) is left entirely to the sim's own step logic; TimeSpeedRadioButtonGroup and TimeControlNode only manage which value is currently selected.

Options

Option	Default	Effect
radius	Half the height of a rendered label Text	Radius of each Aqua radio button circle, computed so buttons visually match the label text size unless overridden
labelOptions	{ font: new PhetFont( 14 ), maxWidth: 130 }	Options for each speed's Text label
spacing	9	Vertical spacing between radio button rows (inherited from VerticalAquaRadioButtonGroup)

The label-to-TimeSpeed mapping is fixed

TimeSpeedRadioButtonGroup builds its items from an internal map of TimeSpeed to a localized string and PhET-iO tandem name — there's no option to relabel or reorder an individual speed's text. If you need custom labels, build your own VerticalAquaRadioButtonGroup<TimeSpeed> directly instead.