RKKnob

A premium rotary knob widget for RadioKit with configurable angle range, optional centre-spring and division snapping.

Constructor

RKKnob({
  required double value,
  required ValueChanged<double> onChanged,
  double min = 0.0,
  double max = 1.0,
  double size = 100.0,
  String? label,
  int? divisions,
  ValueChanged<bool>? onInteractionChanged,
  double minAngle = -135.0,
  double maxAngle = 135.0,
  bool autoCenter = false,
  double center = 0.5,
  Curve springCurve = Curves.easeOutCubic,
  Duration springDuration = const Duration(milliseconds: 500),
  RKKnobVariant variant = RKKnobVariant.standard,
  RKAxis orientation = RKAxis.vertical,
  double rotation = 0.0,
  IconData? centerIcon,
})

Parameters

Parameter	Description
value	Normalised knob position (between min and max).
onChanged	Called with the new value when the user drags.
size	Diameter of the knob widget.
label	Optional text label displayed above the widget.
divisions	If set, the knob snaps to the specified number of steps.
onInteractionChanged	Triggered when the user starts or stops touching the widget.
minAngle / maxAngle	Angular range in degrees (default -135 to +135).
autoCenter	When true, the knob springs back to center after interaction.
center	Normalised centre position used for auto-centering.
springCurve / springDuration	Controls the spring-back animation.
variant	The visual style: standard or steeringWheel.
orientation	Orientation of the knob layout: vertical (default) or horizontal.
rotation	Visual rotation of the widget in radians.
centerIcon	Optional icon to display in the middle of the knob.

Example

double _volume = 0.7;

RKKnob(
  value: _volume,
  onChanged: (v) => setState(() => _volume = v),
  divisions: 10,
  label: 'Vol',
);

Visual Styles

• Standard: A 3D industrial rotary encoder with an animated thumb.
• Steering Wheel: A premium automotive-inspired wheel with dynamic rim glow and a central hub.