Slider class Null safety

A Material Design slider.

Used to select from a range of values.

link
A slider widget, consisting of 5 divisions and showing the default value indicator.

The Sliders value is part of the Stateful widget subclass to change the value setState was called.

To create a local project with this code sample, run:
flutter create --sample=material.Slider.1 mysample

A slider can be used to select from either a continuous or a discrete set of values. The default is to use a continuous range of values from min to max. To use discrete values, use a non-null value for divisions, which indicates the number of discrete intervals. For example, if min is 0.0 and max is 50.0 and divisions is 5, then the slider can take on the discrete values 0.0, 10.0, 20.0, 30.0, 40.0, and 50.0.

The terms for the parts of a slider are:

  • The "thumb", which is a shape that slides horizontally when the user drags it.
  • The "track", which is the line that the slider thumb slides along.
  • The "value indicator", which is a shape that pops up when the user is dragging the thumb to indicate the value being selected.
  • The "active" side of the slider is the side between the thumb and the minimum value.
  • The "inactive" side of the slider is the side between the thumb and the maximum value.

The slider will be disabled if onChanged is null or if the range given by min..max is empty (i.e. if min is equal to max).

The slider widget itself does not maintain any state. Instead, when the state of the slider changes, the widget calls the onChanged callback. Most widgets that use a slider will listen for the onChanged callback and rebuild the slider with a new value to update the visual appearance of the slider. To know when the value starts to change, or when it is done changing, set the optional callbacks onChangeStart and/or onChangeEnd.

By default, a slider will be as wide as possible, centered vertically. When given unbounded constraints, it will attempt to make the track 144 pixels wide (with margins on each side) and will shrink-wrap vertically.

Requires one of its ancestors to be a Material widget.

Requires one of its ancestors to be a MediaQuery widget. Typically, these are introduced by the MaterialApp or WidgetsApp widget at the top of your application widget tree.

To determine how it should be displayed (e.g. colors, thumb shape, etc.), a slider uses the SliderThemeData available from either a SliderTheme widget or the ThemeData.sliderTheme a Theme widget above it in the widget tree. You can also override some of the colors with the activeColor and inactiveColor properties, although more fine-grained control of the look is achieved using a SliderThemeData.

See also:

Inheritance

Constructors

Slider({Key? key, required double value, required ValueChanged<double>? onChanged, ValueChanged<double>? onChangeStart, ValueChanged<double>? onChangeEnd, double min = 0.0, double max = 1.0, int? divisions, String? label, Color? activeColor, Color? inactiveColor, Color? thumbColor, MouseCursor? mouseCursor, SemanticFormatterCallback? semanticFormatterCallback, FocusNode? focusNode, bool autofocus = false})
Creates a Material Design slider.
const
Slider.adaptive({Key? key, required double value, required ValueChanged<double>? onChanged, ValueChanged<double>? onChangeStart, ValueChanged<double>? onChangeEnd, double min = 0.0, double max = 1.0, int? divisions, String? label, MouseCursor? mouseCursor, Color? activeColor, Color? inactiveColor, Color? thumbColor, SemanticFormatterCallback? semanticFormatterCallback, FocusNode? focusNode, bool autofocus = false})
Creates an adaptive Slider based on the target platform, following Material design's Cross-platform guidelines.
const

Properties

activeColor → Color?
The color to use for the portion of the slider track that is active.
final
autofocus → bool
True if this widget will be selected as the initial focus when no other node in its scope is currently focused.
final
divisions → int?
The number of discrete divisions.
final
focusNode → FocusNode?
An optional focus node to use as the focus node for this widget.
final
hashCode → int
The hash code for this object.
nonVirtual">@nonVirtualread-onlyinherited
inactiveColor → Color?
The color for the inactive portion of the slider track.
final
key → Key?
Controls how one widget replaces another widget in the tree.
finalinherited
label → String?
A label to show above the slider when the slider is active and SliderThemeData.showValueIndicator is satisfied.
final
max → double
The maximum value the user can select.
final
min → double
The minimum value the user can select.
final
mouseCursor → MouseCursor?
The cursor for a mouse pointer when it enters or is hovering over the widget.
final
onChanged → ValueChanged<double>?
Called during a drag when the user is selecting a new value for the slider by dragging.
final
onChangeEnd → ValueChanged<double>?
Called when the user is done selecting a new value for the slider.
final
onChangeStart → ValueChanged<double>?
Called when the user starts selecting a new value for the slider.
final
runtimeType → Type
A representation of the runtime type of the object.
read-onlyinherited
semanticFormatterCallback → SemanticFormatterCallback?
The callback used to create a semantic value from a slider value.
final
thumbColor → Color?
The color of the thumb.
final
value → double
The currently selected value for this slider.
final

Methods

createElement() → StatefulElement
Creates a StatefulElement to manage this widget's location in the tree.
inherited
createState() → State<Slider>
Creates the mutable state for this widget at a given location in the tree.
override
debugDescribeChildren() → List<DiagnosticsNode>
Returns a list of DiagnosticsNode objects describing this node's children.
protected">@protectedinherited
debugFillProperties(DiagnosticPropertiesBuilder properties) → void
Add additional properties associated with the node.
override
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed.
inherited
toDiagnosticsNode({String? name, DiagnosticsTreeStyle? style}) → DiagnosticsNode
Returns a debug representation of the object that is used by debugging tools and by DiagnosticsNode.toStringDeep.
inherited
toString({DiagnosticLevel minLevel = DiagnosticLevel.info}) → String
A string representation of this object.
inherited
toStringDeep({String prefixLineOne = '', String? prefixOtherLines, DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String
Returns a string representation of this node and its descendants.
inherited
toStringShallow({String joiner = ', ', DiagnosticLevel minLevel = DiagnosticLevel.debug}) → String
Returns a one-line detailed description of the object.
inherited
toStringShort() → String
A short, textual description of this widget.
inherited

Operators

operator ==(Object other) → bool
The equality operator.
nonVirtual">@nonVirtualinherited