Slider class

A Material Design slider.

Used to select from a range of values.

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

link

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:

• SliderTheme and SliderThemeData for information about controlling the visual appearance of the slider.
• Radio, for selecting among a set of explicit values.
• Checkbox and Switch, for toggling a particular value on or off.
• material.io/design/components/sliders.html
• MediaQuery, from which the text scale factor is obtained.