RangeSlider class

A Material Design range slider.

Used to select a range from a range of values.

This range values are in intervals of 20 because the Range Slider has 5 divisions, from 0 to 100. This means are values are split between 0, 20, 40, 60, 80, and 100. The range values are initialized with 40 and 80 in this demo.

link

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

A range 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 "thumbs", which are the shapes that slide horizontally when the user drags them to change the selected range.
• The "track", which is the horizontal line that the thumbs can be dragged along.
• The "tick marks", which mark the discrete values of a discrete slider.
• The "overlay", which is a highlight that's drawn over a thumb in response to a user tap-down gesture.
• The "value indicators", which are the shapes that pop up when the user is dragging a thumb to show the value being selected.
• The "active" segment of the slider is the segment between the two thumbs.
• The "inactive" slider segments are the two track intervals outside of the slider's thumbs.

The range 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 range 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 range slider will listen for the onChanged callback and rebuild the slider with new values 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 (including margins on each side) and will shrink-wrap vertically.

Requires one of its ancestors to be a Material widget. This is typically provided by a Scaffold widget.

Requires one of its ancestors to be a MediaQuery widget. Typically, a MediaQuery widget is 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 inside 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 colors, and other visual properties is achieved using a SliderThemeData.

See also:

• SliderTheme and SliderThemeData for information about controlling the visual appearance of the slider.
• Slider, for a single-valued 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.