getPreferredSize method Null safety
Returns the preferred size of the shape, based on the given conditions.
The isDiscrete
argument is true if RangeSlider.divisions is non-null.
When true, the slider will render tick marks on top of the track.
The isEnabled
argument is false when RangeSlider.onChanged is null and
true otherwise. When true, the slider will respond to input.
Implementation
Size getPreferredSize(bool isEnabled, bool isDiscrete);