double scrollOffset

The current scroll offset.

The scroll offset is applied to the child widget along the scroll direction before painting. A positive scroll offset indicates that more content in the preferred reading direction is visible.

The scroll offset's value may be above or below the limits defined by the scrollBehavior. This is called "overscrolling" and it can be prevented with the ClampOverscrolls widget.

See also:

Source 

double get scrollOffset => _scrollOffset;