If you pass a ScrollController to a Scrollable2, you can use the controller to
read and write the scroll offset without having to find the Scrollable2State
object.
This patch makes a number of changes to how you can configure a
Scrollable2:
- The ScrollPhysics is now responsible for creating the ScrollPosition.
You can override the ScrollPhysics by supplying a `physics` argument
to `Scrollable`, and the new physics you supply will be applied to
the default physics inherited from the ScrollBehavior.
- This patch removes the ScrollPosition/AbsoluteScrollPosition split as
all clients were operating in pixels anyway and the split made the
code very difficult to follow.
- ScrollPosition no longer depends directly on Scrollable2State.
Instead, it depends on an abstract interface that Scrollable2State
implements. This change has two benefits:
a) It removes the circular dependency between ScrollPosition and
Scrollable2State, which lets us split the code for these classes
(and several other classes that got wrapped up in that cycle) into
separate libraries for easier maintenance.
b) ScrollPosition is no longer bound to Scrollable2, which means you
could use the behavior machinery to drive other sorts of widgets.
For example, we could use it to drive Scrollabe1 if we wanted.
This widget is a start towards replacing PageableList. There are still a number
of features that we'll need to add before this widget can replace PageableList.
This patch adds grid supports to slivers and introduces a ScrollGrid
convenience class for making the common types of scrollable grids.
This patch also deploys ScrollGrid in an example in the Flutter Gallery.
Add SliverList
A SliverList is a linear layout of box children in a viewport that all
have a common, fixed extent along the scroll axis. The layout is similar
to a SliverBlock but more efficient.
