Widgets following widgets.
Select a widget that you want to follow and wrap it with a
Leader widget. Give the
LeaderLink, to share with
Leader( link: _leaderLink, child: YourLeaderWidget(), );
Add a widget that you want to follow your
Leader, and wrap it with a
// Follower appears 20px above the Leader. Follower.withOffset( link: _leaderLink, offset: const Offset(0, -20), leaderAnchor: Alignment.topCenter, followerAnchor: Alignment.bottomCenter, child: YourFollowerWidget(), );
Follower's can position themselves with a constant distance from a
as shown above. Or,
Follower's can choose their exact location on every frame by using
// Follower appears where the aligner says it should. Follower.withAligner( link: _leaderLink, aligner: _aligner, child: YourFollowerWidget(), );
To constrain where your
Follower is allowed to appear, pass a
boundary to your
// Follower is constrained by the given boundary. Follower.withAligner( link: _leaderLink, aligner: _aligner, boundary: _boundary, child: YourFollowerWidget(), );
Building multiple widgets without layouts
Building follower widgets is a bit unusual with Flutter. Typically, whenever we build multiple
widgets in Flutter, we place them in a layout container, such as
But follower widgets don't respect ancestor layout rules. That's the whole point.
follow_the_leader introduces a new container widget, which builds children, but doesn't attempt
to apply any particular layout rules. The primary purpose of this widget is to make it clear to
readers that you aren't trying to layout the children.
BuildInOrder( children: [ MyContentWithALeader(), Follower.withOffset(), Follower.withDynamics(), ], );
BuildInOrder widget builds each child widget in the order that it's provided. This fact is
Leader widgets must be built before their
not impose any
Offset on its children.
BuildInOrder passes its parent's constraints down to the