How to change the alignment of the title of the SliverAppBar?

Question

How to change the alignment of the title in the SliverAppBar when the app bar is expanded? I want to make the title's alignment to the left of the bottom when the app bar is expanded and change it to center when the app bar is collapsed. I tried LayoutBuilder, but I don't know how to check if the app bar is expanded or not.

Answer 1

You can use this as pskink menthioned

class AppSliverPersistentHeaderDelegate extends SliverPersistentHeaderDelegate {
  @override
  Widget build(
      BuildContext context, double shrinkOffset, bool overlapsContent) {
    return Container(
      height: maxExtent,
      color: Colors.deepPurple,
      child: LayoutBuilder(
        builder: (context, constraints) => Stack(
          children: [
              Align(
              alignment: Alignment.lerp(const Alignment(-.95, 0),
                  const Alignment(0, 0), shrinkOffset / maxExtent)!,
              child: Text("Title"),
            ),
          ],
        ),
      ),
    );
  }

  @override
  double get maxExtent => 200;

  @override
  double get minExtent => kToolbarHeight;

  @override
  bool shouldRebuild(covariant SliverPersistentHeaderDelegate oldDelegate) =>
      false;
}