Example: nested custom scroll view flutter
DefaultTabController(
length: _tabs.length, // This is the number of tabs.
child: NestedScrollView(
headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
// These are the slivers that show up in the "outer" scroll view.
return <Widget>[
SliverOverlapAbsorber(
// This widget takes the overlapping behavior of the SliverAppBar,
// and redirects it to the SliverOverlapInjector below. If it is
// missing, then it is possible for the nested "inner" scroll view
// below to end up under the SliverAppBar even when the inner
// scroll view thinks it has not been scrolled.
// This is not necessary if the "headerSliverBuilder" only builds
// widgets that do not overlap the next sliver.
handle: NestedScrollView.sliverOverlapAbsorberHandleFor(context),
sliver: SliverAppBar(
title: const Text('Books'), // This is the title in the app bar.
pinned: true,
expandedHeight: 150.0,
// The "forceElevated" property causes the SliverAppBar to show
// a shadow. The "innerBoxIsScrolled" parameter is true when the
// inner scroll view is scrolled beyond its "zero" point, i.e.
// when it appears to be scrolled below the SliverAppBar.
// Without this, there are cases where the shadow would appear
// or not appear inappropriately, because the SliverAppBar is
// not actually aware of the precise position of the inner
// scroll views.
forceElevated: innerBoxIsScrolled,
bottom: TabBar(
// These are the widgets to put in each tab in the tab bar.
tabs: _tabs.map((String name) => Tab(text: name)).toList(),
),
),
),
];
},
body: TabBarView(
// These are the contents of the tab views, below the tabs.
children: _tabs.map((String name) {
return SafeArea(
top: false,
bottom: false,
child: Builder(
// This Builder is needed to provide a BuildContext that is
// "inside" the NestedScrollView, so that
// sliverOverlapAbsorberHandleFor() can find the
// NestedScrollView.
builder: (BuildContext context) {
return CustomScrollView(
// The "controller" and "primary" members should be left
// unset, so that the NestedScrollView can control this
// inner scroll view.
// If the "controller" property is set, then this scroll
// view will not be associated with the NestedScrollView.
// The PageStorageKey should be unique to this ScrollView;
// it allows the list to remember its scroll position when
// the tab view is not on the screen.
key: PageStorageKey<String>(name),
slivers: <Widget>[
SliverOverlapInjector(
// This is the flip side of the SliverOverlapAbsorber
// above.
handle: NestedScrollView.sliverOverlapAbsorberHandleFor(context),
),
SliverPadding(
padding: const EdgeInsets.all(8.0),
// In this example, the inner scroll view has
// fixed-height list items, hence the use of
// SliverFixedExtentList. However, one could use any
// sliver widget here, e.g. SliverList or SliverGrid.
sliver: SliverFixedExtentList(
// The items in this example are fixed to 48 pixels
// high. This matches the Material Design spec for
// ListTile widgets.
itemExtent: 48.0,
delegate: SliverChildBuilderDelegate(
(BuildContext context, int index) {
// This builder is called for each child.
// In this example, we just number each list item.
return ListTile(
title: Text('Item $index'),
);
},
// The childCount of the SliverChildBuilderDelegate
// specifies how many children this inner list
// has. In this example, each tab has a list of
// exactly 30 items, but this is arbitrary.
childCount: 30,
),
),
),
],
);
},
),
);
}).toList(),
),
),
)