盛年不重来,一日难再晨,及时当勉励,岁月不待人。这篇文章主要讲述带有标签的Flutter SliverAppBar覆盖内容相关的知识,希望能为你提供帮助。
我已经按照本教程(https://medium.com/@diegoveloper/flutter-collapsing-toolbar-sliver-app-bar-14b858e87abe)来创建带有TabBar的CollapsingToolbar。
【带有标签的Flutter SliverAppBar覆盖内容】问题是,当我滚动正文时,内容会覆盖tabBar。
这里是代码:
@override
Widget build(BuildContext context) {
return Scaffold(
body: DefaultTabController(
length: 2,
child: NestedScrollView(
headerSliverBuilder: (BuildContext context, bool innerBoxIsScrolled) {
return <
Widget>
[
SliverAppBar(
expandedHeight: 200.0,
floating: false,
pinned: true,
flexibleSpace: FlexibleSpaceBar(
centerTitle: true,
title: Text("Collapsing Toolbar",
style: TextStyle(
color: Colors.white,
fontSize: 16.0,
)),
background: Image.network(
"https://images.pexels.com/photos/396547/pexels-photo-396547.jpeg?auto=compress&
cs=tinysrgb&
h=350",
fit: BoxFit.cover,
)),
),
SliverPersistentHeader(
delegate: _SliverAppBarDelegate(
TabBar(
labelColor: Colors.black87,
unselectedLabelColor: Colors.grey,
tabs: [
Tab(icon: Icon(Icons.info), text: "Tab 1"),
Tab(icon: Icon(Icons.lightbulb_outline), text: "Tab 2"),
],
),
),
pinned: true,
),
];
},
body: Text("Sample text"),
),
),
);
和代表:
class _SliverAppBarDelegate extends SliverPersistentHeaderDelegate {
_SliverAppBarDelegate(this._tabBar);
final TabBar _tabBar;
@override
double get minExtent =>
_tabBar.preferredSize.height;
@override
double get maxExtent =>
_tabBar.preferredSize.height;
@override
Widget build(
BuildContext context, double shrinkOffset, bool overlapsContent) {
return new Container(
child: _tabBar,
);
}@override
bool shouldRebuild(_SliverAppBarDelegate oldDelegate) {
return false;
}
}
对此有任何想法吗?
答案如果有人遇到相同的问题,我解决此问题的方法是使用:https://pub.dartlang.org/packages/extended_nested_scroll_view
示例:
class _MatchFragmentState extends State<
MatchFragment>
with TickerProviderStateMixin {
TabController primaryTC;
@override
void initState() {
primaryTC = new TabController(length: 3, vsync: this);
super.initState();
}@override
Widget build(BuildContext context) {final double statusBarHeight = MediaQuery.of(context).padding.top;
//var tabBarHeight = primaryTabBar.preferredSize.height;
var pinnedHeaderHeight =
//statusBar height
statusBarHeight +
//pinned SliverAppBar height in header
kToolbarHeight;
return Scaffold(
body: NestedScrollViewRefreshIndicator(
onRefresh: onRefresh,
child: ExtendedNestedScrollView(
headerSliverBuilder: (c, f) {
return <
Widget>
[
SliverAppBar(
pinned: true,
expandedHeight: kExpandedHeight,
title: Text('Title'),
flexibleSpace: FlexibleSpaceBar(
background: Image.network(
"https://images.pexels.com/photos/396547/pexels-photo-396547.jpeg?auto=compress&
cs=tinysrgb&
h=350",
fit: BoxFit.cover,
))
),
)
];
},
pinnedHeaderSliverHeight: pinnedHeaderHeight,
keepOnlyOneInnerNestedScrollPositionActive: true,
body: Column(
children: <
Widget>
[
TabBar(
controller: primaryTC,
labelColor: Colors.black87,
unselectedLabelColor: Colors.grey,
tabs: [
Tab(text: "Tab1"),
Tab(text: "Tab2"),
Tab(text: "Tab3"),
],
),
Expanded(
child: TabBarView(
controller: primaryTC,
children: <
Widget>
[
new Tab1Screen(),
new Tab2Screen(),
new Tab3Screen()
],
),
)
],
)
),
)
);
}
}Future<
Null>
onRefresh() {
final Completer<
Null>
completer = new Completer<
Null>
();
new Timer(const Duration(seconds: 1), () {
completer.complete(null);
});
return completer.future.then((_) {});
}
另一答案一个简单的解决方案是为装饰头赋予装饰颜色
例如
Container(
decoration: BoxDecoration(
color: Colors.white,
),
child: tabBar,
);
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