Flutter BottomNavigationBar with AnimatedContainer语言 - 是什么导致Ren

Question

我的Flutter应用程序使用了一个包裹在AnimatedContainer中的BottomNavigationBar。当动画发生时(通过滚动列表激活)，会发生RenderFlex溢出错误。我想不出是什么原因导致这种情况的发生。

我已经把这个项目简化为简单的代码，希望有人可以尝试一下并找出问题所在。

主类:

class TestMain extends StatefulWidget {
const TestMain({Key? key}) : super(key: key);
@override
State<TestMain> createState() => _TestMain();
}
class BottomNavBarItemData {
String label;Icon icon;Widget screen;
BottomNavBarItemData({required this.label,required this.icon,required this.screen});
}
late ScrollController mainScrollController;
class _TestMain extends State<TestMain> {
int _selectedIndex = 0;
bool _isVisible = true;
@override
void initState() {
_isVisible = true;
mainScrollController = ScrollController();
mainScrollController.addListener(() {
if (mainScrollController.position.userScrollDirection == ScrollDirection.reverse) {
setState(() {
_isVisible = false;
});
}
if (mainScrollController.position.userScrollDirection == ScrollDirection.forward) {
setState(() {
_isVisible = true;
});
}
});
super.initState();
}
final List<BottomNavBarItemData> screens = [
BottomNavBarItemData(
icon: const Icon(Icons.home, size: 25.0, color: Colors.red),
label: 'Page1',
screen: const Screen1(),
),
BottomNavBarItemData(
icon: const Icon(Icons.home, size: 25.0, color: Colors.red),
label: 'Page2',
screen: const Screen2(),
),
];
@override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
extendBody: true,
body: SafeArea(
child: IndexedStack(
index: _selectedIndex,
children: [
...screens.map((e) => e.screen).toList(),
],
),
),
bottomNavigationBar: AnimatedContainer(
duration: const Duration(milliseconds: 400),
height: _isVisible ? 70 : 0.0,
child: SizedBox(
child: BottomNavigationBar(
type: BottomNavigationBarType.fixed,
backgroundColor: Colors.orange,
currentIndex: _selectedIndex,
selectedIconTheme: IconThemeData(color: Colors.white),
selectedItemColor: Colors.white,
selectedFontSize: 14,
unselectedFontSize: 14,
unselectedIconTheme: const IconThemeData(
color: Colors.lightBlueAccent,
),
unselectedItemColor: Colors.lightBlueAccent,
onTap: _onItemTapped,
items: screens.map((e) => BottomNavigationBarItem(
label: e.label,
icon: e.icon,
),
).toList(),
),
),
),
);
}
void _onItemTapped(int index) {
setState(() {
_selectedIndex = index;
});
}
}

和主类调用的两个屏幕:

class Screen1 extends StatefulWidget {
const Screen1({Key? key}) : super(key: key);
@override
State<Screen1> createState() => _Screen1();
}
class _Screen1 extends State<Screen1> {
@override
Widget build(BuildContext context) {
return Container(
color: Colors.white,
child: SingleChildScrollView(
controller: mainScrollController,
physics: const AlwaysScrollableScrollPhysics(),
child: Column(children: [
Container(height: 150, color: Colors.blue),
Container(height: 150, color: Colors.white),
Container(height: 150, color: Colors.blue),
Container(height: 150, color: Colors.white),
Container(height: 150, color: Colors.blue),
Container(height: 150, color: Colors.white),
],),
),
);
}
}
class Screen2 extends StatefulWidget {
const Screen2({Key? key}) : super(key: key);
@override
State<Screen2> createState() => _Screen2();
}
class _Screen2 extends State<Screen2> {
@override
Widget build(BuildContext context) {
return Container(
color: Colors.white,
);
}
}

Answer 1

容器溢出，因为内部项目空间大于动画大小，如35，它将显示溢出。你可以使用不同的动画，但差别不大。

在这种情况下可以使用SizeTransition

class _TestMain extends State<TestMain> with SingleTickerProviderStateMixin {
int _selectedIndex = 0;
bool _isVisible = true;
late final AnimationController _controller = AnimationController(
duration: const Duration(milliseconds: 400),
vsync: this,
)..forward();
late final Animation<double> _animation = CurvedAnimation(
parent: _controller,
curve: Curves.fastOutSlowIn,
);
@override
void dispose() {
_controller.dispose();
super.dispose();
}
@override
void initState() {
_isVisible = true;
mainScrollController = ScrollController();
mainScrollController.addListener(() {
if (mainScrollController.position.userScrollDirection ==
ScrollDirection.reverse) {
_controller.reverse();
setState(() {
_isVisible = false;
});
}
if (mainScrollController.position.userScrollDirection ==
ScrollDirection.forward) {
_controller.forward();
setState(() {
_isVisible = true;
});
}
});
super.initState();
}
final List<BottomNavBarItemData> screens = [
BottomNavBarItemData(
icon: const Icon(Icons.home, size: 25.0, color: Colors.red),
label: 'Page1',
screen: const Screen1(),
),
BottomNavBarItemData(
icon: const Icon(Icons.home, size: 25.0, color: Colors.red),
label: 'Page2',
screen: const Screen2(),
),
];
@override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
extendBody: true,
body: SafeArea(
child: IndexedStack(
index: _selectedIndex,
children: [
...screens.map((e) => e.screen).toList(),
],
),
),
bottomNavigationBar: SizeTransition(
sizeFactor: _animation,
child: SizedBox(
child: BottomNavigationBar(
type: BottomNavigationBarType.fixed,
backgroundColor: Colors.orange,
currentIndex: _selectedIndex,
selectedIconTheme: IconThemeData(color: Colors.white),
selectedItemColor: Colors.white,
selectedFontSize: 14,
unselectedFontSize: 14,
unselectedIconTheme: const IconThemeData(
color: Colors.lightBlueAccent,
),
unselectedItemColor: Colors.lightBlueAccent,
onTap: _onItemTapped,
items: screens
.map(
(e) => BottomNavigationBarItem(
label: e.label,
icon: e.icon,
),
)
.toList(),
),
),
),
);
}
void _onItemTapped(int index) {
setState(() {
_selectedIndex = index;
});
}
}

或

bottomNavigationBar: AnimatedScale(
duration: const Duration(milliseconds: 400),
scale: _isVisible ? 1 : 0.0,
alignment: Alignment.bottomCenter,