flutter - Flutter - 如果 NavigationBar 不可见,如何更改 BottomNavigationBar 的索引?
问题描述
这是我的设置:
主页.dart
final List<Widget> _pages = [
Screen1(),
Screen2(),
Screen3(),
Screen4(),
];
int _selectedPageIndex = 0;
void _selectPage(int index) {
setState(() {
_selectedPageIndex = index;
});}
@override
Widget build(BuildContext context) {
return Scaffold(
extendBodyBehindAppBar: true,
body: _pages[_selectedPageIndex],
bottomNavigationBar: _selectedPageIndex != 2
? Column(mainAxisSize: MainAxisSize.min, children: <Widget>[
...
现在,当我们导航到Screen3()
我隐藏完整BottomNavigationBar
并以全屏显示屏幕时。通过一个按钮,我想导航回任何其他位置。这该怎么做?我不想使用任何路线来关闭。我们如何访问 _selectedPageIndex
或您有其他好主意?
将不胜感激任何想法。
解决方案
您可以在下面复制粘贴运行完整代码
第 1 步:保留以前的索引,从全屏页面返回时需要
void _onItemTapped(int index) {
setState(() {
_previousIndex = _selectedPageIndex;
_selectedPageIndex = index;
});
}
第2步:传递refresh()
callback
到全屏页面这里是Setting()
void refresh() {
setState(() {
_selectedPageIndex = _previousIndex;
});
}
...
case 2:
{
print("settings");
return Settings(
callback: refresh,
);
}
第 3 步:在全屏页面Raised Button
调用这个callback
RaisedButton(
onPressed: () {
widget.callback();
},
child: Text("Go back"),
)
工作演示
完整代码
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
/// This Widget is the main application widget.
class MyApp extends StatelessWidget {
static const String _title = 'Flutter Code Sample';
@override
Widget build(BuildContext context) {
return MaterialApp(
title: _title,
home: MyStatefulWidget(),
);
}
}
class MyStatefulWidget extends StatefulWidget {
MyStatefulWidget({Key key}) : super(key: key);
@override
_MyStatefulWidgetState createState() => _MyStatefulWidgetState();
}
class _MyStatefulWidgetState extends State<MyStatefulWidget> {
int _selectedPageIndex = 0;
int _previousIndex = 0;
void refresh() {
setState(() {
_selectedPageIndex = _previousIndex;
});
}
void _onItemTapped(int index) {
setState(() {
_previousIndex = _selectedPageIndex;
_selectedPageIndex = index;
});
}
Widget pageCaller(int index) {
print(index);
switch (index) {
case 0:
{
return Category();
}
case 1:
{
return Feed();
}
case 2:
{
print("settings");
return Settings(
callback: refresh,
);
}
}
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Home'),
),
body: Center(
child: pageCaller(_selectedPageIndex),
),
bottomNavigationBar: _selectedPageIndex == 2
? null
: BottomNavigationBar(
items: const <BottomNavigationBarItem>[
BottomNavigationBarItem(
icon: Icon(Icons.home),
title: Text('Category'),
),
BottomNavigationBarItem(
icon: Icon(Icons.business),
title: Text('Feed'),
),
BottomNavigationBarItem(
icon: Icon(Icons.school),
title: Text('Settings'),
),
],
currentIndex: _selectedPageIndex,
selectedItemColor: Colors.amber[800],
onTap: _onItemTapped,
),
);
}
}
class Category extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Text("Category"),
),
);
}
}
class Feed extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Text("Feed"),
),
);
}
}
class Settings extends StatefulWidget {
VoidCallback callback;
Settings({this.callback});
@override
_SettingsState createState() => _SettingsState();
}
class _SettingsState extends State<Settings> {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Column(
children: [
Text("This is setting page"),
RaisedButton(
onPressed: () {
widget.callback();
},
child: Text("Go back"),
),
],
));
}
}
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