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when there is insufficient space to support tabs, drawers
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provide a good alternative.
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<topic_end>
|
<topic_start>
|
tab navigation
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in react native, createBottomTabNavigator
|
and TabNavigation are used to
|
show tabs and for tab navigation.
|
flutter provides several specialized widgets for drawer and
|
tab navigation:
|
<code_start>
|
class _MyAppState extends State<MyApp> with SingleTickerProviderStateMixin {
|
late TabController controller = TabController(length: 2, vsync: this);
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@override
|
widget build(BuildContext context) {
|
return TabBar(
|
controller: controller,
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tabs: const <tab>[
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tab(icon: Icon(Icons.person)),
|
tab(icon: Icon(Icons.email)),
|
],
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);
|
}
|
}
|
<code_end>
|
a TabController is required to coordinate the tab selection
|
between a TabBar and a TabBarView.
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the TabController constructor length argument is the total
|
number of tabs. a TickerProvider is required to trigger
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the notification whenever a frame triggers a state change.
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the TickerProvider is vsync. pass the
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vsync: this argument to the TabController constructor
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whenever you create a new TabController.
|
the TickerProvider is an interface implemented
|
by classes that can vend ticker objects.
|
tickers can be used by any object that must be notified whenever a
|
frame triggers, but they’re most commonly used indirectly via an
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AnimationController. AnimationControllers
|
need a TickerProvider to obtain their ticker.
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if you are creating an AnimationController from a state,
|
then you can use the TickerProviderStateMixin
|
or SingleTickerProviderStateMixin
|
classes to obtain a suitable TickerProvider.
|
the scaffold widget wraps a new TabBar widget and
|
creates two tabs. the TabBarView widget
|
is passed as the body parameter of the scaffold widget.
|
all screens corresponding to the TabBar widget’s tabs are
|
children to the TabBarView widget along with the same TabController.
|
<code_start>
|
class _NavigationHomePageState extends State<NavigationHomePage>
|
with SingleTickerProviderStateMixin {
|
late TabController controller = TabController(length: 2, vsync: this);
|
@override
|
widget build(BuildContext context) {
|
return scaffold(
|
bottomNavigationBar: material(
|
color: colors.blue,
|
child: TabBar(
|
tabs: const <tab>[
|
tab(
|
icon: Icon(Icons.person),
|
),
|
tab(
|
icon: Icon(Icons.email),
|
),
|
],
|
controller: controller,
|
),
|
),
|
body: TabBarView(
|
controller: controller,
|
children: const <widget>[homescreen(), TabScreen()],
|
));
|
}
|
}
|
<code_end>
|
<topic_end>
|
<topic_start>
|
drawer navigation
|
in react native, import the needed react-navigation packages and then use
|
createDrawerNavigator and DrawerNavigation.
|
in flutter, we can use the drawer widget in combination with a
|
scaffold to create a layout with a material design drawer.
|
to add a drawer to an app, wrap it in a scaffold widget.
|
the scaffold widget provides a consistent
|
visual structure to apps that follow the
|
material design guidelines. it also supports
|
special material design components,
|
such as drawers, AppBars, and SnackBars.
|
the drawer widget is a material design panel that slides
|
in horizontally from the edge of a scaffold to show navigation
|
links in an application. you can
|
provide a ElevatedButton, a text widget,
|
or a list of items to display as the child to the drawer widget.
|
in the following example, the ListTile
|
widget provides the navigation on tap.
|
<code_start>
|
@override
|
widget build(BuildContext context) {
|
return drawer(
|
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