我正在努力做到这一点：
问题是当我从底表中选择值时。我无法使NewPost小部件通过选择的内容进行重建。
每次我从底表中选择源时，我应该遵循什么方法来打开正确的ImageSource？
希望我的要求明确。在下面的代码中，我尝试实现了Provider程序，希望解决该问题，但我肯定在这里没有指出要点。
PageModule
class PageModule extends StatefulWidget {
static const String id = 'start';
@override
_PageModuleState createState() => _PageModuleState();
}
class _PageModuleState extends State<PageModule> {
int _selectedIndex = 0;
String source = 'gallery';
PageController pageController = PageController(
initialPage: 0,
keepPage: true,
);
void onPageChange(int index) {
setState(() {
_selectedIndex = index;
});
}
void onTabChange(int index) {
setState(() {
_selectedIndex = index;
pageController.jumpToPage(index);
});
}
void _bottomSheet() {
showModalBottomSheet(
shape: kBottomSheetShape,
context: context,
builder: (context) => CameraSelector(
onAction: (String value) {
Provider.of<SharedData>(context).changeSource(value);
onTabChange(2);
},
),
);
}
@override
Widget build(BuildContext context) {
return Provider<SharedData>(
create: (context) => SharedData(),
child: Scaffold(
floatingActionButtonLocation: FloatingActionButtonLocation.centerDocked,
floatingActionButton: FloatingActionButton(
child: const Icon(Icons.camera),
onPressed: () {
_bottomSheet();
},
),
bottomNavigationBar: BottomAppBar(
shape: CircularNotchedRectangle(),
notchMargin: 4.0,
child: new Row(
mainAxisSize: MainAxisSize.max,
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: <Widget>[
IconButton(
icon: Icon(Icons.home),
onPressed: () {
onTabChange(0);
},
),
IconButton(
icon: Icon(Icons.search),
onPressed: () {
onTabChange(1);
},
),
SizedBox(
width: 50.0,
),
IconButton(
icon: Icon(Icons.notifications),
onPressed: () {
onTabChange(3);
},
),
IconButton(
icon: Icon(Icons.person_pin),
onPressed: () {
onTabChange(4);
},
),
],
),
),
body: PageView(
controller: pageController,
physics: NeverScrollableScrollPhysics(),
onPageChanged: (index) {
onPageChange(index);
},
children: <Widget>[
HomeScreen(),
SearchScreen(),
NewPostScreen(),
NotificationScreen(),
ProfileScreen(),
],
),
),
);
}
}
CameraSelector底页
class CameraSelector extends StatelessWidget {
final Function onAction;
CameraSelector({@required this.onAction});
@override
Widget build(BuildContext context) {
return SingleChildScrollView(
child: Container(
padding: EdgeInsets.only(bottom: 45, top: 25),
child: Column(
children: <Widget>[
Heading(
size: kH2,
text: 'Scegli una opzione',
bold: true,
),
SizedBox(
height: 20,
),
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
SelectorButton(
icon: Icons.photo_size_select_actual,
label: 'Libreria',
source: Source.gallery,
action: (String value) {
onAction(value.toLowerCase());
},
),
SizedBox(
width: 20,
),
SelectorButton(
icon: Icons.camera_alt,
label: 'Camera',
source: Source.camera,
action: (String value) {
onAction(value.toLowerCase());
},
),
],
),
],
)),
);
}
}
class SelectorButton extends StatelessWidget {
final IconData icon;
final String label;
final String source;
final Function action;
SelectorButton({
@required this.icon,
@required this.label,
@required this.source,
@required this.action,
});
@override
Widget build(BuildContext context) {
return Container(
decoration: BoxDecoration(
borderRadius: BorderRadius.all(Radius.circular(20)),
),
child: InkWell(
onTap: () {
Navigator.pop(context);
action(source);
},
borderRadius: BorderRadius.all(Radius.circular(20)),
child: Container(
padding: EdgeInsets.symmetric(
vertical: 20,
horizontal: 30,
),
decoration: BoxDecoration(
borderRadius: BorderRadius.all(Radius.circular(20)),
border: Border.all(color: Colors.grey[850], width: 1.5),
),
child: Column(
children: <Widget>[
Icon(
icon,
size: 50.0,
color: Colors.grey[850],
),
SizedBox(
height: 5,
),
Text(
label.toUpperCase(),
style: TextStyle(
fontWeight: FontWeight.bold,
fontSize: 15,
color: Colors.grey[850],
),
)
],
),
),
),
);
}
}
NewPost
static const String id = 'newpost';
@override
_NewPostScreenState createState() => _NewPostScreenState();
}
class _NewPostScreenState extends State<NewPostScreen> {
File _image;
Future getImage() async {
var image = await ImagePicker.pickImage(
source: Provider.of<SharedData>(context).source == 'gallery' ? ImageSource.gallery : ImageSource.camera,
imageQuality: 100,
maxWidth: 1200,
);
setState(() {
_image = image;
});
}
@override
void initState() {
super.initState();
getImage();
}
Widget _bodyBuild() {
if (_image != null) {
return ListView(
shrinkWrap: true,
padding: EdgeInsets.all(20.0),
children: <Widget>[
Heading(
size: kH1,
text: 'Dettagli del post',
bold: true,
),
SizedBox(
height: 20.0,
),
Container(
height: 100.0,
child: Center(
child: Row(
children: <Widget>[
Container(
width: 100,
child: _image == null
? Text('')
: ProfileImage(
size: 50,
image: _image,
),
),
SizedBox(
width: 20.0,
),
Text('qui box per descrizione')
],
),
),
),
SizedBox(
height: 20.0,
),
Container(
decoration: BoxDecoration(
border: Border(top: BorderSide(width: 1.0, color: Colors.grey[400])),
),
),
SizedBox(
height: 20.0,
),
Heading(
size: kH3,
text: 'Tagga gli amici',
bold: true,
),
SizedBox(
height: 20.0,
),
Text('lista dei tag degli amici con un input di ricerca con autocompletamento dei risultati'),
SizedBox(
height: 20.0,
),
Container(
decoration: BoxDecoration(
border: Border(top: BorderSide(width: 1.0, color: Colors.grey[400])),
),
),
SizedBox(
height: 20.0,
),
Heading(
size: kH3,
text: 'Aggiungi tag',
bold: true,
),
SizedBox(
height: 20.0,
),
Text('lista dei tag argomenti con un input di ricerca con autocompletamento dei risultati')
],
);
} else {
return Container();
}
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Nuovo Post'),
),
body: _bodyBuild(),
);
}
}
由于您使用的是provider，而不是initState，因此您要查找的是didChangeDependencies / build
这个想法是，当提供者的状态发生变化时，您正在初始化它而不是在创建时初始化它的状态[]这里是什么样子：
class _MyState extends State<MyStatefulWidget> {
SomeClass previousSomeClass;
@override
void didChangeDependencies() {
super.didChangeDependencies();
final someClass = Provider.of<Something>(context).someClass;
if (someClass != previousSomeClass) {
previousSomeClass = someClass;
getImage();
}
}
void getImage() {...}
}