[英]Flutter: Make list scrollable
這是一個典型的問題,可能被認為是低質量的,但我已經研究了大約兩個小時,我只是想更好地理解這段代碼,所以不僅僅是告訴我如何修復,你能不能也請解釋一下發生了什么。 我相信對於比我更有經驗的人來說,應該很容易發現。
我正在嘗試制作一個可滾動的列表,並繪制列表的每一行,並能夠單擊每個行項目。 但是我的應用程序繪制了所有項目,但我只能看到一些項目,只要屏幕允許,這意味着它是不可滾動的。
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Some App Page'),
),
body: ListView(
children: <Widget>[
Stack(
alignment: const Alignment(1.0, 1.0),
children: <Widget>[
TextField(
controller: cityController,
keyboardType: TextInputType.number,
decoration: const InputDecoration(hintText: 'Enter city...'),
),
TextButton(
onPressed: () {
cityController.clear();
},
child: const Icon(Icons.clear),
),
],
),
ElevatedButton(
onPressed: () {
_futureTime = fetchTimes(int.parse(cityController.text));
if (cityController.text.isNotEmpty) {
setState(() {
cityController.clear(); // Clear value
}); // clear the textField
FocusScope.of(context)
.requestFocus(FocusNode()); // hide the keyboard
}
},
child: const Text('Get City', style: TextStyle(fontSize: 20)),
),
Column(
children: <Widget>[
Center(
child: FutureBuilder<Times>(
future: _futureTime,
builder: (context, snapshot) {
if (!snapshot.hasData) {
return const CircularProgressIndicator();
}
return ListView.builder(
scrollDirection: Axis.vertical,
shrinkWrap: true,
itemBuilder: (BuildContext context, int index) {
return myTimeCard( date, index);
},
itemCount: data == null ? 0 : data.length,
);
},
),
),
],
),
],
),
);
}
Widget myTimeCard(String date, int index) {
return InkWell(
onTap: () {
// Navigate to the next page & pass data.
print("tapped, -> " + index.toString()); // for debugging purpose!
},
child: Stack(
children: <Widget>[
Opacity(
opacity: 1,
child: Container(
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(8.0),
),
),
),
Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Padding(
padding: const EdgeInsets.only(right: 16.0),
child: Text(
index.toString(),
style: const TextStyle(
color: Colors.black,
fontSize: 22.0,
fontWeight: FontWeight.bold),
),
),
],
)
],
)
],
),
);
}
您正在使用兩個相互嵌套的ListView
。 在這種情況下,您可能需要讓 Flutter 知道哪個 ListView 是主要的。 因此,有一個名為primary
的屬性。 嘗試將內部 Listview 的 primary 設置為false
。
return ListView.builder(
primary: false,
scrollDirection: Axis.vertical,
shrinkWrap: true,
itemBuilder: (BuildContext context, int index) {
return myTimeCard( date, index);
},
itemCount: data == null ? 0 : data.length,
);
您分享的代碼無法編譯,因為我沒有額外的上下文,所以我不得不花費一些時間才能使其編譯,請確保將來提供可編譯的代碼。
您面臨的問題是因為主ListView
正在控制滾動,要查看效果嘗試通過按住Get City
按鈕的屏幕滾動。
解決這個問題的方法有很多,看你的目標,是想讓整個屏幕滾動,還是只是數據列表
方式 1. 使整個屏幕可滾動:通過將滾動控制保持在主ListView
中,並使所有下降的小部件不可滾動,在您的情況下,通過使包裝數據的小部件成為Column
而不是ListView
:
class HomeScreen extends StatefulWidget {
const HomeScreen({Key? key}) : super(key: key);
@override
State<HomeScreen> createState() => _HomeScreenState();
}
class _HomeScreenState extends State<HomeScreen> {
final TextEditingController cityController = TextEditingController();
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Some App Page'),
),
body: ListView(
children: <Widget>[
Stack(
alignment: const Alignment(1.0, 1.0),
children: <Widget>[
TextField(
controller: cityController,
keyboardType: TextInputType.number,
decoration: const InputDecoration(hintText: 'Enter city...'),
),
TextButton(
onPressed: () {
cityController.clear();
},
child: const Icon(Icons.clear),
),
],
),
ElevatedButton(
onPressed: () {
_futureTime = fetchTimes(int.parse(cityController.text));
if (cityController.text.isNotEmpty) {
setState(() {
cityController.clear(); // Clear value
}); // clear the textField
FocusScope.of(context)
.requestFocus(FocusNode()); // hide the keyboard
}
},
child: const Text('Get City', style: TextStyle(fontSize: 20)),
),
Column(
children: <Widget>[
Center(
child: FutureBuilder<Times>(
future: _futureTime,
builder: (context, snapshot) {
// if (!snapshot.hasData) {
// return const CircularProgressIndicator();
// }
final data =
// snapshot.data;
List.generate(50, (index) => index.toString());
return Column(
children: [
for (int i = 0; i < data.length; i++)
myTimeCard(data[i], i)
],
);
},
),
),
],
),
],
),
);
}
Widget myTimeCard(String date, int index) {
return InkWell(
onTap: () {
// Navigate to the next page & pass data.
print("tapped, -> " + index.toString()); // for debugging purpose!
},
child: Stack(
children: <Widget>[
Opacity(
opacity: 1,
child: Container(
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(8.0),
),
),
),
Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Padding(
padding: const EdgeInsets.only(right: 16.0),
child: Text(
index.toString(),
style: const TextStyle(
color: Colors.black,
fontSize: 22.0,
fontWeight: FontWeight.bold),
),
),
],
)
],
)
],
),
);
}
}
方式2.使非數據小部件不可滾動,並將滾動控件保留在數據小部件中:可以通過將主ListView
轉換為不可滾動的小部件(在您的情況下為Column
)並將數據列表包裝在Expanded
的小部件,因此它占用了它可以擁有的所有空間(有關擴展的更多信息) :
class HomeScreen extends StatefulWidget {
const HomeScreen({Key? key}) : super(key: key);
@override
State<HomeScreen> createState() => _HomeScreenState();
}
class _HomeScreenState extends State<HomeScreen> {
final TextEditingController cityController = TextEditingController();
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Some App Page'),
),
body: Column(
children: <Widget>[
Stack(
alignment: const Alignment(1.0, 1.0),
children: <Widget>[
TextField(
controller: cityController,
keyboardType: TextInputType.number,
decoration: const InputDecoration(hintText: 'Enter city...'),
),
TextButton(
onPressed: () {
cityController.clear();
},
child: const Icon(Icons.clear),
),
],
),
ElevatedButton(
onPressed: () {
_futureTime = fetchTimes(int.parse(cityController.text));
if (cityController.text.isNotEmpty) {
setState(() {
cityController.clear(); // Clear value
}); // clear the textField
FocusScope.of(context)
.requestFocus(FocusNode()); // hide the keyboard
}
},
child: const Text('Get City', style: TextStyle(fontSize: 20)),
),
FutureBuilder<Times>(
future: _futureTime,
builder: (context, snapshot) {
// if (!snapshot.hasData) {
// return const CircularProgressIndicator();
// }
final data =
// snapshot.data;
List.generate(50, (index) => index.toString());
return Expanded(
child: ListView.builder(
scrollDirection: Axis.vertical,
shrinkWrap: true,
itemBuilder: (BuildContext context, int index) {
return myTimeCard(date, index);
},
itemCount: data == null ? 0 : data.length,
),
);
},
),
],
),
);
}
Widget myTimeCard(String date, int index) {
return InkWell(
onTap: () {
// Navigate to the next page & pass data.
print("tapped, -> " + index.toString()); // for debugging purpose!
},
child: Stack(
children: <Widget>[
Opacity(
opacity: 1,
child: Container(
decoration: BoxDecoration(
borderRadius: BorderRadius.circular(8.0),
),
),
),
Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Padding(
padding: const EdgeInsets.only(right: 16.0),
child: Text(
index.toString(),
style: const TextStyle(
color: Colors.black,
fontSize: 22.0,
fontWeight: FontWeight.bold),
),
),
],
)
],
)
],
),
);
}
}
問題來了,因為我們有兩個可滾動的ListView
。 雖然它們都是可滾動的,但當內部ListView
獲得焦點並且父級變得不聚焦並且滾動事件僅影響內部ListView
並且您不能回滾到父級ListView
時滾動時,一個簡單的解決方案將在內部ListView.builder
上使用NeverScrollableScrollPhysics
.
child: ListView.builder(
physics: NeverScrollableScrollPhysics(),
scrollDirection: Axis.vertical,
singleChildScrollView(
child: ListView.builder(
sinkwrap:true,
physics: NeverScrollableScrollPhysics(),
scrollDirection: Axis.vertical,)
)
簡單易行
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