Flutter 删除特定小部件|颤振&;河豚
如图所示,我正在尝试创建一个骰子列表,以便添加或删除骰子。我试过StateProvider、ChangeNotifier和StateNotifier。每一个都不像我期望的那样有效。我正在尝试创建一个包含dieWidgets列表的提供程序,但我不知道如何在长按时删除特定的die。这张图片显示了一个删除它的弹出菜单,这是一个长期的目标,但是现在只需长按一下删除就可以了。关于如何处理这个问题的想法 main.dartFlutter 删除特定小部件|颤振&;河豚,flutter,riverpod,Flutter,Riverpod,如图所示,我正在尝试创建一个骰子列表,以便添加或删除骰子。我试过StateProvider、ChangeNotifier和StateNotifier。每一个都不像我期望的那样有效。我正在尝试创建一个包含dieWidgets列表的提供程序,但我不知道如何在长按时删除特定的die。这张图片显示了一个删除它的弹出菜单,这是一个长期的目标,但是现在只需长按一下删除就可以了。关于如何处理这个问题的想法 main.dart class DiceNotifier extends ChangeNotifie
class DiceNotifier extends ChangeNotifier {
List<DieWidget> dice = [];
void add() {
dice.add(DieWidget());
notifyListeners();
}
void removeDie(int id) {
// FIXME: Unable to delete a die based on id
print(id);
notifyListeners();
}
}
final diceProvider = ChangeNotifierProvider((_) {
return DiceNotifier();
});
class MyHomePage extends ConsumerWidget {
@override
Widget build(BuildContext context, ScopedReader watch) {
final dice = watch(diceProvider).dice;
return Scaffold(
appBar: AppBar(
title: Text("Dice"),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
...dice,
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: () {
context.read(diceProvider).add();
},
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
class DieWidget extends StatefulWidget {
@override
_DieWidgetState createState() => _DieWidgetState();
}
class _DieWidgetState extends State<DieWidget> {
int value = 0;
int id = 0;
@override
Widget build(BuildContext context) {
return FlatButton(
child: Text(
'$value',
),
onPressed: () {
setState(() {
value++;
id++;
});
// context.read(dieProvider).increment();
},
onLongPress: () {
final dice = context.read(diceProvider);
dice.removeDie(id);
// print(this.value);
},
);
}
}
类通知程序扩展了ChangeNotifier{
列表骰子=[];
void add(){
dice.add(DieWidget());
notifyListeners();
}
无效删除(内部id){
//FIXME:无法根据id删除模具
打印(id);
notifyListeners();
}
}
final diceProvider=ChangeNotifierProvider((){
返回通知程序();
});
类MyHomePage扩展了ConsumerWidget{
@凌驾
小部件构建(BuildContext上下文,ScopeDrawer监视){
最终骰子=手表(骰子提供者)。骰子;
返回脚手架(
appBar:appBar(
标题:文本(“骰子”),
),
正文:中(
子:列(
mainAxisAlignment:mainAxisAlignment.center,
儿童:[
…掷骰子,
],
),
),
浮动操作按钮:浮动操作按钮(
已按下:(){
read(diceProvider.add();
},
子:图标(Icons.add),
),//此尾随逗号使生成方法的自动格式设置更方便。
);
}
}
die_widget.dart
class DiceNotifier extends ChangeNotifier {
List<DieWidget> dice = [];
void add() {
dice.add(DieWidget());
notifyListeners();
}
void removeDie(int id) {
// FIXME: Unable to delete a die based on id
print(id);
notifyListeners();
}
}
final diceProvider = ChangeNotifierProvider((_) {
return DiceNotifier();
});
class MyHomePage extends ConsumerWidget {
@override
Widget build(BuildContext context, ScopedReader watch) {
final dice = watch(diceProvider).dice;
return Scaffold(
appBar: AppBar(
title: Text("Dice"),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
...dice,
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: () {
context.read(diceProvider).add();
},
child: Icon(Icons.add),
), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
class DieWidget extends StatefulWidget {
@override
_DieWidgetState createState() => _DieWidgetState();
}
class _DieWidgetState extends State<DieWidget> {
int value = 0;
int id = 0;
@override
Widget build(BuildContext context) {
return FlatButton(
child: Text(
'$value',
),
onPressed: () {
setState(() {
value++;
id++;
});
// context.read(dieProvider).increment();
},
onLongPress: () {
final dice = context.read(diceProvider);
dice.removeDie(id);
// print(this.value);
},
);
}
}
类DieWidget扩展StatefulWidget{
@凌驾
_DieWidgetState createState();
}
类_diewigetstate扩展状态{
int值=0;
int id=0;
@凌驾
小部件构建(构建上下文){
返回按钮(
子:文本(
“$value”,
),
已按下:(){
设置状态(){
值++;
id++;
});
//read(dieProvider.increment();
},
onLongPress:(){
最终骰子=context.read(骰子提供者);
骰子移除(id);
//打印(此值);
},
);
}
}
一种解决方案是在小部件
类中定义参数值
:
class DiceWidget extends StatefulWidget {
const DiceWidget({ Key key, this.value }) : super(key: key);
int value;
@override
_DiceWidgetState createState() => _DiceWidgetState();
}
并从小部件
访问此数据:
class DiceWidget extends StatefulWidget {
@override
_DiceWidgetState createState() => _DiceWidgetState();
}
class _DiceWidgetState extends State<DiceWidget> {
@override
Widget build(BuildContext context) {
return FlatButton(
child: Text(
widget.value.toString() ?? '',
),
onLongPress: () {
final dice = context.read(diceProvider);
dice.removeDice(widget.value);
// print(widget.value);
},
);
}
}
因此,addDice()
和removeDice()
函数将分别是:
class DiceNotifier extends ChangeNotifier {
List<int> dices = [];
void addDice() {
dices.add(dices.length);
notifyListeners();
}
void removeDice(int id) {
dices.remove(id);
print(id);
notifyListeners();
}
}
整个示例将是:
main.dart
:
class DiceNotifier extends ChangeNotifier {
List<int> dices = [];
void addDice() {
dices.add(dices.length);
notifyListeners();
}
void removeDice(int id) {
dices.remove(id);
print(id);
notifyListeners();
}
}
final diceProvider = ChangeNotifierProvider((_) {
return DiceNotifier();
});
class MyHomePage extends ConsumerWidget {
@override
Widget build(BuildContext context, ScopedReader watch) {
final dices = watch(diceProvider).dices;
return Scaffold(
appBar: AppBar(
title: Text("Dice"),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
...dices.map((d) => DiceWidget(value: d)).toList(),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: () {
context.read(diceProvider).addDice();
},
child: Icon(Icons.add),
),
);
}
}
class DiceWidget extends StatefulWidget {
@override
_DiceWidgetState createState() => _DiceWidgetState();
}
class _DiceWidgetState extends State<DiceWidget> {
@override
Widget build(BuildContext context) {
return FlatButton(
child: Text(
widget.value.toString() ?? '',
),
onLongPress: () {
final dice = context.read(diceProvider);
dice.removeDice(widget.value);
print(widget.value);
},
);
}
}
这太棒了!非常感谢您的时间和帮助。我需要坐久一点,仔细研究一下这一切的逻辑。再次感谢:)