Flutter 颤振将文本字段光标设置为在更改控制器时启动';s文本
我有一个可重用的文本字段类,如下所示:Flutter 颤振将文本字段光标设置为在更改控制器时启动';s文本,flutter,dart,Flutter,Dart,我有一个可重用的文本字段类,如下所示: import 'package:flutter/material.dart'; void main() { runApp(MyApp()); } class MyApp extends StatefulWidget { @override _MyAppState createState() => _MyAppState(); } class _MyAppState extends State<MyApp> { @ov
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatefulWidget {
@override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
String value = "";
@override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: Center(
child: MyTextField(
value: value,
onChange: (val) {
setState(() {
value = val;
});
},
),
),
),
);
}
}
typedef ChangeCallback = void Function(String value);
class MyTextField extends StatefulWidget {
final ChangeCallback onChange;
final String value;
const MyTextField({this.onChange = _myDefaultFunc, this.value = ""});
static _myDefaultFunc(String value){}
@override
_MyTextFieldState createState() => _MyTextFieldState();
}
class _MyTextFieldState extends State<MyTextField> {
final controller = TextEditingController();
@override
void initState() {
controller.text = widget.value;
super.initState();
}
@override
void didUpdateWidget(covariant MyTextField oldWidget) {
controller.text = widget.value;
super.didUpdateWidget(oldWidget);
}
@override
Widget build(BuildContext context) {
return TextField(
controller: controller,
onChanged: (value) {
widget.onChange(value);
},
);
}
}
导入“包装:颤振/材料.省道”;
void main(){
runApp(MyApp());
}
类MyApp扩展了StatefulWidget{
@凌驾
_MyAppState createState()=>\u MyAppState();
}
类MyAppState扩展了状态{
@凌驾
小部件构建(构建上下文){
返回材料PP(
标题:“颤振演示”,
主页:MyHomePage(),
);
}
}
类MyHomePage扩展StatefulWidget{
@凌驾
_MyHomePageState createState()=>\u MyHomePageState();
}
类_MyHomePageState扩展状态{
字符串值=”;
@凌驾
小部件构建(构建上下文){
返回脚手架(
正文:安全区(
儿童:中心(
孩子:MyTextField(
价值:价值,
onChange:(val){
设置状态(){
值=val;
});
},
),
),
),
);
}
}
typedef ChangeCallback=无效函数(字符串值);
类MyTextField扩展StatefulWidget{
最终更改回调onChange;
最终字符串值;
const MyTextField({this.onChange=\u myDefaultFunc,this.value=”“});
静态myDefaultFunc(字符串值){}
@凌驾
_MyTextFieldState createState()=>\u MyTextFieldState();
}
类_MyTextFieldState扩展状态{
最终控制器=文本编辑控制器();
@凌驾
void initState(){
controller.text=widget.value;
super.initState();
}
@凌驾
void didUpdateWidget(协变MyTextField oldWidget){
controller.text=widget.value;
super.didUpdateWidget(oldWidget);
}
@凌驾
小部件构建(构建上下文){
返回文本字段(
控制器:控制器,
一旦更改:(值){
widget.onChange(值);
},
);
}
}
如您所见,如果更改了该值,则会调用
onChange
回调,并且该值会再次发送回TextField
。问题是每次我更新值时,TextField
总是将光标设置为起始位置。可能是因为每次更新后的值都会发送回TextField
?不确定。你能帮我一下吗?传递一个TextEditingController
而不是使用onChanged
方法来获取文本字段的值
class MyTextField extends StatefulWidget {
final TextEditingController controller;
final String defaultValue;
const MyTextField({@required this.controller, this.defaultValue = ''});
@override
_MyTextFieldState createState() => _MyTextFieldState();
}
class _MyTextFieldState extends State<MyTextField> {
@override
void initState() {
widget.controller.text = widget.defaultValue;
super.initState();
}
@override
Widget build(BuildContext context) {
return TextField(
controller: widget.controller,
);
}
}
类MyTextField扩展了StatefulWidget{
最终文本编辑控制器;
最终字符串默认值;
const MyTextField({@required this.controller,this.defaultValue=''''});
@凌驾
_MyTextFieldState createState()=>\u MyTextFieldState();
}
类_MyTextFieldState扩展状态{
@凌驾
void initState(){
widget.controller.text=widget.defaultValue;
super.initState();
}
@凌驾
小部件构建(构建上下文){
返回文本字段(
控制器:widget.controller,
);
}
}
通过这种方式,您可以在父窗口小部件中声明一个
TextEditingController
,以获得与通常使用Flatter的本机TextFormField
一样的值,而无需更新didUpdateWidget中的值
//@override
// void didUpdateWidget(covariant MyTextField oldWidget) {
// controller.text = widget.value;
// super.didUpdateWidget(oldWidget);
// }
我刚刚注释掉了这个函数,代码运行良好
下面是完整的代码
import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatefulWidget {
@override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
String value = "";
@override
Widget build(BuildContext context) {
return Scaffold(
body: SafeArea(
child: Column(children: [
SizedBox(height:50),
Text("text input: $value"),
SizedBox(height:50),
Center(
child: MyTextField(
value: value,
onChange: (val) {
setState(() {
value = val;
});
},
),
),
]),
),
);
}
}
typedef ChangeCallback = void Function(String value);
class MyTextField extends StatefulWidget {
final ChangeCallback onChange;
final String value;
const MyTextField({this.onChange = _myDefaultFunc, this.value = ""});
static _myDefaultFunc(String value) {}
@override
_MyTextFieldState createState() => _MyTextFieldState();
}
class _MyTextFieldState extends State<MyTextField> {
final controller = TextEditingController();
@override
void initState() {
controller.text = widget.value;
super.initState();
}
// @override
// void didUpdateWidget(covariant MyTextField oldWidget) {
// controller.text = widget.value;
// super.didUpdateWidget(oldWidget);
// }
@override
Widget build(BuildContext context) {
return TextField(
controller: controller,
onChanged: (value) {
widget.onChange(value);
},
);
}
}
导入“包装:颤振/材料.省道”;
void main(){
runApp(MyApp());
}
类MyApp扩展了StatefulWidget{
@凌驾
_MyAppState createState()=>\u MyAppState();
}
类MyAppState扩展了状态{
@凌驾
小部件构建(构建上下文){
返回材料PP(
标题:“颤振演示”,
主页:MyHomePage(),
);
}
}
类MyHomePage扩展StatefulWidget{
@凌驾
_MyHomePageState createState()=>\u MyHomePageState();
}
类_MyHomePageState扩展状态{
字符串值=”;
@凌驾
小部件构建(构建上下文){
返回脚手架(
正文:安全区(
子项:列(子项:[
尺寸箱(高度:50),
文本(“文本输入:$value”),
尺寸箱(高度:50),
居中(
孩子:MyTextField(
价值:价值,
onChange:(val){
设置状态(){
值=val;
});
},
),
),
]),
),
);
}
}
typedef ChangeCallback=无效函数(字符串值);
类MyTextField扩展StatefulWidget{
最终更改回调onChange;
最终字符串值;
const MyTextField({this.onChange=\u myDefaultFunc,this.value=”“});
静态myDefaultFunc(字符串值){}
@凌驾
_MyTextFieldState createState()=>\u MyTextFieldState();
}
类_MyTextFieldState扩展状态{
最终控制器=文本编辑控制器();
@凌驾
void initState(){
controller.text=widget.value;
super.initState();
}
//@覆盖
//void didUpdateWidget(协变MyTextField oldWidget){
//controller.text=widget.value;
//super.didUpdateWidget(oldWidget);
// }
@凌驾
小部件构建(构建上下文){
返回文本字段(
控制器:控制器,
一旦更改:(值){
widget.onChange(值);
},
);
}
}