Flutter 将小部件中心与AppBar底部边缘对齐
我需要将小部件的中心与appbar底部边缘对齐。 因此,它将垂直放置,一半在appbar上,另一半在页面主体上 现在我已经将小部件添加到AppBar底部:但它不会与它的水平中心线对齐 现在看起来是这样的:Flutter 将小部件中心与AppBar底部边缘对齐,flutter,flutter-layout,Flutter,Flutter Layout,我需要将小部件的中心与appbar底部边缘对齐。 因此,它将垂直放置,一半在appbar上,另一半在页面主体上 现在我已经将小部件添加到AppBar底部:但它不会与它的水平中心线对齐 现在看起来是这样的: class CustomAppBar extends AppBar { final Widget appBarActionButton; CustomAppBar({Widget title = AppUtils.EMPTY_TEXT_VIEW, this.appB
class CustomAppBar extends AppBar {
final Widget appBarActionButton;
CustomAppBar({Widget title = AppUtils.EMPTY_TEXT_VIEW, this.appBarActionButton}): super(
title: title,
backgroundColor: Colors.blueGrey,
elevation: 0,
bottom: PreferredSize(
child: Stack( //The stack holds the horizontal line and the button aligned cente
alignment: Alignment.center,
children: <Widget>[
Container( //This is the horizontal line
color: Colors.GeneralDividerGray,
height: 1.0,
),
Align(
child: Container(
child: appBarActionButton, //This is the button widget
),
)
],
),
preferredSize: Size.fromHeight(4.0)),
);
}
虽然我希望SelectEnvironment按钮的中间和水平白线将“坐”在appBar的底部边缘
appBar的代码如下所示:
class CustomAppBar extends AppBar {
final Widget appBarActionButton;
CustomAppBar({Widget title = AppUtils.EMPTY_TEXT_VIEW, this.appBarActionButton}): super(
title: title,
backgroundColor: Colors.blueGrey,
elevation: 0,
bottom: PreferredSize(
child: Stack( //The stack holds the horizontal line and the button aligned cente
alignment: Alignment.center,
children: <Widget>[
Container( //This is the horizontal line
color: Colors.GeneralDividerGray,
height: 1.0,
),
Align(
child: Container(
child: appBarActionButton, //This is the button widget
),
)
],
),
preferredSize: Size.fromHeight(4.0)),
);
}
类CustomAppBar扩展了AppBar{
最终小部件appBarActionButton;
CustomAppBar({Widget title=AppUtils.EMPTY_TEXT_VIEW,this.appBarActionButton}):超级(
标题:标题,,
背景颜色:颜色。蓝灰色,
海拔:0,
底部:首选尺寸(
child:Stack(//堆栈保存水平线和对齐的按钮
对齐:对齐.center,
儿童:[
容器(//这是水平线
颜色:Colors.GeneralDividerGray,
高度:1.0,
),
对齐(
子:容器(
child:appBarActionButton,//这是按钮小部件
),
)
],
),
preferredSize:Size.fromHeight(4.0)),
);
}
如果有一个更好的方法来实现这一点,把它以外的appbar它的行,只要它会给同样的效果 最好的方法是通过如下小部件使用切片:
ScrollController scrollController = new ScrollController();
return Stack(
children: [
NestedScrollView(
controller: scrollController,
headerSliverBuilder: (context, value){
return [
// list of widgets in here
];
},
body: Container(
// here, your normal body goes
),
),
Positioned(
top: 50.0,
left: 100.0,
child: Container(
// your centered widget here
),
)
]
);
}
您必须使用SliverAppBar,而不是使用普通的appBar。最好的方法是通过如下小部件使用Sliver:
ScrollController scrollController = new ScrollController();
return Stack(
children: [
NestedScrollView(
controller: scrollController,
headerSliverBuilder: (context, value){
return [
// list of widgets in here
];
},
body: Container(
// here, your normal body goes
),
),
Positioned(
top: 50.0,
left: 100.0,
child: Container(
// your centered widget here
),
)
]
);
}
不要使用普通的appBar,你必须使用SliveAppBar,我认为你应该像这样使用
Stack
和Column
import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart';
typedef void OnWidgetSizeChange(Size size);
class MeasureSize extends StatefulWidget {
final Widget child;
final OnWidgetSizeChange onChange;
const MeasureSize({
Key key,
@required this.onChange,
@required this.child,
}) : super(key: key);
@override
_MeasureSizeState createState() => _MeasureSizeState();
}
class _MeasureSizeState extends State<MeasureSize> {
@override
Widget build(BuildContext context) {
SchedulerBinding.instance.addPostFrameCallback(postFrameCallback);
return Container(
key: widgetKey,
child: widget.child,
);
}
var widgetKey = GlobalKey();
var oldSize;
void postFrameCallback(_) {
var context = widgetKey.currentContext;
if (context == null) return;
var newSize = context.size;
if (oldSize == newSize) return;
oldSize = newSize;
widget.onChange(newSize);
}
}
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
Size s;
@override
Widget build(BuildContext context) {
return Scaffold(
body: Stack(
children: [
Column(
children: [
MeasureSize(
onChange: (size) {
setState(() {
s = size;
});
},
child: AppBar(
title: Text('title'),
),
),
SizedBox(
width: MediaQuery.of(context).size.width,
height: MediaQuery.of(context).size.height - (s?.height ?? 0.0),
child: Center(child: Text('body')))
],
),
Positioned(
top: (s?.height ?? 0.0) - 16.0,
child: Container(
width: MediaQuery.of(context).size.width,
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Container(
height: 32,
color: Colors.red[400],
padding: EdgeInsets.all(6),
child: Center(child: Text('Select Environment'))),
],
),
),
)
],
));
}
}
导入“包装:颤振/材料.省道”;
导入“package:flatter/scheduler.dart”;
typedef void OnWidgetSizeChange(大小);
类MeasureSize扩展StatefulWidget{
最后一个孩子;
最终OnWidgetSizeChange onChange;
常数测量({
关键点,
@需要此.onChange,
@需要这个孩子,
}):super(key:key);
@凌驾
_MeasureSizeState createState()=>_MeasureSizeState();
}
类_MeasureSizeState扩展状态{
@凌驾
小部件构建(构建上下文){
SchedulerBinding.instance.addPostFrameCallback(postFrameCallback);
返回容器(
key:widgetKey,
child:widget.child,
);
}
var widgetKey=GlobalKey();
大小;
无效postFrameCallback(\ux){
var context=widgetKey.currentContext;
if(context==null)返回;
var newSize=context.size;
if(oldSize==newSize)返回;
oldSize=新闻大小;
widget.onChange(newSize);
}
}
void main(){
runApp(MyApp());
}
类MyApp扩展了无状态小部件{
@凌驾
小部件构建(构建上下文){
返回材料PP(
标题:“颤振演示”,
主题:主题数据(
主样本:颜色。蓝色,
视觉密度:视觉密度。自适应平台密度,
),
主页:MyHomePage(标题:“颤振演示主页”),
);
}
}
类MyHomePage扩展StatefulWidget{
MyHomePage({Key,this.title}):超级(Key:Key);
最后的字符串标题;
@凌驾
_MyHomePageState createState()=>\u MyHomePageState();
}
类_MyHomePageState扩展状态{
大小s;
@凌驾
小部件构建(构建上下文){
返回脚手架(
主体:堆栈(
儿童:[
纵队(
儿童:[
测量(
onChange:(大小){
设置状态(){
s=尺寸;
});
},
孩子:AppBar(
标题:文本(“标题”),
),
),
大小盒子(
宽度:MediaQuery.of(context).size.width,
高度:MediaQuery.of(上下文).size.height-(s?.height±0.0),
子对象:中心(子对象:文本('正文'))
],
),
定位(
顶部:(s?高度±0.0)-16.0,
子:容器(
宽度:MediaQuery.of(context).size.width,
孩子:排(
mainAxisAlignment:mainAxisAlignment.center,
儿童:[
容器(
身高:32,
颜色:颜色。红色[400],
填充:边缘设置。全部(6),
子对象:中心(子对象:文本(“选择环境”)),
],
),
),
)
],
));
}
}
我认为你应该像这样使用
堆栈和列
import 'package:flutter/material.dart';
import 'package:flutter/scheduler.dart';
typedef void OnWidgetSizeChange(Size size);
class MeasureSize extends StatefulWidget {
final Widget child;
final OnWidgetSizeChange onChange;
const MeasureSize({
Key key,
@required this.onChange,
@required this.child,
}) : super(key: key);
@override
_MeasureSizeState createState() => _MeasureSizeState();
}
class _MeasureSizeState extends State<MeasureSize> {
@override
Widget build(BuildContext context) {
SchedulerBinding.instance.addPostFrameCallback(postFrameCallback);
return Container(
key: widgetKey,
child: widget.child,
);
}
var widgetKey = GlobalKey();
var oldSize;
void postFrameCallback(_) {
var context = widgetKey.currentContext;
if (context == null) return;
var newSize = context.size;
if (oldSize == newSize) return;
oldSize = newSize;
widget.onChange(newSize);
}
}
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
Size s;
@override
Widget build(BuildContext context) {
return Scaffold(
body: Stack(
children: [
Column(
children: [
MeasureSize(
onChange: (size) {
setState(() {
s = size;
});
},
child: AppBar(
title: Text('title'),
),
),
SizedBox(
width: MediaQuery.of(context).size.width,
height: MediaQuery.of(context).size.height - (s?.height ?? 0.0),
child: Center(child: Text('body')))
],
),
Positioned(
top: (s?.height ?? 0.0) - 16.0,
child: Container(
width: MediaQuery.of(context).size.width,
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Container(
height: 32,
color: Colors.red[400],
padding: EdgeInsets.all(6),
child: Center(child: Text('Select Environment'))),
],
),
),
)
],
));
}
}
导入“包装:颤振/材料.省道”;
导入“package:flatter/scheduler.dart”;
typedef void OnWidgetSizeChange(大小);
类MeasureSize扩展StatefulWidget{
最后一个孩子;
最终OnWidgetSizeChange onChange;
常数测量({
关键点,
@需要此.onChange,
@需要这个孩子,
}):super(key:key);
@凌驾
_MeasureSizeState createState()=>_MeasureSizeState();
}
类_MeasureSizeState扩展状态{
@凌驾
小部件构建(构建上下文){
SchedulerBinding.instance.addPostFrameCallback(postFrameCallback);
返回容器(
key:widgetKey,
child:widget.child,
);
}
var widgetKey=GlobalKey();
大小;
无效postFrameCallback(\ux){
var context=widgetKey.currentContext;
if(context==null)返回;
var newSize=context.size;
if(oldSize==newSize)返回;
oldSize=新闻大小;
widget.onChange(newSize);
}
}
void main(){
runApp(MyApp());
}
类MyApp扩展了无状态小部件{
@凌驾
小部件构建(构建上下文){
返回材料PP(
标题:“颤振演示”,
主题:主题数据(
主样本:颜色。蓝色,
视密度:视密度