Flutter 如果多级列表的节点具有单击时应显示的内容,该怎么办?(高级扩展文件)
对于Flatter项目,我需要一种树状结构,在这种结构中,当单击节点时,不仅会显示节点下方的条目,而且会像Windows中的文件管理器一样显示内容:在智能手机上作为新屏幕,在平板电脑上作为列表右侧的附加区域。Flutter 如果多级列表的节点具有单击时应显示的内容,该怎么办?(高级扩展文件),flutter,Flutter,对于Flatter项目,我需要一种树状结构,在这种结构中,当单击节点时,不仅会显示节点下方的条目,而且会像Windows中的文件管理器一样显示内容:在智能手机上作为新屏幕,在平板电脑上作为列表右侧的附加区域。 不幸的是,标准的ExpansionFile没有这个功能。因为我是一个新手,所以我首先看了源代码,并试图理解最重要的部分(我还在做;-)。然后我做了以下更改: 属性“AlignOpener”现在决定打开/关闭图标是显示在左侧还是右侧 我添加了属性“onTap”和“onLongPress”作为
不幸的是,标准的ExpansionFile没有这个功能。因为我是一个新手,所以我首先看了源代码,并试图理解最重要的部分(我还在做;-)。然后我做了以下更改:
import 'package:meta/meta.dart';
class ItemMaster {
ItemMaster(
{this.id,
@required this.title,
this.subtitle,
this.children = const <ItemMaster>[]});
final int id;
final String title;
final String subtitle;
final List<ItemMaster> children;
}
import'package:meta/meta.dart';
类ItemMaster{
项目主管(
{this.id,
@需要这个标题,
这个,副标题,,
this.children=const[]});
最终int id;
最后的字符串标题;
最后一串字幕;
最后儿童名单;
}
飞镖
import 'master_list_item.dart';
class MasterList {
List<ItemMaster> get items {
return _items;
}
final List<ItemMaster> _items = <ItemMaster>[
ItemMaster(
title: 'Chapter Master List',
id: 1,
children: <ItemMaster>[
ItemMaster(
title: 'Scene A0',
id: 2,
children: <ItemMaster>[
ItemMaster(title: 'Item A0.1', id: 3),
ItemMaster(title: 'Item A0.2', id: 4),
ItemMaster(title: 'Item A0.3', id: 5),
],
),
ItemMaster(title: 'Scene A1', id: 6),
ItemMaster(title: 'Scene A2', id: 7),
],
),
ItemMaster(
title: 'Chapter B',
id: 8,
children: <ItemMaster>[
ItemMaster(title: 'Scene B0', id: 9),
ItemMaster(title: 'Scene B1', id: 10),
],
),
ItemMaster(
title: 'Chapter C',
id: 11,
children: <ItemMaster>[
ItemMaster(title: 'Scene C0', id: 12),
ItemMaster(title: 'Scene C1', id: 13),
ItemMaster(
title: 'Scene C2',
id: 14,
children: <ItemMaster>[
ItemMaster(title: 'Item C2.0', id: 15),
ItemMaster(title: 'Item C2.1', id: 16),
ItemMaster(title: 'Item C2.2', id: 17),
ItemMaster(title: 'Item C2.3', id: 18),
],
),
],
),
];
}
import'master_list_item.dart';
班级总名单{
列出获取项目{
退货(物品);;
}
最终清单_项目=[
项目主管(
标题:“章节主列表”,
id:1,
儿童:[
项目主管(
标题:“场景A0”,
id:2,
儿童:[
ItemMaster(标题:“项目A0.1”,id:3),
ItemMaster(标题:“项目A0.2”,id:4),
ItemMaster(标题:“项目A0.3”,id:5),
],
),
ItemMaster(标题:“场景A1”,id:6),
ItemMaster(标题:“场景A2”,id:7),
],
),
项目主管(
标题:“B章”,
id:8,
儿童:[
ItemMaster(标题:“场景B0”,id:9),
ItemMaster(标题:“场景B1”,id:10),
],
),
项目主管(
标题:“C章”,
id:11,
儿童:[
ItemMaster(标题:“场景C0”,id:12),
ItemMaster(标题:“场景C1”,id:13),
项目主管(
标题:“场景C2”,
身份证号码:14,
儿童:[
ItemMaster(标题:“项目C2.0”,id:15),
ItemMaster(标题:“项目C2.1”,id:16),
ItemMaster(标题:“项目C2.2”,id:17),
ItemMaster(标题:“项目C2.3”,id:18),
],
),
],
),
];
}
主飞镖
import 'package:flutter/material.dart';
import 'advanced_expansion_tile.dart';
import 'master_list_item.dart';
import 'master_list.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
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> {
List<ItemMaster> items;
@override
void initState() {
// TODO: implement initState
super.initState();
items = MasterList().items;
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Container(
child: ListView.builder(
itemCount: items.length,
itemBuilder: (context, int index) => MasterListEntry(items[index]),
)),
),
);
}
}
class MasterListEntry extends StatelessWidget {
const MasterListEntry(this.entry);
final ItemMaster entry;
Widget _buildTiles(ItemMaster root) {
if (root.children.isEmpty)
return ListTile(
title: Text(root.title),
onTap: () => print("onTap listTile"),
);
return AdvancedExpansionTile(
key: PageStorageKey<ItemMaster>(root),
title: Text(root.title),
children: root.children.map(_buildTiles).toList(),
onTap: () => print("onTap AdvancedExpansionTile"),
alignOpener: AlignOpener.Right,
indentListTile: 15.0,
// isInAdvancedMode: true,
);
}
@override
Widget build(BuildContext context) {
return _buildTiles(entry);
}
}
导入“包装:颤振/材料.省道”;
导入“advanced_expansion_tile.dart”;
导入“master_list_item.dart”;
导入“master_list.dart”;
void main()=>runApp(MyApp());
类MyApp扩展了无状态小部件{
//此小部件是应用程序的根。
@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,
),
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{
清单项目;
@凌驾
void initState(){
//TODO:实现initState
super.initState();
项目=主列表()。项目;
}
@凌驾
小部件构建(构建上下文){
返回脚手架(
appBar:appBar(
标题:文本(widget.title),
),
正文:中(
子:容器(
子项:ListView.builder(
itemCount:items.length,
itemBuilder:(context,int index)=>MasterListEntry(items[index]),
)),
),
);
}
}
类MasterListEntry扩展了无状态小部件{
const MasterListEntry(此条目);
最终的ItemMaster条目;
Widget\u buildTiles(ItemMaster根目录){
if(root.children.isEmpty)
返回列表块(
标题:文本(root.title),
onTap:()=>打印(“onTap列表块”),
);
返回高级扩展文件(
密钥:PageStorageKey(根),
标题:文本(root.title),
children:root.children.map(_buildTiles.toList(),
onTap:()=>打印(“onTap高级扩展文件”),
对齐打开器:对齐打开器。对,
indentListTile:15.0,
//isInAdvancedMode:正确,
);
}
@凌驾
小部件构建(构建上下文){
返回(条目);;
}
}
高级扩展\u tile.dart(基于Flatter团队的源代码)
//作者版权所有。版权所有。
//此源代码的使用受BSD样式许可证的约束,该许可证可以
//在许可证文件中找到。
导入“package:flatter/widgets.dart”;
进口“包装:颤振/材料.省道”;
const Duration _kExpand=持续时间(毫秒:200);
枚举对齐开启器{左,右}
类AdvancedExpansionFile扩展StatefulWidget{
常量高级扩展文件({
关键点,
这个,领导,,
这个,拖尾,,
@需要这个标题,
这个背景色,
这个,一个扩展改变了,
这个.onTap,
这是唯一的新闻,
这是我的开瓶器,
这是一块瓷砖,
// Copyright 2017 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'package:flutter/widgets.dart';
import 'package:flutter/material.dart';
const Duration _kExpand = Duration(milliseconds: 200);
enum AlignOpener { Left, Right }
class AdvancedExpansionTile extends StatefulWidget {
const AdvancedExpansionTile({
Key key,
this.leading,
this.trailing,
@required this.title,
this.backgroundColor,
this.onExpansionChanged,
this.onTap,
this.onLongPress,
this.alignOpener,
this.indentListTile,
this.children = const <Widget>[],
this.initiallyExpanded = false,
}) : assert(initiallyExpanded != null),
super(key: key);
/// A widget to display before the title.
///
/// Typically a [CircleAvatar] widget.
final Widget leading;
/// The primary content of the list item.
///
/// Typically a [Text] widget.
final Widget title;
/// Called when the tile expands or collapses.
///
/// When the tile starts expanding, this function is called with the value
/// true. When the tile starts collapsing, this function is called with
/// the value false.
final ValueChanged<bool> onExpansionChanged;
/// The widgets that are displayed when the tile expands.
///
/// Typically [ListTile] widgets.
final List<Widget> children;
/// The color to display behind the sublist when expanded.
final Color backgroundColor;
/// Specifies if the list tile is initially expanded (true) or collapsed (false, the default).
final bool initiallyExpanded;
/// A widget to display instead of a rotating arrow icon.
final Widget trailing;
/// A callback for onTap and onLongPress on the listTile
final GestureTapCallback onTap;
final GestureLongPressCallback onLongPress;
/// The side where the Open/Close-Icon/IconButton will be placed
final AlignOpener alignOpener;
/// indent of listTile (left)
final indentListTile;
@override
_AdvancedExpansionTileState createState() => _AdvancedExpansionTileState();
}
class _AdvancedExpansionTileState extends State<AdvancedExpansionTile>
with SingleTickerProviderStateMixin {
static final Animatable<double> _easeOutTween =
CurveTween(curve: Curves.easeOut);
static final Animatable<double> _easeInTween =
CurveTween(curve: Curves.easeIn);
static final Animatable<double> _halfTween =
Tween<double>(begin: 0.0, end: 0.5);
final ColorTween _borderColorTween = ColorTween();
final ColorTween _headerColorTween = ColorTween();
final ColorTween _iconColorTween = ColorTween();
final ColorTween _backgroundColorTween = ColorTween();
AnimationController _controller;
Animation<double> _iconTurns;
Animation<double> _heightFactor;
Animation<Color> _borderColor;
Animation<Color> _headerColor;
Animation<Color> _iconColor;
Animation<Color> _backgroundColor;
bool _isExpanded = false;
/// If set to true an IconButton will be created. This button will open/close the children
bool _isInAdvancedMode;
AlignOpener _alignOpener;
double _indentListTile;
@override
void initState() {
super.initState();
_controller = AnimationController(duration: _kExpand, vsync: this);
_heightFactor = _controller.drive(_easeInTween);
_iconTurns = _controller.drive(_halfTween.chain(_easeInTween));
_borderColor = _controller.drive(_borderColorTween.chain(_easeOutTween));
_headerColor = _controller.drive(_headerColorTween.chain(_easeInTween));
_iconColor = _controller.drive(_iconColorTween.chain(_easeInTween));
_backgroundColor =
_controller.drive(_backgroundColorTween.chain(_easeOutTween));
_isExpanded =
PageStorage.of(context)?.readState(context) ?? widget.initiallyExpanded;
if (_isExpanded) _controller.value = 1.0;
/// OnTap or onLongPress are handled in the calling widget --> AdvancedExpansionTile is in Advanced Mode
if (widget.onTap != null || widget.onLongPress != null) {
_isInAdvancedMode = true;
} else {
_isInAdvancedMode = false;
}
/// fallback to standard behaviour if aligning isn't set
_alignOpener = widget.alignOpener ?? AlignOpener.Right;
/// if no indent is set the indent will be 0.0
_indentListTile = widget.indentListTile ?? 0.0;
}
@override
void dispose() {
_controller.dispose();
super.dispose();
}
void _handleTap() {
setState(() {
_isExpanded = !_isExpanded;
if (_isExpanded) {
_controller.forward();
} else {
_controller.reverse().then<void>((void value) {
if (!mounted) return;
setState(() {
// Rebuild without widget.children.
});
});
}
PageStorage.of(context)?.writeState(context, _isExpanded);
});
if (widget.onExpansionChanged != null)
widget.onExpansionChanged(_isExpanded);
}
Widget _buildChildren(BuildContext context, Widget child) {
final Color borderSideColor = _borderColor.value ?? Colors.transparent;
return Container(
decoration: BoxDecoration(
color: _backgroundColor.value ?? Colors.transparent,
border: Border(
top: BorderSide(color: borderSideColor),
bottom: BorderSide(color: borderSideColor),
),
),
child: Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
ListTileTheme.merge(
iconColor: _iconColor.value,
textColor: _headerColor.value,
child: ListTile(
onTap: () {
_isInAdvancedMode ? widget.onTap() : _handleTap();
}, // in AdvancedMode a callback will handle the gesture inside the calling widget
onLongPress: () {
_isInAdvancedMode ? widget.onLongPress() : _handleTap();
}, // in AdvancedMode a callback will handle the gesture inside the calling widget
leading: getLeading(),
title: widget.title,
trailing: getTrailing(),
),
),
ClipRect(
child: Padding(
padding: EdgeInsets.only(left: _indentListTile), // set the indent
child: Align(
heightFactor: _heightFactor.value,
child: child,
),
)),
],
),
);
}
@override
void didChangeDependencies() {
final ThemeData theme = Theme.of(context);
_borderColorTween..end = theme.dividerColor;
_headerColorTween
..begin = theme.textTheme.subhead.color
..end = theme.accentColor;
_iconColorTween
..begin = theme.unselectedWidgetColor
..end = theme.accentColor;
_backgroundColorTween..end = widget.backgroundColor;
super.didChangeDependencies();
}
@override
Widget build(BuildContext context) {
final bool closed = !_isExpanded && _controller.isDismissed;
return AnimatedBuilder(
animation: _controller.view,
builder: _buildChildren,
child: closed ? null : Column(children: widget.children),
);
}
/// A method to decide what will be shown in the leading part of the lisTile
getLeading() {
if (_alignOpener.toString() == AlignOpener.Left.toString() &&
_isInAdvancedMode == true) {
return buildIcon(); //IconButton will be created
} else if (_alignOpener.toString() == AlignOpener.Left.toString() &&
_isInAdvancedMode == false) {
return widget.leading ??
RotationTransition(
turns: _iconTurns,
child: const Icon(Icons.expand_more),
);
} else {
return widget.leading;
}
}
/// A method to decide what will be shown in the trailing part of the lisTile
getTrailing() {
if (_alignOpener.toString() == AlignOpener.Right.toString() &&
_isInAdvancedMode == true) {
return buildIcon(); //IconButton will be created
} else if (_alignOpener.toString() == AlignOpener.Right.toString() &&
_isInAdvancedMode == false) {
return widget.trailing ??
RotationTransition(
turns: _iconTurns,
child: const Icon(Icons.expand_more),
);
} else {
return widget.leading;
}
}
/// A widget to build the IconButton for the leading or trailing part of the listTile
Widget buildIcon() {
return Container(
child: RotationTransition(
turns: _iconTurns,
child: IconButton(
icon: Icon(Icons.expand_more),
onPressed: () {
_handleTap();
//toDo: open/close is working but not the animation
},
),
));
}
}