Flutter 使用堆栈中拖动的小部件更新所有附加的小部件
考虑一堆小部件,如图所示。我们可以看到索引0小部件附加了索引1、2、3、4小部件。。。;索引3小部件附带索引4小部件,索引4小部件不附带任何人Flutter 使用堆栈中拖动的小部件更新所有附加的小部件,flutter,draggable,Flutter,Draggable,考虑一堆小部件,如图所示。我们可以看到索引0小部件附加了索引1、2、3、4小部件。。。;索引3小部件附带索引4小部件,索引4小部件不附带任何人 现在,当我拖动一个小部件时,所有附加的小部件也应随之拖动 i、 e.如果我尝试拖动Index2小部件,则拖动的小部件应该是Index2、3、4小部件的堆栈 如果我尝试拖动index 4小部件,则拖动的小部件应该只是index 4小部件 现在我知道我可以在标记可拖动的类的参数时,使用反馈和孩子来处理拖动小部件的更新,但我不知道如何使用它更新所有其他附加
现在,当我拖动一个小部件时,所有附加的小部件也应随之拖动
i、 e.如果我尝试拖动Index2小部件,则拖动的小部件应该是Index2、3、4小部件的堆栈
如果我尝试拖动index 4小部件,则拖动的小部件应该只是index 4小部件 现在我知道我可以在标记可拖动的类的参数时,使用反馈和孩子来处理拖动小部件的更新,但我不知道如何使用它更新所有其他附加的小部件 这是我的密码:
import 'package:flutter/material.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(),
);
}
}
class MyHomePage extends StatefulWidget {
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
List<BlockWidget> blockWidgets;
final List<Color> widgetColors = [Colors.red, Colors.brown, Colors.black, Colors.pink, Colors.grey];
@override
void initState() {
super.initState();
blockWidgets = new List();
for(int i=0; i < widgetColors.length; i++) {
blockWidgets.add(BlockWidget(widgetId: i, widgetColor: widgetColors.elementAt(i)));
}
}
@override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
appBar: AppBar(
title: Text('AppBar'),
),
body: WidgetStacks(
blocks: blockWidgets,
),
);
}
}
const blockHeight = 100.0;
const blockWidth = 100.0;
class BlockWidget {
int widgetId;
Color widgetColor;
BlockWidget({
@required this.widgetId,
@required this.widgetColor,
});
}
class TransformedWidget extends StatefulWidget {
final BlockWidget block;
final int stackIndex;
final List<BlockWidget> attachedBlocks;
TransformedWidget(
{@required this.block,
@required this.stackIndex,
@ required this.attachedBlocks,
});
@override
_TransformedWidgetState createState() => _TransformedWidgetState();
}
class _TransformedWidgetState extends State<TransformedWidget> {
@override
Widget build(BuildContext context) {
return Transform(
transform: Matrix4.identity()
..translate(
widget.stackIndex * (blockHeight / 2),
widget.stackIndex * (blockWidth / 2),
0.0,
),
child: Draggable<Map>(
child: _buildBlock(),
feedback: WidgetStacks(
blocks: widget.attachedBlocks,
),
childWhenDragging: Container(),
),
);
}
Widget _buildBlock() {
return Container(
height: blockHeight,
width: blockWidth,
color: widget.block.widgetColor,
alignment: Alignment.centerLeft,
child: Text(
widget.block.widgetId.toString(),
style: TextStyle(
fontSize: 30.0,
color: Colors.white,
),
),
);
}
}
class WidgetStacks extends StatefulWidget {
final List<BlockWidget> blocks;
WidgetStacks({@required this.blocks});
@override
_WidgetStacksState createState() => _WidgetStacksState();
}
class _WidgetStacksState extends State<WidgetStacks> {
@override
Widget build(BuildContext context) {
return Container(
height: 5 * blockHeight,
width: 5 * blockWidth,
margin: EdgeInsets.all(2.0),
child: Stack(
children: widget.blocks.map((block) {
int index = widget.blocks.indexOf(block);
return TransformedWidget(
block: block,
stackIndex: index,
attachedBlocks: widget.blocks.sublist(index),
);
}).toList(),
),
);
}
}
导入“包装:颤振/材料.省道”;
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(),
);
}
}
类MyHomePage扩展StatefulWidget{
@凌驾
_MyHomePageState createState()=>\u MyHomePageState();
}
类_MyHomePageState扩展状态{
列出区块小部件;
最终列表WidgetColor=[Colors.red,Colors.brown,Colors.black,Colors.pink,Colors.grey];
@凌驾
void initState(){
super.initState();
blockWidgets=新列表();
对于(int i=0;i_TransformedWidgetState();
}
类_TransformedWidgetState扩展状态{
@凌驾
小部件构建(构建上下文){
返回变换(
转换:Matrix4.identity()
…翻译(
widget.stackIndex*(块高/2),
widget.stackIndex*(块宽度/2),
0.0,
),
孩子:拖拉(
子项:_构建块(),
反馈:WidgetStacks(
块:widget.attachedBlocks,
),
ChildWhenDraging:容器(),
),
);
}
小部件_buildBlock(){
返回容器(
高度:块高,
宽度:块宽度,
颜色:widget.block.widgetColor,
对齐:alignment.centerLeft,
子:文本(
widget.block.widgetId.toString(),
样式:TextStyle(
字体大小:30.0,
颜色:颜色,白色,
),
),
);
}
}
类WidgetStacks扩展StatefulWidget{
最后的列表块;
WidgetStacks({@required this.blocks});
@凌驾
_WidgetStacksState createState()=>\u WidgetStacksState();
}
类_WidgetStacksState扩展状态{
@凌驾
小部件构建(构建上下文){
返回容器(
高度:5*块高,
宽度:5*块宽,
边距:所有边集(2.0),
子:堆栈(
子项:widget.blocks.map((块){
int index=widget.blocks.indexOf(block);
返回TransformedWidget(
街区:街区,
stackIndex:index,
attachedBlocks:widget.blocks.sublist(索引),
);
}).toList(),
),
);
}
}
import 'package:flutter/material.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(),
);
}
}
class MyHomePage extends StatefulWidget {
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
List<BlockWidget> blockWidgets;
final List<Color> widgetColors = [
Colors.red,
Colors.brown,
Colors.black,
Colors.pink,
Colors.grey
];
@override
void initState() {
super.initState();
blockWidgets = new List();
for (int i = 0; i < widgetColors.length; i++) {
blockWidgets.add(
BlockWidget(widgetId: i, widgetColor: widgetColors.elementAt(i)));
}
}
@override
Widget build(BuildContext context) {
return Scaffold(
backgroundColor: Colors.white,
appBar: AppBar(
title: Text('AppBar'),
),
body: WidgetStacks(
key:ValueKey('WidgetStacks_${blockWidgets.length}'),
blocks: blockWidgets,
),
);
}
}
const blockHeight = 100.0;
const blockWidth = 100.0;
class BlockWidget {
int widgetId;
Color widgetColor;
BlockWidget({
@required this.widgetId,
@required this.widgetColor,
});
}
class TransformedWidget extends StatefulWidget {
final BlockWidget block;
final int stackIndex;
final List<BlockWidget> attachedBlocks;
final Function() onDragCanceled;
final Function() onDragStart;
TransformedWidget({
Key key,
@required this.block,
@required this.stackIndex,
@required this.attachedBlocks, this.onDragCanceled, this.onDragStart,
}):super(key: key);
@override
_TransformedWidgetState createState() => _TransformedWidgetState();
}
class _TransformedWidgetState extends State<TransformedWidget> {
@override
Widget build(BuildContext context) {
return Transform(
transform: Matrix4.identity()
..translate(
widget.stackIndex * (blockHeight / 2),
widget.stackIndex * (blockWidth / 2),
0.0,
),
child: Draggable<Map>(
key: ValueKey(widget.stackIndex),
onDragStarted: ()=>widget.onDragStart(),
onDraggableCanceled: (_,__)=>widget.onDragCanceled(),
child: _buildBlock(),
feedback: WidgetStacks(
key: ValueKey('WidgetStacks_${widget.attachedBlocks.length}'),
blocks: widget.attachedBlocks,
),
childWhenDragging: Container(),
),
);
}
Widget _buildBlock() => Material(
child: Container(
height: blockHeight,
width: blockWidth,
color: widget.block.widgetColor,
alignment: Alignment.centerLeft,
child: Text(
widget.block.widgetId.toString(),
style: TextStyle(
fontSize: 30.0,
color: Colors.white,
),
),
),
);
}
class WidgetStacks extends StatefulWidget {
final List<BlockWidget> blocks;
WidgetStacks({@required this.blocks, Key key}):super(key:key);
@override
_WidgetStacksState createState() => _WidgetStacksState();
}
class _WidgetStacksState extends State<WidgetStacks> {
ValueNotifier<List<BlockWidget>> blocksToBeShownNotifier;
@override
void initState() {
blocksToBeShownNotifier = ValueNotifier<List<BlockWidget>>(widget.blocks);
super.initState();
}
@override
Widget build(BuildContext context) {
return Container(
height: 5 * blockHeight,
width: 5 * blockWidth,
margin: EdgeInsets.all(2.0),
child: ValueListenableBuilder<List<BlockWidget>>(
valueListenable: blocksToBeShownNotifier,
builder: (BuildContext context,List<BlockWidget> value, Widget child) {
return Stack(
children: value.map((block) {
int index = value.indexOf(block);
return TransformedWidget(
key: ValueKey(block.widgetId),
block: block,
stackIndex: index,
onDragStart:(){
blocksToBeShownNotifier.value = widget.blocks.sublist(0, index);
},
onDragCanceled:(){
blocksToBeShownNotifier.value = widget.blocks;
},
attachedBlocks: widget.blocks.sublist(index),
);
}).toList(),
);
},),
);
}
}
导入“包装:颤振/材料.省道”;
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(),
);
}
}
类MyHomePage扩展StatefulWidget{
@凌驾
_MyHomePageState createState()=>\u MyHomePageState();
}
类_MyHomePageState扩展状态{
列出区块小部件;
最终列表WidgetColor=[
颜色,红色,
颜色,棕色,
颜色,黑色,
颜色,粉色,
颜色。灰色
];
@凌驾
void initState(){
super.initState();
blockWidgets=新列表();
对于(int i=0;i