颤振-如何以编程方式自动滚动到具有动态高度的索引 [英] flutter - How to auto scroll to index with dynamic height programmatically

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问题描述

根据Flutter的

解决方案

滚动到索引包

此软件包为Flutter可滚动小部件提供了用于固定/可变行高的滚动到索引机制.
这是一个小部件级别的库，意味着您可以在任何Flutter可滚动小部件中使用此机制.

用法

pubspec.yaml

  scroll_to_index:任意

示例来自

因此它不能支持100％

Ref:

第一个屏幕记录代码

 //版权所有(C)2019 Potix Corporation.版权所有.//历史记录:2019年4月24日星期二09:29//作者:杰里·陈(Jerry Chen)将'dart:math'导入为数学；导入'package:flutter/material.dart';导入'package:scroll_to_index/scroll_to_index.dart';void main()=>runApp(MyApp());MyApp类扩展了StatelessWidget {//此小部件是您的应用程序的根.@override窗口小部件build(BuildContext context){返回MaterialApp(标题:滚动至索引演示"，主题:ThemeData(primarySwatch:Colors.blue，)，主页:MyHomePage(标题:滚动至索引演示")，);}}类MyHomePage扩展了StatefulWidget {MyHomePage({Key key，this.title}):超级(key:key);最终的字符串标题；@override_MyHomePageState createState()=>_MyHomePageState();}类_MyHomePageState扩展State< MyHomePage>{静态const maxCount = 100;最终随机数= math.Random();最终的scrollDirection = Axis.vertical;AutoScrollController控制器；List< List< int>>randomList;@override无效的initState(){super.initState();控制器= AutoScrollController(viewportBoundaryGetter:()=>Rect.fromLTRB(0，0，0，MediaQuery.of(context).padding.bottom)，轴:scrollDirection);randomList = List.generate(maxCount，(index)=< int> [index，(1000 * random.nextDouble()).toInt()]);}@override窗口小部件build(BuildContext context){返回脚手架(appBar:AppBar(标题:文本(widget.title)，)，正文:ListView(scrollDirection:scrollDirection，控制器:控制器，子代:randomList.map< Widget>(((data){返回填充(填充:EdgeInsets.all(8)，子级:_getRow(data [0]，math.max(data [1] .toDouble()，50.0))，);}).toList()，)，floatActionButton:FloatingActionButton(onPressed:_scrollToIndex，工具提示:增量"，子级:Text(counter.toString())，)，);}整数计数器= -1;未来_scrollToIndex()异步{setState((){计数器++;如果(计数器> = maxCount)计数器= 0;});等待controller.scrollToIndex(counter，preferredPosition:AutoScrollPosition.begin);controller.highlight(counter);}小部件_getRow(int index，double height){返回_wrapScrollTag(索引:索引，子代:集装箱(填充:EdgeInsets.all(8)，对齐方式:Alignment.topCenter，高度:高度装饰:BoxDecoration(border:Border.all(颜色:Colors.lightBlue，宽度:4)，borderRadius:BorderRadius.circular(12))，子代:文字('index:$ index，height:$ height')，));}小部件_wrapScrollTag({int index，小部件子级})=>AutoScrollTag(键:ValueKey(index)，控制器:控制器，索引:索引，孩子:孩子，highlightColor:Colors.black.withOpacity(0.1)，);}

第二屏记录代码:

 //版权所有(C)2019 Potix Corporation.版权所有.//历史记录:2019年4月24日星期二09:29//作者:杰里·陈(Jerry Chen)将'dart:math'导入为数学；导入'package:flutter/material.dart';导入'package:scroll_to_index/scroll_to_index.dart';void main()=>runApp(MyApp());MyApp类扩展了StatelessWidget {//此小部件是您的应用程序的根.@override窗口小部件build(BuildContext context){返回MaterialApp(标题:滚动至索引演示"，主题:ThemeData(primarySwatch:Colors.blue，)，主页:MyHomePage(标题:滚动至索引演示")，);}}类MyHomePage扩展了StatefulWidget {MyHomePage({Key key，this.title}):超级(key:key);最终的字符串标题；@override_MyHomePageState createState()=>_MyHomePageState();}类_MyHomePageState扩展State< MyHomePage>{最终的scrollDirection = Axis.vertical;var rnd = math.Random();整数最小值= 50;最大整数= 200;AutoScrollController控制器；@override无效的initState(){super.initState();控制器= AutoScrollController(viewportBoundaryGetter:()=>Rect.fromLTRB(0，0，0，MediaQuery.of(context).padding.bottom)，轴:scrollDirection)；}@override窗口小部件build(BuildContext context){返回脚手架(appBar:AppBar(标题:文本(widget.title)，)，正文:ListView.builder(scrollDirection:scrollDirection，控制器:控制器，itemBuilder :(上下文，i)=>填充(填充:EdgeInsets.all(8)，子级:_getRow(i，(min + rnd.nextInt(max-min)).toDouble())，)，)，floatActionButton:FloatingActionButton(onPressed:_scrollToIndex，工具提示:增量"，子级:Text(counter.toString())，)，);}整数计数器= -1;未来_scrollToIndex()异步{setState((){计数器++;});等待controller.scrollToIndex(counter，preferredPosition:AutoScrollPosition.begin);controller.highlight(counter);}小部件_getRow(int index，double height){返回_wrapScrollTag(索引:索引，子代:集装箱(填充:EdgeInsets.all(8)，对齐方式:Alignment.topCenter，高度:高度装饰:BoxDecoration(边框:Border.all(颜色:Colors.lightBlue，宽度:4)，borderRadius:BorderRadius.circular(12))，子代:文字('index:$ index，height:$ height')，))；}Widget _wrapScrollTag({int index，Widget child})=>AutoScrollTag(键:ValueKey(index)，控制器:控制器，索引:索引，孩子:孩子，highlightColor:Colors.black.withOpacity(0.1)，);}

According to Flutter's issue here , The Auto-Scroll to Index where each cell/item has dynamic height is currently not supported. I have tried another solution but no works.

so, What's a temporary solution to make ListView with AutoScroll for dynamic height?

Any Idea?

解决方案

Your question

so, What's a temporary solution to make ListView with AutoScroll for dynamic height?

Screen Record

solution

scroll-to-index package

This package provides the scroll to index mechanism for fixed/variable row height for Flutter scrollable widget.

This is a widget level library, means you can use this mechanism inside any Flutter scrollable widget.

Usage

pubspec.yaml

 scroll_to_index: any

Example From quire-io/scroll-to-index: scroll to index with fixed/variable row height inside Flutter scrollable widget

Usage - Controller

controller.scrollToIndex(index, preferPosition: AutoScrollPosition.begin)

Usage - ListView

ListView(
scrollDirection: scrollDirection,
controller: controller,
children: randomList.map<Widget>((data) {
    final index = data[0];
    final height = data[1];
    return AutoScrollTag(
    key: ValueKey(index),
    controller: controller,
    index: index,
    child: Text('index: $index, height: $height'),
    highlightColor: Colors.black.withOpacity(0.1),
    );
}).toList(),
)

Extra anunixercoder asked

Is this for finite or infinite list ?

Using ListView.builder to simulate an infinite list

    ListView.builder(
    scrollDirection: scrollDirection,
    controller: controller,
    itemBuilder: (context, i) => Padding(
      padding: EdgeInsets.all(8),
      child: _getRow(i, (min + rnd.nextInt(max - min)).toDouble()),
    ),

It got 18 right of 22 tries , about (81%) or near to it

Screen Record

so it not suported 100%

Ref :

1st screen record code

//Copyright (C) 2019 Potix Corporation. All Rights Reserved.
//History: Tue Apr 24 09:29 CST 2019
// Author: Jerry Chen

import 'dart:math' as math;

import 'package:flutter/material.dart';
import 'package:scroll_to_index/scroll_to_index.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: 'Scroll To Index Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Scroll To Index Demo'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  static const maxCount = 100;
  final random = math.Random();
  final scrollDirection = Axis.vertical;

  AutoScrollController controller;
  List<List<int>> randomList;

  @override
  void initState() {
    super.initState();
    controller = AutoScrollController(
      viewportBoundaryGetter: () => Rect.fromLTRB(0, 0, 0, MediaQuery.of(context).padding.bottom),
      axis: scrollDirection
    );
    randomList = List.generate(maxCount, (index) => <int>[index, (1000 * random.nextDouble()).toInt()]);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: ListView(
        scrollDirection: scrollDirection,
        controller: controller,
        children: randomList.map<Widget>((data) {
          return Padding(
            padding: EdgeInsets.all(8),
            child: _getRow(data[0], math.max(data[1].toDouble(), 50.0)),
          );
        }).toList(),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _scrollToIndex,
        tooltip: 'Increment',
        child: Text(counter.toString()),
      ),
    );
  }

  int counter = -1;
  Future _scrollToIndex() async {
    setState(() {
      counter++;

      if (counter >= maxCount)
        counter = 0;
    });

    await controller.scrollToIndex(counter, preferPosition: AutoScrollPosition.begin);
    controller.highlight(counter);
  }

  Widget _getRow(int index, double height) {
    return _wrapScrollTag(
      index: index,
      child: Container(
        padding: EdgeInsets.all(8),
        alignment: Alignment.topCenter,
        height: height,
        decoration: BoxDecoration(
          border: Border.all(
            color: Colors.lightBlue,
            width: 4
          ),
          borderRadius: BorderRadius.circular(12)
        ),
        child: Text('index: $index, height: $height'),
      )
    );
  }

  Widget _wrapScrollTag({int index, Widget child})
  => AutoScrollTag(
    key: ValueKey(index),
    controller: controller,
    index: index,
    child: child,
    highlightColor: Colors.black.withOpacity(0.1),
  );
}

2nd screen record code :

//Copyright (C) 2019 Potix Corporation. All Rights Reserved.
//History: Tue Apr 24 09:29 CST 2019
// Author: Jerry Chen

import 'dart:math' as math;

import 'package:flutter/material.dart';
import 'package:scroll_to_index/scroll_to_index.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: 'Scroll To Index Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Scroll To Index Demo'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  final scrollDirection = Axis.vertical;
  var rnd = math.Random();
  int min = 50;
  int max = 200;
  AutoScrollController controller;
  @override
  void initState() {
    super.initState();
    controller = AutoScrollController(
        viewportBoundaryGetter: () =>
            Rect.fromLTRB(0, 0, 0, MediaQuery.of(context).padding.bottom),
        axis: scrollDirection);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: ListView.builder(
        scrollDirection: scrollDirection,
        controller: controller,
        itemBuilder: (context, i) => Padding(
          padding: EdgeInsets.all(8),
          child: _getRow(i, (min + rnd.nextInt(max - min)).toDouble()),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _scrollToIndex,
        tooltip: 'Increment',
        child: Text(counter.toString()),
      ),
    );
  }

  int counter = -1;
  Future _scrollToIndex() async {
    setState(() {
      counter++;
    });

    await controller.scrollToIndex(counter,
        preferPosition: AutoScrollPosition.begin);
    controller.highlight(counter);
  }

  Widget _getRow(int index, double height) {
    return _wrapScrollTag(
        index: index,
        child: Container(
          padding: EdgeInsets.all(8),
          alignment: Alignment.topCenter,
          height: height,
          decoration: BoxDecoration(
              border: Border.all(color: Colors.lightBlue, width: 4),
              borderRadius: BorderRadius.circular(12)),
          child: Text('index: $index, height: $height'),
        ));
  }

  Widget _wrapScrollTag({int index, Widget child}) => AutoScrollTag(
        key: ValueKey(index),
        controller: controller,
        index: index,
        child: child,
        highlightColor: Colors.black.withOpacity(0.1),
      );
}

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颤振-如何以编程方式自动滚动到具有动态高度的索引 [英] flutter - How to auto scroll to index with dynamic height programmatically

问题描述

解决方案

用法

Ref:

第一个屏幕记录代码

第二屏记录代码:

Your question

Screen Record

solution

Usage

Usage - Controller

Usage - ListView

Extra anunixercoder asked

Screen Record

Ref :

1st screen record code

2nd screen record code :

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颤振-如何以编程方式自动滚动到具有动态高度的索引 [英] flutter - How to auto scroll to index with dynamic height programmatically

问题描述

解决方案

用法

Ref:

第一个屏幕记录代码

第二屏记录代码:

Your question

Screen Record

solution

Usage

Usage - Controller

Usage - ListView

Extra anunixercoder asked

Screen Record

Ref :

1st screen record code

2nd screen record code :

相关文章

移动开发最新文章

热门教程

热门工具

登录 关闭

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