颤振扩展瓦片去除尾随

Question

我有一个 exoansiontile，我希望它像一个盒子，一切都居中，问题是如果我添加一个太长的文本，我会得到溢出错误，我认为这是由尾随引起的膨胀瓦。这是一张图片： https://gyazo.com/c29329106dc5dcb162b71b5f41951b67

代码如下：

ExpansionTile(

    trailing: Text(''),
    leading: Container(
        margin: new EdgeInsets.only(left: 0, top: 10.0, right: 0.0, bottom: 0.0),
        child: Image.asset(
            'images/food.png'
        )),
    title: Row(
        children: < Widget > [


            Padding(
                padding: const EdgeInsets.only(right: 0, left: 10, top: 15, bottom: 15),
                    child: Column(textDirection: TextDirection.ltr, crossAxisAlignment: CrossAxisAlignment.start, children: < Widget > [



                        Container(
                            margin: new EdgeInsets.only(left: 0.0, top: 7.0, right: 0.0, bottom: 3.0),
                            child: Text(
                                'Food System', textAlign: TextAlign.left,
                                style: TextStyle(
                                    color: Colors.white,
                                    fontSize: 25,
                                ),
                            )),
                        Text(
                            'Customize the food system', textAlign: TextAlign.left,
                            style: TextStyle(

                                color: Colors.white,
                                fontSize: 15,
                            ),
                        )

                    ])),

        ], ),
    children: < Widget > [



        Container(
            width: 300,
            margin: new EdgeInsets.only(left: 10.0, top: 0.0, right: 10.0, bottom: 10.0),
            color: Colors.transparent,
            child: new Container(


                padding: new EdgeInsets.all(20),
                child: Column(crossAxisAlignment: CrossAxisAlignment.start, children: < Widget > [
                    Container(
                        margin: new EdgeInsets.only(left: 15.0, top: .0, right: 20.0, bottom: 5.0),
                        child: Text('Storage', style: TextStyle(color: Colors.white, fontSize: 20, fontWeight: FontWeight.bold)), ),
                    Center(child: Column(children: < Widget > [
                        Container(
                            child: Column(children: < Widget > [
                                Text('2.4 KG left        -        7 Days', style: TextStyle(color: Colors.white, fontSize: 20)),
                                Text('200 G / Meal  - 600 G / Day', style: TextStyle(color: Colors.white, fontSize: 20)),
                            ], ),
                            margin: new EdgeInsets.only(left: 0, top: 0, right: 0, bottom: 10.0),
                        )

                    ], )),
                    Container(
                        margin: new EdgeInsets.only(left: 18.0, top: .0, right: 20.0, bottom: 5.0),
                        child: Text('Meal times', style: TextStyle(color: Colors.white, fontSize: 20, fontWeight: FontWeight.bold)), ),
                    Center(child: Column(children: < Widget > [

                        Text('1.   Breakfast   -   8:30 AM', style: TextStyle(color: Colors.white, fontSize: 20)),
                        Text('2.   Lunch         -   2:00 PM', style: TextStyle(color: Colors.white, fontSize: 20)),
                        Text('3.   Dinner        -   9:15  PM', style: TextStyle(color: Colors.white, fontSize: 20)),
                    ], ))
                ], ), )
        ),




        Container(
            height: 50.0,
            width: 300,

            margin: new EdgeInsets.only(left: 10.0, top: 10.0, right: 10.0, bottom: 10.0),
            color: Colors.transparent,
            child: new Container(
                decoration: new BoxDecoration(
                    color: Colors.blue,
                    gradient: LinearGradient(
                        begin: Alignment.topRight,
                        end: Alignment.bottomLeft,
                        colors: [Color(0xff37b9ff), Color(0xff5d3afd)]),
                    borderRadius: new BorderRadius.only(
                        topLeft: const Radius.circular(40.0),
                            topRight: const Radius.circular(40.0),
                                bottomLeft: const Radius.circular(40.0),
                                    bottomRight: const Radius.circular(40.0),

                    )
                ),
                child: Center(child:

                    Text('Edit', style: TextStyle(color: Colors.white, fontSize: 15))

                    , )
            )
        ),
    ]

Answer 1

请创建一个空文件并将此代码复制到该文件中... 我修改了颤振扩展瓷砖的一部分。 我删除了尾随...

// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// @dart = 2.8

import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';

//import 'colors.dart';
//import 'icons.dart';
//import 'list_tile.dart';
//import 'theme.dart';
//import 'theme_data.dart';

const Duration _kExpand = Duration(milliseconds: 200);

/// A single-line [ListTile] with a trailing button that expands or collapses
/// the tile to reveal or hide the [children].
///
/// This widget is typically used with [ListView] to create an
/// "expand / collapse" list entry. When used with scrolling widgets like
/// [ListView], a unique [PageStorageKey] must be specified to enable the
/// [MyExpansionTile] to save and restore its expanded state when it is scrolled
/// in and out of view.
///
/// See also:
///
///  * [ListTile], useful for creating expansion tile [children] when the
///    expansion tile represents a sublist.
///  * The "Expand/collapse" section of
///    <https://material.io/guidelines/components/lists-controls.html>.
class MyExpansionTile extends StatefulWidget {
  /// Creates a single-line [ListTile] with a trailing button that expands or collapses
  /// the tile to reveal or hide the [children]. The [initiallyExpanded] property must
  /// be non-null.
  const MyExpansionTile({
    Key key,
    this.leading,
    @required this.title,
    this.subtitle,
    this.backgroundColor,
    this.onExpansionChanged,
    this.children = const <Widget>[],
    /*this.trailing,*/
    this.initiallyExpanded = false,
    this.maintainState = false,
    this.tilePadding,
    this.expandedCrossAxisAlignment,
    this.expandedAlignment,
    this.childrenPadding,
  }) : assert(initiallyExpanded != null),
       assert(maintainState != null),
       assert(
       expandedCrossAxisAlignment != CrossAxisAlignment.baseline,
       'CrossAxisAlignment.baseline is not supported since the expanded children '
           'are aligned in a column, not a row. Try to use another constant.',
       ),
       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;

  /// Additional content displayed below the title.
  ///
  /// Typically a [Text] widget.
  final Widget subtitle;

  /// 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;

//  /// A widget to display instead of a rotating arrow icon.
//  final Widget trailing;

  /// Specifies if the list tile is initially expanded (true) or collapsed (false, the default).
  final bool initiallyExpanded;

  /// Specifies whether the state of the children is maintained when the tile expands and collapses.
  ///
  /// When true, the children are kept in the tree while the tile is collapsed.
  /// When false (default), the children are removed from the tree when the tile is
  /// collapsed and recreated upon expansion.
  final bool maintainState;

  /// Specifies padding for the [ListTile].
  ///
  /// Analogous to [ListTile.contentPadding], this property defines the insets for
  /// the [leading], [title], [subtitle] and [trailing] widgets. It does not inset
  /// the expanded [children] widgets.
  ///
  /// When the value is null, the tile's padding is `EdgeInsets.symmetric(horizontal: 16.0)`.
  final EdgeInsetsGeometry tilePadding;

  /// Specifies the alignment of [children], which are arranged in a column when
  /// the tile is expanded.
  ///
  /// The internals of the expanded tile make use of a [Column] widget for
  /// [children], and [Align] widget to align the column. The `expandedAlignment`
  /// parameter is passed directly into the [Align].
  ///
  /// Modifying this property controls the alignment of the column within the
  /// expanded tile, not the alignment of [children] widgets within the column.
  /// To align each child within [children], see [expandedCrossAxisAlignment].
  ///
  /// The width of the column is the width of the widest child widget in [children].
  ///
  /// When the value is null, the value of `expandedAlignment` is [Alignment.center].
  final Alignment expandedAlignment;

  /// Specifies the alignment of each child within [children] when the tile is expanded.
  ///
  /// The internals of the expanded tile make use of a [Column] widget for
  /// [children], and the `crossAxisAlignment` parameter is passed directly into the [Column].
  ///
  /// Modifying this property controls the cross axis alignment of each child
  /// within its [Column]. Note that the width of the [Column] that houses
  /// [children] will be the same as the widest child widget in [children]. It is
  /// not necessarily the width of [Column] is equal to the width of expanded tile.
  ///
  /// To align the [Column] along the expanded tile, use the [expandedAlignment] property
  /// instead.
  ///
  /// When the value is null, the value of `expandedCrossAxisAlignment` is [CrossAxisAlignment.center].
  final CrossAxisAlignment expandedCrossAxisAlignment;

  /// Specifies padding for [children].
  ///
  /// When the value is null, the value of `childrenPadding` is [EdgeInsets.zero].
  final EdgeInsetsGeometry childrenPadding;

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

class _MyExpansionTileState extends State<MyExpansionTile> 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;

  @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) as bool ?? widget.initiallyExpanded;
    if (_isExpanded)
      _controller.value = 1.0;
  }

  @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: _handleTap,
              contentPadding: widget.tilePadding,
              leading: widget.leading,
              title: widget.title,
              subtitle: widget.subtitle,
              /*trailing: widget.trailing ?? RotationTransition(
                turns: _iconTurns,
                child: const Icon(Icons.expand_more),
              ),*/
            ),
          ),
          ClipRect(
            child: Align(
              alignment: widget.expandedAlignment ?? Alignment.center,
              heightFactor: _heightFactor.value,
              child: child,
            ),
          ),
        ],
      ),
    );
  }

  @override
  void didChangeDependencies() {
    final ThemeData theme = Theme.of(context);
    _borderColorTween.end = theme.dividerColor;
    _headerColorTween
      ..begin = theme.textTheme.subtitle1.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;
    final bool shouldRemoveChildren = closed && !widget.maintainState;

    final Widget result = Offstage(
      child: TickerMode(
        child: Padding(
          padding: widget.childrenPadding ?? EdgeInsets.zero,
          child: Column(
            crossAxisAlignment: widget.expandedCrossAxisAlignment ?? CrossAxisAlignment.center,
            children: widget.children,
          ),
        ),
        enabled: !closed,
      ),
      offstage: closed
    );

    return AnimatedBuilder(
      animation: _controller.view,
      builder: _buildChildren,
      child: shouldRemoveChildren ? null : result,
    );
  }
}
 

Answer 2

我尝试了建议的解决方案，但我发现自己没有必要覆盖任何内容或使用其他库。怎么样？

你可以试试这段代码：

trailing: (shouldBeEmpty)
      ? const SizedBox()
      : Icon(
          selected
            ? Icons.keyboard_arrow_up
            : Icons.keyboard_arrow_down,
          color: Colors.red,
        ),

我添加了一个附加条件，但基本上如果您想隐藏尾随，请将 SizedBox() 或任何 non-visible 小部件作为尾随。

Answer 3

        controlAffinity: ListTileControlAffinity.leading,
        leading: SizedBox.shrink(),

这几乎可以消除尾随，对我来说已经足够了