问题
i have a exoansiontile and i want it to be like a box, everything centered, the problem is that if i add a text that is too long, i get the overflow error and i think this is caused by the trailing of the expansion tile. Here is a picture: https://gyazo.com/c29329106dc5dcb162b71b5f41951b67
Here is the code:
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))
, )
)
),
]
回答1:
please create an Empty file an copy this code into that ... I modified some part of flutter Expansion tile . I removed trailing ...
// 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,
);
}
}
来源：https://stackoverflow.com/questions/64132151/flutter-expansion-tile-remove-trailing