Когда это возможно .. Используйте виджеты зависимости от родительского размера, вместо ручного вычисления дочерних размеров.
- FittedBox . Можно масштабировать размер шрифта дочернего виджета в соответствии с размером родительского элемента и параметром подгонки.
- ConstrainedBox , BoxConstraints.tightFor
- Expanded . Вы, наверное, знаете, как это работает.
введите описание изображения здесь
import 'dart:math';
import 'package:flutter/material.dart';
import 'package:flutter/rendering.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: Scaffold(
body: SafeArea(
child: MyHomePage(),
),
),
);
}
}
class MyHomePage extends StatefulWidget {
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
@override
Widget build(BuildContext context) {
return CustomScrollView(
slivers: [
SliverPersistentHeader(
pinned: true,
floating: false,
delegate: DashboardHeaderPersistentDelegate(),
),
SliverList(
delegate: SliverChildBuilderDelegate(
(_, i) => Card(
margin: EdgeInsets.all(10),
child: Padding(
padding: const EdgeInsets.all(8.0),
child: Row(
mainAxisAlignment: MainAxisAlignment.spaceAround,
children: [
Expanded(
flex: 1,
child: Text(i.toString()),
),
Expanded(
flex: 3,
child: Text('Text'),
),
],
)),
),
childCount: 100),
),
],
);
}
}
const categories = [
'Grocieries',
'Transport',
'House Rent',
'Shopping',
'Career'
];
const categoriesIcons = [
Icons.ac_unit,
Icons.access_alarms,
Icons.dashboard,
Icons.accessible_forward,
Icons.backspace,
];
class DashboardHeaderPersistentDelegate extends SliverPersistentHeaderDelegate {
@override
Widget build(
BuildContext context, double shrinkOffset, bool overlapsContent) {
double shrinkPercentage = min(1, shrinkOffset / (maxExtent - minExtent));
return Container(
decoration: BoxDecoration(
border: Border.all(
color: Colors.blueAccent,
),
),
child: Material(
elevation: 0,
shadowColor: Colors.white,
child: SafeArea(
child: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
ConstrainedBox(
constraints: BoxConstraints.tightFor(
height: max(60, 100 * (1 - shrinkPercentage)),
),
child: FittedBox(
child: Container(
padding: EdgeInsets.all(20),
width: 200,
child: Text(
'\$ 5329.05',
style: TextStyle(
fontFamily: 'Barlow',
fontSize: 30,
fontWeight: FontWeight.w500,
),
),
),
),
),
Expanded(
child: Stack(
alignment: Alignment.bottomCenter,
children: [
if (shrinkPercentage != 1)
Opacity(
opacity: 1 - shrinkPercentage,
child: _buildInformationWidget(context),
),
if (shrinkPercentage != 0)
Opacity(
opacity: shrinkPercentage,
child: Padding(
padding: const EdgeInsets.symmetric(horizontal: 8),
child: _buildCollapsedInformationWidget(),
),
)
],
),
)
],
),
),
),
);
}
Widget _buildInformationWidget(BuildContext context) => ClipRect(
child: OverflowBox(
maxWidth: double.infinity,
maxHeight: double.infinity,
child: FittedBox(
fit: BoxFit.fitWidth,
alignment: Alignment.center,
child: Container(
width: MediaQuery.of(context).size.width,
child: Column(
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Text(
'AVAILABLE BALANCE',
style: TextStyle(
fontSize: 12,
fontWeight: FontWeight.w900,
color: Colors.black26),
),
Padding(
padding: const EdgeInsets.only(top: 16),
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Container(
width: 100,
child: Text(
'\$ 11200',
textAlign: TextAlign.right,
style: TextStyle(
fontFamily: 'Barlow',
fontSize: 18,
fontWeight: FontWeight.w700,
color: Colors.green[400]),
),
),
Text(
' I ',
style: TextStyle(fontSize: 20, color: Colors.black12),
),
Container(
width: 100,
child: Text(
'\$ 400',
style: TextStyle(
fontFamily: 'Barlow',
fontSize: 18,
fontWeight: FontWeight.w700,
color: Colors.red[400]),
),
)
],
),
),
Container(
margin: EdgeInsets.only(left: 12, top: 12),
alignment: Alignment.centerLeft,
child: Text(
"CATEGORIES",
style: TextStyle(
fontSize: 12,
fontWeight: FontWeight.w900,
color: Colors.black26),
),
),
Container(
height: 88,
child: ListView.builder(
scrollDirection: Axis.horizontal,
itemCount: categories.length,
itemBuilder: (context, index) {
return Padding(
padding: EdgeInsets.only(
left: (index == 0) ? 24.0 : 8.0,
right: (index == categories.length - 1)
? 24.0
: 8.0),
child: _buildCategoryItem(
categoriesIcons[index], categories[index], .9),
);
}),
)
],
),
),
),
),
);
Widget _buildCollapsedInformationWidget() => Row(
children: [
Text("Recent"),
Spacer(),
Container(
child: Text(
'\$ 11200',
textAlign: TextAlign.right,
style: TextStyle(
fontFamily: 'Barlow',
fontSize: 14,
fontWeight: FontWeight.w700,
color: Colors.green[400]),
),
),
Text(
' I ',
style: TextStyle(fontSize: 20, color: Colors.black12),
),
Container(
child: Text(
'\$ 400',
style: TextStyle(
fontFamily: 'Barlow',
fontSize: 14,
fontWeight: FontWeight.w700,
color: Colors.red[400]),
),
)
],
);
Widget _buildCategoryItem(
IconData data, String categoryTitle, double percentage) =>
Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Stack(
alignment: Alignment.center,
children: <Widget>[
Container(
decoration: BoxDecoration(
border: Border.all(width: 1, color: Colors.black12),
borderRadius: BorderRadius.circular(28),
color: Colors.blue[400]),
child: Padding(
padding: const EdgeInsets.all(10.0),
child: Icon(
data,
size: 28,
color: Colors.white,
),
),
),
Container(
width: 40,
height: 40,
child: CircularProgressIndicator(
value: percentage,
strokeWidth: 2,
valueColor: AlwaysStoppedAnimation(Colors.white),
),
)
],
),
Container(
width: 72,
alignment: Alignment.center,
child: Text(categoryTitle,
overflow: TextOverflow.ellipsis,
textAlign: TextAlign.center,
maxLines: 1,
style: TextStyle(
fontSize: 14,
fontWeight: FontWeight.w400,
color: Colors.black45)),
)
],
);
@override
double get maxExtent => 300;
@override
double get minExtent => 80;
@override
bool shouldRebuild(SliverPersistentHeaderDelegate oldDelegate) => true;
}