forked from lxm_flutter/FlutterUnit
124 lines
3.6 KiB
Dart
124 lines
3.6 KiB
Dart
import 'package:flutter/material.dart';
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import 'package:flutter/rendering.dart';
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/// create by 张风捷特烈 on 2020/9/21
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/// contact me by email 1981462002@qq.com
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/// 说明: 304 SliverLayoutBuilder Sliver布局构造器 Sliver家族一员，在滑动过程中可以通过回调出的 SliverConstraints 对象进行子组件的构造。
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// {
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// "widgetId": 304,
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// "name": 'SliverLayoutBuilder基本使用',
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// "priority": 1,
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// "subtitle": "【builder】 : 组件构造器 【SliverLayoutWidgetBuilder】",
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// }
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class SliverLayoutBuilderDemo extends StatefulWidget {
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const SliverLayoutBuilderDemo({Key? key}) : super(key: key);
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@override
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_SliverLayoutBuilderDemoState createState() =>
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_SliverLayoutBuilderDemoState();
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}
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class _SliverLayoutBuilderDemoState extends State<SliverLayoutBuilderDemo> {
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final List<Color> data = [
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Colors.orange[50]!,
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Colors.orange[100]!,
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Colors.orange[200]!,
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Colors.orange[300]!,
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Colors.orange[400]!,
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Colors.orange[500]!,
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Colors.orange[600]!,
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Colors.orange[700]!,
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Colors.orange[800]!,
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Colors.orange[900]!,
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];
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@override
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Widget build(BuildContext context) {
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return SizedBox(
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height: 300,
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child: CustomScrollView(
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physics: const BouncingScrollPhysics(parent: AlwaysScrollableScrollPhysics()),
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slivers: <Widget>[
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_buildSliverAppBar(),
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SliverLayoutBuilder(
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builder: _buildSliver,
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),
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_buildSliverList(),
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],
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),
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);
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}
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Widget _buildSliverList() => SliverFixedExtentList(
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itemExtent: 50,
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delegate: SliverChildBuilderDelegate(
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(_, int index) => Container(
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alignment: Alignment.center,
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width: 100,
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height: 60,
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color: data[index],
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child: Text(
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colorString(data[index]),
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style: const TextStyle(color: Colors.white, shadows: [
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Shadow(
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color: Colors.black,
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offset: Offset(.5, .5),
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blurRadius: 2)
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]),
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),
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),
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childCount: data.length),
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);
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Widget _buildSliverAppBar() {
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return SliverAppBar(
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expandedHeight: 120.0,
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leading: Container(
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margin: const EdgeInsets.all(10),
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child: Image.asset('assets/images/icon_head.webp')),
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title: const Text('张风捷特烈'),
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actions: _buildActions(),
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elevation: 5,
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pinned: true,
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backgroundColor: Colors.orange,
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flexibleSpace: FlexibleSpaceBar(
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titlePadding: const EdgeInsets.only(left: 55, bottom: 15), //标题边距
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collapseMode: CollapseMode.parallax, //视差效果
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background: Image.asset(
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"assets/images/caver.webp",
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fit: BoxFit.cover,
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),
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),
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);
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}
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List<Widget> _buildActions() => <Widget>[
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IconButton(
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onPressed: () {},
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icon: const Icon(
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Icons.star_border,
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color: Colors.white,
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),
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)
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];
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String colorString(Color color) =>
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"#${color.value.toRadixString(16).padLeft(8, '0').toUpperCase()}";
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Widget _buildSliver(BuildContext context, SliverConstraints constraints) {
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return SliverToBoxAdapter(
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child: Container(
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alignment: Alignment.center,
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height: constraints.remainingPaintExtent / 3,
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color: Colors.red,
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child: const Text(
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"SliverLayoutBuilder",
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style: TextStyle(color: Colors.white, fontSize: 20),
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),
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),
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);
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}
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}
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