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| 1 | +import 'package:flutter/material.dart'; |
| 2 | +import 'package:flutter_samples/animations/list_details/character.dart'; |
| 3 | + |
| 4 | +const itemSize = 150.0; |
| 5 | + |
| 6 | +class ShrinkTopListPage extends StatefulWidget { |
| 7 | + @override |
| 8 | + _ShrinkTopListPageState createState() => _ShrinkTopListPageState(); |
| 9 | +} |
| 10 | + |
| 11 | +class _ShrinkTopListPageState extends State<ShrinkTopListPage> { |
| 12 | + final scrollController = ScrollController(); |
| 13 | + |
| 14 | + void onListen() { |
| 15 | + setState(() {}); |
| 16 | + } |
| 17 | + |
| 18 | + @override |
| 19 | + void initState() { |
| 20 | + characters.addAll(List.from(characters)); |
| 21 | + scrollController.addListener(onListen); |
| 22 | + super.initState(); |
| 23 | + } |
| 24 | + |
| 25 | + @override |
| 26 | + void dispose() { |
| 27 | + scrollController.removeListener(onListen); |
| 28 | + super.dispose(); |
| 29 | + } |
| 30 | + |
| 31 | + @override |
| 32 | + Widget build(BuildContext context) { |
| 33 | + return Scaffold( |
| 34 | + appBar: AppBar( |
| 35 | + title: Text('Shrink top List'), |
| 36 | + ), |
| 37 | + body: Padding( |
| 38 | + padding: const EdgeInsets.only(left: 15.0, right: 15.0, top: 15.0), |
| 39 | + child: CustomScrollView( |
| 40 | + controller: scrollController, |
| 41 | + slivers: <Widget>[ |
| 42 | + SliverToBoxAdapter( |
| 43 | + child: Placeholder( |
| 44 | + fallbackHeight: 100.0, |
| 45 | + ), |
| 46 | + ), |
| 47 | + SliverAppBar( |
| 48 | + automaticallyImplyLeading: false, |
| 49 | + title: Text( |
| 50 | + 'My Characters', |
| 51 | + style: TextStyle(color: Colors.black), |
| 52 | + ), |
| 53 | + pinned: true, |
| 54 | + backgroundColor: Colors.transparent, |
| 55 | + elevation: 0, |
| 56 | + ), |
| 57 | + SliverToBoxAdapter( |
| 58 | + child: const SizedBox( |
| 59 | + height: 50, |
| 60 | + ), |
| 61 | + ), |
| 62 | + SliverList( |
| 63 | + delegate: SliverChildBuilderDelegate( |
| 64 | + (context, index) { |
| 65 | + final heightFactor = 0.6; |
| 66 | + final character = characters[index]; |
| 67 | + final itemPositionOffset = index * itemSize * heightFactor; |
| 68 | + final difference = scrollController.offset - itemPositionOffset; |
| 69 | + final percent = 1.0 - (difference / (itemSize * heightFactor)); |
| 70 | + double opacity = percent; |
| 71 | + double scale = percent; |
| 72 | + if (opacity > 1.0) opacity = 1.0; |
| 73 | + if (opacity < 0.0) opacity = 0.0; |
| 74 | + if (percent > 1.0) scale = 1.0; |
| 75 | + |
| 76 | + return Align( |
| 77 | + heightFactor: heightFactor, |
| 78 | + child: Opacity( |
| 79 | + opacity: opacity, |
| 80 | + child: Transform( |
| 81 | + alignment: Alignment.center, |
| 82 | + transform: Matrix4.identity()..scale(scale, 1.0), |
| 83 | + child: Card( |
| 84 | + shape: RoundedRectangleBorder( |
| 85 | + borderRadius: BorderRadius.only( |
| 86 | + topLeft: Radius.circular(20.0), |
| 87 | + topRight: Radius.circular(20.0), |
| 88 | + ), |
| 89 | + ), |
| 90 | + color: Color(character.color), |
| 91 | + child: SizedBox( |
| 92 | + height: itemSize, |
| 93 | + child: Row( |
| 94 | + children: <Widget>[ |
| 95 | + Expanded( |
| 96 | + child: Padding( |
| 97 | + padding: const EdgeInsets.all(15.0), |
| 98 | + ), |
| 99 | + ), |
| 100 | + Image.asset(character.avatar), |
| 101 | + ], |
| 102 | + ), |
| 103 | + ), |
| 104 | + ), |
| 105 | + ), |
| 106 | + ), |
| 107 | + ); |
| 108 | + }, |
| 109 | + childCount: characters.length, |
| 110 | + ), |
| 111 | + ), |
| 112 | + ], |
| 113 | + ), |
| 114 | + ), |
| 115 | + ); |
| 116 | + } |
| 117 | +} |
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