/
long_list.dart
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/
long_list.dart
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import 'package:flutter/material.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/widgets.dart';
import 'package:git_touch/models/theme.dart';
import 'package:git_touch/utils/utils.dart';
import 'package:provider/provider.dart';
import '../widgets/loading.dart';
import '../widgets/link.dart';
import '../widgets/error_reload.dart';
class LongListPayload<T, K> {
T header;
int totalCount;
String cursor;
List<K> leadingItems;
List<K>? trailingItems;
LongListPayload({
required this.header,
required this.totalCount,
required this.cursor,
required this.leadingItems,
this.trailingItems,
});
}
// This is a scaffold for issue and pull request
// Since the list could be very long, and some users may only want to to check trailing items
// We should load leading and trailing items at first fetching, and do load more in the middle
// e.g. https://github.com/reactjs/rfcs/pull/68
class LongListStatefulScaffold<T, K> extends StatefulWidget {
final Widget title;
final Widget Function(T t)? trailingBuilder;
final Widget Function(T t) headerBuilder;
final Widget Function(K k) itemBuilder;
final Future<LongListPayload<T, K>> Function() onRefresh;
final Future<LongListPayload<T, K>> Function(String? cursor) onLoadMore;
LongListStatefulScaffold({
required this.title,
this.trailingBuilder,
required this.headerBuilder,
required this.itemBuilder,
required this.onRefresh,
required this.onLoadMore,
});
@override
_LongListStatefulScaffoldState<T, K> createState() =>
_LongListStatefulScaffoldState();
}
class _LongListStatefulScaffoldState<T, K>
extends State<LongListStatefulScaffold<T, K>> {
late bool loading;
bool loadingMore = false;
String error = '';
LongListPayload<T, K>? payload;
@override
void initState() {
super.initState();
_refresh();
}
Future<void> _refresh() async {
// Fimber.d('long list scaffold refresh');
setState(() {
error = '';
loading = true;
});
try {
payload = await widget.onRefresh();
} catch (err) {
error = err.toString();
throw err;
} finally {
if (mounted) {
setState(() {
loading = false;
});
}
}
}
Future<void> _loadMore() async {
// Fimber.d('long list scaffold load more');
setState(() {
loadingMore = true;
});
try {
LongListPayload<T?, K> _payload =
await widget.onLoadMore(payload!.cursor);
payload!.totalCount = _payload.totalCount;
payload!.cursor = _payload.cursor;
payload!.leadingItems.addAll(_payload.leadingItems);
} finally {
if (mounted) {
setState(() {
loadingMore = false;
});
}
}
}
Widget _buildItem(BuildContext context, int index) {
final theme = Provider.of<ThemeModel>(context);
if (index % 2 == 1) {
return CommonStyle.border;
}
int realIndex = index ~/ 2;
if (realIndex < payload!.leadingItems.length) {
return widget.itemBuilder(payload!.leadingItems[realIndex]);
} else if (realIndex == payload!.leadingItems.length) {
var count = payload!.totalCount -
payload!.leadingItems.length +
payload!.trailingItems!.length;
return Container(
padding: CommonStyle.padding,
child: Center(
child: LinkWidget(
onTap: _loadMore,
child: Container(
padding: CommonStyle.padding,
decoration: BoxDecoration(
border: Border.all(color: theme.palette.text),
),
child: Column(
children: <Widget>[
Text('$count hidden items',
style:
TextStyle(color: theme.palette.text, fontSize: 15)),
Padding(padding: EdgeInsets.only(top: 4)),
loadingMore
? CupertinoActivityIndicator()
: Text(
'Load more...',
style: TextStyle(
color: theme.palette.primary, fontSize: 16),
),
],
),
),
),
),
);
} else {
return widget.itemBuilder(payload!
.trailingItems![realIndex - payload!.leadingItems.length - 1]);
}
}
int get _itemCount {
int count = payload!.leadingItems.length + payload!.trailingItems!.length;
if (payload!.totalCount > count) {
count++;
}
return 2 * count; // including bottom border
}
Widget _buildSliver() {
if (error.isNotEmpty) {
return SliverToBoxAdapter(
child: ErrorReload(text: error, onTap: _refresh));
} else if (loading) {
// TODO:
return SliverToBoxAdapter(child: Loading(more: false));
} else {
return SliverList(
delegate:
SliverChildBuilderDelegate(_buildItem, childCount: _itemCount),
);
}
}
@override
Widget build(BuildContext context) {
switch (Provider.of<ThemeModel>(context).theme) {
case AppThemeType.cupertino:
List<Widget> slivers = [
CupertinoSliverRefreshControl(onRefresh: _refresh)
];
if (payload != null) {
slivers.add(
SliverToBoxAdapter(child: widget.headerBuilder(payload!.header)),
);
}
slivers.add(_buildSliver());
return CupertinoPageScaffold(
navigationBar: CupertinoNavigationBar(
middle: widget.title,
trailing: payload == null
? null
: widget.trailingBuilder!(payload!.header),
),
child: SafeArea(
child: CupertinoScrollbar(
child: CustomScrollView(slivers: slivers),
),
),
);
default:
return Scaffold(
appBar: AppBar(
title: widget.title,
actions: payload == null
? null
: [widget.trailingBuilder!(payload!.header)],
),
body: RefreshIndicator(
onRefresh: _refresh,
child: Scrollbar(
child: CustomScrollView(slivers: [
if (payload != null)
SliverToBoxAdapter(
child: widget.headerBuilder(payload!.header)),
_buildSliver(),
]),
),
),
);
}
}
}