217 lines
5.4 KiB
Dart
217 lines
5.4 KiB
Dart
import 'package:flutter/material.dart';
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import 'package:flutter/cupertino.dart';
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import 'package:flutter/widgets.dart';
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import '../providers/settings.dart';
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import '../widgets/error_reload.dart';
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import '../widgets/loading.dart';
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import '../widgets/empty.dart';
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class ListPayload<T, K> {
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K cursor;
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List<T> items;
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bool hasMore;
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ListPayload({this.items, this.cursor, this.hasMore});
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}
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// This is a scaffold for infinite scroll screens
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class ListScaffold<T, K> extends StatefulWidget {
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final Widget title;
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// final IconData trailingIconData;
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// final Function trailingOnTap;
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final Widget Function(T payload) itemBuilder;
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final Future<ListPayload<T, K>> Function() onRefresh;
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final Future<ListPayload<T, K>> Function(K cursor) onLoadMore;
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ListScaffold({
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@required this.title,
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// this.trailingIconData,
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// this.trailingOnTap,
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@required this.itemBuilder,
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@required this.onRefresh,
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@required this.onLoadMore,
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});
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@override
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_ListScaffoldState createState() => _ListScaffoldState();
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}
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class _ListScaffoldState<T, K> extends State<ListScaffold<T, K>> {
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bool loading = false;
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bool loadingMore = false;
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String error = '';
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List<T> items = [];
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K cursor;
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bool hasMore;
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ScrollController _controller = ScrollController();
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@override
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void initState() {
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super.initState();
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_refresh();
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_controller.addListener(() {
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if (_controller.offset + 100 > _controller.position.maxScrollExtent &&
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!_controller.position.outOfRange &&
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!loading &&
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!loadingMore &&
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hasMore) {
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_loadMore();
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}
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});
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}
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Future<void> _refresh() async {
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// print('list scaffold refresh');
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setState(() {
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error = '';
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loading = true;
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});
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try {
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var _payload = await widget.onRefresh();
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items = _payload.items;
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cursor = _payload.cursor;
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hasMore = _payload.hasMore;
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} catch (err) {
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// print(err);
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error = err.toString();
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} finally {
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if (mounted) {
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setState(() {
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loading = false;
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});
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}
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}
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}
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Future<void> _loadMore() async {
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print('list scaffold load more');
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setState(() {
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loadingMore = true;
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});
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try {
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var _payload = await widget.onLoadMore(cursor);
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items.addAll(_payload.items);
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cursor = _payload.cursor;
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hasMore = _payload.hasMore;
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} catch (err) {
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print(err);
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} finally {
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if (mounted) {
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setState(() {
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loadingMore = false;
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});
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}
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}
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}
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Widget _buildItem(BuildContext context, int index) {
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if (index == 2 * items.length) {
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if (hasMore) {
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return Loading(more: true);
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} else {
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return Container();
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}
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}
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if (index % 2 == 1) {
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return Container(
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decoration: BoxDecoration(
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border: Border(bottom: BorderSide(color: Colors.black12)),
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),
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);
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}
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return widget.itemBuilder(items[index ~/ 2]);
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}
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Widget _buildSliver(BuildContext context) {
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if (error.isNotEmpty) {
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return SliverToBoxAdapter(
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child: ErrorReload(text: error, reload: _refresh),
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);
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} else if (loading) {
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return SliverToBoxAdapter(child: Loading(more: false));
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} else if (items.isEmpty) {
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return SliverToBoxAdapter(child: EmptyWidget());
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} else {
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return SliverList(
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delegate: SliverChildBuilderDelegate(
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_buildItem,
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childCount: 2 * items.length + 1,
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),
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);
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}
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}
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Widget _buildBody(BuildContext context) {
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if (error.isNotEmpty) {
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return ErrorReload(text: error, reload: _refresh);
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} else if (loading) {
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return Loading(more: false);
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} else if (items.isEmpty) {
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return EmptyWidget();
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} else {
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return ListView.builder(
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controller: _controller,
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itemCount: 2 * items.length + 1,
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itemBuilder: _buildItem,
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);
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}
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}
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@override
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Widget build(BuildContext context) {
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switch (SettingsProvider.of(context).theme) {
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case ThemeMap.cupertino:
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List<Widget> slivers = [
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CupertinoSliverRefreshControl(onRefresh: widget.onRefresh)
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];
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// if (widget.header != null) {
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// slivers.add(SliverToBoxAdapter(child: widget.header));
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// }
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slivers.add(_buildSliver(context));
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return CupertinoPageScaffold(
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navigationBar: CupertinoNavigationBar(
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middle: widget.title,
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// trailing: Link(
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// child: Icon(
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// widget.trailingIconData,
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// size: 24,
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// color: Colors.blueAccent,
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// ),
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// beforeRedirect: widget.trailingOnTap,
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// bgColor: Colors.transparent,
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// ),
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),
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child: SafeArea(
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child: CustomScrollView(
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controller: _controller,
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slivers: slivers,
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),
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),
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);
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default:
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return Scaffold(
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appBar: AppBar(
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title: widget.title,
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// actions: widget.trailingIconData == null
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// ? []
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// : <Widget>[
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// IconButton(
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// icon: Icon(widget.trailingIconData),
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// onPressed: widget.trailingOnTap,
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// )
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// ],
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),
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body: RefreshIndicator(
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onRefresh: widget.onRefresh,
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child: _buildBody(context),
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),
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);
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}
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}
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}
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