git-touch-android-ios-app/lib/scaffolds/list_stateful.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';
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import 'package:git_touch/scaffolds/common.dart';
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import 'package:git_touch/utils/utils.dart';
import 'package:provider/provider.dart';
import '../widgets/error_reload.dart';
import '../widgets/loading.dart';
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import '../widgets/empty.dart';
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class ListPayload<T, K> {
K cursor;
List<T> items;
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bool hasMore;
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ListPayload({this.items, this.cursor, this.hasMore});
}
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// This is a scaffold for infinite scroll screens
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class ListStatefulScaffold<T, K> extends StatefulWidget {
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final Widget title;
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final Widget Function() actionBuilder;
final Widget Function(T payload) itemBuilder;
final Future<ListPayload<T, K>> Function() onRefresh;
final Future<ListPayload<T, K>> Function(K cursor) onLoadMore;
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ListStatefulScaffold({
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@required this.title,
@required this.itemBuilder,
@required this.onRefresh,
@required this.onLoadMore,
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this.actionBuilder,
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});
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@override
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_ListStatefulScaffoldState<T, K> createState() =>
_ListStatefulScaffoldState();
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}
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class _ListStatefulScaffoldState<T, K>
extends State<ListStatefulScaffold<T, K>> {
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bool loading = false;
bool loadingMore = false;
String error = '';
List<T> items = [];
K cursor;
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bool hasMore;
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ScrollController _controller = ScrollController();
@override
void initState() {
super.initState();
_refresh();
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_controller.addListener(onScroll);
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}
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@override
void dispose() {
_controller.dispose();
super.dispose();
}
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void onScroll() {
// Fimber.d(_controller.position.maxScrollExtent - _controller.offset);
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if (_controller.position.maxScrollExtent - _controller.offset < 100 &&
!_controller.position.outOfRange &&
!loading &&
!loadingMore &&
hasMore) {
_loadMore();
}
}
// FIXME: if items not enough, fetch next page
// This should be triggered after build
void _makeSureItemsFill() {
Future.delayed(Duration(milliseconds: 300)).then((_) {
onScroll();
});
}
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Future<void> _refresh({bool force = false}) async {
// Fimber.d('list scaffold refresh');
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setState(() {
error = '';
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loading = true;
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if (force) {
items = [];
}
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});
try {
var _payload = await widget.onRefresh();
items = _payload.items;
cursor = _payload.cursor;
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hasMore = _payload.hasMore;
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} catch (err) {
error = err.toString();
throw err;
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} finally {
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if (mounted) {
setState(() {
loading = false;
});
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_makeSureItemsFill();
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}
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}
}
Future<void> _loadMore() async {
// Fimber.d('list scaffold load more');
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setState(() {
loadingMore = true;
});
try {
var _payload = await widget.onLoadMore(cursor);
items.addAll(_payload.items);
cursor = _payload.cursor;
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hasMore = _payload.hasMore;
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} catch (err) {
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error = err.toString();
throw err;
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} finally {
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if (mounted) {
setState(() {
loadingMore = false;
});
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_makeSureItemsFill();
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}
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}
}
Widget _buildItem(BuildContext context, int index) {
if (index == 2 * items.length) {
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if (hasMore) {
return Loading(more: true);
} else {
return Container();
}
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}
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if (index % 2 == 1) {
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return CommonStyle.border;
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}
return widget.itemBuilder(items[index ~/ 2]);
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}
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Widget _buildCupertinoSliver() {
if (error.isNotEmpty) {
return SliverToBoxAdapter(
child: ErrorReload(text: error, onTap: _refresh),
);
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} else if (loading && items.isEmpty) {
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return SliverToBoxAdapter(child: Loading(more: false));
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} else if (items.isEmpty) {
return SliverToBoxAdapter(child: EmptyWidget());
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} else {
return SliverList(
delegate: SliverChildBuilderDelegate(
_buildItem,
childCount: 2 * items.length + 1,
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),
);
}
}
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Widget _buildMaterial() {
if (error.isNotEmpty) {
return ErrorReload(text: error, onTap: _refresh);
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} else if (loading && items.isEmpty) {
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return Loading(more: false);
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} else if (items.isEmpty) {
return EmptyWidget();
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} else {
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return Scrollbar(
child: ListView.builder(
controller: _controller,
itemCount: 2 * items.length + 1,
itemBuilder: _buildItem,
),
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);
}
}
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Widget _buildBody() {
switch (Provider.of<ThemeModel>(context).theme) {
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case AppThemeType.cupertino:
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return CupertinoScrollbar(
child: CustomScrollView(
controller: _controller,
slivers: [
CupertinoSliverRefreshControl(onRefresh: _refresh),
_buildCupertinoSliver(),
],
),
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);
default:
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return RefreshIndicator(
onRefresh: _refresh,
child: _buildMaterial(),
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);
}
}
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@override
Widget build(BuildContext context) {
return CommonScaffold(
title: widget.title,
body: _buildBody(),
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action: widget.actionBuilder == null ? null : widget.actionBuilder(),
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);
}
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}