A loading more list which supports ListView,GridView,WaterfallFlow and Slivers.
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- add library to your pubspec.yaml
dependencies:
loading_more_list: any
- import library in dart file
import 'package:loading_more_list/loading_more_list.dart';
LoadingMoreBase is data collection for loading more. override loadData method to load your data. set hasMore to false when it has no more data.
class TuChongRepository extends LoadingMoreBase<TuChongItem> {
int pageindex = 1;
bool _hasMore = true;
bool forceRefresh = false;
@override
bool get hasMore => (_hasMore && length < 30) || forceRefresh;
@override
Future<bool> refresh([bool clearBeforeRequest = false]) async {
_hasMore = true;
pageindex = 1;
//force to refresh list when you don't want clear list before request
//for the case, if your list already has 20 items.
forceRefresh = !clearBeforeRequest;
var result = await super.refresh(clearBeforeRequest);
forceRefresh = false;
return result;
}
@override
Future<bool> loadData([bool isloadMoreAction = false]) async {
String url = "";
if (this.length == 0) {
url = "https://api.tuchong.com/feed-app";
} else {
int lastPostId = this[this.length - 1].postId;
url =
"https://api.tuchong.com/feed-app?post_id=$lastPostId&page=$pageindex&type=loadmore";
}
bool isSuccess = false;
try {
//to show loading more clearly, in your app,remove this
await Future.delayed(Duration(milliseconds: 500));
var result = await HttpClientHelper.get(url);
var source = TuChongSource.fromJson(json.decode(result.body));
if (pageindex == 1) {
this.clear();
}
for (var item in source.feedList) {
if (item.hasImage && !this.contains(item) && hasMore) this.add(item);
}
_hasMore = source.feedList.length != 0;
pageindex++;
isSuccess = true;
} catch (exception, stack) {
isSuccess = false;
print(exception);
print(stack);
}
return isSuccess;
}
}
almost of arguments are the same as official.
following arguments are made for loading more.
ListConfig and SliverListConfig
| argument | description | default |
|---|---|---|
| itemBuilder | The item builder of list. | required |
| sourceList | The source list of data which extends LoadingMoreBase. | required |
| showGlowLeading | Whether to show the overscroll glow on the side with negative scroll offsets. | 0.0 |
| showGlowTrailing | Whether to show the overscroll glow on the side with positive scroll offsets. | - |
| lastChildLayoutType | Layout type of last child(loadmore/no more item). | LastChildLayoutType.foot |
| viewportBuilder | The builder to get indexs in viewport. | - |
| closeToTrailing | Whether make layout close to trailing. | false |
| collectGarbage | Call when collect garbage and return indexs to collect. | - |
| gridDelegate | The delegate for GridView. | - |
| waterfallFlowDelegate | The delegate for WaterfallFlow. | - |
| indicatorBuilder | widget builder for different loading state. | IndicatorWidget |
| padding | The amount of space by which to inset the child sliver for SliverListConfig | - |
WaterfallFlowDelegate
| argument | description | default |
|---|---|---|
| crossAxisCount | The number of children in the cross axis. | required |
| mainAxisSpacing | The number of logical pixels between each child along the main axis. | 0 |
| crossAxisSpacing | The number of logical pixels between each child along the cross axis. | 0 |
LoadingMoreList
| argument | description | default |
|---|---|---|
| listConfig | ListConfig | required |
| onScrollNotification | Called when a ScrollNotification of the appropriate type arrives at this location in the tree. | - |
LoadingMoreSliverList
| argument | description | default |
|---|---|---|
| sliverListConfig | SliverListConfig | required |
LoadingMoreCustomScrollView
| argument | description | default |
|---|---|---|
| onScrollNotification | Called when a ScrollNotification of the appropriate type arrives at this location in the tree. | - |
| rebuildCustomScrollView | in NestedScrollView, rebuild CustomScrollView, viewport can be computed again. | false |
LoadingMoreList(
ListConfig<TuChongItem>(
itemBuilder: ItemBuilder.itemBuilder,
sourceList: listSourceRepository,
padding: EdgeInsets.all(0.0),
),
),define GridView with gridDelegate argument.
LoadingMoreList(
ListConfig<TuChongItem>(
itemBuilder: ItemBuilder.itemBuilder,
sourceList: listSourceRepository,
padding: EdgeInsets.all(0.0),
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 2,
crossAxisSpacing: 3.0,
mainAxisSpacing: 3.0,
),
),
),
define WaterfallFlow with waterfallFlowDelegate argument.
LoadingMoreList(
ListConfig<TuChongItem>(
waterfallFlowDelegate: WaterfallFlowDelegate(
crossAxisCount: 2,
crossAxisSpacing: 5,
mainAxisSpacing: 5,
),
itemBuilder: _buildItem,
sourceList: listSourceRepository,
padding: EdgeInsets.all(5.0),
),
), |
 |
|---|
following codes are show how to build loading more list within CustomScrollView.
LoadingMoreCustomScrollView(
slivers: <Widget>[
SliverAppBar(
pinned: true,
title: Text("MultipleSliverDemo"),
),
///SliverList
LoadingMoreSliverList(SliverListConfig<TuChongItem>(
itemBuilder: ItemBuilder.itemBuilder,
sourceList: listSourceRepository,
)),
SliverToBoxAdapter(
child: Container(
alignment: Alignment.center,
child: Text("Next list"),
color: Colors.blue,
height: 100.0,
),
),
///SliverGrid
LoadingMoreSliverList(
SliverListConfig<TuChongItem>(
itemBuilder: ItemBuilder.itemBuilder,
sourceList: listSourceRepository1,
gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(
crossAxisCount: 2,
crossAxisSpacing: 3.0,
mainAxisSpacing: 3.0,
),
),
),
SliverPersistentHeader(
delegate: CommonExtentSliverPersistentHeaderDelegate(
Container(
alignment: Alignment.center,
child: Text("Pinned Content"),
color: Colors.red,
),
100.0),
pinned: true,
),
///SliverWaterfallFlow
LoadingMoreSliverList(
SliverListConfig<TuChongItem>(
itemBuilder: buildWaterfallFlowItem,
sourceList: listSourceRepository2,
padding: EdgeInsets.symmetric(horizontal: 5.0),
waterfallFlowDelegate: WaterfallFlowDelegate(
crossAxisCount: 2,
crossAxisSpacing: 5,
mainAxisSpacing: 5,
),
),
),
],
), |
 |
|---|
define loading status with indicatorBuilder argument.
enum IndicatorStatus {
None,
LoadingMoreBusying,
FullScreenBusying,
Error,
FullScreenError,
NoMoreLoad,
Empty
} LoadingMoreList(
ListConfig<TuChongItem>(
itemBuilder: ItemBuilder.itemBuilder,
sourceList: listSourceRepository,
indicatorBuilder: _buildIndicator,
padding: EdgeInsets.all(0.0),
),
),
//you can use IndicatorWidget or build yourself widget
//in this demo, we define all status.
Widget _buildIndicator(BuildContext context, IndicatorStatus status) {
//if your list is sliver list ,you should build sliver indicator for it
//isSliver=true, when use it in sliver list
bool isSliver = false;
Widget widget;
switch (status) {
case IndicatorStatus.None:
widget = Container(height: 0.0);
break;
case IndicatorStatus.LoadingMoreBusying:
widget = Row(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Container(
margin: EdgeInsets.only(right: 5.0),
height: 15.0,
width: 15.0,
child: getIndicator(context),
),
Text("正在加载...不要着急")
],
);
widget = _setbackground(false, widget, 35.0);
break;
case IndicatorStatus.FullScreenBusying:
widget = Row(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: <Widget>[
Container(
margin: EdgeInsets.only(right: 0.0),
height: 30.0,
width: 30.0,
child: getIndicator(context),
),
Text("正在加载...不要着急")
],
);
widget = _setbackground(true, widget, double.infinity);
if (isSliver) {
widget = SliverFillRemaining(
child: widget,
);
} else {
widget = CustomScrollView(
slivers: <Widget>[
SliverFillRemaining(
child: widget,
)
],
);
}
break;
case IndicatorStatus.Error:
widget = Text(
"好像出现了问题呢？",
);
widget = _setbackground(false, widget, 35.0);
widget = GestureDetector(
onTap: () {
listSourceRepository.errorRefresh();
},
child: widget,
);
break;
case IndicatorStatus.FullScreenError:
widget = Text(
"好像出现了问题呢？",
);
widget = _setbackground(true, widget, double.infinity);
widget = GestureDetector(
onTap: () {
listSourceRepository.errorRefresh();
},
child: widget,
);
if (isSliver) {
widget = SliverFillRemaining(
child: widget,
);
} else {
widget = CustomScrollView(
slivers: <Widget>[
SliverFillRemaining(
child: widget,
)
],
);
}
break;
case IndicatorStatus.NoMoreLoad:
widget = Text("没有更多的了。。不要拖了");
widget = _setbackground(false, widget, 35.0);
break;
case IndicatorStatus.Empty:
widget = EmptyWidget(
"这里是空气！",
);
widget = _setbackground(true, widget, double.infinity);
if (isSliver) {
widget = SliverToBoxAdapter(
child: widget,
);
} else {
widget = CustomScrollView(
slivers: <Widget>[
SliverFillRemaining(
child: widget,
)
],
);
}
break;
}
return widget;
}
track the indexes are collect, you can collect garbage at that monment(for example Image cache)
LoadingMoreList(
ListConfig<TuChongItem>(
collectGarbage: (List<int> indexes) {
///collectGarbage
indexes.forEach((index) {
final item = listSourceRepository[index];
if (item.hasImage) {
final provider = ExtendedNetworkImageProvider(
item.imageUrl,
);
provider.evict();
}
});
},
),
),track the indexes go into the viewport, it's not include cache extent.
LoadingMoreList(
ListConfig<TuChongItem>(
viewportBuilder: (int firstIndex, int lastIndex) {
print("viewport : [$firstIndex,$lastIndex]");
},
closeToTrailing: true
),
),build lastChild as special child in the case that it is loadmore/no more item.
enum LastChildLayoutType {
/// as default child
none,
/// follow max child trailing layout offset and layout with full cross axis extend
/// last child as loadmore item/no more item in [ExtendedGridView] and [WaterfallFlow]
/// with full cross axis extend
fullCrossAxisExtend,
/// as foot at trailing and layout with full cross axis extend
/// show no more item at trailing when children are not full of viewport
/// if children is full of viewport, it's the same as fullCrossAxisExtend
foot,
}when reverse property of List is true, layout is as following. it likes chat list, and new session will insert to zero index. but it's not right when items are not full of viewport.
trailing
-----------------
| |
| |
| item2 |
| item1 |
| item0 |
-----------------
leading
to solve it, you could set closeToTrailing to true, layout is as following. support [ExtendedGridView],[ExtendedList],[WaterfallFlow]. and it also works when reverse is flase, layout will close to trailing.
trailing
-----------------
| item2 |
| item1 |
| item0 |
| |
| |
-----------------
leading
LoadingMoreList(
ListConfig<TuChongItem>(
closeToTrailing: true
),
),