extended_scroll

Description:

extended scroll

extended_scroll package for flutter. #
make method ensureVisible support offsetTop
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Getting Started #
Add the package to your pubspec.yaml:
extended_scroll: ^3.2.0
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example #
详细见example
In your dart file, import the library:
import 'package:extended_scroll/extended_scroll.dart';
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class DetailPage extends StatefulWidget {
const DetailPage({super.key});

static const String name = "/detailPage";

@override
State<DetailPage> createState() => _DetailPageState();
}

class _DetailPageState extends State<DetailPage> {
late final ExtendedScrollController _scrollController;
late final RefreshController _refreshController;

bool isTabClicked = false;

//good、comment、detail、betterGoods card keys
final cardKeys = <GlobalKey>[
GlobalKey(debugLabel: 'detail_card_0'),
GlobalKey(debugLabel: 'detail_card_1'),
GlobalKey(debugLabel: 'detail_card_2'),
GlobalKey(debugLabel: 'detail_card_3')
];

@override
void initState() {
_scrollController = ExtendedScrollController();
_refreshController = RefreshController();
super.initState();
}

@override
void dispose() {
_scrollController.dispose();
_refreshController.dispose();
super.dispose();
}

@override
Widget build(BuildContext context) {
return StoreBuilder<AppState>(
onInit: (store) async {
await store.dispatch(InitPageAction());
},
onDispose: (store) {
store.dispatch(ChangeTopTabIndexAction(0));
},
builder: (context, store) {
bool isLoading = store.state.detailPageState.isLoading;

List<Widget> stackWidgets = [];
if (isLoading) {
stackWidgets.add(loadingWidget(context));
} else {
stackWidgets.add(NotificationListener<ScrollNotification>(
onNotification: (ScrollNotification notification) {
double distance = notification.metrics.pixels;
store.dispatch(ChangePageScrollYAction(distance));

if (isTabClicked) return false;
int newIndex = findFirstVisibleItemIndex(cardKeys, context);
store.dispatch(ChangeTopTabIndexAction(newIndex));
return false;
},
child: Container(
child: SmartRefresher(
controller: _refreshController,
enablePullUp: true,
enablePullDown: false,
onLoading: () async {
store.dispatch(LoadMoreAction(
store.state.detailPageState.pageNum + 1,
() => loadMoreSuccess(_refreshController),
() => loadMoreFail(_refreshController),
));
},
child: ExtendedCustomScrollView(
controller: _scrollController,
slivers: [
goodsInfo(context, cardKeys[0]),
appraiseInfo(context, cardKeys[1]),
detailCard(context, cardKeys[2]),
storeGoodsHeader(context, cardKeys[3]),
storeGoods(context)
],
),
),
),
));
}

stackWidgets.add(
Positioned(
top: 0,
left: 0,
child: tabHeader(
context,
onChange: (index) {
isTabClicked = true;
store.dispatch(ChangeTopTabIndexAction(index));
scroll2PositionByTabIndex(index);
},
),
),
);

return AnnotatedRegion<SystemUiOverlayStyle>(
value: SystemUiOverlayStyle.dark,
child: Column(
children: [
Expanded(
flex: 1,
child: Scaffold(
body: Stack(
children: stackWidgets,
),
floatingActionButton: BackToTop(_scrollController),
),
),
fixedBottom(context)
],
),
);
},
);
}

void scroll2PositionByTabIndex(int index) {
RenderSliverToBoxAdapter? keyRenderObject = cardKeys[index].currentContext?.findAncestorRenderObjectOfType<RenderSliverToBoxAdapter>();
if (keyRenderObject != null) {
_scrollController.position
.ensureVisible(keyRenderObject, offsetTop: 42 + getStatusHeight(context), duration: const Duration(milliseconds: 300), curve: Curves.linear)
.then((value) => isTabClicked = false);
}
}

int findFirstVisibleItemIndex(List<GlobalKey<State<StatefulWidget>>> cardKeys, BuildContext context) {
int i = 0;
for (; i < cardKeys.length; i++) {
RenderSliverToBoxAdapter? keyRenderObject = cardKeys[i].currentContext?.findAncestorRenderObjectOfType<RenderSliverToBoxAdapter>();
if (keyRenderObject != null) {

final dy = (keyRenderObject.parentData as SliverPhysicalParentData).paintOffset.dy;
if (dy > 42 + getStatusHeight(context)) {
break;
}
}
}
final newIndex = i == 0 ? 0 : i - 1;
return newIndex;
}
}

```.
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