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Home Page: https://pub.dev/packages/flutter_widgets

License: BSD 3-Clause "New" or "Revised" License

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flutter.widgets's Issues

ScrollablePositionedList: Provide a header builder

This is very useful when creating Apps that support book libraries. It is always good to show the reader the data in the book. I currently use the NestedScrollView with headerSliverBuilder but has bugs in the scroll, sometimes jumps.

ScrollablePositionedList: make itemCount optional

v0.1.8 didn't fit flutter version range in environment

Some code are using functions of BuildContext such as findAncestorStateOfType which doesn't exist before flutter 1.12 but the environment in pubspec.yaml is flutter: ^1.9.1.
This makes the app which is using flutter 1.9 or 1.10 failure when building.

ScrollablePositionedList '_scrollableListState != null': is not true.

I am getting crash when the screen which have
ScrollablePositionedList getting closed/disposed (back button)

I am using ChangeNotifierProvider and Consumer pattern.

The error happen after the notifyListeners() in provider get called then I press back button.

the Error:

The following assertion was thrown while finalizing the widget tree:
'package:flutter_widgets/src/scrollable_positioned_list/src/scrollable_positioned_list.dart': Failed assertion: line 195 pos 12: '_scrollableListState != null': is not true.

Either the assertion indicates an error in the framework itself, or we should provide substantially more information in this error message to help you determine and fix the underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
  https://github.com/flutter/flutter/issues/new?template=BUG.md

When the exception was thrown, this was the stack: 
#2      ItemScrollController._detach (package:flutter_widgets/src/scrollable_positioned_list/src/scrollable_positioned_list.dart:195:12)
#3      _ScrollablePositionedListState.dispose (package:flutter_widgets/src/scrollable_positioned_list/src/scrollable_positioned_list.dart:232:34)
#4      StatefulElement.unmount (package:flutter/src/widgets/framework.dart:4435:12)
#5      _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1748:13)
#6      _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1746:7)

My Code:

class AyahListPage extends StatefulWidget {

  Surah surah;

  AyahListPage(this.surah);

  @override
  _AyahListPageState createState() => _AyahListPageState();
}

class _AyahListPageState extends State<AyahListPage> {
  AyahPool_Provider ayahPool_Provider = AyahPool_Provider();

  ItemScrollController itemScrollController;
  ItemPositionsListener itemPositionListener;


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

  @override
  Widget build(BuildContext context) {

    MasterProvider masterProvider = Provider.of<MasterProvider>(context);


    return FutureBuilder(
      future: loadTask(),
      builder: (context, snapshot) {

        if(! snapshot.hasData)
          return CircularProgressIndicator();

        return ChangeNotifierProvider<AyahPool_Provider>(
            create: (context) => ayahPool_Provider,
            child: Scaffold(
                appBar: AppBar(title: Text(masterProvider.appTitle)),
                body: Container(margin: EdgeInsets.all(8),
                    child:
                    Consumer<AyahPool_Provider>(
                        builder: (context, provider, _) {

                          var checkBox = CheckboxListTile(title: Text('Trans'),value: provider.ayahMode_withWordTrans,
                            onChanged: (flag) {
                              provider.ayahMode_withWordTrans = flag;
                            },);

                          var checkBox_2 = CheckboxListTile(title: Text('Lemma'),value: provider.ayahMode_withWordLemma,
                            onChanged: (flag) {
                              provider.ayahMode_withWordLemma = flag;
                            },);

                          var pageContent = Column(children: <Widget>[Wrap(children: <Widget>[checkBox, checkBox_2]),
                            Expanded(child: AyahListView(widget.surah))],);

                          return pageContent;


                        }))));

      },
    );



  }

  Future<AyahList> loadTask() async {
    ayahPool_Provider.surah = widget.surah;
    ayahPool_Provider.bislAllah_glyph = await DAO_TB_Glyph.db_getBismallah();
    ayahPool_Provider.ayahList = await DAO_TB_Glyph.db_getBySurah_asAyahList(widget.surah.ID);
    return ayahPool_Provider.ayahList;
  }


   // --------------- Ayah List part ----------------------------

  Widget AyahListView(Surah surah) {
    ayahPool_Provider.addBismAllahItem_ifSurahHave(widget.surah);

    var ayahList_listView = listView_fromAyahList(ayahPool_Provider);

    return ayahList_listView;
  }

  Widget listView_fromAyahList(AyahPool_Provider ayahPool_Provider,
      {double size = Quran_Ui.quranText_defaultSize}) {


    // This is to scroll to specific item (LATER).
    itemScrollController = ItemScrollController(); //TODO: this make bug if i set it.
    itemPositionListener = ItemPositionsListener.create();
    var listView = ScrollablePositionedList.builder(
        itemCount: ayahPool_Provider.ayahList.ayahList.length,
        itemPositionsListener: itemPositionListener,
        itemScrollController: itemScrollController,
        itemBuilder: (BuildContext context, int index) {
          Ayah ayah = ayahPool_Provider.ayahList.ayahList[index];

          if (ayah.translationAndExplaination_mapList != null || ayah.isThisBismallahItem())
            return buildAyahItem(index, ayahPool_Provider, size);

          return FutureBuilder(
              future: loadTransBox(ayahPool_Provider.surah, ayah),
              builder: (context, snapshot) {
                // this will hide the widget if the data still not loaded
                double opacityVal = (snapshot.hasData) ? 1 : 0;
                return Opacity(
                    child: buildAyahItem(
                        index, ayahPool_Provider, size),
                    opacity: opacityVal);
              }
          );
        });

    return listView;

  }

VisibilityDetector does not allow to set updateTime

It is needed to detect changes after every frame, but updateInterval is constantly set to 500ms. Real case: to detect unread messages in chat if user scrolls so fast. Sould be customizable

Can't build app on Android or IOS

indepent from the platform i can't build the app.
it gave me this error

Compiler message:
../.pub-cache/hosted/pub.dartlang.org/flutter_widgets-0.1.5/lib/src/visibility_detector/src/visibility_detector_layer.dart:277:18: Error: This expression has type 'void' and can't be used.
return super.addToScene(builder, layerOffset);

BoxShadow showing above the other widgets in ScrollablePositionedList

I have Container as the child of the ScrollablePositionedList's item builder and the Container has some decoration and box-shadow. However, the box-shadow is showing above the other list items.

I tried using ListView's builder and its working as expected, not showing the box-shadow above the other list items. Any suggestions on what's causing the issue?

ScrollablePositionedList.builder(
itemCount: services.length,
itemBuilder: (context, index) {
  var service = services[index];
  return Container(
    padding:
        EdgeInsets.symmetric(horizontal: 30, vertical: 15),
    margin: EdgeInsets.symmetric(horizontal: 20, vertical: 5),
    decoration: BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.all(Radius.circular(15)),
        boxShadow: [
          BoxShadow(
              color: Color(0x1a000000),
              blurRadius: 20,
              spreadRadius: 0,
              offset: Offset(0, 10))
        ]),
    child: Row(
      mainAxisAlignment: MainAxisAlignment.spaceBetween,
      children: <Widget>[
        SizedBox(
          width: 200,
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.start,
            children: <Widget>[
              Text(
                service.name,
                style: TextStyle(fontSize: 20),
              ),
              Text(
                service.description,
                style: TextStyle(fontSize: 12),
                overflow: TextOverflow.ellipsis,
                maxLines: 2,
              ),
            ],
          ),
        ),
        MaterialButton(
          minWidth: 0,
          child: Text('Edit'),
          onPressed: () {
            Navigator.push(
                context,
                MaterialPageRoute(
                    builder: (context) => AddServiceDetails(
                          serviceEdit: _serviceChanged,
                        )));
          },
          shape: new RoundedRectangleBorder(
              borderRadius: BorderRadius.all(
            Radius.circular(10),
          )),
          clipBehavior: Clip.antiAlias,
          textColor: Colors.teal,
        )
      ],
    ),
  );
}),

ScrollablePositionedList: There seems to be a problem with the widget's state when back to the previous screen when if use listen.

I'm taking the scroll index to save the position in the database that the user stopped reading. For this I am using a Listen as shown in the image. Except that when returning to the previous screen it seems to give a bug related to the state of the ScrollablePositionedList.

ScrollablePositionedList: Another exception was thrown: NoSuchMethodError: invalid member on null: '_jumpTo'

_jumpTo wont work in stateless widget


class NewsListView extends StatelessWidget {
  final List<News> news;
  final News focusedNews;
  final ItemScrollController _scrollController = ItemScrollController();
  BuildContext context;
  int focusedIndex;
  NewsListView(this.news, {this.defaultItemAction, this.focusedNews, Key key})
      : super(key: key);
  final NewsListItemActions defaultItemAction;

  @override
  Widget build(BuildContext context) {
    WidgetsBinding.instance
        .addPostFrameCallback((_) => _scrollToFocused());
    this.context = context;
    return Scrollbar(
        child: news.isEmpty
            ? Text("loading..")
            : ScrollablePositionedList.builder(
                itemScrollController: _scrollController,
                itemCount: news.length,
                itemBuilder: (context, index) {
                  var data = news[index];
                  var isFocused =
                      focusedNews != null ? data.id == focusedNews.id : false;
                  if (isFocused) focusedIndex = index;
                  return NewsListItem(
                    data,
                    isFocused: isFocused,
                    actions: defaultItemAction,
                  );
                },
              ));
  }

  _scrollToFocused() {
    print("index $focusedIndex");
    if (focusedIndex != null) {
      _scrollController.jumpTo(index: focusedIndex);
      print('scroll jumped to $focusedIndex');
    }
  }
}

Another exception was thrown: NoSuchMethodError: invalid member on null: '_jumpTo'

Provider still uses 3.x instead of 4.x

We updated our project to provider 4.x and now we can't use flutter_widgets. because it still uses 3.x

ScrollablePositionedList should be bounce when jumping to the end of the list

Now it's stopped at the jumping position and will not trigger the physical reaction.

ScrollablePositionedList: Index out of range on a new state

ScrollablePositionedList in a new state brings the index with value outside current Range. Everything indicates that the index value is the first build.

ScrollablePositionedList rebuild a deleted list item

Hello,

I am using a ScrollablePositionedList coupled with a ChangeNotifierProvider.
I want to give the user the possibility to delete an item of the list.

The user click on the delete button associated to an item.
Then provider is called and remove this item from the model.
Then notifyListeners() is called.
ScrollablePositionedList is rebuild with the updated list of item.

For some reasons, the widget associated to the deleted item is also rebuild, which causes an error.

For now, if it occurs, I return an empty container but it is only a quick fix.

I'm pretty sure the problem comes from ScrollablePositionedList because everything works fine with a ListView.

Here is a minimal example to reproduce the problem:

import 'package:flutter/material.dart';
import 'package:flutter_widgets/flutter_widgets.dart';
import 'package:provider/provider.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider<MyModel>(
      builder: (context) => MyModel(),
      child: MaterialApp(
        home: Scaffold(
          appBar: AppBar(title: const Text('My App')),
          body: Container(
            padding: const EdgeInsets.only(left: 16.0),
            width: 200,
            child: Consumer<MyModel>(
              builder: (context, myModel, child) {
                print('Build ScrollablePositionedList');
                print('itemIDs: ${myModel.itemIDs}');
                print('itemsMap: ${myModel.itemsMap}');
                return ScrollablePositionedList.builder(
                  scrollDirection: Axis.vertical,
                  itemCount: myModel.itemIDs.length,
                  itemBuilder: (BuildContext context, int index) {
                    final itemID = myModel.itemIDs[index];
                    return CustomItem(
                      key: Key('customItem_$itemID'),
                      itemID: itemID,
                    );
                  },
                );
              },
            ),
          ),
        ),
      ),
    );
  }
}

class CustomItem extends StatelessWidget {
  const CustomItem({
    Key key,
    this.itemID,
  }) : super(key: key);

  final String itemID;

  @override
  Widget build(BuildContext context) {
    final myModel = Provider.of<MyModel>(context);
    print('Build CustomItem $itemID');

    // DEBUG ********
    if (myModel.itemsMap[itemID] == null) {
      print('Building a deleted item...');
      return Container(
        width: 0.0,
        height: 0.0,
      );
    }
    // **************

    return Row(
      children: <Widget>[
        Text(myModel.itemsMap[itemID]['label']),
        IconButton(
          icon: Icon(Icons.delete),
          disabledColor: Colors.grey,
          onPressed: myModel.itemIDs.length > 1 ? () => myModel.removeItem(itemID) : null,
        )
      ],
    );
  }
}

class MyModel with ChangeNotifier {
  List<String> itemIDs = ['A', 'B', 'C'];
  Map<String, Map<String, dynamic>> itemsMap = {
    'A': {
      'label': 'Item A',
    },
    'B': {
      'label': 'Item B',
    },
    'C': {
      'label': 'Item C',
    },
  };

  void removeItem(itemID) {
    print('Remove item $itemID');
    final itemIndex = itemIDs.indexWhere((id) => id == itemID);
    if (itemIndex > -1) {
      itemIDs.removeAt(itemIndex);
      itemsMap.remove(itemID);
    }

    notifyListeners();
  }
}

flutter_widgets 0.1.6-dev.1 is incompatible with flutter v1.9.1+hotfix.2

As a followup of #20 being fixed, I tried upgrade to flutter v1.9.1+hotfix.2 (now beta and I am assuming it will become stable soon), but pub get complains that intl in flutter sdk (0.15.8) is behind what flutter_widgets requires (0.16.0):

Because every version of app_ui from path depends on hux from path which depends on flutter_widgets 0.1.6-dev.1, every version of app_ui from path requires flutter_widgets 0.1.6-dev.1.
And because flutter_widgets >=0.1.6-dev.1 depends on intl ^0.16.0 and every version of flutter_localizations from sdk depends on intl 0.15.8, app_ui from path is incompatible with flutter_localizations from sdk.
So, because hue_blue_app depends on app_ui from path which depends on flutter_localizations any from sdk, version solving failed.
pub get failed (1)

Is it strictly needed for flutter_widgets to use 0.16.0?

ScrollablePositionedList: Assert when reuse the ScrollablePositionedList

Well, it's not breaking things, just an assert triggered when dispose.

flutter doctor -v:

[✓] Flutter (Channel master, v1.10.1-pre.42, on Mac OS X 10.14.5 18F132, locale zh-Hans-CN)
    • Flutter version 1.10.1-pre.42 at /Users/li9s/github/flutter
    • Framework revision 681178ab45 (71 minutes ago), 2019-09-09 16:47:49 +0800
    • Engine revision c9ea4dba8d
    • Dart version 2.5.0 (build 2.5.0-dev.4.0 ec7ec4ecf7)

 
[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.0)
    • Android SDK at /Users/li9s/Library/Android/sdk
    • Android NDK location not configured (optional; useful for native profiling support)
    • Platform android-29, build-tools 29.0.0
    • ANDROID_HOME = /Users/li9s/Library/Android/sdk
    • ANDROID_SDK_ROOT = /Users/li9s/Library/Android/sdk
    • Java binary at: /Applications/Dev/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1343-b01)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 10.3)
    • Xcode at /Applications/Dev/Xcode.app/Contents/Developer
    • Xcode 10.3, Build version 10G8
    • CocoaPods version 1.7.1

[✓] Android Studio (version 3.4)
    • Android Studio at /Applications/Dev/Android Studio.app/Contents
    • Flutter plugin version 36.0.1
    • Dart plugin version 183.6270
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1343-b01)

[✓] Android Studio (version 3.4)
    • Android Studio at /Applications/Dev/Android Studio.app/Contents
    • Flutter plugin version 36.0.1
    • Dart plugin version 183.6270
    • Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1343-b01)

[✓] IntelliJ IDEA Ultimate Edition (version 2019.1.3)
    • IntelliJ at /Applications/Dev/IntelliJ IDEA.app
    • Flutter plugin version 37.1.3
    • Dart plugin version 191.7830

[✓] Connected device (1 available)
    • LON AL00 • TEV0216C22001731 • android-arm64 • Android 9 (API 28)

I/flutter (12153): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (12153): The following assertion was thrown while finalizing the widget tree:
I/flutter (12153): 'package:mhwo/third_party/scrollable_positioned_list/scrollable_positioned_list.dart': Failed
I/flutter (12153): assertion: line 157 pos 12: '_scrollableListState != null': is not true.
I/flutter (12153): 
I/flutter (12153): Either the assertion indicates an error in the framework itself, or we should provide substantially
I/flutter (12153): more information in this error message to help you determine and fix the underlying cause.
I/flutter (12153): In either case, please report this assertion by filing a bug on GitHub:
I/flutter (12153):   https://github.com/flutter/flutter/issues/new?template=BUG.md
I/flutter (12153): 
I/flutter (12153): When the exception was thrown, this was the stack:
I/flutter (12153): #2      ItemScrollController._detach (package:mhwo/third_party/scrollable_positioned_list/scrollable_positioned_list.dart:157:12)
I/flutter (12153): #3      _ScrollablePositionedListState.dispose (package:mhwo/third_party/scrollable_positioned_list/scrollable_positioned_list.dart:192:34)
I/flutter (12153): #4      StatefulElement.unmount (package:flutter/src/widgets/framework.dart:4135:12)
I/flutter (12153): #5      _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1738:13)
I/flutter (12153): #6      _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1736:7)
I/flutter (12153): #7      ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3983:14)
I/flutter (12153): #8      _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1734:13)
I/flutter (12153): #9      _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1736:7)
I/flutter (12153): #10     ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3983:14)
I/flutter (12153): #11     _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1734:13)
I/flutter (12153): #12     _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1736:7)
I/flutter (12153): #13     MultiChildRenderObjectElement.visitChildren (package:flutter/src/widgets/framework.dart:5218:16)
I/flutter (12153): #14     _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1734:13)
I/flutter (12153): #15     _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1736:7)
I/flutter (12153): #16     ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3983:14)
I/flutter (12153): #17     _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1734:13)
I/flutter (12153): #18     _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1736:7)
I/flutter (12153): #19     ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3983:14)
I/flutter (12153): #20     _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1734:13)

VisibilityDetector no longer compiles

When trying to include VisibilityDetector, any flutter command fails with

Running Gradle task 'assembleDevelopmentDebug'...

Compiler message:
../../../../.pub-cache/hosted/pub.dartlang.org/flutter_widgets-0.1.5/lib/src/visibility_detector/src/visibility_detector_layer.dart:277:18: Error: This expression has type 'void' and can't be used.
    return super.addToScene(builder, layerOffset);
                 ^

This is due to a breaking change which hasn't been fixed here.

https://github.com/flutter/flutter/pull/36402/files#diff-58600d3d2645a66835eb03f3c41b447bR848

Cancel timers when the VisibilityDetector is removed.

VisibilityDetector

The VisibilityDetector should cancel timers, when it is removed from the widget tree.

For example the following test case should work:

void main() {
  testWidgets('Does not crash without waiting for the update interval.',
      (WidgetTester tester) async {
    final _uniqueKey = UniqueKey();
    await tester.pumpWidget(MaterialApp(home: VisibilityDetector(
        key: _uniqueKey,
        child: Container(),
        onVisibilityChanged: (_) {})));
    await tester.pumpWidget(Placeholder());
    // await widgetTester.pump(VisibilityDetectorController.instance.updateInterval);
  }, timeout: Timeout.none);
}

But it fails with Timer still pending.

Currently we have to uncomment the last line to make it work. This looks like an issue with cancelling timers, or flutter not correctly identifying cancelled timers.

ScrollablePositionedList - shrinkWrap

Could you add the shrinkWrap property to the ScrollablePositionedList ?
It will be used in the UnboundedCustomScrollView. In this class shrinkWrap is always false.

Flutter crash when spamming scrollTo

Not sure is related to this flutter/flutter#28037 or this package problem.

I want observe the ScrollablePositionedList offset

I'm not only need ScrollablePositionedList current scroll index, but also need to know current offset, what should I do

ScrollablePositionedList: calling the builder for an element that has been removed from the array

Hi! If I open the list and put the starting position at the end, and then delete the last element, a situation arises when the widget tries to call the builder for the index, which is already outside the bounds of the array. Is it possible to make the list not look at the starting position and automatically scrolling to the lower border if an empty space appears?

ScrollablePositionedList builder itemsCount zero

Hi. It's so disappointing. When itemCount is zero it executes builder with index 0
The same goes when itemCount: 1

ScrollablePositionedList.builder(
  itemCount: 0,
  itemBuilder: (context, index) =>
      Text('Item $index'),
)

Please fix this. Thanks

Why FeatureDisocery widget is not exported

Is there any reason why FeatureDiscovery widget is not exported publicly?

I can import package:flutter_widgets/src/feature_discovery/feature_discovery.dart', but this gives me warning while running flutter analyze.

ScrollablePositionList return _scrollableListState == null inside PageView

I can't put a ScrollablePositionList inside a PageView. Returns me an error: ... scrollable_positioned_list.dart ': Failed assertion: line 152 pos 12:' _scrollableListState == null ': is not true.

FeatureDiscovery for non-icon widgets

Currently FeatureDiscovery only supports discovery of Icon widgets. Imagine a situation when feature that you want your users to discover is not an icon eg.:

a Button - sometimes buttons have only text without an icon, like "Select All", "Send to all" or "Mark as done",
a TextField - you could guide users though required form inputs when they see fairly complex form for the first time,
a ScrollList - when it is not obvious that part of the screen can be scrolled eg. with Google Calendar for Android one cannot tell that it can be scrolled left and right to previous and next month.

In such cases it would be good to have the ability to use the same widget (that gives users the same look and feel) as for other part of app (that were using icons).

ScrollablePositionedList: Provide, if possible, a method to capture the last Scroll index, where the scroll it left off.

Think that the user is reading a book. The Listen does this, but even if you always pick the biggest index listened, you lose a lot in performance by recording all the indexes in bank. if we could always get the last one index (referent to beginning of the screen) it would be great.

Build Gallery app as part of presubmit tests

In PR #8, I accidentally submitted the wrong import line in gallery/lib/gallery.dart and broke its build. This was not caught by the presubmit test, which surprised me.

ScrollablePositionedList: Exception when setState

NullPointer happens when the page is detached from window, if (mounted) maybe needed.

NoSuchMethodError
NoSuchMethodError: The method 'markNeedsBuild' was called on null. Receiver: null Tried calling: markNeedsBuild
1 #0 State.setState (package:flutter/src/widgets/framework.dart:1168)
2 #1 _ScrollablePositionedListState._startScroll.<anonymous closure> (package:flutter_widgets/src/scrollable_positioned_list/src/scrollable_positioned_list.dart:409)
3 #2 _ScrollablePositionedListState._startScroll.<anonymous closure> (package:flutter_widgets/src/scrollable_positioned_list/src/scrollable_positioned_list.dart:420)
4 #3 _rootRunUnary (dart:async/zone.dart:1134)
5 #4 _CustomZone.runUnary (dart:async/zone.dart:1031)
6 #5 _FutureListener.handleValue (dart:async/future_impl.dart:139)
7 #6 Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:680)
8 #7 Future._propagateToListeners (dart:async/future_impl.dart:709)
9 #8 Future._completeWithValue (dart:async/future_impl.dart:524)
10 #9 Future.wait.<anonymous closure> (dart:async/future.dart:400)
11 #10 _rootRunUnary (dart:async/zone.dart:1134)
12 #11 _CustomZone.runUnary (dart:async/zone.dart:1031)
13 #12 _FutureListener.handleValue (dart:async/future_impl.dart:139)
14 #13 Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:680)
15 #14 Future._propagateToListeners (dart:async/future_impl.dart:709)
16 #15 Future._completeWithValue (dart:async/future_impl.dart:524)
17 #16 Future.wait.<anonymous closure> (dart:async/future.dart:400)
18 #17 _rootRunUnary (dart:async/zone.dart:1134)
19 #18 _CustomZone.runUnary (dart:async/zone.dart:1031)
20 #19 _FutureListener.handleValue (dart:async/future_impl.dart:139)
21 #20 Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:680)
22 #21 Future._propagateToListeners (dart:async/future_impl.dart:709)
23 #22 Future._completeWithValue (dart:async/future_impl.dart:524)
24 #23 Future._asyncComplete.<anonymous closure> (dart:async/future_impl.dart:554)
25 #24 _rootRun (dart:async/zone.dart:1126)
26 #25 _CustomZone.run (dart:async/zone.dart:1023)
27 #26 _CustomZone.runGuarded (dart:async/zone.dart:925)
28 #27 _CustomZone.bindCallbackGuarded.<anonymous closure> (dart:async/zone.dart:965)
29 #28 _microtaskLoop (dart:async/schedule_microtask.dart:43)
30 #29 _startMicrotaskLoop (dart:async/schedule_microtask.dart:52)

(ScrollablePositionedList) When alignment is 0, and I want to scroll to the last few items in list,it will have bounce effect

As the title describes, I hope that it has bounce effect when using my finger ,but when using ItemScrollController to scroll to bottom and aligment is 0, i dont want it has this effect......

[scrollable_positioned_list] Combine with the infinite_listview pacakge

Is it possible to combine the package with the infinite_listview package?
The features I'm looking to combine from the packages is the listener of the currently visible items in the list and the infinite scrolling.

Issue in the other package: #7

ScrollablePositionedList: every item gets rebuilt when adding an entry at 0

Every widget children widget gets rebuilt when adding a child at position 0.

If I try to add a child at the end of the list only the new widgets are built.

I tried to add a key, but it doesn't help.

ScrollablePositionedList: Use ScrollablePositionedList inside a CustomScrollVIew

It would be awesome to be able to use ScrollablePositionedList inside a CustomScrollView.
I am currently working on a MVP that uses Slivers for reading some content, and by using ScrollablePositionedList with another library, I would be able to save the position inside the content when the user has left the page on any device.

can not get 0.1.3 of scrollable_positioned_list

depends on scrollable_positioned_list ^0.1.3 which doesn't match any versions, version solving failed

ScrollablePositionedList: When an item is jumped or scroll to in a list in PageView, the position is not properly maintained when the pages are changed

ScrollablePositionedList: observe the ScrollablePositionedList offset

I'm not only need ScrollablePositionedList current scroll index, but also need to know current offset, what should I do

  itemPositionListener.itemPositions.addListener((positions) => {

    });

and , this will be error

ScrollablePositionedList scroll to last index will perform bounse effect

ScrollablePositionedList scroll to last index will perform bounse effect , indeed we need the list scrollto the end of widget

VisibilityDetector VisibilityFraction no longer 0 when new route slides on top

After upgrading to flutter_widgets: 0.1.6 to make it compatible with latest Flutter release, when sliding a route on top of the route with the visibility widget, is now still considered visible with fractions of ~ 0.8601489100280483, while in reality, should be zero.

When switching tabs or opening a root route, visible fraction is set to 0 as expected.

The route I'm pushing on top of the element is custom

import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';

class OBSlideRightRoute<T> extends PageRouteBuilder<T> {
  final Widget widget;
  final Key key;

  OBSlideRightRoute({this.widget, this.key})
      : super(
            opaque: false,
            transitionDuration: const Duration(milliseconds: 200),
            pageBuilder: (BuildContext context, Animation<double> animation,
                Animation<double> secondaryAnimation) {
              return Dismissible(
                  background: const DecoratedBox(decoration: const BoxDecoration(
                      color: Color.fromARGB(0, 0, 0, 0)
                  ),),
                  direction: DismissDirection.startToEnd,
                  onDismissed: (direction) {
                    Navigator.pop(context);
                  },
                  key: key,
                  child: Material(
                    child: widget,
                  ));
            },
            transitionsBuilder: (BuildContext context,
                Animation<double> animation,
                Animation<double> secondaryAnimation,
                Widget child) {
              return SlideTransition(
                  position: new Tween<Offset>(
                    begin: const Offset(1.0, 0.0),
                    end: Offset.zero,
                  ).animate(
                      CurvedAnimation(parent: animation, curve: Curves.fastOutSlowIn)),
                  child: child);
            });
}

`flutter run` doesn't work for the Gallery app

run script:

# cleanup
	cd $(FLU_EX_FSPATH) && flutter clean

	flutter emulators
	flutter emulators --launch apple_ios_simulator
	#flutter emulators --launch Pixel_2_API_28
	
	#cd $(FLU_EX_FSPATH) && flutter run -d all
	cd $(FLU_EX_FSPATH) && flutter run

Crash log:

Flutter crash report; please file at https://github.com/flutter/flutter/issues.

## command

flutter run

## exception

FileSystemException: FileSystemException: Cannot open file, path = '/Users/apple/workspace/go/src/github.com/google/flutter.widgets/gallery/ios/Runner.xcodeproj/project.pbxproj' (OS Error: No such file or directory, errno = 2)

```
#0      _File.open.<anonymous closure> (dart:io/file_impl.dart:364:9)
#1      _rootRunUnary (dart:async/zone.dart:1132:38)
#2      _CustomZone.runUnary (dart:async/zone.dart:1029:19)
#3      _FutureListener.handleValue (dart:async/future_impl.dart:126:18)
#4      Future._propagateToListeners.handleValueCallback (dart:async/future_impl.dart:639:45)
#5      Future._propagateToListeners (dart:async/future_impl.dart:668:32)
#6      Future._completeWithValue (dart:async/future_impl.dart:483:5)
#7      Future._asyncComplete.<anonymous closure> (dart:async/future_impl.dart:513:7)
#8      _rootRun (dart:async/zone.dart:1124:13)
#9      _CustomZone.run (dart:async/zone.dart:1021:19)
#10     _CustomZone.bindCallback.<anonymous closure> (dart:async/zone.dart:947:23)
#11     _microtaskLoop (dart:async/schedule_microtask.dart:41:21)
#12     _startMicrotaskLoop (dart:async/schedule_microtask.dart:50:5)
#13     _runPendingImmediateCallback (dart:isolate/runtime/libisolate_patch.dart:115:13)
#14     _RawReceivePortImpl._handleMessage (dart:isolate/runtime/libisolate_patch.dart:172:5)
```

## flutter doctor

```
�[32m[✓]�[39m Flutter (Channel dev, v1.2.0, on Mac OS X 10.14.3 18D42, locale en-DE)
    �[32m•�[39m Flutter version 1.2.0 at /Users/apple/workspace/flutter/flutter_macos_v0.2.8-beta/flutter
    �[32m•�[39m Framework revision 06b979c4d5 (7 days ago), 2019-01-25 14:27:35 -0500
    �[32m•�[39m Engine revision 36acd02c94
    �[32m•�[39m Dart version 2.1.1 (build 2.1.1-dev.3.2 f4afaee422)

�[33m[!]�[39m Android toolchain - develop for Android devices (Android SDK version 28.0.3)
    �[32m•�[39m Android SDK at /Users/apple/Library/Android/sdk
    �[32m•�[39m Android NDK location not configured (optional; useful for native profiling support)
    �[32m•�[39m Platform android-28, build-tools 28.0.3
    �[32m•�[39m ANDROID_HOME = /Users/apple/Library/Android/sdk
    �[32m•�[39m Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    �[32m•�[39m Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b01)
    �[31m✗�[39m Android license status unknown.

�[32m[✓]�[39m iOS toolchain - develop for iOS devices (Xcode 10.1)
    �[32m•�[39m Xcode at /Applications/Xcode.app/Contents/Developer
    �[32m•�[39m Xcode 10.1, Build version 10B61
    �[32m•�[39m ios-deploy 1.9.4
    �[32m•�[39m CocoaPods version 1.5.3

�[32m[✓]�[39m Android Studio (version 3.3)
    �[32m•�[39m Android Studio at /Applications/Android Studio.app/Contents
    �[32m•�[39m Flutter plugin version 32.0.1
    �[32m•�[39m Dart plugin version 182.5124
    �[32m•�[39m Java version OpenJDK Runtime Environment (build 1.8.0_152-release-1248-b01)

�[32m[✓]�[39m VS Code (version 1.30.2)
    �[32m•�[39m VS Code at /Applications/Visual Studio Code.app/Contents
    �[32m•�[39m Flutter extension version 2.22.3

�[32m[✓]�[39m Connected device (1 available)
    �[32m•�[39m iPhone 8 Plus • 356EB044-F3C1-45CA-9CEE-C5A5BCC933A0 • ios • iOS 12.1 (simulator)

�[33m!�[39m Doctor found issues in 1 category.
```

[VisibilityDetector] onVisibilityChanged not triggering when ListView children scrolled into view

I tried using VisibilityDetector inside a ListView thinking that it would trigger when items were scrolled into view, but that didn't reliably work. 😢

(I'm sorry, but I don't have time to debug this right now; at least, I will record this issue.)

ScrollablePositionedList: Adding highlight effect to the scrolled item after scroll_to/jump_to func

Is it possible to apply a highlight/shaking animation to the scrolled item after scroll/jump_to func? May be give some hints howto?

Using [ScrollablePositionedList] will report an error: 'minScrollExtent <= maxScrollExtent': is not true.

'package:flutter/src/widgets/scroll_position.dart': Failed assertion: line 457 pos 14: 'minScrollExtent <= maxScrollExtent': is not true.

My code

ScrollablePositionedList.builder(
        itemCount: dataList.length,
        itemBuilder: (context, i) {
          if (dataList.isEmpty) return Container();

          return Padding(
            padding: const EdgeInsets.only(bottom: 5.0),
            child: Row(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: <Widget>[
                Text("${dataList[i].roleName}："),
                dataList[i].imgUrl == null
                    ? Flexible(
                        child: Text(dataList[i].text),
                      )
                    : Flexible(
                        child: CachedNetworkImage(imageUrl: dataList[i].imgUrl),
                      )
              ],
            ),
          );
        },
        itemScrollController: itemScrollController,
      )

Allow alignment outside of 0..1 in ScrollablePositionedList

[linked_scroll_controller] How to add unique keys to scrollables when linking dynamically?

If you add controllers dynamically, the corresponding scrollables must be given unique keys to avoid the scroll offset going out of sync.

LinkedScrollControllerGroup controllers;
List scrollCTRLList;  

createAndLinkControllers(count) {
    for (var i = 0; i < count; i++) {
      var scrollControllerInstance = ScrollController();
      scrollControllerInstance = controllers.addAndGet();
      scrollCTRLList.add(scrollControllerInstance);
    }
  }

I have been building a custom data table widget for FlutterWeb use in particular. It can be scrolled in both directions. There is a single ListView.builder (for horizontal scrolling) and it holds dynamically added ListView.builders (for vertical scrolling as columns).

I've just figured out that the vertical scrollers go out of sync, unfortunately. It happens when some vertical ListView.builders are out of the visible area.

As I said, I can scroll horizontally. For example, 0-1-2-3-4 columns are visible. I scroll down to an arbitrary point such as somewhere near the 250th row. Then I scroll to right to see the 3-4-5-6 columns. The columns 5-6 were invisible until I scroll. At that moment they are out of sync.

If I then scroll up or down they become in sync immediately.

How can I solve that?

Is this project abandoned ?

@tvolkert
No commits since initial commit on Sep 2017. Is this project abandoned or moved to another repo ?

ScrollablePositionedList: Not scrolling to the position

I have a list where i have dynamic row sizes. When i use jump to method it works perfectly but it's not smooth . So i tried using scroll To but it scrolls to a certain distance and then stops. It doesn't animate to the specific index . Also can you add more animations to this package.

ScrollablePositionedList: Support for ScrollablePositionedList.separated?

Is it possible to get a ScrollablePositionedList equivalent for ListView.separated? Sure, it is possible to optionally build the separator within the itembuilder, but would be a nice feature to have, thanks!

The last item should be this bottom of screen when jumping to the end of the list by using ScrollablePositionedList

C:\Users\ad>flutter doctor
Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, v1.9.1+hotfix.4, on Microsoft Windows [Version 10.0.18362.356], locale zh-CN)
[√] Android toolchain - develop for Android devices (Android SDK version 29.0.2)
[√] Android Studio (version 3.5)
[√] Connected device (1 available)

jump last item code：
Widget get jumpControlButtons => Row( children: <Widget>[ const Text('jump to'), jumpButton(0), jumpButton(5), jumpButton(10), jumpButton(100), //jumpButton(1000), jumpButton(numberOfItems-1), ], );
it should be：

not this:

Question: Try to recover the state of ScrollablePositionedList

I want to save the offset for a ScrollablePositionedList and recover it if the state has disposed and init again.
I noticed there are two parameters to do the jumping, one is the 'index' and the other one is 'alignment'.
And I found there are 'itemLeadingEdge' and 'itemTrailingEdge' in the ItemPosition from the ItemPositionsListener, which are likely the same thing as alignment.
But I'm not sure which one to use. I did some test about it, which makes me more confused.

The first question is about the index. I try to jump to index 0, but the index from the ItemPosition is 6. I don't know if it's an inner variable or not. Can I save it and use it when recovering the List? Like jumpTo(index:6) to recover the actual index 0?

The second question is about alignment. It is limited from 0.0 to 1.0. I noticed the itemLeadingEdge could be negative so it cannot be used directly. itemTrailingEdge is always positive but it can be more than 1.0. I also noticed that itemTrailingEdge minus itemLeadingEdge is always the same - maybe it represents as the item height?

I tried to use above parameters to do the recover. It seems that I can go to the same offset, but the index is 1 right before the actual index.
I'm currently digging the code deeper to find out what happened, but it would be more helpful to know the idea of these parameters.

Thank you!

@tarobins

VisibilityDetector not working with AppLifecycleState

When my app go to background or come back to foreground, nothing is called in VisibilityDetector. Is there any way to do this?

ScrollablePositionedList: Provide shrinkWrap

This is required when adding ScrollablePositionedList in a BottomSheet.
Currently it expands fully with a lot of white spaces.