I'm using the scrollable_positioned_list package, and have it rendering a large dynamic list. It works very well. However, I need my list to have a scrollbar (something like this). So far, this is impossible.
Does anyone know how to do it?
My code looks as follows:
Scrollbar( child: ScrollablePositionedList.builder( physics: const ClampingScrollPhysics( parent: AlwaysScrollableScrollPhysics(), ), itemCount: posts.length + 1, itemBuilder: (context, index) { if (index == 0) { return Container( height: 200, color: Colors.green, child: const Center( child: Text('post content'), ), ); } else if (posts[index - 1].isRoot) { return Container( padding: const EdgeInsets.symmetric(vertical: 15), margin: const EdgeInsets.symmetric(vertical: 5), color: Colors.redAccent, child: Text('ROOT COMMENT, index: ${index - 1}'), ); } else { return Container( padding: const EdgeInsets.symmetric(vertical: 15), margin: const EdgeInsets.symmetric(vertical: 5), color: Colors.lightBlueAccent, child: Text('Threaded comment, index: ${index - 1}'), ); } }, itemScrollController: itemScrollController, itemPositionsListener: itemPositionsListener, ), ),I realize a ScrollBar needs to have the same ScrollController as the scroll view it's wrapping, however, I'm not sure how to get this because ScrollablePositionedList doesn't have a ScrollController.
Errors in my terminal after running the project with the solution provided (little snippet of it):
Performing hot restart... ../../tools/flutter/.pub-cache/git/flutter.widgets-6d6dac5f19b577338d912d3c9a45d26593e0a475/packages/scrollable_positioned_list/lib/src/scrollable_positioned_list.dart:437:24: Warning: Operand of null-awareoperation '!' has type 'SchedulerBinding' whichexcludes null.Performing hot restart... - 'SchedulerBinding' is from'package:flutter/src/scheduler/binding.dart' ('../../tools/flutter/packages/flutter/lib/src/sche duler/binding.dart').Performing hot restart... SchedulerBinding.instance!.addPostFrameCallbac k((_) {Performing hot restart... ^Performing hot restart... ../../tools/flutter/.pub-cache/git/flutter.widgets-6d6dac5f19b577338d912d3c9a45d26593e0a475/packages/scrollable_positioned_list/lib/src/scrollable_positioned_list.dart:484:26: Warning: Operand of null-awareoperation '!' has type 'SchedulerBinding' whichexcludes null.Performing hot restart... - 'SchedulerBinding' is from'package:flutter/src/scheduler/binding.dart' ('../../tools/flutter/packages/flutter/lib/src/sche duler/binding.dart').Performing hot restart... SchedulerBinding.instance!.addPostFrameCallb ack((_) {Performing hot restart... ^Performing hot restart... ../../tools/flutter/.pub-cache/git/flutter.widgets-6d6dac5f19b577338d912d3c9a45d26593e0a475/packages/scrollable_positioned_list/lib/src/positioned_list.dart:298:24: Warning: Operand of null-aware operation'!' has type 'SchedulerBinding' which excludes null.Performing hot restart... - 'SchedulerBinding' is from'package:flutter/src/scheduler/binding.dart' ('../../tools/flutter/packages/flutter/lib/src/sche duler/binding.dart').Performing hot restart... SchedulerBinding.instance!.addPostFrameCallbac k((_) {Performing hot restart... ^Performing hot restart... Restarted application in 195ms.After fixing the warnings (reply to comment), this now occurs randomly when using it:
The following assertion was thrown while notifying status listeners for AnimationController:The Scrollbar's ScrollController has no ScrollPosition attached.A Scrollbar cannot be painted without a ScrollPosition.The Scrollbar attempted to use the provided ScrollController. This ScrollController should beassociated with the ScrollView that the Scrollbar is being applied to. When providing yourownScrollController, ensure both the Scrollbar and the Scrollable widget use the same one.When the exception was thrown, this was the stack:#0 RawScrollbarState._debugCheckHasValidScrollPosition.<anonymous closure>(package:flutter/src/widgets/scrollbar.dart:1475:9)#1 RawScrollbarState._debugCheckHasValidScrollPosition(package:flutter/src/widgets/scrollbar.dart:1500:6)#2 RawScrollbarState._validateInteractions(package:flutter/src/widgets/scrollbar.dart:1445:14)#3 AnimationLocalStatusListenersMixin.notifyStatusListeners(package:flutter/src/animation/listener_helpers.dart:233:19)#4 AnimationController._checkStatusChanged(package:flutter/src/animation/animation_controller.dart:815:7)#5 AnimationController._startSimulation(package:flutter/src/animation/animation_controller.dart:749:5)#6 AnimationController._animateToInternal(package:flutter/src/animation/animation_controller.dart:612:12)#7 AnimationController.reverse(package:flutter/src/animation/animation_controller.dart:494:12)#8 RawScrollbarState._maybeStartFadeoutTimer.<anonymous closure>(package:flutter/src/widgets/scrollbar.dart:1630:37)(elided 11 frames from class _RawReceivePortImpl, class _Timer, dart:async, anddart:async-patch)The AnimationController notifying status listeners was: AnimationController#72402(◀ 1.000)