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Acknowledgements

This package is originally based on the excellent work from Dimibe/sticky_grouped_list (which has not been updated for over a year) and also incorporates changes from th8m0z/sticky_grouped_list. We would like to express our sincere respect and gratitude to the original authors and contributors of these repositories.

Key Features and Enhancements Added in This Package:

• Added onGroupChanged callback to StickyGroupedListView for tracking group changes during scrolling.
• groupSeparatorBuilder is now an optional parameter, allowing for more flexible usage.
• Extended ItemPositionsListener with topItemIndex and lastItemIndex support for advanced scroll tracking.
• Improved performance.
• Variable item and group separator heights now supported.

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A ListView in which list items can be grouped to sections. Based on scrollable_positioned_list, which enables programatically scrolling of the list.

Features

• Easy creation of chat-like interfaces.
• List items can be separated in groups.
• For the groups an individual header can be set.
• Sticky headers with floating option.
• All fields from ScrollablePositionedList available.

Getting Started

Add the package to your pubspec.yaml:

advanced_grouped_list: ^1.0.3

In your dart file, import the library:

import 'package:advanced_grouped_list/advanced_grouped_list.dart';

Create a AdvancedGroupedListView Widget:

 final GroupedItemScrollController itemScrollController = GroupedItemScrollController();
 final ItemPositionsListener itemPositionsListener = ItemPositionsListener.create();

 AdvancedGroupedListView<dynamic, String>(
   elements: _elements,
   // groupBy is now optional
   // You can omit it if you don't need group headers
   groupBy: (dynamic element) => element['group'],
   // groupSeparatorBuilder is now optional
   // You can omit it if you don't need group headers
   groupSeparatorBuilder: (dynamic element) => Text(element['group']),
   itemBuilder: (context, dynamic element) => Text(element['name']),
   itemComparator: (e1, e2) => e1['name'].compareTo(e2['name']), // optional
   elementIdentifier: (element) => element.name, // optional - see below for usage
   itemScrollController: itemScrollController, // optional
   itemPositionsListener: itemPositionsListener, // optional
   order: AdvancedGroupedListOrder.ASC, // optional
   // New: onGroupChanged callback
   onGroupChanged: (group) {
     // Called when the top visible group changes
     print('Current group: $group');
   },
 );

If you are using the GroupedItemScrollController you can scroll or jump to an specific position in the list programatically:

1. By using the index, which will scroll to the element at position index:

  itemScrollController.scrollTo(index: 4, duration: Duration(seconds: 2));
  itemScrollController.jumpTo(index: 4);

2. By using a pre defined element identifier. The identifier is defined by a Function which takes one element and returns a unique identifier of any type. The methods scrollToElement and jumpToElement can be used to jump to an element by providing the elements identifier instead of the index:

  final GroupedItemScrollController itemScrollController = GroupedItemScrollController();

  AdvancedGroupedListView<dynamic, String>(
    elements: _elements,
    elementIdentifier: (element) => element.name
    itemScrollController: itemScrollController, 
    [...]
  );

  itemScrollController.scrollToElement(identifier: 'item-1', duration: Duration(seconds: 2));
  itemScrollController.jumpToElement(identifier: 'item-2');

Example: Using topItemIndex and lastItemIndex with minVisibility

final topIndex = itemPositionsListener.topItemIndex();
final lastIndex = itemPositionsListener.lastItemIndex(minVisibility: 0.5); // consider as visible if at least 50% of the item is visible on the screen

Parameters:

Name	Description	Required	Default value
elements	A list of the data you want to display in the list	required	-
itemBuilder / indexedItemBuilder	Function which returns a Widget which defines the item. indexedItemBuilder provides the current index as well. If both are defined indexedItemBuilder is preferred	yes, either of them	-
groupBy	Function which maps an element to its grouped value. Now optional	no	-
groupSeparatorBuilder	Function which gets an element and returns a Widget which defines the group header separator. Now optional	no	-
separator	A Widget which defines a separator between items inside a group	no	no separator
floatingHeader	When set to true the sticky header will float over the list	no	false
stickyHeaderBackgroundColor	Defines the background color of the sticky header	no	Color(0xffF7F7F7)
itemScrollController	Instead of an ItemScrollController a GroupedItemScrollController needs to be provided.	no	-
elementIdentifier	Used by itemScrollController and defines the unique identifier for each element.	no	-
order	Change to StickyGroupedListOrder.DESC to reverse the group sorting	no	StickyGroupedListOrder.ASC
groupComparator	Can be used to define a custom sorting for the groups. Otherwise the natural sorting order is used	no	-
itemComparator	Can be used to define a custom sorting for the elements inside each group. Otherwise the natural sorting order is used	no	-
reverse	Scrolls in opposite from reading direction (Starting at bottom and scrolling up). Same as in scrollable_positioned_list.	no	false
onGroupChanged	Callback that is called when the top visible group changes. Receives the group value as a parameter.	no	-
scrollOffsetController	Controller to programmatically control and listen to the scroll offset of the list.	no	-
scrollOffsetListener	Listener that receives updates about the current scroll offset.	no	-
itemPositionsListener	Provides access to the current item positions in the list. Enables advanced scroll tracking, including topItemIndex and lastItemIndex with optional minVisibility.	no	-

GroupedItemScrollController.srollTo() and GroupedItemScrollController.jumpTo() automatically set the alignment so that the item is fully visible aligned under the group header. Both methods take automaticAlignment as an additional optional parameter which needs to be set to true if alignment is specified.

Also the fields from ScrollablePositionedList.builder can be used.

Highlight - Chat Dialog

Easy creation of chat-like dialogs. Just set the option reverse to true and the option order to AdvancedGroupedListOrder.DESC. A full example can be found in the examples. The list will be scrolled to the end in the initial state and therefore scrolling will be against redeaing direction.

Used packages:

Package name	Copyright	License
scrollable_positioned_list	Copyright 2018 the Dart project authors, Inc. All rights reserved	BSD 3-Clause "New" or "Revised" License
sticky_grouped_list	Copyright 2022 Dimitrios Begnis. All rights reserved	BSD 3-Clause "New" or "Revised" License