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:

sticky_grouped_list: ^3.1.0

In your dart file, import the library:

import 'package:sticky_grouped_list/sticky_grouped_list.dart';

Create a StickyGroupedListView Widget:

 final GroupedItemScrollController itemScrollController = GroupedItemScrollController();

 StickyGroupedListView<dynamic, String>(
   elements: _elements,
   groupBy: (dynamic element) => element['group'],
   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
   order: StickyGroupedListOrder.ASC, // optional
 );

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();

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

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

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 an 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	required	-
groupSeparatorBuilder	Function which gets a element and returns an Widget which defines the group header separator	required	-
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

GroupedItemScrollController.srollTo() and GroupedItemScrollController.jumpTo() automatic set the alignment so that the item is fully visible aligned under the group header. Both methods take automaticAlignment as a additional optional paramenter 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 StickyGroupedListOrder.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.

Difference between grouped_list and sticky_grouped_list:

TThe list views in the GroupedList package are based on the default flutter listview and the silver list. This package is based on the scrollable_positioned_list which enables the possibility to programatically scroll to certain positions in the list. So if you need the ability to programatically scroll the list use the this package otherwise I would recommend to use the GroupedList package.

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