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Overview

The CometChatMentionsFormatter class is a part of the CometChat UI Kit, a ready-to-use chat UI widget library for integrating CometChat into your Android applications. This class provides functionality to format mentions within text messages displayed in the chat interface. Mentions allow users to reference other users within a conversation, providing a convenient way to direct messages or involve specific participants.
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Features

  • Mention Formatting: Automatically formats mentions within text messages based on provided styles and settings.
  • Customizable Styles: Allows customization of text styles for mentions, including colors, fonts, and background colors.
  • User and Group Member Mentions: Supports mentions for both individual users and group members, providing flexibility in communication scenarios.
  • Mention List Generation: Generates a list of suggested mentions based on user input, facilitating easy selection of recipients during message composition.
  • Mention Click Handling: Provides a listener interface for handling click events on mentions, enabling custom actions to be performed when a mention is tapped by the user.

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Usage

To integrate the CometChatMentionsFormatter class into your application:
  1. Initialization: Create an instance of the CometChatMentionsFormatter class and configure it with desired settings, such as mention text styles and limit settings.
  2. Set Mention Listeners: Set listeners for handling mention click events (setOnMentionClick).
  3. Format Messages: Use the prepareLeftMessageBubbleSpan, prepareRightMessageBubbleSpan, prepareComposerSpan, and prepareConversationSpan methods to format text messages with mentions appropriately for display in the chat interface.
  4. Customization: Customize the appearance and behavior of mentions by adjusting the text styles, colors, and other formatting properties as needed.
Below is an example demonstrating how to use the CometChatMentionsFormatter class in widgets such as CometChatConversations, CometChatMessageList, CometChatMessageComposer. 
textFormatters: [
    CometChatMentionsFormatter(
      messageBubbleTextStyle: (theme, alignment,{forConversation = false}) => 
        TextStyle(
            color: alignment==BubbleAlignment.left? Colors.orange : Colors.pink,
            fontSize: 14,
            fontWeight: FontWeight.bold
        ),
    )
]

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Actions

Actions dictate how a widget functions. They are divided into two types: Predefined and User-defined. You can override either type, allowing you to tailor the behavior of the widget to fit your specific needs.
onMentionTap
Setting a listener for mention-click events in Message Bubbles enhances interactivity within the chat. This listener is activated when a mention is clicked, returning the corresponding user object. This feature transforms mentions into interactive links, enabling more in-depth and contextual engagement with the user associated with the clicked mention. 
CometChatMessages(
  user: user,
  messageListConfiguration: MessageListConfiguration(
      textFormatters: [
        CometChatMentionsFormatter(
          onMentionTap: (mention, mentionedUser, {message}) {
            final snackBar = SnackBar(
              content: const Text('Tap on Mentioned User', style: TextStyle(color: Colors.lightBlueAccent)),
              action: SnackBarAction(
                label: 'Undo',
                onPressed: () {
                  // TODO("Not yet implemented")
                },
              ),
            );
            ScaffoldMessenger.of(context).showSnackBar(snackBar);
          },
          messageBubbleTextStyle: (theme, alignment,{forConversation = false}) => TextStyle(
              color: alignment==BubbleAlignment.left? Colors.orange : Colors.greenAccent,
              fontSize: 14,
              fontWeight: FontWeight.bold
          ),
        )
      ]
  ),
)
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Customization

PropertyDescriptionCode
trackingCharacterThe character that triggers the mention search.String? trackingCharacter
patternThe regex pattern to identify mentions.RegExp? pattern
showLoadingIndicatorWhether to show a loading indicator during mention search.bool? showLoadingIndicator
onSearchCallback function to perform search when mention is triggered.void Function(String)? onSearch
onErrorCallback function to handle errors during mention search.void Function(String)? onError
themeThe theme for styling the mentions formatter.ThemeData? theme
messageThe message in which mentions are to be formatted.String? message
messageBubbleTextStyleThe text style for the message bubble.TextStyle? messageBubbleTextStyle
messageInputTextStyleThe text style for the message input.TextStyle? messageInputTextStyle
composerIdThe unique identifier for the composer.String? composerId
suggestionListEventSinkThe event sink for the suggestion list.EventSink<List<User>>? suggestionListEventSink
previousTextEventSinkThe event sink for the previous text before mention.EventSink<String>? previousTextEventSink
userThe user to be mentioned.User? user
groupThe group in which mentions are to be formatted.Group? group
groupMembersRequestBuilderThe request builder for fetching group members to mention.GroupMembersRequestBuilder? groupMembersRequestBuilder
usersRequestBuilderThe request builder for fetching users to mention.UsersRequestBuilder? usersRequestBuilder
mentionsTypeThe type of mentions (e.g., user, group).MentionsType? mentionsType
onMentionTapCallback function to handle mention tap actions.void Function(User)? onMentionTap
visibleInDefines where the mentions are visible.Set<ComposerMentionVisibility>? visibleIn

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Advance

For advanced-level customization, you can set the style of the Mentions formatters. This lets you tailor each aspect of the widget to fit your exact needs and application aesthetics. You can create and define your formatters style.

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Composer Mention Text Style

Assigns the list of text formatters. If the provided list is not null, it sets the list. Otherwise, it assigns the default text formatters retrieved from the data source. To configure the existing Mentions look and feel for CometChatMessageComposer refer to the below code snippet 
CometChatMessages(
    user: user,
    messageComposerConfiguration: MessageComposerConfiguration(
        textFormatters: [
            CometChatMentionsFormatter(
                messageInputTextStyle: (theme) {
                    return const TextStyle(
                    color: Colors.lightBlueAccent,
                    fontSize: 14,
                    fontWeight: FontWeight.bold
                );
            },
        )
        ]
    )
)
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Message Bubble Mention Text Style

Assigns the list of text formatters. If the provided list is not null, it sets the list. Otherwise, it assigns the default text formatters retrieved from the data source. To configure the existing Mentions look and feel for CometChatMessageList 
CometChatMessages(
  user: user,
  messageListConfiguration: MessageListConfiguration(
      textFormatters: [
        CometChatMentionsFormatter(
          messageBubbleTextStyle: (theme, alignment,{forConversation = false}) => TextStyle(
              color: alignment==BubbleAlignment.left? Colors.orange : Colors.greenAccent,
              fontSize: 14,
              fontWeight: FontWeight.bold
          ),
        )
      ]
  ),
)
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Conversations Mention Text Style

Assigns the list of text formatters. If the provided list is not null, it sets the list. Otherwise, it assigns the default text formatters retrieved from the data source. To configure the existing Mentions look and feel for CometChatConversations 
CometChatConversations(
  textFormatters: [
    CometChatMentionsFormatter(
      messageBubbleTextStyle: (theme, alignment,{forConversation = false}) =>
          const TextStyle(
              color: Colors.lightBlueAccent,
              fontSize: 14,
              fontWeight: FontWeight.bold
          ),
    )
  ],
)
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