custom_embed_blocks.md

Custom Embed Blocks

Sometimes you want to add some custom content inside your text, custom widgets inside of them. An example is adding notes to the text, or anything custom that you want to add in your text editor.

The only thing that you need is to add a CustomBlockEmbed and provide a builder for it to the embedBuilders parameter, to transform the data inside of the Custom Block into a widget!

Here is an example:

Starting with the CustomBlockEmbed, here we extend it and add the methods that are useful for the 'Note' widget, which will be the Document, used by the flutter_quill to render the rich text.

class NotesBlockEmbed extends CustomBlockEmbed {
  const NotesBlockEmbed(String value) : super(noteType, value);

  static const String noteType = 'notes';

  static NotesBlockEmbed fromDocument(Document document) =>
      NotesBlockEmbed(jsonEncode(document.toDelta().toJson()));

  Document get document => Document.fromJson(jsonDecode(data));
}

After that, we need to map this "notes" type into a widget. In that case, I used a ListTile with a text to show the plain text resume of the note, and the onTap function to edit the note. Don't forget to add this method to the QuillEditor after that!

class NotesEmbedBuilder extends EmbedBuilder {
  NotesEmbedBuilder({required this.addEditNote});

  Future<void> Function(BuildContext context, {Document? document}) addEditNote;

  @override
  String get key => 'notes';

  @override
  Widget build(
    BuildContext context,
    QuillController controller,
    Embed node,
    bool readOnly,
    bool inline,
    TextStyle textStyle,
  ) {
    final notes = NotesBlockEmbed(node.value.data).document;

    return Material(
      color: Colors.transparent,
      child: ListTile(
        title: Text(
          notes.toPlainText().replaceAll('\n', ' '),
          maxLines: 3,
          overflow: TextOverflow.ellipsis,
        ),
        leading: const Icon(Icons.notes),
        onTap: () => addEditNote(context, document: notes),
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(10),
          side: const BorderSide(color: Colors.grey),
        ),
      ),
    );
  }
}

And finally, we write the function to add/edit this note. The showDialog function shows the QuillEditor to edit the note after the user ends the edition, we check if the document has something, and if it has, we add or edit the NotesBlockEmbed inside of a BlockEmbed.custom (this is a little detail that will not work if you don't pass the CustomBlockEmbed inside of a BlockEmbed.custom).

Future<void> _addEditNote(BuildContext context, {Document? document}) async {
  final isEditing = document != null;
  final quillEditorController = QuillController(
    document: document ?? Document(),
    selection: const TextSelection.collapsed(offset: 0),
  );

  await showDialog(
    context: context,
    builder: (context) => AlertDialog(
      titlePadding: const EdgeInsets.only(left: 16, top: 8),
      title: Row(
        mainAxisAlignment: MainAxisAlignment.spaceBetween,
        children: [
          Text('${isEditing ? 'Edit' : 'Add'} note'),
          IconButton(
            onPressed: () => Navigator.of(context).pop(),
            icon: const Icon(Icons.close),
          )
        ],
      ),
      content: QuillEditor.basic(
        configurations: const QuillEditorConfigurations(
          controller: quillEditorController,
          readOnly: false,
        ),
      ),
    ),
  );

  if (quillEditorController.document.isEmpty()) return;

  final block = BlockEmbed.custom(
    NotesBlockEmbed.fromDocument(quillEditorController.document),
  );
  final controller = _controller!;
  final index = controller.selection.baseOffset;
  final length = controller.selection.extentOffset - index;

  if (isEditing) {
    final offset = getEmbedNode(controller, controller.selection.start).offset;
    controller.replaceText(
        offset, 1, block, TextSelection.collapsed(offset: offset));
  } else {
    controller.replaceText(index, length, block, null);
  }
}

And voila, we have a custom widget inside of the rich text editor!

1. For more info and a video example, see the PR of this feature
2. For more details, check out this YouTube video