flutter-quill/example/lib/pages/read_only_page.dart

import 'package:flutter/material.dart';
import 'package:flutter_quill/widgets/controller.dart';
import 'package:flutter_quill/widgets/editor.dart';

import '../widgets/demo_scaffold.dart';

class ReadOnlyPage extends StatefulWidget {
  @override
  _ReadOnlyPageState createState() => _ReadOnlyPageState();
}

class _ReadOnlyPageState extends State<ReadOnlyPage> {
  final FocusNode _focusNode = FocusNode();

  bool _edit = false;

  @override
  Widget build(BuildContext context) {
    return DemoScaffold(
      documentFilename: 'sample_data.json',
      builder: _buildContent,
      showToolbar: _edit == true,
      floatingActionButton: FloatingActionButton.extended(
          label: Text(_edit == true ? 'Done' : 'Edit'),
          onPressed: _toggleEdit,
          icon: Icon(_edit == true ? Icons.check : Icons.edit)),
    );
  }

  Widget _buildContent(BuildContext context, QuillController? controller) {
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: Container(
        decoration: BoxDecoration(
          color: Colors.white,
          border: Border.all(color: Colors.grey.shade200),
        ),
        child: QuillEditor(
          controller: controller!,
          scrollController: ScrollController(),
          scrollable: true,
          focusNode: _focusNode,
          autoFocus: true,
          readOnly: !_edit,
          enableInteractiveSelection: true,
          expands: false,
          padding: EdgeInsets.zero,
        ),
      ),
    );
  }

  void _toggleEdit() {
    setState(() {
      _edit = !_edit;
    });
  }
}