flutter_quill : How to handle changes to a QuillEditor

I want to if QuillController().document.isEmpty() is false, button is active. otherwise, true make button is inactive. this code make user can not write content in quillEditor. I think setState((){}) is problem. because, I delete setState, user can write content, but button is not change by QuillController().document.isEmpty()

@override
void initState(){
super.initState();
_contentEditingController = QuillController(
          document: Document(),
          selection: const TextSelection.collapsed(offset: 0),
          onSelectionChanged: (data) {
            if (_titleEditingController.text.isEmpty ||
                _contentEditingController.document.isEmpty()) {
              _isButtonActive = false;
            } else {
              _isButtonActive = true;
            }
            setState(() {});
          });}

or

Widget _contentContainer() {
    _contentEditingController.document.changes.listen((event) {
      if (_titleEditingController.text.isEmpty ||
          _contentEditingController.document.isEmpty()) {
        setState(() => _isButtonActive = false);
      } else {
        setState(() => _isButtonActive = true);
      }
    });
    return Expanded(
        child: Scrollbar(
      controller: _scrollController,
      child: QuillEditor(
        controller: _contentEditingController,
        scrollController: _scrollController,
        scrollable: true,
        expands: true,
        readOnly: false,
        focusNode: FocusNode(),
        autoFocus: false,
        padding: EdgeInsets.symmetric(horizontal: 15.0.w, vertical: 10.0.h),
        placeholder: "내용을 입력해주세요",
      ),
    ));
  }