Flutter DropdownButton2

Intro

Flutter's core Dropdown Button widget with a steady dropdown menu and many other options you can customize to your needs.

• Features
• Options
• Installation
• Usage and Examples
  • 1. Simple DropdownButton2 with no styling
  • 2. DropdownButton2 with few styling and customization
  • 3. DropdownButton2 with separator widgets like dividers
  • 4. DropdownButton2 as Multiselect Dropdown with Checkboxes
  • 5. DropdownButton2 as Searchable Dropdown
  • 6. DropdownButton2 as Popup menu button using customButton parameter
  • 7. Using DropdownButtonFormField2 with Form
• CustomDropdownButton2 Widget "customize it to your needs"

Features

• Dropdown menu always open below the button "as long as it's possible otherwise it'll open to the end of the screen" and you can edit its position by using the offset parameter.
• You can control how (button, button's icon, dropdown menu and menu items) will be displayed "read Options below".
• You can align (hint & value) and customize them.
• You can edit the scrollbar's radius,thickness and isAlwaysShow.
• You can set max height for the dropdown menu & it'll become scrollable if there are more items.
• If you pass Null to dropdownMaxHeight parameter or didn't use it, the dropdown menu will take max height possible for the items and will become scrollable if there are more items.
• If you have long scrollable list, the dropdown menu will auto scroll to current selected item and show it at the middle of the menu if possible.
• Wrap DropdownButton2 with DropdownButtonHideUnderline to hide the underline.
• A Custom widget of the DropdownButton2 below to make it more reusable. You can customize it to your needs and use it throughout all your app easily as shown in the examples.
• You can use DropdownButton2 with items of different heights like dividers as shown in the examples.
• You can use DropdownButton2 as Multiselect Dropdown with Checkboxes as shown in the examples.
• You can use DropdownButton2 as Searchable Dropdown as shown in the examples.
• You can use DropdownButton2 as a popup menu button by using the parameter customButton. You can pass Icon,Image or any widget and customize it as shown in the examples.
• You can also use DropdownButtonFormField2 the same way with all options above and use it inside Form as shown in the examples.
• Use decoration parameter for the DropdownButtonFormField2 to add borders, label and more.
• You can customize DropdownButtonFormField2 width by wrapping it with Padding or with SizedBox and give it the width you want.

Options

DropdownButton2:

Subclass ButtonStyleData:

Subclass IconStyleData:

Subclass DropdownStyleData:

Subclass MenuItemStyleData:

Subclass DropdownSearchData:

DropdownButtonFormField2 (In addition to the above):

Installation

add this line to pubspec.yaml

dependencies:
  dropdown_button2: ^3.1.0

import package

import 'package:dropdown_button2/dropdown_button2.dart';

Usage and Examples

1. Simple DropdownButton2 with no styling:

final List<String> items = [
  'Item1',
  'Item2',
  'Item3',
  'Item4',
];
final valueListenable = ValueNotifier<String?>(null);

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Center(
      child: DropdownButtonHideUnderline(
        child: DropdownButton2<String>(
          isExpanded: true,
          hint: Text(
            'Select Item',
            style: TextStyle(
              fontSize: 14,
              color: Theme.of(context).hintColor,
            ),
          ),
          items: items
              .map(
                (String item) => DropdownItem<String>(
                  value: item,
                  height: 40,
                  child: Text(
                    item,
                    style: const TextStyle(
                      fontSize: 14,
                    ),
                  ),
                ),
              )
              .toList(),
          valueListenable: valueListenable,
          onChanged: (String? value) {
            valueListenable.value = value;
          },
          buttonStyleData: const ButtonStyleData(
            padding: EdgeInsets.symmetric(horizontal: 16),
            height: 40,
            width: 140,
          ),
        ),
      ),
    ),
  );
}

2. DropdownButton2 with few styling and customization:

final List<String> items = [
  'Item1',
  'Item2',
  'Item3',
  'Item4',
  'Item5',
  'Item6',
  'Item7',
  'Item8',
];
final valueListenable = ValueNotifier<String?>(null);

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Center(
      child: DropdownButtonHideUnderline(
        child: DropdownButton2<String>(
          isExpanded: true,
          hint: const Row(
            children: [
              Icon(
                Icons.list,
                size: 16,
                color: Colors.yellow,
              ),
              SizedBox(
                width: 4,
              ),
              Expanded(
                child: Text(
                  'Select Item',
                  style: TextStyle(
                    fontSize: 14,
                    fontWeight: FontWeight.bold,
                    color: Colors.yellow,
                  ),
                  overflow: TextOverflow.ellipsis,
                ),
              ),
            ],
          ),
          items: items
              .map(
                (String item) => DropdownItem<String>(
                  value: item,
                  height: 40,
                  child: Text(
                    item,
                    style: const TextStyle(
                      fontSize: 14,
                      fontWeight: FontWeight.bold,
                      color: Colors.white,
                    ),
                    overflow: TextOverflow.ellipsis,
                  ),
                ),
              )
              .toList(),
          valueListenable: valueListenable,
          onChanged: (value) {
            valueListenable.value = value;
          },
          buttonStyleData: ButtonStyleData(
            height: 50,
            width: 160,
            padding: const EdgeInsets.only(left: 14, right: 14),
            decoration: BoxDecoration(
              borderRadius: BorderRadius.circular(14),
              border: Border.all(
                color: Colors.black26,
              ),
              color: Colors.redAccent,
            ),
            elevation: 2,
          ),
          iconStyleData: const IconStyleData(
            icon: Icon(
              Icons.arrow_forward_ios_outlined,
            ),
            iconSize: 14,
            iconEnabledColor: Colors.yellow,
            iconDisabledColor: Colors.grey,
          ),
          dropdownStyleData: DropdownStyleData(
            maxHeight: 200,
            width: 200,
            decoration: BoxDecoration(
              borderRadius: BorderRadius.circular(14),
              color: Colors.redAccent,
            ),
            offset: const Offset(-20, 0),
            scrollbarTheme: ScrollbarThemeData(
              radius: const Radius.circular(40),
              thickness: WidgetStateProperty.all(6),
              thumbVisibility: WidgetStateProperty.all(true),
            ),
          ),
          menuItemStyleData: const MenuItemStyleData(
            padding: EdgeInsets.only(left: 14, right: 14),
          ),
        ),
      ),
    ),
  );
}

3. DropdownButton2 with separator widgets like dividers:

final List<String> items = [
  'Item1',
  'Item2',
  'Item3',
  'Item4',
];
final valueListenable = ValueNotifier<String?>(null);

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Center(
      child: DropdownButtonHideUnderline(
        child: DropdownButton2<String>(
          isExpanded: true,
          hint: Text(
            'Select Item',
            style: TextStyle(
              fontSize: 14,
              color: Theme.of(context).hintColor,
            ),
          ),
          items: items
              .map(
                (String item) => DropdownItem<String>(
                  value: item,
                  height: 40,
                  child: Padding(
                    padding: const EdgeInsets.symmetric(horizontal: 8.0),
                    child: Text(
                      item,
                      style: const TextStyle(
                        fontSize: 14,
                      ),
                    ),
                  ),
                ),
              )
              .toList(),
          dropdownSeparator: const DropdownSeparator(
            height: 4,
            child: Padding(
              padding: EdgeInsets.symmetric(horizontal: 8.0),
              child: Divider(),
            ),
          ),
          valueListenable: valueListenable,
          onChanged: (value) {
            valueListenable.value = value;
          },
          buttonStyleData: const ButtonStyleData(
            padding: EdgeInsets.symmetric(horizontal: 16),
            height: 40,
            width: 140,
          ),
          dropdownStyleData: const DropdownStyleData(
            maxHeight: 200,
          ),
          menuItemStyleData: const MenuItemStyleData(
            padding: EdgeInsets.symmetric(horizontal: 8.0),
          ),
          iconStyleData: const IconStyleData(
            openMenuIcon: Icon(Icons.arrow_drop_up),
          ),
        ),
      ),
    ),
  );
}

4. DropdownButton2 as Multiselect Dropdown with Checkboxes:

final List<String> items = [
  'All',
  'Item1',
  'Item2',
  'Item3',
  'Item4',
];
final multiValueListenable = ValueNotifier<List<String>>([]);

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Center(
      child: DropdownButtonHideUnderline(
        child: DropdownButton2<String>(
          isExpanded: true,
          hint: Text(
            'Select Items',
            style: TextStyle(
              fontSize: 14,
              color: Theme.of(context).hintColor,
            ),
          ),
          items: items.map((item) {
            return DropdownItem(
              value: item,
              height: 40,
              closeOnTap: false,
              child: ValueListenableBuilder<List<String>>(
                valueListenable: multiValueListenable,
                builder: (context, multiValue, _) {
                  final isSelected = multiValue.contains(item);
                  return Container(
                    height: double.infinity,
                    padding: const EdgeInsets.symmetric(horizontal: 16.0),
                    child: Row(
                      children: [
                        if (isSelected)
                          const Icon(Icons.check_box_outlined)
                        else
                          const Icon(Icons.check_box_outline_blank),
                        const SizedBox(width: 16),
                        Expanded(
                          child: Text(
                            item,
                            style: const TextStyle(
                              fontSize: 14,
                            ),
                          ),
                        ),
                      ],
                    ),
                  );
                },
              ),
            );
          }).toList(),
          multiValueListenable: multiValueListenable,
          onChanged: (value) {
            final multiValue = multiValueListenable.value;
            final isSelected = multiValue.contains(value);
            if (value == 'All') {
              isSelected
                  ? multiValueListenable.value = []
                  : multiValueListenable.value = List.from(items);
            } else {
              multiValueListenable.value = isSelected
                  ? ([...multiValue]..remove(value))
                  : [...multiValue, value!];
            }
          },
          selectedItemBuilder: (context) {
            return items.map(
              (item) {
                return ValueListenableBuilder<List<String>>(
                  valueListenable: multiValueListenable,
                  builder: (context, multiValue, _) {
                    return Container(
                      alignment: AlignmentDirectional.center,
                      child: Text(
                        multiValue.where((item) => item != 'All').join(', '),
                        style: const TextStyle(
                          fontSize: 14,
                          overflow: TextOverflow.ellipsis,
                        ),
                        maxLines: 1,
                      ),
                    );
                  },
                );
              },
            ).toList();
          },
          buttonStyleData: const ButtonStyleData(
            padding: EdgeInsets.only(left: 16, right: 8),
            height: 40,
            width: 140,
          ),
          menuItemStyleData: const MenuItemStyleData(
            padding: EdgeInsets.zero,
          ),
        ),
      ),
    ),
  );
}

5. DropdownButton2 as Searchable Dropdown:

final List<String> items = [
  'A_Item1',
  'A_Item2',
  'A_Item3',
  'A_Item4',
  'B_Item1',
  'B_Item2',
  'B_Item3',
  'B_Item4',
];

final valueListenable = ValueNotifier<String?>(null);
final TextEditingController textEditingController = TextEditingController();

@override
void dispose() {
  textEditingController.dispose();
  super.dispose();
}

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Center(
      child: DropdownButtonHideUnderline(
        child: DropdownButton2<String>(
          isExpanded: true,
          hint: Text(
            'Select Item',
            style: TextStyle(
              fontSize: 14,
              color: Theme.of(context).hintColor,
            ),
          ),
          items: items
              .map(
                (item) => DropdownItem(
                  value: item,
                  height: 40,
                  child: Text(
                    item,
                    style: const TextStyle(
                      fontSize: 14,
                    ),
                  ),
                ),
              )
              .toList(),
          valueListenable: valueListenable,
          onChanged: (value) {
            valueListenable.value = value;
          },
          buttonStyleData: const ButtonStyleData(
            padding: EdgeInsets.symmetric(horizontal: 16),
            height: 40,
            width: 200,
          ),
          dropdownStyleData: const DropdownStyleData(
            maxHeight: 200,
          ),
          dropdownSearchData: DropdownSearchData(
            searchController: textEditingController,
            searchBarWidgetHeight: 50,
            searchBarWidget: Container(
              height: 50,
              padding: const EdgeInsets.only(
                top: 8,
                bottom: 4,
                right: 8,
                left: 8,
              ),
              child: TextFormField(
                expands: true,
                maxLines: null,
                controller: textEditingController,
                decoration: InputDecoration(
                  isDense: true,
                  contentPadding: const EdgeInsets.symmetric(
                    horizontal: 10,
                    vertical: 8,
                  ),
                  hintText: 'Search for an item...',
                  hintStyle: const TextStyle(fontSize: 12),
                  border: OutlineInputBorder(
                    borderRadius: BorderRadius.circular(8),
                    gapPadding: 0,
                  ),
                ),
              ),
            ),
            noResultsWidget: const Padding(
              padding: EdgeInsets.all(8),
              child: Text('No Item Found!'),
            ),
            searchMatchFn: (item, searchValue) {
              return item.value.toString().contains(searchValue);
            },
          ),
          //This to clear the search value when you close the menu
          onMenuStateChange: (isOpen) {
            if (!isOpen && mounted) {
              textEditingController.clear();
            }
          },
        ),
      ),
    ),
  );
}

6. DropdownButton2 as Popup menu button using customButton parameter:

Example 1 using icon:

class PopupIconExample extends StatefulWidget {
  const PopupIconExample({super.key});

  @override
  State<PopupIconExample> createState() => _PopupIconExampleState();
}

class _PopupIconExampleState extends State<PopupIconExample> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: DropdownButtonHideUnderline(
          child: DropdownButton2(
            customButton: const Icon(
              Icons.list,
              size: 46,
              color: Colors.red,
            ),
            items: [
              ..._MenuItems.firstItems.map(
                (item) => DropdownItem<_MenuItem>(
                  value: item,
                  height: 48,
                  child: _MenuItems.buildItem(item),
                ),
              ),
              const DropdownItem<Divider>(
                enabled: false,
                height: 8,
                child: Divider(),
              ),
              ..._MenuItems.secondItems.map(
                (item) => DropdownItem<_MenuItem>(
                  value: item,
                  height: 48,
                  child: _MenuItems.buildItem(item),
                ),
              ),
            ],
            onChanged: (value) {
              _MenuItems.onChanged(context, value! as _MenuItem);
            },
            dropdownStyleData: DropdownStyleData(
              width: 160,
              padding: const EdgeInsets.symmetric(vertical: 6),
              decoration: BoxDecoration(
                borderRadius: BorderRadius.circular(4),
                color: Colors.redAccent,
              ),
              offset: const Offset(0, 8),
            ),
            menuItemStyleData: const MenuItemStyleData(
              padding: EdgeInsets.only(left: 16, right: 16),
            ),
          ),
        ),
      ),
    );
  }
}

class _MenuItem {
  const _MenuItem({
    required this.text,
    required this.icon,
  });

  final String text;
  final IconData icon;
}

abstract class _MenuItems {
  static const List<_MenuItem> firstItems = [home, share, settings];
  static const List<_MenuItem> secondItems = [logout];

  static const home = _MenuItem(text: 'Home', icon: Icons.home);
  static const share = _MenuItem(text: 'Share', icon: Icons.share);
  static const settings = _MenuItem(text: 'Settings', icon: Icons.settings);
  static const logout = _MenuItem(text: 'Log Out', icon: Icons.logout);

  static Widget buildItem(_MenuItem item) {
    return Row(
      children: [
        Icon(item.icon, color: Colors.white, size: 22),
        const SizedBox(
          width: 10,
        ),
        Expanded(
          child: Text(
            item.text,
            style: const TextStyle(
              color: Colors.white,
            ),
          ),
        ),
      ],
    );
  }

  static void onChanged(BuildContext context, _MenuItem item) {
    switch (item) {
      case _MenuItems.home:
        //Do something
        break;
      case _MenuItems.settings:
        //Do something
        break;
      case _MenuItems.share:
        //Do something
        break;
      case _MenuItems.logout:
        //Do something
        break;
    }
  }
}

Example 2 using image and openWithLongPress parameter:

class PopupImageExample extends StatefulWidget {
  const PopupImageExample({super.key});

  @override
  State<PopupImageExample> createState() => _PopupImageExampleState();
}

class _PopupImageExampleState extends State<PopupImageExample> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: DropdownButtonHideUnderline(
          child: DropdownButton2(
            customButton: Container(
              height: 240,
              width: 240,
              decoration: BoxDecoration(
                borderRadius: BorderRadius.circular(40),
                image: const DecorationImage(
                  image: AssetImage(
                    'assets/images/city.jpg',
                  ),
                  fit: BoxFit.cover,
                ),
              ),
            ),
            openWithLongPress: true,
            items: [
              ..._MenuItems.firstItems.map(
                (item) => DropdownItem<_MenuItem>(
                  value: item,
                  height: 48,
                  child: _MenuItems.buildItem(item),
                ),
              ),
              const DropdownItem<Divider>(
                enabled: false,
                height: 8,
                child: Divider(),
              ),
              ..._MenuItems.secondItems.map(
                (item) => DropdownItem<_MenuItem>(
                  value: item,
                  height: 48,
                  child: _MenuItems.buildItem(item),
                ),
              ),
            ],
            onChanged: (value) {
              _MenuItems.onChanged(context, value! as _MenuItem);
            },
            buttonStyleData: ButtonStyleData(
              // This is necessary for the ink response to match our customButton radius.
              decoration: BoxDecoration(
                borderRadius: BorderRadius.circular(40),
              ),
            ),
            dropdownStyleData: DropdownStyleData(
              width: 160,
              padding: const EdgeInsets.symmetric(vertical: 6),
              decoration: BoxDecoration(
                borderRadius: BorderRadius.circular(4),
                color: Colors.redAccent,
              ),
              offset: const Offset(40, -4),
            ),
            menuItemStyleData: const MenuItemStyleData(
              padding: EdgeInsets.only(left: 16, right: 16),
            ),
          ),
        ),
      ),
    );
  }
}

class _MenuItem {
  const _MenuItem({
    required this.text,
    required this.icon,
  });

  final String text;
  final IconData icon;
}

class _MenuItems {
  static const List<_MenuItem> firstItems = [like, share, download];
  static const List<_MenuItem> secondItems = [cancel];

  static const like = _MenuItem(text: 'Like', icon: Icons.favorite);
  static const share = _MenuItem(text: 'Share', icon: Icons.share);
  static const download = _MenuItem(text: 'Download', icon: Icons.download);
  static const cancel = _MenuItem(text: 'Cancel', icon: Icons.cancel);

  static Widget buildItem(_MenuItem item) {
    return Row(
      children: [
        Icon(
          item.icon,
          color: Colors.white,
          size: 22,
        ),
        const SizedBox(
          width: 10,
        ),
        Expanded(
          child: Text(
            item.text,
            style: const TextStyle(
              color: Colors.white,
            ),
          ),
        ),
      ],
    );
  }

  static void onChanged(BuildContext context, _MenuItem item) {
    switch (item) {
      case _MenuItems.like:
        //Do something
        break;
      case _MenuItems.share:
        //Do something
        break;
      case _MenuItems.download:
        //Do something
        break;
      case _MenuItems.cancel:
        //Do something
        break;
    }
  }
}

7. Using DropdownButtonFormField2 with Form:

final List<String> genderItems = [
  'Male',
  'Female',
];
final valueListenable = ValueNotifier<String?>(null);

final _formKey = GlobalKey<FormState>();

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Form(
      key: _formKey,
      child: Padding(
        padding: const EdgeInsets.symmetric(horizontal: 80),
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            TextFormField(
              decoration: InputDecoration(
                contentPadding: const EdgeInsets.all(16),
                hintText: 'Enter Your Full Name.',
                hintStyle: const TextStyle(fontSize: 14),
                border: OutlineInputBorder(
                  borderRadius: BorderRadius.circular(15),
                  gapPadding: 0,
                ),
              ),
            ),
            const SizedBox(height: 30),
            DropdownButtonFormField2<String>(
              isExpanded: true,
              decoration: InputDecoration(
                contentPadding:
                    const EdgeInsets.symmetric(vertical: 16, horizontal: 16),
                border: OutlineInputBorder(
                  borderRadius: BorderRadius.circular(15),
                  gapPadding: 0,
                ),
                // Add more decoration..
              ),
              hint: const Text(
                'Select Your Gender',
                style: TextStyle(fontSize: 14),
              ),
              items: genderItems
                  .map(
                    (item) => DropdownItem<String>(
                      value: item,
                      child: Text(
                        item,
                        style: const TextStyle(
                          fontSize: 14,
                        ),
                      ),
                    ),
                  )
                  .toList(),
              valueListenable: valueListenable,
              validator: (value) {
                if (value == null) {
                  return 'Please select gender.';
                }
                return null;
              },
              onChanged: (value) {
                valueListenable.value = value;
              },
              iconStyleData: const IconStyleData(
                icon: Icon(
                  Icons.arrow_drop_down,
                  color: Colors.black45,
                ),
              ),
              dropdownStyleData: DropdownStyleData(
                decoration: BoxDecoration(
                  borderRadius: BorderRadius.circular(15),
                ),
              ),
              menuItemStyleData: const MenuItemStyleData(
                useDecorationHorizontalPadding: true,
              ),
            ),
            const SizedBox(height: 30),
            TextButton(
              onPressed: () {
                if (_formKey.currentState!.validate()) {
                  // Do something.
                }
              },
              child: const Text('Submit Button'),
            ),
          ],
        ),
      ),
    ),
  );
}

How to make a reusable DropdownButton2 for your app

class CustomDropdownButton2 extends StatelessWidget {
  const CustomDropdownButton2({
    required this.hint,
    required this.valueListenable,
    required this.dropdownItems,
    required this.onChanged,
    this.selectedItemBuilder,
    this.hintAlignment,
    this.valueAlignment,
    this.buttonHeight,
    this.buttonWidth,
    this.buttonPadding,
    this.buttonDecoration,
    this.buttonElevation,
    this.icon,
    this.iconSize,
    this.iconEnabledColor,
    this.iconDisabledColor,
    this.itemHeight,
    this.itemPadding,
    this.dropdownHeight,
    this.dropdownWidth,
    this.dropdownPadding,
    this.dropdownDecoration,
    this.dropdownElevation,
    this.scrollbarRadius,
    this.scrollbarThickness,
    this.scrollbarAlwaysShow,
    this.offset = Offset.zero,
    super.key,
  });
  final String hint;
  final ValueListenable<String?>? valueListenable;
  final List<String> dropdownItems;
  final ValueChanged<String?>? onChanged;
  final DropdownButton2Builder? selectedItemBuilder;
  final Alignment? hintAlignment;
  final Alignment? valueAlignment;
  final double? buttonHeight, buttonWidth;
  final EdgeInsetsGeometry? buttonPadding;
  final BoxDecoration? buttonDecoration;
  final int? buttonElevation;
  final Widget? icon;
  final double? iconSize;
  final Color? iconEnabledColor;
  final Color? iconDisabledColor;
  final double? itemHeight;
  final EdgeInsetsGeometry? itemPadding;
  final double? dropdownHeight, dropdownWidth;
  final EdgeInsetsGeometry? dropdownPadding;
  final BoxDecoration? dropdownDecoration;
  final int? dropdownElevation;
  final Radius? scrollbarRadius;
  final double? scrollbarThickness;
  final bool? scrollbarAlwaysShow;
  final Offset offset;

  @override
  Widget build(BuildContext context) {
    return DropdownButtonHideUnderline(
      child: DropdownButton2<String>(
        //To avoid long text overflowing.
        isExpanded: true,
        hint: Container(
          alignment: hintAlignment,
          child: Text(
            hint,
            overflow: TextOverflow.ellipsis,
            maxLines: 1,
            style: TextStyle(
              fontSize: 14,
              color: Theme.of(context).hintColor,
            ),
          ),
        ),
        valueListenable: valueListenable,
        items: dropdownItems
            .map(
              (String item) => DropdownItem<String>(
                value: item,
                height: itemHeight ?? 40,
                child: Container(
                  alignment: valueAlignment,
                  child: Text(
                    item,
                    overflow: TextOverflow.ellipsis,
                    maxLines: 1,
                    style: const TextStyle(
                      fontSize: 14,
                    ),
                  ),
                ),
              ),
            )
            .toList(),
        onChanged: onChanged,
        selectedItemBuilder: selectedItemBuilder,
        buttonStyleData: ButtonStyleData(
          height: buttonHeight ?? 40,
          width: buttonWidth ?? 140,
          padding: buttonPadding ?? const EdgeInsets.only(left: 14, right: 14),
          decoration:
              buttonDecoration ??
              BoxDecoration(
                borderRadius: BorderRadius.circular(14),
                border: Border.all(
                  color: Colors.black45,
                ),
              ),
          elevation: buttonElevation,
        ),
        iconStyleData: IconStyleData(
          icon: icon ?? const Icon(Icons.arrow_forward_ios_outlined),
          iconSize: iconSize ?? 12,
          iconEnabledColor: iconEnabledColor,
          iconDisabledColor: iconDisabledColor,
        ),
        dropdownStyleData: DropdownStyleData(
          //Max height for the dropdown menu & becoming scrollable if there are more items. If you pass Null it will take max height possible for the items.
          maxHeight: dropdownHeight ?? 200,
          width: dropdownWidth ?? 140,
          padding: dropdownPadding,
          decoration:
              dropdownDecoration ??
              BoxDecoration(
                borderRadius: BorderRadius.circular(14),
              ),
          elevation: dropdownElevation ?? 8,
          //Null or Offset(0, 0) will open just under the button. You can edit as you want.
          offset: offset,
          scrollbarTheme: ScrollbarThemeData(
            radius: scrollbarRadius ?? const Radius.circular(40),
            thickness: scrollbarThickness != null
                ? WidgetStateProperty.all<double>(scrollbarThickness!)
                : null,
            thumbVisibility: scrollbarAlwaysShow != null
                ? WidgetStateProperty.all<bool>(scrollbarAlwaysShow!)
                : null,
          ),
        ),
        menuItemStyleData: MenuItemStyleData(
          padding: itemPadding ?? const EdgeInsets.only(left: 14, right: 14),
        ),
      ),
    );
  }
}

Thanks

If something is missing or you want to add some feature, feel free to open a ticket or contribute!

LICENSE: MIT