Flutter DropdownButton2

Intro

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

Image

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 add dividers as items with different height by passing dividers indexes to customItemsIndexes and the height to customItemsHeight 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

For DropdownButton2:

OptionDescriptionTypeRequired
itemsThe list of items the user can selectList<DropdownMenuItemYes
hintThe placeholder displayed before the user choose an itemWidgetNo
disabledHintThe placeholder displayed if the dropdown is disabledWidgetNo
valueThe value of the currently selected DropdownMenuItemTNo
onChangedCalled when the user selects an itemValueChanged<T?>No
onMenuStateChangeCalled when the dropdown menu is opened or closedFunction(bool isOpen)No
selectedItemBuilderHow the selected item will be displayed on buttonDropdownButtonBuilderNo
buttonHeightThe height of the buttondoubleNo
buttonWidthThe width of the buttondoubleNo
buttonPaddingThe inner padding of the ButtonEdgeInsetsGeometryNo
buttonDecorationThe decoration of the ButtonBoxDecorationNo
buttonElevationThe elevation of the ButtonintNo
iconThe suffix icon of the dropdown buttonWidgetNo
iconOnClickShows different icon when dropdown menu openWidgetNo
iconSizeThe size of the icondoubleNo
iconEnabledColorThe color of the icon if the button is enabledColorNo
iconDisabledColorThe color of the icon if the button is disabledColorNo
itemHeightThe height of menu itemsdoubleNo
itemPaddingThe padding of menu itemsEdgeInsetsGeometryNo
dropdownMaxHeightThe maximum height of the dropdown menudoubleNo
dropdownWidthThe width of the dropdown menudoubleNo
dropdownPaddingThe inner padding of the dropdown menuEdgeInsetsGeometryNo
dropdownDecorationThe decoration of the dropdown menuBoxDecorationNo
dropdownElevationThe elevation of the dropdown menuintNo
selectedItemHighlightColorThe highlight color of the current selected itemColorNo
scrollbarRadiusThe radius of the scrollbar's cornersRadiusNo
scrollbarThicknessThe thickness of the scrollbardoubleNo
scrollbarAlwaysShowAlways show the scrollbar even when a scroll is not underwayboolNo
offsetChanges the position of the dropdown menuOffsetNo
customButtonUses custom widget like icon,image,etc.. instead of the default buttonWidgetNo
customItemsIndexesIndexes of the items you want to give different height (useful for adding dividers)ListNo
customItemsHeightThe height of the items you passed their indexes using customItemsIndexes parameterdoubleNo
isExpandedMakes the button's inner contents expanded (set true to avoid long text overflowing)boolNo
openWithLongPressOpens the dropdown menu on long-pressing instead of tappingboolNo
dropdownOverButtonOpens the dropdown menu over the button instead of below itboolNo
dropdownFullScreenOpens the dropdown menu in fullscreen mode (Above AppBar & TabBar)boolNo
focusColorThe color of button when it has input focus using traditional interfaces (keyboard and mouse)ColorNo
barrierDismissibleWhether you can dismiss this route by tapping the modal barrierboolNo
barrierColorThe color to use for the modal barrier. If this is null, the barrier will be transparentColorNo
barrierLabelThe semantic label used for a dismissible barrierStringNo
searchControllerThe controller used for searchable dropdowns, if null, then it'll perform as a normal dropdownTextEditingControllerNo
searchInnerWidgetThe widget to be shown at the top of the dropdown menu for searchable dropdownsWidgetNo
searchMatchFnThe match function used for searchable dropdowns, if null, defaultFn will be usedSearchMatchFnNo

For DropdownButtonFormField2 "In addition to the above":

OptionDescriptionTypeRequired
decorationThe decoration of the dropdown button form fieldInputDecorationNo
onSavedCalled with the current selected item when the form is savedFormFieldSetterNo
validatorCalled to validates if the input is invalid and display error textFormFieldValidatorNo
autovalidateModeUsed to enable/disable auto validationAutovalidateModeNo

Installation

add this line to pubspec.yaml



dependencies:

  dropdown_button2: ^1.7.1

import package


import 'package:dropdown_button2/dropdown_button2.dart';

Usage and Examples

1. Simple DropdownButton2 with no styling:

Image
final List<String> items = [
  'Item1',
  'Item2',
  'Item3',
  'Item4',
];
String? selectedValue;

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Center(
      child: DropdownButtonHideUnderline(
        child: DropdownButton2(
          hint: Text(
            'Select Item',
            style: TextStyle(
              fontSize: 14,
              color: Theme
                      .of(context)
                      .hintColor,
            ),
          ),
          items: items
                  .map((item) =>
                  DropdownMenuItem<String>(
                    value: item,
                    child: Text(
                      item,
                      style: const TextStyle(
                        fontSize: 14,
                      ),
                    ),
                  ))
                  .toList(),
          value: selectedValue,
          onChanged: (value) {
            setState(() {
              selectedValue = value as String;
            });
          },
          buttonHeight: 40,
          buttonWidth: 140,
          itemHeight: 40,
        ),
      ),
    ),
  );
}

2. DropdownButton2 with some styling and customization:

Image
final List<String> items = [
  'Item1',
  'Item2',
  'Item3',
  'Item4',
  'Item5',
  'Item6',
  'Item7',
  'Item8',
];
String? selectedValue;

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Center(
      child: DropdownButtonHideUnderline(
        child: DropdownButton2(
          isExpanded: true,
          hint: Row(
            children: const [
              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((item) =>
                  DropdownMenuItem<String>(
                    value: item,
                    child: Text(
                      item,
                      style: const TextStyle(
                        fontSize: 14,
                        fontWeight: FontWeight.bold,
                        color: Colors.white,
                      ),
                      overflow: TextOverflow.ellipsis,
                    ),
                  ))
                  .toList(),
          value: selectedValue,
          onChanged: (value) {
            setState(() {
              selectedValue = value as String;
            });
          },
          icon: const Icon(
            Icons.arrow_forward_ios_outlined,
          ),
          iconSize: 14,
          iconEnabledColor: Colors.yellow,
          iconDisabledColor: Colors.grey,
          buttonHeight: 50,
          buttonWidth: 160,
          buttonPadding: const EdgeInsets.only(left: 14, right: 14),
          buttonDecoration: BoxDecoration(
            borderRadius: BorderRadius.circular(14),
            border: Border.all(
              color: Colors.black26,
            ),
            color: Colors.redAccent,
          ),
          buttonElevation: 2,
          itemHeight: 40,
          itemPadding: const EdgeInsets.only(left: 14, right: 14),
          dropdownMaxHeight: 200,
          dropdownWidth: 200,
          dropdownPadding: null,
          dropdownDecoration: BoxDecoration(
            borderRadius: BorderRadius.circular(14),
            color: Colors.redAccent,
          ),
          dropdownElevation: 8,
          scrollbarRadius: const Radius.circular(40),
          scrollbarThickness: 6,
          scrollbarAlwaysShow: true,
          offset: const Offset(-20, 0),
        ),
      ),
    ),
  );
}

3. How to add different height items like dividers:

Image
final List<String> items = [
  'Item1',
  'Item2',
  'Item3',
  'Item4',
];
String? selectedValue;

List<DropdownMenuItem<String>> _addDividersAfterItems(List<String> items) {
  List<DropdownMenuItem<String>> _menuItems = [];
  for (var item in items) {
    _menuItems.addAll(
      [
        DropdownMenuItem<String>(
          value: item,
          child: Padding(
            padding: const EdgeInsets.symmetric(horizontal: 8.0),
            child: Text(
              item,
              style: const TextStyle(
                fontSize: 14,
              ),
            ),
          ),
        ),
        //If it's last item, we will not add Divider after it.
        if (item != items.last)
          const DropdownMenuItem<String>(
            enabled: false,
            child: Divider(),
          ),
      ],
    );
  }
  return _menuItems;
}

List<int> _getDividersIndexes() {
  List<int> _dividersIndexes = [];
  for (var i = 0; i < (items.length * 2) - 1; i++) {
    //Dividers indexes will be the odd indexes
    if (i.isOdd) {
      _dividersIndexes.add(i);
    }
  }
  return _dividersIndexes;
}

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Center(
      child: DropdownButtonHideUnderline(
        child: DropdownButton2(
          isExpanded: true,
          hint: Text(
            'Select Item',
            style: TextStyle(
              fontSize: 14,
              color: Theme
                      .of(context)
                      .hintColor,
            ),
          ),
          items: _addDividersAfterItems(items),
          customItemsIndexes: _getDividersIndexes(),
          customItemsHeight: 4,
          value: selectedValue,
          onChanged: (value) {
            setState(() {
              selectedValue = value as String;
            });
          },
          buttonHeight: 40,
          buttonWidth: 140,
          itemHeight: 40,
          itemPadding: const EdgeInsets.symmetric(horizontal: 8.0),
        ),
      ),
    ),
  );
}

4. DropdownButton2 as Multiselect Dropdown with Checkboxes:

Image
final List<String> items = [
  'Item1',
  'Item2',
  'Item3',
  'Item4',
];
List<String> selectedItems = [];

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Center(
      child: DropdownButtonHideUnderline(
        child: DropdownButton2(
          isExpanded: true,
          hint: Align(
            alignment: AlignmentDirectional.center,
            child: Text(
              'Select Items',
              style: TextStyle(
                fontSize: 14,
                color: Theme.of(context).hintColor,
              ),
            ),
          ),
          items: items.map((item) {
            return DropdownMenuItem<String>(
              value: item,
              //disable default onTap to avoid closing menu when selecting an item
              enabled: false,
              child: StatefulBuilder(
                builder: (context, menuSetState) {
                  final _isSelected = selectedItems.contains(item);
                  return InkWell(
                    onTap: () {
                      _isSelected
                              ? selectedItems.remove(item)
                              : selectedItems.add(item);
                      //This rebuilds the StatefulWidget to update the button's text
                      setState(() {});
                      //This rebuilds the dropdownMenu Widget to update the check mark
                      menuSetState(() {});
                    },
                    child: Container(
                      height: double.infinity,
                      padding: const EdgeInsets.symmetric(horizontal: 16.0),
                      child: Row(
                        children: [
                          _isSelected
                                  ? const Icon(Icons.check_box_outlined)
                                  : const Icon(Icons.check_box_outline_blank),
                          const SizedBox(width: 16),
                          Text(
                            item,
                            style: const TextStyle(
                              fontSize: 14,
                            ),
                          ),
                        ],
                      ),
                    ),
                  );
                },
              ),
            );
          }).toList(),
          //Use last selected item as the current value so if we've limited menu height, it scroll to last item.
          value: selectedItems.isEmpty ? null : selectedItems.last,
          onChanged: (value) {},
          buttonHeight: 40,
          buttonWidth: 140,
          itemHeight: 40,
          itemPadding: EdgeInsets.zero,
          selectedItemBuilder: (context) {
            return items.map(
                      (item) {
                return Container(
                  alignment: AlignmentDirectional.center,
                  padding: const EdgeInsets.symmetric(horizontal: 16.0),
                  child: Text(
                    selectedItems.join(', '),
                    style: const TextStyle(
                      fontSize: 14,
                      overflow: TextOverflow.ellipsis,
                    ),
                    maxLines: 1,
                  ),
                );
              },
            ).toList();
          },
        ),
      ),
    ),
  );
}

5. DropdownButton2 as Searchable Dropdown:

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

String? selectedValue;
final TextEditingController textEditingController = TextEditingController();

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

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Center(
      child: DropdownButtonHideUnderline(
        child: DropdownButton2(
          isExpanded: true,
          hint: Text(
            'Select Item',
            style: TextStyle(
              fontSize: 14,
              color: Theme.of(context).hintColor,
            ),
          ),
          items: items
                  .map((item) => DropdownMenuItem<String>(
            value: item,
            child: Text(
              item,
              style: const TextStyle(
                fontSize: 14,
              ),
            ),
          ))
                  .toList(),
          value: selectedValue,
          onChanged: (value) {
            setState(() {
              selectedValue = value as String;
            });
          },
          buttonHeight: 40,
          buttonWidth: 200,
          itemHeight: 40,
          dropdownMaxHeight: 200,
          searchController: textEditingController,
          searchInnerWidget: Padding(
            padding: const EdgeInsets.only(
              top: 8,
              bottom: 4,
              right: 8,
              left: 8,
            ),
            child: TextFormField(
              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),
                ),
              ),
            ),
          ),
          searchMatchFn: (item, searchValue) {
            return (item.value.toString().contains(searchValue));
          },
          //This to clear the search value when you close the menu
          onMenuStateChange: (isOpen) {
            if (!isOpen) {
              textEditingController.clear();
            }
          },
        ),
      ),
    ),
  );
}

6. DropdownButton2 as Popup menu button using customButton parameter:

Example 1 using icon:

Image
class CustomButtonTest extends StatefulWidget {
  const CustomButtonTest({Key? key}) : super(key: key);

  @override
  State<CustomButtonTest> createState() => _CustomButtonTestState();
}

class _CustomButtonTestState extends State<CustomButtonTest> {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: DropdownButtonHideUnderline(
          child: DropdownButton2(
            customButton: const Icon(
              Icons.list,
              size: 46,
              color: Colors.red,
            ),
            customItemsIndexes: const [3],
            customItemsHeight: 8,
            items: [
              ...MenuItems.firstItems.map(
                        (item) =>
                        DropdownMenuItem<MenuItem>(
                          value: item,
                          child: MenuItems.buildItem(item),
                        ),
              ),
              const DropdownMenuItem<Divider>(enabled: false, child: Divider()),
              ...MenuItems.secondItems.map(
                        (item) =>
                        DropdownMenuItem<MenuItem>(
                          value: item,
                          child: MenuItems.buildItem(item),
                        ),
              ),
            ],
            onChanged: (value) {
              MenuItems.onChanged(context, value as MenuItem);
            },
            itemHeight: 48,
            itemPadding: const EdgeInsets.only(left: 16, right: 16),
            dropdownWidth: 160,
            dropdownPadding: const EdgeInsets.symmetric(vertical: 6),
            dropdownDecoration: BoxDecoration(
              borderRadius: BorderRadius.circular(4),
              color: Colors.redAccent,
            ),
            dropdownElevation: 8,
            offset: const Offset(0, 8),
          ),
        ),
      ),
    );
  }
}

class MenuItem {
  final String text;
  final IconData icon;

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

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,
        ),
        Text(
          item.text,
          style: const TextStyle(
            color: Colors.white,
          ),
        ),
      ],
    );
  }

  static 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:

Image
class CustomButtonTest extends StatefulWidget {
  const CustomButtonTest({Key? key}) : super(key: key);

  @override
  State<CustomButtonTest> createState() => _CustomButtonTestState();
}

class _CustomButtonTestState extends State<CustomButtonTest> {
  @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: NetworkImage(
                    'https://cdn.pixabay.com/photo/2020/05/11/06/20/city-5156636_960_720.jpg',
                  ),
                  fit: BoxFit.cover,
                ),
              ),
            ),
            openWithLongPress: true,
            customItemsIndexes: const [3],
            customItemsHeight: 8,
            items: [
              ...MenuItems.firstItems.map(
                        (item) =>
                        DropdownMenuItem<MenuItem>(
                          value: item,
                          child: MenuItems.buildItem(item),
                        ),
              ),
              const DropdownMenuItem<Divider>(enabled: false, child: Divider()),
              ...MenuItems.secondItems.map(
                        (item) =>
                        DropdownMenuItem<MenuItem>(
                          value: item,
                          child: MenuItems.buildItem(item),
                        ),
              ),
            ],
            onChanged: (value) {
              MenuItems.onChanged(context, value as MenuItem);
            },
            itemHeight: 48,
            itemPadding: const EdgeInsets.only(left: 16, right: 16),
            dropdownWidth: 160,
            dropdownPadding: const EdgeInsets.symmetric(vertical: 6),
            dropdownDecoration: BoxDecoration(
              borderRadius: BorderRadius.circular(4),
              color: Colors.redAccent,
            ),
            dropdownElevation: 8,
            offset: const Offset(40, -4),
          ),
        ),
      ),
    );
  }
}

class MenuItem {
  final String text;
  final IconData icon;

  const MenuItem({
    required this.text,
    required this.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,
        ),
        Text(
          item.text,
          style: const TextStyle(
            color: Colors.white,
          ),
        ),
      ],
    );
  }

  static 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:

Image

final List<String> genderItems = [
  'Male',
  'Female',
];

String? selectedValue;

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.symmetric(
                  horizontal: 20,
                  vertical: 20,
                ),
                hintText: 'Enter Your Full Name.',
                hintStyle: const TextStyle(fontSize: 14),
                border: OutlineInputBorder(
                  borderRadius: BorderRadius.circular(15),
                ),
              ),
            ),
            const SizedBox(height: 30),
            DropdownButtonFormField2(
              decoration: InputDecoration(
                //Add isDense true and zero Padding.
                //Add Horizontal padding using buttonPadding and Vertical padding by increasing buttonHeight instead of add Padding here so that The whole TextField Button become clickable, and also the dropdown menu open under The whole TextField Button.
                isDense: true,
                contentPadding: EdgeInsets.zero,
                border: OutlineInputBorder(
                  borderRadius: BorderRadius.circular(15),
                ),
                //Add more decoration as you want here
                //Add label If you want but add hint outside the decoration to be aligned in the button perfectly.
              ),
              isExpanded: true,
              hint: const Text(
                'Select Your Gender',
                style: TextStyle(fontSize: 14),
              ),
              icon: const Icon(
                Icons.arrow_drop_down,
                color: Colors.black45,
              ),
              iconSize: 30,
              buttonHeight: 60,
              buttonPadding: const EdgeInsets.only(left: 20, right: 10),
              dropdownDecoration: BoxDecoration(
                borderRadius: BorderRadius.circular(15),
              ),
              items: genderItems
                      .map((item) =>
                      DropdownMenuItem<String>(
                        value: item,
                        child: Text(
                          item,
                          style: const TextStyle(
                            fontSize: 14,
                          ),
                        ),
                      ))
                      .toList(),
              validator: (value) {
                if (value == null) {
                  return 'Please select gender.';
                }
              },
              onChanged: (value) {
                //Do something when changing the item if you want.
              },
              onSaved: (value) {
                selectedValue = value.toString();
              },
            ),
            const SizedBox(height: 30),
            TextButton(
              onPressed: () {
                if (_formKey.currentState!.validate()) {
                  _formKey.currentState!.save();
                }
              },
              child: const Text('Submit Button'),
            ),
          ],
        ),
      ),
    ),
  );
}

CustomDropdownButton2 Widget "customize it to your needs"

class CustomDropdownButton2 extends StatelessWidget {
  final String hint;
  final String? value;
  final List<String> dropdownItems;
  final ValueChanged<String?>? onChanged;
  final DropdownButtonBuilder? 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;

  const CustomDropdownButton2({
    required this.hint,
    required this.value,
    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,
    Key? key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return DropdownButtonHideUnderline(
      child: DropdownButton2(
        //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,
            ),
          ),
        ),
        value: value,
        items: dropdownItems
                .map((item) => DropdownMenuItem<String>(
          value: item,
          child: Container(
            alignment: valueAlignment,
            child: Text(
              item,
              overflow: TextOverflow.ellipsis,
              maxLines: 1,
              style: const TextStyle(
                fontSize: 14,
              ),
            ),
          ),
        ))
                .toList(),
        onChanged: onChanged,
        selectedItemBuilder: selectedItemBuilder,
        icon: icon ?? const Icon(Icons.arrow_forward_ios_outlined),
        iconSize: iconSize ?? 12,
        iconEnabledColor: iconEnabledColor,
        iconDisabledColor: iconDisabledColor,
        buttonHeight: buttonHeight ?? 40,
        buttonWidth: buttonWidth ?? 140,
        buttonPadding:
        buttonPadding ?? const EdgeInsets.only(left: 14, right: 14),
        buttonDecoration: buttonDecoration ??
                BoxDecoration(
                  borderRadius: BorderRadius.circular(14),
                  border: Border.all(
                    color: Colors.black45,
                  ),
                ),
        buttonElevation: buttonElevation,
        itemHeight: itemHeight ?? 40,
        itemPadding: itemPadding ?? const EdgeInsets.only(left: 14, right: 14),
        //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.
        dropdownMaxHeight: dropdownHeight ?? 200,
        dropdownWidth: dropdownWidth ?? 140,
        dropdownPadding: dropdownPadding,
        dropdownDecoration: dropdownDecoration ??
                BoxDecoration(
                  borderRadius: BorderRadius.circular(14),
                ),
        dropdownElevation: dropdownElevation ?? 8,
        scrollbarRadius: scrollbarRadius ?? const Radius.circular(40),
        scrollbarThickness: scrollbarThickness,
        scrollbarAlwaysShow: scrollbarAlwaysShow,
        //Null or Offset(0, 0) will open just under the button. You can edit as you want.
        offset: offset,
        dropdownOverButton: false, //Default is false to show menu below button
      ),
    );
  }
}

How simple you can use it:

Image
final List<String> items = [
  'Item1',
  'Item2',
  'Item3',
  'Item4',
  'Item5',
  'Item6',
  'Item7',
  'Item8',
];
String? selectedValue;

@override
Widget build(BuildContext context) {
  return Scaffold(
    body: Center(
      child: CustomDropdownButton2(
        hint: 'Select Item',
        dropdownItems: items,
        value: selectedValue,
        onChanged: (value) {
          setState(() {
            selectedValue = value;
          });
        },
      ),
    ),
  );
}

Thanks

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

LICENSE: MIT

Libraries

custom_dropdown_button2