How can we change the width/padding of a Flutter DropdownMenuItem in a Dropdown?

Question

In Flutter, I can build a Dropdown with DropdownMenuItems, like this:

The DropdownMenuItems I add are always wider than the dropdown itself:

How do you adjust the width of the DropdownMenuItem, or remove the extra horizontal padding?

My DropdownMenuItem widget looks like this:

DropdownMenuItem(
    value: unit.name,
    child: Text('hey'),
);

while my Dropdown widget looks like this:

return Container(
    width: 300.0,
    child: DropdownButtonHideUnderline(
      child: DropdownButton(
        value: name,
        items: listOfDropdownMenuItems,
        onChanged: onChanged,
        style: Theme.of(context).textTheme.title,
      ),
    ),
);

Answer 1

you can change DropdownMenu width using width property in side DropdownMenu. following example may be solve your proble.

in build method find out screen width double width = MediaQuery.sizeOf(context).width;

double width = MediaQuery.sizeOf(context).width;

double halfScreenWidth = width / 2;

List genderList = ['Male', 'Female', 'Other'];
String genderValue = "";

DropdownMenu<String>(
                  initialSelection: genderList.first,
                  width: halfScreenWidth, // Add this line you also add direct width 200
                  label: Text("Gender"),
                  onSelected: (value) {
                    setState(() {
                      genderValue = value.toString();
                    });
                  },
                  dropdownMenuEntries: genderList.map<DropdownMenuEntry<String>>((String value) {
                    return DropdownMenuEntry<String>(
                        value: value, label: value);
                  }).toList(),
                ),

Answer 2

In my case this is working.

                  Container(
                    decoration: BoxDecoration(
                        border: Border.all(
                            color: ContactColors.hint2, width: 2)),
                    width: double.infinity,
                    margin: const EdgeInsets.all(5),
                    child: DropdownButtonHideUnderline(
                        child: DropdownButton<String>(
                      hint: new Text("Select City"),
                      isExpanded: true,
                      alignment: Alignment.center,
                      value: dropdownValue,
                      icon: const Icon(Icons.arrow_downward),
                      elevation: 16,
                      style: const TextStyle(color: ContactColors.white),
                      onChanged: (String? value) {
                        // This is called when the user selects an item.
                        setState(() {
                          dropdownValue = value!;
                        });
                      },
                      items: list
                          .map<DropdownMenuItem<String>>((String value) {
                        return DropdownMenuItem<String>(
                          value: value,
                          child: Container(
                            margin: const EdgeInsets.all(10),
                            child: Text(value,
                                style: const TextStyle(
                                    color: ContactColors.primaryColor)),
                          ),
                        );
                      }).toList(),
                    )),
                  ),

Answer 3

I solved it by adding isExpanded: true then wraping dropdown to a container then again wraping to padding widget this worked for me

code : -

Container(
                        height: 60,
                        width: double.infinity,
                         decoration: BoxDecoration(
                          borderRadius: BorderRadius.circular(10),
                    border: Border.all(color: borderContainerColor, width: 3)),
                        child: Padding(
                          padding: const EdgeInsets.all(8.0), //here include this to get padding
                          child: DropdownButton(

                            isExpanded: true,
                            underline: Container(),

                            alignment: Alignment.bottomCenter,


                            elevation: 0,
                            borderRadius: BorderRadius.circular(5 ),
                            value: dropdownvalue,
                            icon: const Icon(Icons.keyboard_arrow_down),

                            items: items.map((String items) {
                              return DropdownMenuItem(
                                value: items,
                                child: Text(items),
                              );
                            }).toList(),
                            onChanged: (String? newValue) {
                              setState(() {
                                dropdownvalue = newValue!;
                              });
                            },
                          ),
                        ),
                      ),

Answer 4

Try with this parameter isDense it will shrink the widget and extra padding will be removed just like this

DropdownButton(
          isDense: true,
          value : lname_listValue,
          items: casteEDList.map((String items)
                   {
                       return DropdownMenuItem(
                              value: items,
                              child: Text(items),);
                   }).toList(),
                   onChanged: (String? newValue) {
                              setState(() {
                              lname_listValue = newValue!;
                              },);
                   },
  ),

Answer 5

isExpanded: true will stretch the width to full screen. But if you want a customise drop-down. Here is my customdropdown.dart

import 'package:flutter/material.dart';
class CustomDropDown extends StatelessWidget {
  final value;
  final List<String> itemsList;
  final Color dropdownColor;
  final Function(dynamic value) onChanged;
  const CustomDropDown({
    @required this.value,
    @required this.itemsList,
    this.dropdownColor,
    @required this.onChanged,
    Key key,
  }) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Padding(
      padding: EdgeInsets.only(left: 20, top: 3, bottom: 3, right: 20),
      child: Container(
        decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(10),
          color: Colors.white,
        ),
        child: DropdownButtonHideUnderline(
          child: Padding(
            padding: const EdgeInsets.only(left: 14.0, right: 14),
            child: DropdownButton(
              isExpanded: true,
              dropdownColor: dropdownColor,
              value: value,
              items: itemsList
                  .map((String item) => DropdownMenuItem<String>(
                        value: item,
                        child: Text(item),
                      ))
                  .toList(),
              onChanged: (value) => onChanged(value),
            ),
          ),
        ),
      ),
    );
  }
}

Now you can call it like this.

CustomDropDown(
   value: selectedValue,
   itemsList: ['Music', 'Photographer'],
   onChanged: (value) {
        setState(() {
            selectedValue = value;
        });
    },
),

Answer 6

I solved this problem with changing isExpanded to true;

return Container(
    width: 300.0,
    child: DropdownButtonHideUnderline(
      child: DropdownButton(
        isExpanded: true,
        value: name,
        items: listOfDropdownMenuItems,
        onChanged: onChanged,
        style: Theme.of(context).textTheme.title,
      ),
    ),
);

Answer 7

This feature has been added. See https://github.com/flutter/flutter/pull/14849

You can now wrap it in a ButtonTheme and set alignedDropdown to true.

return Container(
    width: 300.0,
    child: DropdownButtonHideUnderline(
      child: ButtonTheme(
        alignedDropdown: true,
          child: DropdownButton(
            value: name,
            items: listOfDropdownMenuItems,
            onChanged: onChanged,
            style: Theme.of(context).textTheme.title,
         ),
      ),
    ),
);