How should I customize DropdownButtons and DropdownMenuItems in Flutter?

Question

The default DropdownButton with DropdownMenuItems returns a light-grey dropdown. How should I customize the dropdown (e.g. background color, dropdown width)? I can change the style property in both DropdownButton and DropdownMenuItem, like this:

return new DropdownButton(
      value: ...,
      items: ...,
      onChanged: ...,
      style: new TextStyle(
        color: Colors.white,
      ),
    );

but this doesn't change the dropdown's background color.

Should I copy DropdownMenu and extend it? Does Flutter plan to add customization for this widget in the near future?

Answer 1

I am using following class

import 'package:flutter/material.dart';
import 'package:safe/utils/app_ui.dart';

class LabeledDropdown<T> extends StatefulWidget {
  final String heading;
  final List<DropdownMenuItem<T>> items;
  final T? value;
  final ValueChanged<T?> onChanged;

  const LabeledDropdown({
    super.key,
    required this.heading,
    required this.items,
    required this.value,
    required this.onChanged,
  });

  @override
  State<LabeledDropdown<T>> createState() => _LabeledDropdownState<T>();
}

class _LabeledDropdownState<T> extends State<LabeledDropdown<T>> {
  @override
  Widget build(BuildContext context) {
    return Column(
      crossAxisAlignment: CrossAxisAlignment.start,
      children: [
        Text(widget.heading, style: const TextStyle(fontSize: 14)),
        const SizedBox(height: 8),
        DropdownButtonFormField<T>(
          decoration: InputDecoration(
            fillColor: Colors.white, // Background color
            filled: true, // Enable filling
            border: OutlineInputBorder(
              borderSide: BorderSide.none, // Remove border
              borderRadius: BorderRadius.all(
                Radius.circular(cornerRadius),
              ), //set border radius
            ),
          ),
          value: widget.value,
          items: widget.items,
          onChanged: widget.onChanged,
          hint: const Text("Select an option"),
        ),
      ],
    );
  }
}

no need to wrap DropdownButtonFormField inside a Container to set borders and change the background color... you can set the fillColor and filled properties to change the background color ...

you can use this

 child: LabeledDropdown<String>(
          heading: 'District*',
          items:
              _options.map((option) {
                return DropdownMenuItem<String>(
                  value: option,
                  child: Text(option),
                );
              }).toList(),
          value: _selectedValue,
          onChanged: (value) {
            setState(() {
              _selectedValue = value;
            });
          },
        ),

where options are

    final List<String> _options = [
    'Option One',
    'Option two',
    'Option three',
    'Option four',
  ];

and here are the end result

Answer 2

I recently upgraded my Flutter SDK from version 3.0.0 to 3.22.2, and I noticed that the background color of my DropdownButtonFormField has changed automatically. I did not make any changes to the code, and it was working perfectly before the upgrade. Below is my code for the

please suggest me best solution for the Dropdown background color

DropdownButtonFormField:

DropdownButtonFormField<String>(
  decoration: const InputDecoration(
    fillColor: Colors.transparent,
    filled: true,
    contentPadding: EdgeInsets.only(right: 10, left: 10),
    border: OutlineInputBorder(
      borderSide: BorderSide(color: Color(0xFFE6E5E9), width: 1),
      borderRadius: BorderRadius.all(
        Radius.circular(10.0),
      ),
    ),
    focusedBorder: OutlineInputBorder(
      borderSide: BorderSide(color: Color(0xFF09304B), width: 1),
      borderRadius: BorderRadius.all(
        Radius.circular(10.0),
      ),
    ),
    enabledBorder: OutlineInputBorder(
      borderSide: BorderSide(color: Color(0xFFE6E5E9), width: 1),
      borderRadius: BorderRadius.all(
        Radius.circular(10.0),
      ),
    ),
  ),
  elevation: 1,
  validator: (value) {
    print("sdfds");
  },
  isExpanded: true,
  hint: const Text(
    "Select Payment Purpose*",
    style: TextStyle(
      color: Color(0xFF0F0F18),
      fontWeight: FontWeight.w400,
      fontFamily: 'inter',
      fontSize: 14,
    ),
  ),
  iconSize: 30,
  iconEnabledColor: Colors.black,
  icon: const Icon(
    Icons.keyboard_arrow_down_sharp,
    size: 20,
  ),
  value: selectedValue,
  items: Constants.transactionPurposeList
      .map<DropdownMenuItem<String>>((TransactionPurposeList value) {
    return DropdownMenuItem<String>(
      value: value.name!,
      child: Text(value.name!),
    );
  }).toList(),
  onChanged: (value) {
    setState(() {
      selectedValue = value;
      isSelectPurpose = false;
    });
  },
)

transactionPurposeList access from Rest API

Answer 3

To create own custom drop down widget you can use below code value - selected dropdown value items - list of dropdownitem you can pass onChanged - pass function that will be invoked when you select from dropdown

import 'package:flutter/material.dart';

class SDropDown extends StatefulWidget {
  final String value;
  final List<DropdownMenuItem<String>> items;
  final Function(String?)? onChanged;
  const SDropDown[enter image description here][1](
      {Key? key, required this.value, required this.items, this.onChanged})
      : super(key: key);

  @override
  _SDropDownState createState() => _SDropDownState();
}

class _SDropDownState extends State<SDropDown> {
  @override
  Widget build(BuildContext context) {
    ThemeData theme = Theme.of(context);
    return Container(
      padding: const EdgeInsets.symmetric(horizontal: 10, vertical: 3),
      decoration: BoxDecoration(
          color: Colors.white, borderRadius: BorderRadius.circular(10)),
      child: DropdownButton<String>(
        isExpanded: true,
        value: widget.value,
        items: widget.items,
        onChanged: widget.onChanged,
        underline: const SizedBox(),
        dropdownColor: theme.primaryColor,
        style: const TextStyle(color: Colors.black),
      ),
    );
  }
}

Answer 4

you can use the dropdown_button2 package. You can use the dropdownDecoration property to customize the dropdown menu appearance. This is the best package I found to fully customize a DropdownButton

Answer 5

I was able to change the background for the Dropdown by wrapping it in a Container with the color property set.

Before:

After:

Here's the code:

Define these values in the widget state:

final items = ['One', 'Two', 'Three', 'Four'];
String selectedValue = 'Four';

then use this code

Container(
  padding: EdgeInsets.symmetric(horizontal: 10, vertical: 5),
  decoration: BoxDecoration(
      color: Colors.white, borderRadius: BorderRadius.circular(10)),

  // dropdown below..
  child: DropdownButton<String>(
      value: selectedValue,
      onChanged: (String newValue) =>
        setState(() => selectedValue = newValue),
      items: items
          .map<DropdownMenuItem<String>>(
              (String value) => DropdownMenuItem<String>(
                    value: value,
                    child: Text(value),
                  ))
          .toList(),

      // add extra sugar..
      icon: Icon(Icons.arrow_drop_down),
      iconSize: 42,
      underline: SizedBox(),
  ),
);

Answer 6

https://api.flutter.dev/flutter/material/DropdownButton/style.html will help you to figure out some stylings.

DropdownButton(
  dropdownColor: Colors.grey,
  value: this.repeatType,
  onChanged: (String? value) {
    print(value);
    setState(() {
      this.repeatType = value!;
    });
  },
  selectedItemBuilder: (BuildContext context) {
    return this.repeatTypes.map((String value) {
      return Text(
        this.repeatType,
        style: const TextStyle(color: Colors.white),
      );
    }).toList();
  },
  items: this
      .repeatTypes
      .map((item) => DropdownMenuItem(
            child: Text(
              item,
              style: TextStyle(color: Colors.green),
            ),
            value: item,
          ))
      .toList())

Answer 7

You can wrap it with container like this:

Container(
  margin: const EdgeInsets.all(15.0),
  padding: const EdgeInsets.only(left: 10.0, right: 10.0),
  decoration: BoxDecoration(
      color: Colors.white,
      border: Border.all(color: Colors.white)
  ),
  child: DropdownButton(
    dropdownColor: Colors.white,
    style: TextStyle(
      color: Colors.black,
      backgroundColor: Colors.white,
    ),
    value: 'ar',
    items: [
      DropdownMenuItem(child: Text('English'), value: 'en'),
      DropdownMenuItem(child: Text('العربية'), value: 'ar'),
    ],
  ),
)

The output:

Answer 8

Use this for color

 DropdownButtonFormField(
              items: null,
              onChanged: null,
              dropdownColor: Colors.red,
            ),

Answer 9

You can do something very simple in the latest version of Flutter.

The DropdownButton class has an inbuilt variable called 'dropdownColor' which can be assigned any color you need directly, without changing any 'ThemeData'. Automatically changes the color of the dropdown menu items as well.

Answer 10

If you want the DropdownButton to fill the space that it is in, use the property isExpanded and set it to true

DropdownButton<String>(
   isExpanded: true,
)

Answer 11

As Collin said, your DropdownMenuItem will follow your ThemeData class. Not only its backgroundColor will match the canvasColor in your ThemeData class, but also it will follow the same TextStyle.

So, for a quick example:

new ThemeData(
        fontFamily: "Encode Sans", //my custom font
        canvasColor: _turquoise, //my custom color
//other theme data)

Furthermore, if you want to control the width of the menu, you can feed its child property a new Container and add the desired width, check the following GIF, I started with width: 100.0 then hot reloaded after changing it to 200.0, notice how the width was manipulated, just make sure you use a suitable width so that you do not get overflow problems later on when you use the menu within a more complex layout.

class TestPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title:new Text ("Test"),
      ),
      body: new Center(
        child: new DropdownButton(items: new List.generate(20, (int index){
          return new DropdownMenuItem(child: new Container(
            child: new Text ("Item#$index"),
            width: 200.0, //200.0 to 100.0
          ));
        })
            , onChanged: null)
      ),
    );
  }
}

Answer 12

You can accomplish this by wrapping the DropdownButton in a Theme widget and overriding the canvasColor.

import 'package:flutter/material.dart';

void main() {
  runApp(new MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      home: new MyHomePage(),
    );
  }
}

class MyHomePage extends StatefulWidget {
  State createState() => new MyHomePageState();
}

class MyHomePageState extends State<MyHomePage> {
  int _value = 42;

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      body: new Center(
        child: new Theme(
          data: Theme.of(context).copyWith(
            canvasColor: Colors.blue.shade200,
          ),
          child: new DropdownButton(
            value: _value,
            items: <DropdownMenuItem<int>>[
              new DropdownMenuItem(
                child: new Text('Foo'),
                value: 0,
              ),
              new DropdownMenuItem(
                child: new Text('Bar'),
                value: 42,
              ),
            ],
            onChanged: (int value) {
              setState(() {
                _value = value;
              });
            },
          ),
        ),
      ),
    );
  }
}