如何在 flutter 中为下拉按钮制作圆角边框？

Question

如何添加圆角矩形边框？下面的代码不会在屏幕上产生任何边框。

Container(margin: EdgeInsets.only(top: 10.0, right: 10.0, left: 10.0),
 width: double.infinity,
 // decoration: ShapeDecoration(
 //  shape: RoundedRectangleBorder(
 //   borderRadius:BorderRadius.all(Radius.circular(5.0)),
 //                             ),

 child: DropdownButtonHideUnderline(
  child: Container(
   margin: EdgeInsets.only(
    left: 10.0, right: 10.0),
     child: new DropdownButton<UserTest>(...),
                           ),
                          ),
                   ),

Answer 1

您需要指定 side: 属性。默认为 BorderSide.none.

      decoration: ShapeDecoration(
        shape: RoundedRectangleBorder(
          side: BorderSide(width: 1.0, style: BorderStyle.solid),
          borderRadius: BorderRadius.all(Radius.circular(5.0)),
        ),
      ),

Answer 2

Container(width: 200.0,
          height: 50.0,
          decoration: BoxDecoration(
          borderRadius: BorderRadius.circular(7.0),
          border: Border.all(color: Colors.blueGrey)),
                         child: DropdownButton<String>(
                         hint: Text("Messaging"),
                         items: <String>['Messaging', 'Chating', 'No Longer Interested', 'Document Request'].map((String value) {
                            return new DropdownMenuItem<String>(
                              value: value,
                              child: new Text(value),
                            );
                          }).toList(),
                          onChanged: (_) {},
                      ),
                      )

Answer 3

如果你想要的是这个...

那么给你

    import 'package:flutter/material.dart';

class RoundedBorderDropdown extends StatelessWidget {
  final List<String> _dropdownValues = [
    "One",
    "Two",
    "Three",
    "Four",
    "Five"
  ]; //The list of values we want on the dropdown

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Rounded Border Button in AppBar'),
      ),
      body: Center(
        child: Container(
          padding: EdgeInsets.symmetric(horizontal: 10.0),
          decoration: BoxDecoration(
            borderRadius: BorderRadius.circular(15.0),
            border: Border.all(
                color: Colors.red, style: BorderStyle.solid, width: 0.80),
          ),
          child: DropdownButton(
            items: _dropdownValues
                .map((value) => DropdownMenuItem(
                      child: Text(value),
                      value: value,
                    ))
                .toList(),
            onChanged: (String value) {},
            isExpanded: false,
            value: _dropdownValues.first,
          ),
        ),
      ),
    );
  }
}

这是礼貌inducesmile

快乐编码...

Answer 4

使用表单字段变体，您可以使用 OutlineInputBorder InputBorder，通常用于输入文本字段：

DropdownButtonFormField(
  ...
  decoration: const InputDecoration(
    border: OutlineInputBorder(),
  ),
),

表单字段执行此操作的方式可以复制并用于常规 DropdownButton:

InputDecorator(
  decoration: const InputDecoration(border: OutlineInputBorder()),
  child: DropdownButtonHideUnderline(
    child: DropdownButton(
      ...
    ),
  ),
),

Answer 5

Container(
    decoration: BoxDecoration(
      borderRadius: BorderRadius.circular(20.0),
      border: Border.all(
        color: HexColor('#C88A3D'),
        width: 3.0
      )
    ),
    child: Container(
      decoration: new BoxDecoration(borderRadius:
      BorderRadius.circular(20.0),
      color: Colors.white,),
    )
  ),

Answer 6

将其包裹在 Material 中并移除 DropDown 边框

Material(
    borderRadius: BorderRadius.circular(40),
    child: SizedBox(
      width: MediaQuery.of(context).size.width / 1.08,
      child: DropdownButton(
        style: style.copyWith(color: Colors.black),
        isExpanded: true,
        underline: DropdownButtonHideUnderline(child: Container()),
        value: value,
        items: ...
   
    ),
  )

Answer 7

Column(
    crossAxisAlignment : CrossAxisAlignment.start,
    children: <Widget> [
        Text('Gender:'),
        InputDecorator(
            decoration: InputDecoration(
                border: OutlineInputBorder(borderRadius: const BorderRadius.all(Radius.circular(4.0)),
                contentPadding: EdgeInsets.all(10),
            ),
            child: DropdownButtonHideUnderline(
                child: DropdownButton<String>(
                    value: gender,
                    isDense: true,
                    isExpanded: true,
                    items: [
                        DropdownMenuItem(child: Text("Select Gender"), value: ""),
                        DropdownMenuItem(child: Text("Male"), value: "Male"),
                        DropdownMenuItem(child: Text("Female"), value: "Female"),
                    ],
                    onChanged: (newValue) {
                        setState(() {
                        });
                    },
                ),
            ),
        ),
    ]
),

如何在 flutter 中为下拉按钮制作圆角边框？

How to make rounded border for dropdownbutton in flutter?

spinner

drop-down-menu

flutter

flutter-layout