如何在flutter中为下拉按钮制作圆形边框？

Question

如何添加圆角矩形边框？以下代码未在屏幕上显示任何边框。

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

对于表单域变体，您可以使用OutlineInputBorder InputBorder, 通常用于输入文本域：

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

表单字段执行此操作的方式可以复制并与常规一起使用DropdownButton：

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

Answer 2

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(() {
                        });
                    },
                ),
            ),
        ),
    ]
),

Answer 3

您需要指定side:属性。默认情况下为BorderSide.none。

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

Answer 4

如果你想要的是这个

那么你去

    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,
          ),
        ),
      ),
    );
  }
}

那是礼貌引诱

快乐编码....