如何在Flutter中为必填字段设置红色星号（*）

Question

我正在尝试在 RichText 小部件中获得一个红色星号 ()；我可以使用样式属性。但它会使整个文本变红。我只希望星号 () 为红色。任何线索，如何实现它？

这是我的 RichText 小工具，现在我可以看到一个星号 (*)，颜色与其余文本相同。

RichText(
    text: TextSpan(
        text: '$labelText *',
        style: TextStyle(
            color: labelColor, fontWeight: fontWeight, fontSize: fontSize)),
    textScaleFactor: labelTextScale,
    maxLines: labelMaxLines,
    overflow: overflow,
    textAlign: textAlign,
  );

Answer 1

我知道怎么做了。 TextSpan 有一个 children 属性，它以一个 List 作为值。

所以我为星号 (*) 分配了一个 TextSpan。

 RichText(
    text: TextSpan(
        text: '$labelText',
        style: TextStyle(
            color: labelColor, fontWeight: fontWeight, fontSize: fontSize),
        children: [
           TextSpan(
                  text: ' *',
                  style: TextStyle(
                      color: Colors.red,
                      fontWeight: fontWeight,
                      fontSize: fontSize))
        ]),
    textScaleFactor: labelTextScale,
    maxLines: labelMaxLines,
    overflow: overflow,
    textAlign: textAlign,
  ),

Answer 2

你可以使用这个：

class FormField extends StatelessWidget {
  final String label;
  final bool withAsterisk;
  const FormField({Key key, @required this.label, @required this.withAsterisk})
      : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Stack(children: [
      Container(
        padding: EdgeInsets.fromLTRB(16, 16, 16, 0),
        child: TextFormField(
          decoration: InputDecoration(
              border: OutlineInputBorder(),
              focusedBorder: OutlineInputBorder(),
              errorBorder: OutlineInputBorder(
                borderSide: const BorderSide(color: Colors.red, width: 1),
              )),
        ),
      ),
      Padding(
        padding: const EdgeInsets.only(left: 32, top: 10),
        child: RichText(
          text: TextSpan(
            children: <TextSpan>[
              TextSpan(
                  text: ' $label',
                  style: TextStyle(
                      backgroundColor:
                          Theme.of(context).scaffoldBackgroundColor,
                      color: DsColor.textColorDrkGrey,
                      fontWeight: FontWeight.w400,
                      fontSize: 12)),
              TextSpan(
                  text: withAsterisk ? '* ' : ' ',
                  style: TextStyle(
                      fontWeight: FontWeight.w500,
                      fontSize: 12,
                      backgroundColor:
                          Theme.of(context).scaffoldBackgroundColor,
                      color: Colors.red)),
            ],
          ),
        ),
      ),
    ]);
  }
}

用法：

FormField(
  label: "Name",
  withAsterisk: true,
),
FormField(
  label: "Phone",
  withAsterisk: false,
)

Answer 3

You Can Use This even you can change the colors of all the characters in TextSpan via children property.

下面是我的示例代码你自己搞定吧:

Here is output you can view it

import 'package:flutter/material.dart';

void main() {
  runApp(MaterialApp(
    title: 'Navigation Basics',
    home: HomePage(),
  ));
}

class HomePage extends StatelessWidget {
  String labelText = "Ayush Kumar ";
  
  
  @override
  Widget build(BuildContext context) {
    return Scaffold(
     body:Center(
       child:RichText(
    text: TextSpan(
        text: '$labelText',
        style: TextStyle(
            color: Colors.black,
            fontSize:30.0,
          fontWeight: FontWeight.bold,
        ),
        children: [
           TextSpan(
                  text: ' *',
                  style: TextStyle(
                      color: Colors.red,
                         fontSize:30.0,
                    fontWeight: FontWeight.bold,
                    )),
           TextSpan(
                  text: ' *',
                  style: TextStyle(
                      color: Colors.blue,
                    fontSize:30.0,
                    fontWeight: FontWeight.bold,
                    )),
        ])),
     
     
     ),
      
  );
 }
}

Answer 4

升级 flutter 到 2.5.3，您将获得一个“标签”小部件来自定义您的标签。你可以随心所欲地改变。

 decoration: InputDecoration(
          label: Row(
            children: [
              CustomText(widget.label,
                  font: Font.NUNITO_REGULAR, color: ColorResource.COLOR_cacaca),
              if (widget.isMandatory)
                const CustomText(" *",
                    font: Font.NUNITO_REGULAR,
                    color: ColorResource.COLOR_DB4437)
            ],
          ),

如何在Flutter中为必填字段设置红色星号（*）

How to set a red asterisk (*) for sign of is mandatory field in Flutter

dart

flutter

flutter-layout