如何在flutter中的任何小部件周围制作渐变阴影？

Question

例子：

请注意，小部件的颜色无关紧要，只有它周围阴影的颜色。

我一直在尝试编辑 BoxShadow 的源代码，它只有100行长，但我没有取得太大的成功。

任何帮助，将不胜感激！ 谢谢！

Answer 1

通过使用this ，我实现了你想要的。

import 'package:flutter/material.dart';

import 'gradient_decoration.dart';

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

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: _buildBody(),
      floatingActionButton: FloatingActionButton(
        onPressed: () {},
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ),
    );
  }

  Widget _buildBody() {
    return Center(
      child: Container(
        width: 300,
        height: 80,
        decoration: GradientShadowBoxDecoration(
            borderRadius: BorderRadius.circular(20),
            boxShadow: [
              BoxShadow(
                offset: Offset(0.0, 0.0),
                blurRadius: 25,
              ),
            ],
            gradient: LinearGradient(
              begin: Alignment.centerLeft,
              end: Alignment.centerRight,
              colors: [
                Colors.blue,
                Colors.purple,
              ],
            )),
        child: Center(
          child: Text(
            'Login',
            style: TextStyle(
              fontSize: 25.0,
              fontWeight: FontWeight.bold,
              color: Colors.white,
            ),
          ),
        ),
      ),
    );
  }
}