使用BoxDecoration和BoxShadow。

下面是一个操作以下选项的可视化演示:

不透明度 x抵消 y抵消 模糊半径 扩散半径

动图在色彩方面做得不太好。你可以自己在设备上试试。

以下是演示的完整代码:

import 'package:flutter/material.dart';

void main() => runApp(MyApp());

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

class ShadowDemo extends StatefulWidget {
  @override
  _ShadowDemoState createState() => _ShadowDemoState();
}

class _ShadowDemoState extends State<ShadowDemo> {
  var _image = NetworkImage('https://placebear.com/300/300');

  var _opacity = 1.0;
  var _xOffset = 0.0;
  var _yOffset = 0.0;
  var _blurRadius = 0.0;
  var _spreadRadius = 0.0;

  @override
  Widget build(BuildContext context) {
    return Stack(
      children: <Widget>[
        Center(
          child:
          Container(
            decoration: BoxDecoration(
              color: Color(0xFF0099EE),
              boxShadow: [
                BoxShadow(
                  color: Color.fromRGBO(0, 0, 0, _opacity),
                  offset: Offset(_xOffset, _yOffset),
                  blurRadius: _blurRadius,
                  spreadRadius: _spreadRadius,
                )
              ],
            ),
            child: Image(image:_image, width: 100, height: 100,),
          ),
        ),
        Align(
          alignment: Alignment.bottomCenter,
          child: Padding(
            padding: const EdgeInsets.only(bottom: 80.0),
            child: Column(
              children: <Widget>[
                Spacer(),
                Slider(
                  value: _opacity,
                  min: 0.0,
                  max: 1.0,
                  onChanged: (newValue) =>
                  {
                    setState(() => _opacity = newValue)
                  },
                ),
                Slider(
                  value: _xOffset,
                  min: -100,
                  max: 100,
                  onChanged: (newValue) =>
                  {
                    setState(() => _xOffset = newValue)
                  },
                ),
                Slider(
                  value: _yOffset,
                  min: -100,
                  max: 100,
                  onChanged: (newValue) =>
                  {
                    setState(() => _yOffset = newValue)
                  },
                ),
                Slider(
                  value: _blurRadius,
                  min: 0,
                  max: 100,
                  onChanged: (newValue) =>
                  {
                    setState(() => _blurRadius = newValue)
                  },
                ),
                Slider(
                  value: _spreadRadius,
                  min: 0,
                  max: 100,
                  onChanged: (newValue) =>
                  {
                    setState(() => _spreadRadius = newValue)
                  },
                ),
              ],
            ),
          ),
        )
      ],
    );
  }
}

检查BoxShadow和BoxDecoration

Container可以带一个BoxDecoration(脱离你最初发布的代码)，它带一个boxShadow

return Container(
  margin: EdgeInsets.only(left: 30, top: 100, right: 30, bottom: 50),
  height: double.infinity,
  width: double.infinity,
  decoration: BoxDecoration(
    color: Colors.white,
    borderRadius: BorderRadius.only(
      topLeft: Radius.circular(10),
        topRight: Radius.circular(10),
        bottomLeft: Radius.circular(10),
        bottomRight: Radius.circular(10)
    ),
    boxShadow: [
      BoxShadow(
        color: Colors.grey.withOpacity(0.5),
        spreadRadius: 5,
        blurRadius: 7,
        offset: Offset(0, 3), // changes position of shadow
      ),
    ],
  ),
)

class ShadowContainer extends StatelessWidget {
  ShadowContainer({
    Key key,
    this.margin = const EdgeInsets.fromLTRB(0, 10, 0, 8),
    this.padding = const EdgeInsets.symmetric(horizontal: 8),
    this.circular = 4,
    this.shadowColor = const Color.fromARGB(
        128, 158, 158, 158), //Colors.grey.withOpacity(0.5),
    this.backgroundColor = Colors.white,
    this.spreadRadius = 1,
    this.blurRadius = 3,
    this.offset = const Offset(0, 1),
    @required this.child,
  }) : super(key: key);

  final Widget child;
  final EdgeInsetsGeometry margin;
  final EdgeInsetsGeometry padding;
  final double circular;
  final Color shadowColor;
  final double spreadRadius;
  final double blurRadius;
  final Offset offset;
  final Color backgroundColor;

  @override
  Widget build(BuildContext context) {
    return Container(
      margin: margin,
      padding: padding,
      decoration: BoxDecoration(
        color: backgroundColor,
        borderRadius: BorderRadius.circular(circular),
        boxShadow: [
          BoxShadow(
            color: shadowColor,
            spreadRadius: spreadRadius,
            blurRadius: blurRadius,
            offset: offset,
          ),
        ],
      ),
      child: child,
    );
  }
}

我就是这么做的

    Container(
  decoration: new BoxDecoration(
    boxShadow: [
      BoxShadow(
        color: Colors.grey[200],
        blurRadius: 2.0, // has the effect of softening the shadow
        spreadRadius: 2.0, // has the effect of extending the shadow
        offset: Offset(
          5.0, // horizontal, move right 10
          5.0, // vertical, move down 10
        ),
      )
    ],
  ),
  child: Container( 
       color: Colors.white, //in your example it's blue, pink etc..
       child: //your content
  )

截图:

Using BoxShadow (more customizations): Container( width: 100, height: 100, decoration: BoxDecoration( color: Colors.teal, borderRadius: BorderRadius.circular(20), boxShadow: [ BoxShadow( color: Colors.red, blurRadius: 4, offset: Offset(4, 8), // Shadow position ), ], ), ) Using PhysicalModel: PhysicalModel( color: Colors.teal, elevation: 8, shadowColor: Colors.red, borderRadius: BorderRadius.circular(20), child: SizedBox.square(dimension: 100), ) Using Card: Card( elevation: 8, shadowColor: Colors.red, child: Container( width: 100, height: 100, color: Colors.teal, ), ) Using Material: Material( elevation: 8, color: Colors.teal, shadowColor: Colors.red, borderRadius: BorderRadius.circular(20), child: SizedBox.square(dimension: 100), )

在容器内使用shadowColor材质，如下所示:

Container(
  decoration: BoxDecoration(
      borderRadius: BorderRadius.only(
          bottomLeft: Radius.circular(10),
          bottomRight: Radius.circular(10)),
      boxShadow: [
        BoxShadow(
            color: Color(0xffA22447).withOpacity(.05),
            offset: Offset(0, 0),
            blurRadius: 20,
            spreadRadius: 3)
      ]),
  child: Material(
    borderRadius: BorderRadius.only(
        bottomLeft: Radius.circular(10),
        bottomRight: Radius.circular(10)),
    elevation: 5,
    shadowColor: Color(0xffA22447).withOpacity(.05),
    color: Color(0xFFF7F7F7),
    child: SizedBox(
      height: MediaQuery.of(context).size.height / 3,
    ),
  ),
)