Stack Widget

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Example: #1 [Basic Stack]

import 'package:flutter/material.dart';
void main()=>runApp(MaterialApp(home: MyApp(),));

class MyApp extends StatefulWidget{
  @override  MyAppState createState()=>MyAppState();
}
class MyAppState extends State<MyApp>{
  @override  Widget build(BuildContext context){
    return Scaffold(
      appBar: AppBar(
        title: Text('Stack Widget Demo'),
        centerTitle: true,
      ),
      body: Stack(
        children: <Widget>[
          Container(
            width: 200,
            height: 200,
            color: Colors.amber,
          )
        ],
      ),
    );
  }
}

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Example: #2 [Center ]

import 'package:flutter/material.dart';
void main()=>runApp(MaterialApp(home: MyApp(),));

class MyApp extends StatefulWidget{
  @override  MyAppState createState()=>MyAppState();
}
class MyAppState extends State<MyApp>{
  @override  Widget build(BuildContext context){
    return Scaffold(
      appBar: AppBar(
        title: Text('Stack Widget Demo'),
        centerTitle: true,
      ),
      body: Center(
       child: Stack(
          children: <Widget>[
            Container(
              width: 200,
              height: 200,
              color: Colors.amber,
            )
          ],
        ),
      )

    );
  }
}

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Example: #3[One each other]

import 'package:flutter/material.dart';
void main()=>runApp(MaterialApp(home: MyApp(),));

class MyApp extends StatefulWidget{
  @override  MyAppState createState()=>MyAppState();
}
class MyAppState extends State<MyApp>{
  @override  Widget build(BuildContext context){
    return Scaffold(
      appBar: AppBar(
        title: Text('Stack Widget Demo'),
        centerTitle: true,
      ),
      body: Center(
       child: Stack(
          children: <Widget>[
            Container(
              width: 200,
              height: 200,
              color: Colors.amber,
            ),
            Container(
              width: 150,
              height: 150,
              color: Colors.green,
            ),
            Container(
              width: 100,
              height: 100,
              color: Colors.red,
            ),
          ],
        ),
      )

    );
  }
}

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Example: #4[stack widget and alignment]

import 'package:flutter/material.dart';

import 'package:flutter/services.dart';

void main() => {

  SystemChrome.setSystemUIOverlayStyle(

  SystemUiOverlayStyle(statusBarColor: Colors.white)),

  runApp(MaterialApp(

    debugShowCheckedModeBanner: false,

    home: MyApp()))};

class MyApp extends StatefulWidget {

  @override

  MyAppState createState() => MyAppState();

}

class MyAppState extends State<MyApp> {

  @override

  Widget build(BuildContext context) {

    return Scaffold(

      backgroundColor: Colors.white,

      body: Center(  

        child: Stack(  

         // alignment: Alignment.topCenter,

         //alignment: Alignment.topRight,

          //alignment: Alignment.centerLeft,

          //alignment: Alignment.centerRight,

          //alignment: Alignment.bottomLeft,

          //alignment: Alignment.bottomRight,

          alignment: Alignment.bottomCenter,

          children: [

            Container(  

              width: 200,

              height: 200,

              color: Colors.red,

            ),

            Container(  

              width: 50,

              height: 50,

              color: Colors.green,

            ),

          ],

        ),

      ),

    );

  }

}

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Example: #5

import 'package:flutter/material.dart';

void main() => {

  runApp(MaterialApp(

    debugShowCheckedModeBanner: false,

    home: MyApp()))};

class MyApp extends StatefulWidget {

  @override

  MyAppState createState() => MyAppState();

}

class MyAppState extends State<MyApp> {

  @override

  Widget build(BuildContext context) {

    return Scaffold(

      backgroundColor: Colors.white,

      body: Center(  

        child: Stack(  

        //fit: StackFit.loose, 

        // default value is loose

       // fit: StackFit.expand,

       overflow: Overflow.visible,

       //clipBehavior: Clip.none,

        alignment: Alignment.topLeft,

          children: [

            Container(  

              width: 200,

              height: 200,

              color: Colors.red,

            ),

            Container(  

              width: 100,

              height: 100,

              color: Colors.yellow,

            ),

            Positioned( 

              top: 50, 

              left: 50,

               //top: 200, 

              //left: 200,

              child: Container(  

                width: 200,

                height: 200,

                color: Colors.green,

              ),

            )

          ],

        ),

      ),

    );

  }

}

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Example: #6

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Example: #7

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Example: #8