This is a demo to show of the DotsIndicator

dots_indicator.dart

import 'package:flutter/material.dart';
import 'dart:math';

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

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

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

  final String title;

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

class _MyHomePageState extends State<MyHomePage> {
  PageController pageController = PageController();



  @override
  Widget build(BuildContext context) {
//     double width = MediaQuery.of(context).size.width;
//     double height = MediaQuery.of(context).size.height;
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Stack(
         alignment: Alignment.center,
          children: <Widget>[
            PageView.builder(
              itemCount: 5,
              controller: pageController,
              itemBuilder: (BuildContext context, int index) {
                return Padding(
                  padding: EdgeInsets.all(30),
                  child: Container(
                  height: 200,
                  width: 200,
                  color: Colors.red
                ));
              },
            ),
           Positioned(
                bottom: 10,
                child: Center(
                  child: DotsIndicator(
                    controller: pageController,
                    itemCount: 5,
                    color: Colors.black,
//                     dotSize: 2.5,
//                     maxZoom: 2,
//                     dotSpacing: 8,
                  ),
                ),
              ),
          ],
        )
    );
  }
}

class DotsIndicator extends AnimatedWidget {
  DotsIndicator(
      {this.controller,
      this.itemCount,
      this.onPageSelected,
      this.color: Colors.white,
      this.dotSize = 4.0,
      this.maxZoom = 2,
      this.dotSpacing = 18})
      : super(listenable: controller);

  /// The PageController that this DotsIndicator is representing.
  final PageController controller;

  /// The number of items managed by the PageController
  final int itemCount;

  /// Called when a dot is tapped
  final ValueChanged<int> onPageSelected;

  /// The color of the dots.
  ///
  /// Defaults to `Colors.white`.
  final Color color;

  // The base size of the dots
  final double dotSize;

  // The increase in the size of the selected dot
  final double maxZoom;

  // The distance between the center of each dot
  final double dotSpacing;

  Widget _buildDot(int index) {
    double selectedness = Curves.easeOut.transform(
      max(
        0.0,
        1.0 - ((controller.page ?? controller.initialPage) - index).abs(),
      ),
    );
    double zoom = 1.0 + (maxZoom - 1.0) * selectedness;
    return new Container(
      width: dotSpacing,
      child: new Center(
        child: new Material(
          color: color,
          type: MaterialType.circle,
          child: new Container(
            width: dotSize * zoom,
            height: dotSize * zoom,
            child: new InkWell(
              onTap: () => onPageSelected(index),
            ),
          ),
        ),
      ),
    );
  }

  Widget build(BuildContext context) {
    return LayoutBuilder(builder: (context, constraints) {
      return Container(
        height: (dotSize * maxZoom) + 1,
        constraints: BoxConstraints(maxWidth: constraints.maxWidth / 2),
        child: new Row(
          mainAxisAlignment: MainAxisAlignment.center,
          children: new List<Widget>.generate(itemCount, _buildDot),
        ),
      );
    });
  }
}