The issue is this, if I use the Page Indicator and set the length property to a large value, it overflowed from the screen which make the app look like it crashes. The code is PageViewIndicator( pageIndexNotifier: _currentPageNotifier, length: 20, indicatorPadding: EdgeInsets.all(5.0), normalBuilder: (animationController, index) => Circle( size: 8.0, color: Colors.black87, ), highlightedBuilder: (animationController, index) => ScaleTransition( scale: CurvedAnimation( parent: animationController, curve: Curves.ease, ), child: Circle( size: 20.0, color: Colors.grey, ), ), );

Hi, basically same issue as this one - https://github.com/leocavalcante/page_view_indicator/issues/1 If PageViewIndicator is inside StreamBuilder and item count is dynamically changed, the number of indicators stays the same. Here is a quick code to reproduce the issue:

import 'dart:async';

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

class App extends StatefulWidget {
  @override
  _AppState createState() => _AppState();
}

class _AppState extends State<App> {
  final pageIndexNotifier = ValueNotifier<int>(0);
  int _counter = 2;
  StreamController<int> _events;

  @override
  void initState() {
    super.initState();
    _events = StreamController<int>();
    _events.add(_counter);
  }

  void _incrementCounter() {
    _counter++;
    _events.add(_counter);
  }

  void _decrementCounter() {
    if (_counter > 1) {
      _counter--;
      _events.add(_counter);
    }
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: StreamBuilder<int>(
          stream: _events.stream,
          builder: (context, snapshot) {
            if (!snapshot.hasData) {
              return const SizedBox.shrink();
            }

            return Stack(
              alignment: FractionalOffset.bottomCenter,
              children: <Widget>[
                PageView.builder(
                  onPageChanged: (index) => pageIndexNotifier.value = index,
                  itemCount: snapshot.data,
                  itemBuilder: (context, index) {
                    return Container(
                      decoration: BoxDecoration(color: Colors.accents[index]),
                    );
                  },
                ),
                _buildExample1(snapshot.data),
                Center(
                  child: Text(snapshot.data.toString()),
                ),
              ],
            );
          },
        ),
        floatingActionButton: Column(
          crossAxisAlignment: CrossAxisAlignment.end,
          mainAxisAlignment: MainAxisAlignment.end,
          children: <Widget>[
            FloatingActionButton(
              onPressed: _incrementCounter,
              tooltip: 'Increment',
              child: Icon(Icons.exposure_plus_1),
            ),
            const SizedBox(height: 16),
            FloatingActionButton(
              onPressed: _decrementCounter,
              tooltip: 'Decrement',
              child: Icon(Icons.exposure_neg_1),
            ),
          ],
        ),
      ),
    );
  }

  PageViewIndicator _buildExample1(int length) {
    return PageViewIndicator(
      pageIndexNotifier: pageIndexNotifier,
      length: length,
      normalBuilder: (animationController, index) => Circle(
        size: 8.0,
        color: Colors.black87,
      ),
      highlightedBuilder: (animationController, index) => ScaleTransition(
        scale: CurvedAnimation(
          parent: animationController,
          curve: Curves.ease,
        ),
        child: Circle(
          size: 12.0,
          color: Colors.accents.elementAt(9),
        ),
      ),
    );
  }
}

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

I'm using the PageViewIndicator inside a StreamBuilder. The streamBuilder returns a List of object. When object is added in the list and the StreamBuilder is triggered, the PageViewIndicator is NOT updated (number of dot stays the same).

If I try to insert a "basic" Text Widget, the Text is updated correctly with the number of objects in my list

There was a bug with marking the previous page as normal if currentPage was different than 0. e.g: CurrentPage is (5) PageIndexNotifier is (5)

After changing page from 5 to 6 listener will invoke and it will mark _prevPage indicator as normal but _prevPage was 0, not 5.

Great work on this. How do you adjust padding or spaces between the dots? For instance, I might want the dots to be aligned much closer together. How can this be achieved? If possible, it will be helpful to include that somewhere in the README.md examples.

Can I ask why _addIndicatorsListener is called in didUpdateWidget? Currently everytime the widget tree gets rebuilt, duplicate listener is added to the list of widget.pageIndexNotifier listeners and it can sum up to infinite number of duplicate listeners.

https://github.com/leocavalcante/page_view_indicator/blob/1876bb6e3a49157a205f44980eae12b0f4e1c16d/lib/page_view_indicator.dart#L94

As the pageIndexNotifier is the same object every rebuild time, it's safe to add the listener only in initState.

if I build widget currentPage: 1,then setpageIndexNotifier.value = 0,the indicator don't change.

because the initial value of _prevPage in _PageViewIndicatorState is 0.

maybe the initial value of _prevPage should be null.

The pageIndexNotifier.addListener was being invoked in initState but initState is called only once in the widget's life cycle so when you navigated from one screen to another the indicator stops working. I moved the call to a method that is called in build.

Thank you for the nice plugin, easy to use, works perfectly. Have one issue though - didn't find a way to navigate PageView on certain page when user tap on the page's dot. It is quite standard behavior for such kind of navigation. Will appreciate a help with how to get such behavior.