PageView PageController initialPage refresh

[shingohu]

In MyApp, the children of PageView is dynamic, so I hope that every time the number of children changes, PageView jumps to the initialPage position, and then it doesn't work. I don't know how to update the initialPage position

[robin7331]

Did you try using the jumpToPage Method of the PageController after inserting a new page?

[shingohu]

@robin7331 When and where to use this method？

[robin7331]

Could you share your code of the widget your PageView/Controller is in?

[shingohu]

@robin7331 ok

import 'package:flutter/material.dart';

class BannerWidget extends StatefulWidget {
  //item的宽高比例
  final itemRatio;
  final viewportFraction; //page的比例
  final List<Widget> items;
  final EdgeInsetsGeometry margin;
  final virtualCount;
  final PageController pageController;

  BannerWidget({
    Key key,
    @required this.items,
    this.itemRatio: 2 / 2,
    this.viewportFraction: 0.8,
    EdgeInsetsGeometry margin,
    PageController pageController,
    this.virtualCount: 10000,
  })  : assert(items != null, "must set items"),
        margin = margin ?? EdgeInsets.all(10),
        pageController = pageController ??
            PageController(
                viewportFraction: viewportFraction,
                initialPage: items.length < 2 ? 0 : virtualCount,
                keepPage: false),
        
        super(key: key);

  _BannerWidgetState createState() => _BannerWidgetState();
}

class _BannerWidgetState extends State<BannerWidget> {
  void initState() {
    
    
    super.initState();
  }

  @override
  void didUpdateWidget(BannerWidget oldWidget) {
    super.didUpdateWidget(oldWidget);
    
  }

  @override
  Widget build(BuildContext context) {
    return LayoutBuilder(
      builder: (context, constraints) {
        final width = constraints.biggest.width;
        final ratio = widget.itemRatio;
        final viewportFraction = widget.viewportFraction;
        final margin = widget.margin;
        var pageController = widget.pageController;

        final items = widget.items;
        return GestureDetector(
          child: Container(
              width: width,
              height: items.length == 0
                  ? 0
                  : (width * viewportFraction - 2 * (margin.horizontal)) /
                          ratio +
                      margin.vertical,
              child: PageView.builder(
                onPageChanged: (index) {
                  print("index");
                },
                itemBuilder: (context, index) {
                  var realIndex;
                  if (items.length < 2) {
                    realIndex = 0;
                  } else {}

                  return AspectRatio(
                    aspectRatio: ratio,
                    child: Container(
                      color: Colors.blue,
                      margin: margin,
                      width: width * viewportFraction - 2 * (margin.horizontal),
                      child: Center(
                        child: Text("$index"),
                      ),
                    ),
                  );
                },
                controller: pageController,
                itemCount: items.length < 2 ? items.length : null,
              )),
        );
      },
    );
  }
}

how to use

Widget _bannerWidget() {
    return BannerWidget(items: <Widget>[Text("1"),Text("2")],itemRatio: 582/240);
  }

[zoechi]

Please consider asking support questions in one of the other channels listed at http://flutter.io/support .

[dariotrombello]

Can be closed I guess

[zoechi]

@dariotrombello Thanks!
I added the waiting for customer response label for that.
If there is no additional response from the original poster, a bot will close the issue after a month (not very reliable) or if not I'll do it manually after a while.

[stefansidler1993]

check this code in your widget PageController(initialPage: 1, keepPage: false); the magic is setting keepPage

[longxf]

How to solve it in the end?

[majunchang]

check this code in your widget PageController(initialPage: 1, keepPage: false); the magic is setting keepPage

It's not going to work

[stefansidler1993]

check this code in your widget PageController(initialPage: 1, keepPage: false); the magic is setting keepPage

It's not going to work

Why it’s not going to work ?

[github-actions]

This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.