[BUG] Switching from portrait to landscape orientation in gallery mode skips ahead of selected image

[flikkr]

Describe the bug When in gallery mode and switching from portrait to landscape, the image displayed is not always the same and sometimes jumps 2 images ahead of the current one.

To Reproduce

1. Use the following code:

   
   import 'package:flutter/material.dart';
   import 'package:photo_view/photo_view.dart';
   import 'package:photo_view/photo_view_gallery.dart';

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

class MyApp extends StatelessWidget { @override Widget build(BuildContext context) { return MaterialApp( title: 'Welcome to Flutter', home: DemoPage(), ); } }

class DemoPage extends StatefulWidget { @override _DemoPageState createState() => _DemoPageState(); }

class _DemoPageState extends State { List media = [ MediaItem(imgUrl: 'https://picsum.photos/seed/1/200/300'), MediaItem(imgUrl: 'https://picsum.photos/seed/2/200/300'), MediaItem(imgUrl: 'https://picsum.photos/seed/3/200/300'), MediaItem(imgUrl: 'https://picsum.photos/seed/4/200/300'), MediaItem(imgUrl: 'https://picsum.photos/seed/5/200/300'), ];

@override Widget build(BuildContext context) { return Scaffold( appBar: AppBar(title: Text('Photo gallery')), body: GridView.builder( padding: const EdgeInsets.all(4.0), gridDelegate: SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 3), itemCount: media?.length ?? 0, itemBuilder: (_, i) { return Container( margin: const EdgeInsets.all(4.0), child: GestureDetector( child: Image.network( media[i].imgUrl, fit: BoxFit.cover, ), onTap: () => Navigator.of(context).push( MaterialPageRoute( builder: (context) => PhotoView( options: Options( galleryItems: media, initialIndex: i, backgroundDecoration: const BoxDecoration( color: Colors.black, ), ), ), ), ), ), ); }, ), ); } }

class MediaItem { static int count = 0; final int id; final String imgUrl; final NetworkImage image;

MediaItem({this.imgUrl}) : id = count++, image = NetworkImage(imgUrl); }

class Options { final Decoration backgroundDecoration; final int initialIndex; final PageController pageController; final List galleryItems;

Options({ this.backgroundDecoration, this.initialIndex, @required this.galleryItems, }) : pageController = PageController(initialPage: initialIndex); }

class PhotoView extends StatefulWidget { final Options options;

PhotoView({this.options});

@override State createState() { return _PhotoViewState(); } }

class _PhotoViewState extends State { int currentIndex;

@override void initState() { currentIndex = widget.options.initialIndex; super.initState(); }

void onPageChanged(int index) { setState(() { currentIndex = index; }); }

@override Widget build(BuildContext context) { return Scaffold( body: Container( decoration: widget.options.backgroundDecoration, constraints: BoxConstraints.expand( height: MediaQuery.of(context).size.height, ), child: Stack( alignment: Alignment.bottomRight, children: [ PhotoViewGallery.builder( scrollPhysics: const BouncingScrollPhysics(), builder: _buildItem, itemCount: widget.options.galleryItems.length, backgroundDecoration: widget.options.backgroundDecoration, pageController: widget.options.pageController, onPageChanged: onPageChanged, ), Container( padding: const EdgeInsets.all(20.0), child: Text( "Image ${currentIndex + 1}", style: const TextStyle( color: Colors.white, fontSize: 17.0, decoration: null, ), ), ) ], ), ), ); }

PhotoViewGalleryPageOptions _buildItem(BuildContext context, int index) { final MediaItem item = widget.options.galleryItems[index]; return PhotoViewGalleryPageOptions( imageProvider: item.image, initialScale: PhotoViewComputedScale.contained, minScale: PhotoViewComputedScale.contained, maxScale: PhotoViewComputedScale.covered * 1.5, heroAttributes: PhotoViewHeroAttributes(tag: item.id), ); } }

2. Select 3rd, 4th, or 5th picture (in portrait orientation)
3. Rotate the device

**What is the current behavior?**
Shown image is different from selected image after changing orientation

**Expected behavior**
Selected and shown image should be the same

**Screenshots**
![ezgif-6-da40573d94ce](https://user-images.githubusercontent.com/32480176/90272231-65d4ef80-de5d-11ea-801d-9b7ccf234cfc.gif)

**Is this a *feature* or report a *bug*?**
Bug

**Which versions of Flutter/Photo View, and which browser / OS are affected by this issue? Did this work in previous versions of Photo View?**
Flutter 1.20
photo_view: ^0.10.0

[haytham-c01]

The same problem occurs here, it happens with the 2nd half of images.

[darioxtx]

Issue related with https://github.com/flutter/flutter/issues/60288