Hero animation with gallery flicker Flutter - image

Question

I'm trying to create a basic Hero animation between a gallery grid view page (using photo manager plugin) and a detail page. When the hero animation is done both back and forward, the picture is flickering .
Here is the example I've made :
The full code runnable :
import 'dart:io';
import 'dart:typed_data';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:photo_manager/photo_manager.dart';
void main() {
runApp(const TestApp());
}
class TestApp extends StatefulWidget {
const TestApp({Key? key}) : super(key: key);
#override
State<TestApp> createState() => _TestAppState();
}
class _TestAppState extends State<TestApp> {
final List<AssetEntity> assetsList = [];
bool granted = false;
void loadAssets() async {
granted = await PhotoManager.requestPermission();
if (granted) {
FilterOptionGroup option = FilterOptionGroup()
..addOrderOption(const OrderOption(
type: OrderOptionType.createDate,
asc: false,
));
final albums = await PhotoManager.getAssetPathList(filterOption: option, type: RequestType.image);
print("albums : $albums");
if (albums.isNotEmpty) {
var alb = albums.where((element) {
return element.name == 'Test';
});
var album = alb.first;
// Now that we got the album, fetch all the assets it contains
List<AssetEntity> currentList =
await album.getAssetListRange(start: 0, end: 200);
// Update the state and notify UI
assetsList.clear();
assetsList.addAll(currentList);
}
setState(() {});
}
}
#override
void initState() {
loadAssets();
super.initState();
}
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: granted
? _gridView()
: Center(
child: Container(
color: Colors.blue,
width: 200,
height: 200,
child: TextButton(
onPressed: () async {
granted = await PhotoManager.requestPermission();
setState(() {});
},
child: const Text(
"Ask permission",
style: TextStyle(color: Colors.white),
),
)),
)),
);
}
Widget _gridView() {
return GridView.builder(
itemCount: assetsList.length,
gridDelegate:
const SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 3),
itemBuilder: (context, index) {
return Hero(
createRectTween: (Rect? begin, Rect? end) {
RectTween _rectTween = RectTween(begin: begin, end: end);
return _rectTween;
},
tag: assetsList[index].id,
child: GalleryThumbnail(
asset: assetsList[index],
onTap: (bytes) {
Navigator.push(context, MaterialPageRoute(builder: (context) {
return DetailsPage(asset: assetsList[index], bytes: bytes);
}));
},
));
});
}
}
class GalleryThumbnail extends StatelessWidget {
final AssetEntity asset;
final ValueChanged<Uint8List> onTap;
const GalleryThumbnail({Key? key, required this.asset, required this.onTap})
: super(key: key);
#override
Widget build(BuildContext context) {
return FutureBuilder<Uint8List?>(
future: Platform.isIOS
? asset.thumbDataWithOption(
ThumbOption.ios(
width: 500,
height: 500,
deliveryMode: DeliveryMode.opportunistic,
resizeMode: ResizeMode.fast,
resizeContentMode: ResizeContentMode.fit,
quality: 100
// resizeContentMode: ResizeContentMode.fill,
),
)
: asset.thumbDataWithSize(250, 250),
builder: (_, snapshot) {
final bytes = snapshot.data;
if (snapshot.hasError) {
return Container();
}
// If we have no data
if (bytes == null) return Container();
// If there's data, display it as an image
return GestureDetector(
onTap: () {
onTap(bytes);
},
child: Image.memory(bytes, fit: BoxFit.cover,gaplessPlayback: true,));
},
);
}
}
class DetailsPage extends StatefulWidget {
final AssetEntity asset;
final Uint8List bytes;
const DetailsPage({Key? key, required this.asset, required this.bytes})
: super(key: key);
#override
_DetailsPageState createState() => _DetailsPageState();
}
class _DetailsPageState extends State<DetailsPage> {
late ImageProvider _imageProvider;
Future<void> loadFile() async {
try {
File? file = await widget.asset.file;
if (file == null) return;
_imageProvider = Image.file(file).image;
setState(() {});
} catch (e) {
print("error to load file : " + e.toString());
}
}
#override
void initState() {
_imageProvider = Image.memory(widget.bytes).image;
loadFile();
super.initState();
}
#override
Widget build(BuildContext context) {
double ratio = widget.asset.height / widget.asset.width;
return Scaffold(
body: Stack(
children: [
Hero(
createRectTween: (Rect? begin, Rect? end) {
RectTween _rectTween = RectTween(begin: begin, end: end);
return _rectTween;
},
tag: widget.asset.id,
child: Center(
child: Image(image: _imageProvider,
width: MediaQuery.of(context).size.width,
height: MediaQuery.of(context).size.height*ratio,
gaplessPlayback: true),
),
),
const SafeArea(
child: Padding(
padding: EdgeInsets.all(8.0),
child: BackButton(),
)),
],
),
);
}
}
I've implemented hero animation somewhere else in my project and I'm not getting this behavior where as here I do.
Why this is happening and how to correct this ?

Answer 1

Add
transitionOnUserGestures: true,
to Hero() widget in current & next page

Answer 2

This happens because the Hero of the image thumbail wraps the FutureBuilder, and then the future triggers again during the animation, wraps the Image instead of the FutureBuilder.