Image Cache Clear Issue

image_cache_clear_issue.dart

import 'package:flutter/material.dart';
import 'dart:async';
import 'dart:convert';
import 'dart:io';
import 'package:http/http.dart' as http;
import 'package:flutter/painting.dart' as painting;

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

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

class PhotosPage extends StatefulWidget {
  @override
  _PhotosPageState createState() => _PhotosPageState();
}

class _PhotosPageState extends State<PhotosPage> {
  Future<List<Photo>> _futurePhotos;

  @override
  void initState() {
    super.initState();
    _futurePhotos = JsonPlaceholderApi().getPhotos();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text("Photos"),),
      body: RefreshIndicator(
        child: Center(
          child: FutureBuilder<List<Photo>>(
            future: _futurePhotos,
            builder: (context, snapshot) {
              if (snapshot.hasData) {
                return _getGridView(snapshot.data);
              } else if (snapshot.hasError) {
                return getErrorMessage(snapshot.error, _onRetryPressed);
              }
              // By default, show a loading spinner
              return CircularProgressIndicator();
            },
          ),
        ), onRefresh: _handleRefresh,
      ),
    );
  }

  _getGridView(List<Photo> data) {
    if (data.isNotEmpty) {
      return GridView.builder(
        itemCount: data.length,
        itemBuilder: (context, index) {
          return _getGridItem(data[index]);
        },
        gridDelegate:
        SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 2),
      );
    } else {
      return Center(child: Text('No data found.'));
    }
  }

  _getGridItem(Photo photo) {
    return GridTile(
      child: Image.network(
        photo.thumbnailUrl,
        fit: BoxFit.cover,
      ),
      footer: Container(
          color: Color(0x60000000),
          padding: EdgeInsets.all(8.0),
          child: Text(
            photo.title,
            style: TextStyle(color: Colors.white),
          )),
    );
  }

  _onRetryPressed() {
    setState(() {
      _futurePhotos = JsonPlaceholderApi().getPhotos();
    });
  }

  Future<Null> _handleRefresh() async {
      setState(() {
      _futurePhotos = JsonPlaceholderApi().getPhotos();
    });
    painting.imageCache.clear();
    return null;
  }

}


class JsonPlaceholderApi {
  static const String baseUrl = 'jsonplaceholder.typicode.com';
  static const String photosPath = 'photos';

  Future<List<Photo>> getPhotos() async {
    final uri = Uri.https(baseUrl, photosPath);

    final jsonResponse = await _getJsonResponse(uri);

    final photos = jsonResponse
        .map<Photo>((dynamic item) => Photo.fromJson(item))
        .toList();

    return photos;
  }

  Future<List<dynamic>> _getJsonResponse(Uri uri) async {
    var httpResponse = await http.get(uri);

    if (httpResponse.statusCode == HttpStatus.OK) {
      var jsonResponse = json.decode(httpResponse.body);
      return jsonResponse;
    } else {
      throw Exception('\nStatus code:${httpResponse.statusCode}');
    }
  }
}


class Photo {
  final int albumId;
  final int id;
  final String title;
  final String url;
  final String thumbnailUrl;

  Photo.fromJson(Map<String, dynamic> jsonMap)
      : this.albumId = jsonMap['albumId'],
        this.id = jsonMap['id'],
        this.title = jsonMap['title'],
        this.url = jsonMap['url'],
        this.thumbnailUrl = jsonMap['thumbnailUrl'];
}

getErrorMessage(Object error, VoidCallback onRetryPressed) {
  var errorMessage;
  if (error is TimeoutException) {
    errorMessage = 'Time out';
  } else if (error is IOException) {
    errorMessage = 'No Internet Connection';
  } else {
    errorMessage = error.toString();
  }
  return Column(
    mainAxisAlignment: MainAxisAlignment.center,
    children: <Widget>[
      Text(
        "$errorMessage",
        textAlign: TextAlign.center,
      ),
      SizedBox(
        height: 16.0,
      ),
      RaisedButton(
        onPressed: onRetryPressed,
        child: Text('Retry'),
      ),
    ],
  );
}