// Copyright 2014 The Flutter Authors. All rights reserved. // Use of this source code is governed by a BSD-style license that can be // found in the LICENSE file. import 'dart:async'; import 'dart:io'; import 'dart:typed_data'; import 'dart:ui' as ui; import 'package:flutter/foundation.dart'; import 'binding.dart'; import 'debug.dart'; import 'image_provider.dart' as image_provider; import 'image_stream.dart'; /// The dart:io implementation of [image_provider.NetworkImage]. @immutable class NetworkImage extends image_provider.ImageProvider<image_provider.NetworkImage> implements image_provider.NetworkImage { /// Creates an object that fetches the image at the given URL. /// /// The arguments [url] and [scale] must not be null. const NetworkImage(this.url, { this.scale = 1.0, this.headers }) : assert(url != null), assert(scale != null); @override final String url; @override final double scale; @override final Map<String, String>? headers; @override Future<NetworkImage> obtainKey(image_provider.ImageConfiguration configuration) { return SynchronousFuture<NetworkImage>(this); } @override ImageStreamCompleter load(image_provider.NetworkImage key, image_provider.DecoderCallback decode) { // Ownership of this controller is handed off to [_loadAsync]; it is that // method's responsibility to close the controller's stream when the image // has been loaded or an error is thrown. final StreamController<ImageChunkEvent> chunkEvents = StreamController<ImageChunkEvent>(); return MultiFrameImageStreamCompleter( codec: _loadAsync(key as NetworkImage, chunkEvents, decode), chunkEvents: chunkEvents.stream, scale: key.scale, debugLabel: key.url, informationCollector: () { return <DiagnosticsNode>[ DiagnosticsProperty<image_provider.ImageProvider>('Image provider', this), DiagnosticsProperty<image_provider.NetworkImage>('Image key', key), ]; }, ); } // Do not access this field directly; use [_httpClient] instead. // We set `autoUncompress` to false to ensure that we can trust the value of // the `Content-Length` HTTP header. We automatically uncompress the content // in our call to [consolidateHttpClientResponseBytes]. static final HttpClient _sharedHttpClient = HttpClient()..autoUncompress = false; static HttpClient get _httpClient { HttpClient client = _sharedHttpClient; assert(() { if (debugNetworkImageHttpClientProvider != null) client = debugNetworkImageHttpClientProvider!(); return true; }()); return client; } Future<ui.Codec> _loadAsync( NetworkImage key, StreamController<ImageChunkEvent> chunkEvents, image_provider.DecoderCallback decode, ) async { try { assert(key == this); final Uri resolved = Uri.base.resolve(key.url); final HttpClientRequest request = await _httpClient.getUrl(resolved); headers?.forEach((String name, String value) { request.headers.add(name, value); }); final HttpClientResponse response = await request.close(); if (response.statusCode != HttpStatus.ok) { // The network may be only temporarily unavailable, or the file will be // added on the server later. Avoid having future calls to resolve // fail to check the network again. throw image_provider.NetworkImageLoadException(statusCode: response.statusCode, uri: resolved); } final Uint8List bytes = await consolidateHttpClientResponseBytes( response, onBytesReceived: (int cumulative, int? total) { chunkEvents.add(ImageChunkEvent( cumulativeBytesLoaded: cumulative, expectedTotalBytes: total, )); }, ); if (bytes.lengthInBytes == 0) throw Exception('NetworkImage is an empty file: $resolved'); return decode(bytes); } catch (e) { // Depending on where the exception was thrown, the image cache may not // have had a chance to track the key in the cache at all. // Schedule a microtask to give the cache a chance to add the key. scheduleMicrotask(() { PaintingBinding.instance!.imageCache!.evict(key); }); rethrow; } finally { chunkEvents.close(); } } @override bool operator ==(Object other) { if (other.runtimeType != runtimeType) return false; return other is NetworkImage && other.url == url && other.scale == scale; } @override int get hashCode => ui.hashValues(url, scale); @override String toString() => '${objectRuntimeType(this, 'NetworkImage')}("$url", scale: $scale)'; }