Separate web and io implementations of network image (#34112)

* add web and io implemenations of network and asset image

* fix foundation import

* update to remove extra asset image indirection

* skip chunk test

* address comments

* disable non-functional test

* disable all golden tests

* address comments

packages/flutter/lib/src/painting/_network_image_io.dart

@@ -0,0 +1,124 @@
+// Copyright 2019 The Chromium 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 implemenation of [image_provider.NetworkImage].
+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) {
+    // 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, chunkEvents),
+      chunkEvents: chunkEvents.stream,
+      scale: key.scale,
+      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,
+  ) 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)
+        throw Exception('HTTP request failed, statusCode: ${response?.statusCode}, $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: $resolved');
+
+      return PaintingBinding.instance.instantiateImageCodec(bytes);
+    } finally {
+      chunkEvents.close();
+    }
+  }
+
+  @override
+  bool operator ==(dynamic other) {
+    if (other.runtimeType != runtimeType)
+      return false;
+    final NetworkImage typedOther = other;
+    return url == typedOther.url
+        && scale == typedOther.scale;
+  }
+
+  @override
+  int get hashCode => ui.hashValues(url, scale);
+
+  @override
+  String toString() => '$runtimeType("$url", scale: $scale)';
+}

packages/flutter/lib/src/painting/_network_image_web.dart

@@ -0,0 +1,73 @@
+// Copyright 2019 The Chromium 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:ui' as ui;
+
+import 'package:flutter/foundation.dart';
+
+import 'image_provider.dart' as image_provider;
+import 'image_stream.dart';
+
+/// The dart:html implemenation of [image_provider.NetworkImage].
+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) {
+    return MultiFrameImageStreamCompleter(
+      codec: _loadAsync(key),
+      scale: key.scale,
+      informationCollector: () {
+        return <DiagnosticsNode>[
+          DiagnosticsProperty<image_provider.ImageProvider>('Image provider', this),
+          DiagnosticsProperty<NetworkImage>('Image key', key),
+        ];
+      },
+    );
+  }
+
+  Future<ui.Codec> _loadAsync(NetworkImage key) async {
+    assert(key == this);
+
+    final Uri resolved = Uri.base.resolve(key.url);
+    // This API only exists in the web engine implementation and is not
+    // contained in the analyzer summary for Flutter.
+    return ui.webOnlyInstantiateImageCodecFromUrl(resolved); // ignore: undefined_function
+  }
+
+  @override
+  bool operator ==(dynamic other) {
+    if (other.runtimeType != runtimeType) {
+      return false;
+    }
+    final NetworkImage typedOther = other;
+    return url == typedOther.url && scale == typedOther.scale;
+  }
+
+  @override
+  int get hashCode => ui.hashValues(url, scale);
+
+  @override
+  String toString() => '$runtimeType("$url", scale: $scale)';
+}

packages/flutter/lib/src/painting/image_provider.dart

@@ -11,8 +11,9 @@ import 'dart:ui' show Size, Locale, TextDirection, hashValues;
 import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 
+import '_network_image_io.dart'
+  if (dart.library.html) '_network_image_web.dart' as network_image;
 import 'binding.dart';
-import 'debug.dart';
 import 'image_cache.dart';
 import 'image_stream.dart';
 
@@ -478,110 +479,25 @@ abstract class AssetBundleImageProvider extends ImageProvider<AssetBundleImageKe
 // TODO(ianh): Find some way to honor cache headers to the extent that when the
 // last reference to an image is released, we proactively evict the image from
 // our cache if the headers describe the image as having expired at that point.
-class NetworkImage extends ImageProvider<NetworkImage> {
+abstract class NetworkImage extends ImageProvider<NetworkImage> {
   /// Creates an object that fetches the image at the given URL.
   ///
-  /// The arguments must not be null.
-  const NetworkImage(this.url, { this.scale = 1.0, this.headers })
-    : assert(url != null),
-      assert(scale != null);
+  /// The arguments [url] and [scale] must not be null.
+  const factory NetworkImage(String url, { double scale, Map<String, String> headers }) = network_image.NetworkImage;
 
   /// The URL from which the image will be fetched.
-  final String url;
+  String get url;
 
   /// The scale to place in the [ImageInfo] object of the image.
-  final double scale;
+  double get scale;
 
   /// The HTTP headers that will be used with [HttpClient.get] to fetch image from network.
-  final Map<String, String> headers;
+  ///
+  /// When running flutter on the web, headers are not used.
+  Map<String, String> get headers;
 
   @override
-  Future<NetworkImage> obtainKey(ImageConfiguration configuration) {
-    return SynchronousFuture<NetworkImage>(this);
-  }
-
-  @override
-  ImageStreamCompleter load(NetworkImage key) {
-    // 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, chunkEvents),
-      chunkEvents: chunkEvents.stream,
-      scale: key.scale,
-      informationCollector: () sync* {
-        yield DiagnosticsProperty<ImageProvider>('Image provider', this);
-        yield DiagnosticsProperty<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,
-  ) 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)
-        throw Exception('HTTP request failed, statusCode: ${response?.statusCode}, $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: $resolved');
-
-      return PaintingBinding.instance.instantiateImageCodec(bytes);
-    } finally {
-      chunkEvents.close();
-    }
-  }
-
-  @override
-  bool operator ==(dynamic other) {
-    if (other.runtimeType != runtimeType)
-      return false;
-    final NetworkImage typedOther = other;
-    return url == typedOther.url
-        && scale == typedOther.scale;
-  }
-
-  @override
-  int get hashCode => hashValues(url, scale);
-
-  @override
-  String toString() => '$runtimeType("$url", scale: $scale)';
+  ImageStreamCompleter load(NetworkImage key);
 }
 
 /// Decodes the given [File] object as an image, associating it with the given

packages/flutter/lib/src/painting/image_resolution.dart

@@ -5,7 +5,6 @@
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
-import 'dart:io';
 import 'dart:ui' show hashValues;
 
 import 'package:flutter/foundation.dart';
@@ -265,10 +264,13 @@ class AssetImage extends AssetBundleImageProvider {
       return _naturalResolution;
     }
 
-    final File assetPath = File(key);
-    final Directory assetDir = assetPath.parent;
+    final Uri assetUri = Uri.parse(key);
+    String directoryPath = '';
+    if (assetUri.pathSegments.length > 1) {
+      directoryPath = assetUri.pathSegments[assetUri.pathSegments.length - 2];
+    }
 
-    final Match match = _extractRatioRegExp.firstMatch(assetDir.path);
+    final Match match = _extractRatioRegExp.firstMatch(directoryPath);
     if (match != null && match.groupCount > 0)
       return double.parse(match.group(1));
     return _naturalResolution; // i.e. default to 1.0x

packages/flutter/test/painting/image_provider_test.dart

@@ -253,7 +253,7 @@ void main() {
           expect(events[i].cumulativeBytesLoaded, math.min((i + 1) * chunkSize, kTransparentImage.length));
           expect(events[i].expectedTotalBytes, kTransparentImage.length);
         }
-      });
+      }, skip: isBrowser);
     });
   });
 }

packages/flutter/test/painting/image_resolution_test.dart

@@ -11,7 +11,6 @@ import 'package:flutter/painting.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 
-
 class TestAssetBundle extends CachingAssetBundle {
   TestAssetBundle(this._assetBundleMap);
 

packages/flutter/test/widgets/image_headers_test.dart

@@ -41,7 +41,7 @@ void main() {
       });
       return client;
     });
-  });
+  }, skip: isBrowser);
 }
 
 class MockHttpClient extends Mock implements HttpClient {}