Revert "Add API for discovering assets (#118410)" (#119273)

This reverts commit 2b8f2d05.

dev/benchmarks/microbenchmarks/lib/foundation/decode_and_parse_asset_manifest.dart

@@ -2,7 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import 'package:flutter/services.dart' show AssetManifest, PlatformAssetBundle, rootBundle;
+import 'dart:convert';
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/services.dart' show PlatformAssetBundle;
 import 'package:flutter/widgets.dart';
 
 import '../common.dart';
@@ -15,12 +18,16 @@ void main() async {
   final BenchmarkResultPrinter printer = BenchmarkResultPrinter();
   WidgetsFlutterBinding.ensureInitialized();
   final Stopwatch watch = Stopwatch();
-  final PlatformAssetBundle bundle = rootBundle as PlatformAssetBundle;
+  final PlatformAssetBundle bundle = PlatformAssetBundle();
 
+  final ByteData assetManifestBytes = await bundle.load('money_asset_manifest.json');
   watch.start();
   for (int i = 0; i < _kNumIterations; i++) {
-    await AssetManifest.loadFromAssetBundle(bundle);
     bundle.clear();
+    final String json = utf8.decode(assetManifestBytes.buffer.asUint8List());
+    // This is a test, so we don't need to worry about this rule.
+    // ignore: invalid_use_of_visible_for_testing_member
+    await AssetImage.manifestParser(json);
   }
   watch.stop();
 

packages/flutter/lib/services.dart

@@ -11,7 +11,6 @@
 library services;
 
 export 'src/services/asset_bundle.dart';
-export 'src/services/asset_manifest.dart';
 export 'src/services/autofill.dart';
 export 'src/services/binary_messenger.dart';
 export 'src/services/binding.dart';

packages/flutter/lib/src/services/asset_bundle.dart

@@ -96,22 +96,12 @@ abstract class AssetBundle {
   }
 
   /// Retrieve a string from the asset bundle, parse it with the given function,
-  /// and return that function's result.
+  /// and return the function's result.
   ///
   /// Implementations may cache the result, so a particular key should only be
   /// used with one parser for the lifetime of the asset bundle.
   Future<T> loadStructuredData<T>(String key, Future<T> Function(String value) parser);
 
-  /// Retrieve [ByteData] from the asset bundle, parse it with the given function,
-  /// and return that function's result.
-  ///
-  /// Implementations may cache the result, so a particular key should only be
-  /// used with one parser for the lifetime of the asset bundle.
-  Future<T> loadStructuredBinaryData<T>(String key, FutureOr<T> Function(ByteData data) parser) async {
-    final ByteData data = await load(key);
-    return parser(data);
-  }
-
   /// If this is a caching asset bundle, and the given key describes a cached
   /// asset, then evict the asset from the cache so that the next time it is
   /// loaded, the cache will be reread from the asset bundle.
@@ -164,16 +154,6 @@ class NetworkAssetBundle extends AssetBundle {
     return parser(await loadString(key));
   }
 
-  /// Retrieve [ByteData] from the asset bundle, parse it with the given function,
-  /// and return the function's result.
-  ///
-  /// The result is not cached. The parser is run each time the resource is
-  /// fetched.
-  @override
-  Future<T> loadStructuredBinaryData<T>(String key, FutureOr<T> Function(ByteData data) parser) async {
-    return parser(await load(key));
-  }
-
   // TODO(ianh): Once the underlying network logic learns about caching, we
   // should implement evict().
 
@@ -193,7 +173,6 @@ abstract class CachingAssetBundle extends AssetBundle {
   // TODO(ianh): Replace this with an intelligent cache, see https://github.com/flutter/flutter/issues/3568
   final Map<String, Future<String>> _stringCache = <String, Future<String>>{};
   final Map<String, Future<dynamic>> _structuredDataCache = <String, Future<dynamic>>{};
-  final Map<String, Future<dynamic>> _structuredBinaryDataCache = <String, Future<dynamic>>{};
 
   @override
   Future<String> loadString(String key, { bool cache = true }) {
@@ -242,66 +221,16 @@ abstract class CachingAssetBundle extends AssetBundle {
     return completer.future;
   }
 
-  /// Retrieve bytedata from the asset bundle, parse it with the given function,
-  /// and return the function's result.
-  ///
-  /// The result of parsing the bytedata is cached (the bytedata itself is not).
-  /// For any given `key`, the `parser` is only run the first time.
-  ///
-  /// Once the value has been parsed, the future returned by this function for
-  /// subsequent calls will be a [SynchronousFuture], which resolves its
-  /// callback synchronously.
-  @override
-  Future<T> loadStructuredBinaryData<T>(String key, FutureOr<T> Function(ByteData data) parser) {
-    if (_structuredBinaryDataCache.containsKey(key)) {
-      return _structuredBinaryDataCache[key]! as Future<T>;
-    }
-
-    // load can return a SynchronousFuture in certain cases, like in the
-    // flutter_test framework. So, we need to support both async and sync flows.
-    Completer<T>? completer; // For async flow.
-    SynchronousFuture<T>? result; // For sync flow.
-
-    load(key)
-      .then<T>(parser)
-      .then<void>((T value) {
-        result = SynchronousFuture<T>(value);
-        if (completer != null) {
-          // The load and parse operation ran asynchronously. We already returned
-          // from the loadStructuredBinaryData function and therefore the caller
-          // was given the future of the completer.
-          completer.complete(value);
-        }
-      }, onError: (Object error, StackTrace stack) {
-        completer!.completeError(error, stack);
-      });
-
-    if (result != null) {
-      // The above code ran synchronously. We can synchronously return the result.
-      _structuredBinaryDataCache[key] = result!;
-      return result!;
-    }
-
-    // Since the above code is being run asynchronously and thus hasn't run its
-    // `then` handler yet, we'll return a completer that will be completed
-    // when the handler does run.
-    completer = Completer<T>();
-    _structuredBinaryDataCache[key] = completer.future;
-    return completer.future;
-  }
-
   @override
   void evict(String key) {
     _stringCache.remove(key);
     _structuredDataCache.remove(key);
-    _structuredBinaryDataCache.remove(key);
   }
 
   @override
   void clear() {
     _stringCache.clear();
     _structuredDataCache.clear();
-    _structuredBinaryDataCache.clear();
   }
 
   @override
@@ -343,7 +272,7 @@ class PlatformAssetBundle extends CachingAssetBundle {
     bool debugUsePlatformChannel = false;
     assert(() {
       // dart:io is safe to use here since we early return for web
-      // above. If that code is changed, this needs to be guarded on
+      // above. If that code is changed, this needs to be gaurded on
       // web presence. Override how assets are loaded in tests so that
       // the old loader behavior that allows tests to load assets from
       // the current package using the package prefix.

packages/flutter/lib/src/services/asset_manifest.dart

-// 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 'package:flutter/foundation.dart';
-
-import 'asset_bundle.dart';
-import 'message_codecs.dart';
-
-const String _kAssetManifestFilename = 'AssetManifest.bin';
-
-/// Contains details about available assets and their variants.
-/// See [Asset variants](https://docs.flutter.dev/development/ui/assets-and-images#asset-variants)
-/// to learn about asset variants and how to declare them.
-abstract class AssetManifest {
-  /// Loads asset manifest data from an [AssetBundle] object and creates an
-  /// [AssetManifest] object from that data.
-  static Future<AssetManifest> loadFromAssetBundle(AssetBundle bundle) {
-    return bundle.loadStructuredBinaryData(_kAssetManifestFilename, _AssetManifestBin.fromStandardMessageCodecMessage);
-  }
-
-  /// Lists the keys of all main assets. This does not include assets
-  /// that are variants of other assets.
-  ///
-  /// The logical key maps to the path of an asset specified in the pubspec.yaml
-  /// file at build time.
-  ///
-  /// See [Specifying assets](https://docs.flutter.dev/development/ui/assets-and-images#specifying-assets)
-  /// and [Loading assets](https://docs.flutter.dev/development/ui/assets-and-images#loading-assets) for more
-  /// information.
-  List<String> listAssets();
-
-  /// Retrieves metadata about an asset and its variants.
-  ///
-  /// Note that this method considers a main asset to be a variant of itself and
-  /// includes it in the returned list.
-  ///
-  /// Throws an [ArgumentError] if [key] cannot be found within the manifest. To
-  /// avoid this, use a key obtained from the [listAssets] method.
-  List<AssetMetadata> getAssetVariants(String key);
-}
-
-// Lazily parses the binary asset manifest into a data structure that's easier to work
-// with.
-//
-// The binary asset manifest is a map of asset keys to a list of objects
-// representing the asset's variants.
-//
-// The entries with each variant object are:
-//  - "asset": the location of this variant to load it from.
-//  - "dpr": The device-pixel-ratio that the asset is best-suited for.
-//
-// New fields could be added to this object schema to support new asset variation
-// features, such as themes, locale/region support, reading directions, and so on.
-class _AssetManifestBin implements AssetManifest {
-  _AssetManifestBin(Map<Object?, Object?> standardMessageData): _data = standardMessageData;
-
-  factory _AssetManifestBin.fromStandardMessageCodecMessage(ByteData message) {
-    final dynamic data = const StandardMessageCodec().decodeMessage(message);
-    return _AssetManifestBin(data as Map<Object?, Object?>);
-  }
-
-  final Map<Object?, Object?> _data;
-  final Map<String, List<AssetMetadata>> _typeCastedData = <String, List<AssetMetadata>>{};
-
-  @override
-  List<AssetMetadata> getAssetVariants(String key) {
-    // We lazily delay typecasting to prevent a performance hiccup when parsing
-    // large asset manifests. This is important to keep an app's first asset
-    // load fast.
-    if (!_typeCastedData.containsKey(key)) {
-      final Object? variantData = _data[key];
-      if (variantData == null) {
-        throw ArgumentError('Asset key $key was not found within the asset manifest.');
-      }
-      _typeCastedData[key] = ((_data[key] ?? <Object?>[]) as Iterable<Object?>)
-        .cast<Map<Object?, Object?>>()
-        .map((Map<Object?, Object?> data) => AssetMetadata(
-            key: data['asset']! as String,
-            targetDevicePixelRatio: data['dpr']! as double,
-            main: false,
-        ))
-        .toList();
-
-      _data.remove(key);
-    }
-
-    final AssetMetadata mainAsset = AssetMetadata(key: key,
-      targetDevicePixelRatio: null,
-      main: true
-    );
-
-    return <AssetMetadata>[mainAsset, ..._typeCastedData[key]!];
-  }
-
-  @override
-  List<String> listAssets() {
-    return <String>[..._data.keys.cast<String>(), ..._typeCastedData.keys];
-  }
-}
-
-/// Contains information about an asset.
-@immutable
-class AssetMetadata {
-  /// Creates an object containing information about an asset.
-  const AssetMetadata({
-    required this.key,
-    required this.targetDevicePixelRatio,
-    required this.main,
-  });
-
-  /// The device pixel ratio that this asset is most ideal for. This is determined
-  /// by the name of the parent folder of the asset file. For example, if the
-  /// parent folder is named "3.0x", the target device pixel ratio of that
-  /// asset will be interpreted as 3.
-  ///
-  /// This will be null if the parent folder name is not a ratio value followed
-  /// by an "x".
-  ///
-  /// See [Declaring resolution-aware image assets](https://docs.flutter.dev/development/ui/assets-and-images#resolution-aware)
-  /// for more information.
-  final double? targetDevicePixelRatio;
-
-  /// The asset's key, which is the path to the asset specified in the pubspec.yaml
-  /// file at build time.
-  final String key;
-
-  /// Whether or not this is a main asset. In other words, this is true if
-  /// this asset is not a variant of another asset.
-  ///
-  /// See [Asset variants](https://docs.flutter.dev/development/ui/assets-and-images#asset-variants)
-  /// for more about asset variants.
-  final bool main;
-}

packages/flutter/test/services/asset_bundle_test.dart

@@ -14,28 +14,16 @@ class TestAssetBundle extends CachingAssetBundle {
 
   @override
   Future<ByteData> load(String key) async {
-    loadCallCount[key] = (loadCallCount[key] ?? 0) + 1;
+    loadCallCount[key] = loadCallCount[key] ?? 0 + 1;
     if (key == 'AssetManifest.json') {
       return ByteData.view(Uint8List.fromList(const Utf8Encoder().convert('{"one": ["one"]}')).buffer);
     }
 
-    if (key == 'AssetManifest.bin') {
-      return const StandardMessageCodec().encodeMessage(<String, Object>{
-        'one': <Object>[]
-      })!;
-    }
-
-    if (key == 'counter') {
-      return ByteData.view(Uint8List.fromList(const Utf8Encoder().convert(loadCallCount[key]!.toString())).buffer);
-    }
-
     if (key == 'one') {
       return ByteData(1)..setInt8(0, 49);
     }
-
     throw FlutterError('key not found');
   }
-
 }
 
 void main() {
@@ -52,7 +40,7 @@ void main() {
     final String assetString = await bundle.loadString('one');
     expect(assetString, equals('1'));
 
-    expect(bundle.loadCallCount['one'], 2);
+    expect(bundle.loadCallCount['one'], 1);
 
     late Object loadException;
     try {
@@ -113,69 +101,4 @@ void main() {
       ),
     );
   }, skip: isBrowser); // https://github.com/flutter/flutter/issues/56314
-
-  test('CachingAssetBundle caches results for loadString, loadStructuredData, and loadBinaryStructuredData', () async {
-    final TestAssetBundle bundle = TestAssetBundle();
-
-    final String firstLoadStringResult = await bundle.loadString('counter');
-    final String secondLoadStringResult = await bundle.loadString('counter');
-    expect(firstLoadStringResult, '1');
-    expect(secondLoadStringResult, '1');
-
-    final String firstLoadStructuredDataResult = await bundle.loadStructuredData('AssetManifest.json', (String value) => Future<String>.value('one'));
-    final String secondLoadStructuredDataResult = await bundle.loadStructuredData('AssetManifest.json', (String value) => Future<String>.value('two'));
-    expect(firstLoadStructuredDataResult, 'one');
-    expect(secondLoadStructuredDataResult, 'one');
-
-    final String firstLoadStructuredBinaryDataResult = await bundle.loadStructuredBinaryData('AssetManifest.bin', (ByteData value) => Future<String>.value('one'));
-    final String secondLoadStructuredBinaryDataResult = await bundle.loadStructuredBinaryData('AssetManifest.bin', (ByteData value) => Future<String>.value('two'));
-    expect(firstLoadStructuredBinaryDataResult, 'one');
-    expect(secondLoadStructuredBinaryDataResult, 'one');
-  });
-
-  test("CachingAssetBundle.clear clears all cached values'", () async {
-    final TestAssetBundle bundle = TestAssetBundle();
-
-    await bundle.loadString('counter');
-    bundle.clear();
-    final String secondLoadStringResult = await bundle.loadString('counter');
-    expect(secondLoadStringResult, '2');
-
-    await bundle.loadStructuredData('AssetManifest.json', (String value) => Future<String>.value('one'));
-    bundle.clear();
-    final String secondLoadStructuredDataResult = await bundle.loadStructuredData('AssetManifest.json', (String value) => Future<String>.value('two'));
-    expect(secondLoadStructuredDataResult, 'two');
-
-    await bundle.loadStructuredBinaryData('AssetManifest.bin', (ByteData value) => Future<String>.value('one'));
-    bundle.clear();
-    final String secondLoadStructuredBinaryDataResult = await bundle.loadStructuredBinaryData('AssetManifest.bin', (ByteData value) => Future<String>.value('two'));
-    expect(secondLoadStructuredBinaryDataResult, 'two');
-  });
-
-  test('CachingAssetBundle.evict evicts a particular key from the cache', () async {
-    final TestAssetBundle bundle = TestAssetBundle();
-
-    await bundle.loadString('counter');
-    bundle.evict('counter');
-    final String secondLoadStringResult = await bundle.loadString('counter');
-    expect(secondLoadStringResult, '2');
-
-    await bundle.loadStructuredData('AssetManifest.json', (String value) => Future<String>.value('one'));
-    bundle.evict('AssetManifest.json');
-    final String secondLoadStructuredDataResult = await bundle.loadStructuredData('AssetManifest.json', (String value) => Future<String>.value('two'));
-    expect(secondLoadStructuredDataResult, 'two');
-
-    await bundle.loadStructuredBinaryData('AssetManifest.bin', (ByteData value) => Future<String>.value('one'));
-    bundle.evict('AssetManifest.bin');
-    final String secondLoadStructuredBinaryDataResult = await bundle.loadStructuredBinaryData('AssetManifest.bin', (ByteData value) => Future<String>.value('two'));
-    expect(secondLoadStructuredBinaryDataResult, 'two');
-  });
-
-  test('loadStructuredBinaryData correctly loads ByteData', () async {
-    final TestAssetBundle bundle = TestAssetBundle();
-    final Map<Object?, Object?> assetManifest =
-      await bundle.loadStructuredBinaryData('AssetManifest.bin', (ByteData data) => const StandardMessageCodec().decodeMessage(data) as Map<Object?, Object?>);
-    expect(assetManifest.keys.toList(), equals(<String>['one']));
-    expect(assetManifest['one'], <Object>[]);
-  });
 }

packages/flutter/test/services/asset_manifest_test.dart

-// 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 'package:flutter/services.dart';
-import 'package:flutter_test/flutter_test.dart';
-
-class TestAssetBundle extends AssetBundle {
-  @override
-  Future<ByteData> load(String key) async {
-    if (key == 'AssetManifest.bin') {
-      final Map<String, List<Object>> binManifestData = <String, List<Object>>{
-        'assets/foo.png': <Object>[
-          <String, Object>{
-            'asset': 'assets/2x/foo.png',
-            'dpr': 2.0
-          }
-        ],
-        'assets/bar.png': <Object>[],
-      };
-
-      final ByteData data = const StandardMessageCodec().encodeMessage(binManifestData)!;
-      return data;
-    }
-
-    throw ArgumentError('Unexpected key');
-  }
-
-  @override
-  Future<T> loadStructuredData<T>(String key, Future<T> Function(String value) parser) async {
-    return parser(await loadString(key));
-  }
-}
-
-
-void main() {
-  TestWidgetsFlutterBinding.ensureInitialized();
-
-  test('loadFromBundle correctly parses a binary asset manifest', () async {
-    final AssetManifest manifest = await AssetManifest.loadFromAssetBundle(TestAssetBundle());
-
-    expect(manifest.listAssets(), unorderedEquals(<String>['assets/foo.png', 'assets/bar.png']));
-
-    final List<AssetMetadata> fooVariants = manifest.getAssetVariants('assets/foo.png');
-    expect(fooVariants.length, 2);
-    final AssetMetadata firstFooVariant = fooVariants[0];
-    expect(firstFooVariant.key, 'assets/foo.png');
-    expect(firstFooVariant.targetDevicePixelRatio, null);
-    expect(firstFooVariant.main, true);
-    final AssetMetadata secondFooVariant = fooVariants[1];
-    expect(secondFooVariant.key, 'assets/2x/foo.png');
-    expect(secondFooVariant.targetDevicePixelRatio, 2.0);
-    expect(secondFooVariant.main, false);
-
-    final List<AssetMetadata> barVariants = manifest.getAssetVariants('assets/bar.png');
-    expect(barVariants.length, 1);
-    final AssetMetadata firstBarVariant = barVariants[0];
-    expect(firstBarVariant.key, 'assets/bar.png');
-    expect(firstBarVariant.targetDevicePixelRatio, null);
-    expect(firstBarVariant.main, true);
-  });
-
-  test('getAssetVariants throws if given a key not contained in the asset manifest', () async {
-    final AssetManifest manifest = await AssetManifest.loadFromAssetBundle(TestAssetBundle());
-
-    expect(() => manifest.getAssetVariants('invalid asset key'), throwsArgumentError);
-  });
-}