Make image resolution more strict, clean gallery pubspec.yaml (#17241) (#17322)

examples/flutter_gallery/pubspec.yaml

@@ -84,10 +84,6 @@ flutter:
   assets:
     - lib/gallery/example_code.dart
     - packages/flutter_gallery_assets/white_logo/logo.png
-    - packages/flutter_gallery_assets/white_logo/1.5x/logo.png
-    - packages/flutter_gallery_assets/white_logo/2.5x/logo.png
-    - packages/flutter_gallery_assets/white_logo/3.0x/logo.png
-    - packages/flutter_gallery_assets/white_logo/4.0x/logo.png
     - packages/flutter_gallery_assets/videos/butterfly.mp4
     - packages/flutter_gallery_assets/animated_flutter_lgtm.gif
     - packages/flutter_gallery_assets/animated_flutter_stickers.webp

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

@@ -5,6 +5,7 @@
 import 'dart:async';
 import 'dart:collection';
 import 'dart:convert';
+import 'dart:io';
 import 'dart:ui' show hashValues;
 
 import 'package:flutter/foundation.dart';
@@ -56,6 +57,10 @@ const String _kAssetManifestFileName = 'AssetManifest.json';
 /// icons/2.0x/heart.png
 /// ```
 ///
+/// assets/icons/3.0x/heart.png would be a valid variant of
+/// assets/icons/heart.png.
+///
+///
 /// ## Fetching assets
 ///
 /// When fetching an image provided by the app itself, use the [assetName]
@@ -166,6 +171,7 @@ class AssetImage extends AssetBundleImageProvider {
     final AssetBundle chosenBundle = bundle ?? configuration.bundle ?? rootBundle;
     Completer<AssetBundleImageKey> completer;
     Future<AssetBundleImageKey> result;
+
     chosenBundle.loadStructuredData<Map<String, List<String>>>(_kAssetManifestFileName, _manifestParser).then<void>(
       (Map<String, List<String>> manifest) {
         final String chosenName = _chooseVariant(
@@ -252,10 +258,18 @@ class AssetImage extends AssetBundleImageProvider {
       return candidates[lower];
   }
 
-  static final RegExp _extractRatioRegExp = new RegExp(r'/?(\d+(\.\d*)?)x/');
+  static final RegExp _extractRatioRegExp = new RegExp(r'/?(\d+(\.\d*)?)x$');
 
   double _parseScale(String key) {
-    final Match match = _extractRatioRegExp.firstMatch(key);
+
+    if ( key == assetName){
+      return _naturalResolution;
+    }
+
+    final File assetPath = new File(key);
+    final Directory assetDir = assetPath.parent;
+
+    final Match match = _extractRatioRegExp.firstMatch(assetDir.path);
     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_resolution_test.dart

+// Copyright 2017 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:convert';
+import 'dart:typed_data';
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/painting.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+
+class TestAssetBundle extends CachingAssetBundle {
+
+  Map<String, List<String>> _assetBundleMap;
+
+  TestAssetBundle(this._assetBundleMap);
+
+  Map<String, int> loadCallCount = <String, int>{};
+
+  String get _assetBundleContents {
+    return json.encode(_assetBundleMap);
+  }
+
+  @override
+  Future<ByteData> load(String key) async {
+    if (key == 'AssetManifest.json')
+      return new ByteData.view(new Uint8List.fromList(
+          const Utf8Encoder().convert(_assetBundleContents)).buffer);
+
+    loadCallCount[key] = loadCallCount[key] ?? 0 + 1;
+    if (key == 'one')
+      return new ByteData(1)
+        ..setInt8(0, 49);
+    throw new FlutterError('key not found');
+  }
+}
+
+void main() {
+  group('1.0 scale device tests', () {
+    void _buildAndTestWithOneAsset(String mainAssetPath) {
+      final Map<String, List<String>> assetBundleMap = <String, List<String>>{};
+
+      assetBundleMap[mainAssetPath] = <String>[];
+
+      final AssetImage assetImage = new AssetImage(
+          mainAssetPath,
+          bundle: new TestAssetBundle(assetBundleMap));
+      const ImageConfiguration configuration = const ImageConfiguration();
+
+      assetImage.obtainKey(configuration)
+          .then(expectAsync1((AssetBundleImageKey bundleKey) {
+        expect(bundleKey.name, mainAssetPath);
+        expect(bundleKey.scale, 1.0);
+      }));
+    }
+
+    test('When asset is main variant check scale is 1.0', () {
+      _buildAndTestWithOneAsset('assets/normalFolder/normalFile.png');
+    });
+
+
+    test(
+        'When asset path and key are the same string even though it could be took as a 3.0x variant',
+            () async {
+          _buildAndTestWithOneAsset('assets/parentFolder/3.0x/normalFile.png');
+        });
+
+
+    test(
+        'When asset path contains variant identifier as part of parent folder name scale is 1.0',
+            () {
+          _buildAndTestWithOneAsset(
+              'assets/parentFolder/__3.0x__/leafFolder/normalFile.png');
+        });
+
+
+    test(
+        'When asset path contains variant identifier as part of leaf folder name scale is 1.0',
+            () {
+          _buildAndTestWithOneAsset(
+              'assets/parentFolder/__3.0x_leaf_folder_/normalFile.png');
+        });
+
+
+    test(
+        'When asset path contains variant identifier as part of parent folder name scale is 1.0',
+            () {
+          _buildAndTestWithOneAsset(
+              'assets/parentFolder/__3.0x__/leafFolder/normalFile.png');
+        });
+
+    test(
+        'When asset path contains variant identifier in parent folder scale is 1.0',
+            () {
+          _buildAndTestWithOneAsset(
+              'assets/parentFolder/3.0x/leafFolder/normalFile.png');
+        });
+  });
+
+
+  group('High-res device behavior tests', () {
+    test('When asset is not main variant check scale is not 1.0', () {
+      const String mainAssetPath = 'assets/normalFolder/normalFile.png';
+      const String variantPath = 'assets/normalFolder/3.0x/normalFile.png';
+
+      final Map<String, List<String>> assetBundleMap =
+      <String, List<String>>{};
+
+      assetBundleMap[mainAssetPath] = <String>[mainAssetPath, variantPath];
+
+      final TestAssetBundle testAssetBundle = new TestAssetBundle(
+          assetBundleMap);
+
+      final AssetImage assetImage = new AssetImage(
+          mainAssetPath,
+          bundle: testAssetBundle);
+
+      // we have the exact match for this scale, let's use it
+      assetImage.obtainKey(const ImageConfiguration())
+          .then(expectAsync1((AssetBundleImageKey bundleKey) {
+        expect(bundleKey.name, mainAssetPath);
+        expect(bundleKey.scale, 1.0);
+      }));
+
+      // we also have the exact match for this scale, let's use it
+      assetImage.obtainKey(new ImageConfiguration(
+          bundle: testAssetBundle,
+          devicePixelRatio: 3.0))
+          .then(expectAsync1((AssetBundleImageKey bundleKey) {
+        expect(bundleKey.name, variantPath);
+        expect(bundleKey.scale, 3.0);
+      }));
+    });
+
+    test(
+        'When high-res device and high-res asset not present in bundle then  return main variant', () {
+      const String mainAssetPath = 'assets/normalFolder/normalFile.png';
+
+      final Map<String, List<String>> assetBundleMap =
+      <String, List<String>>{};
+
+      assetBundleMap[mainAssetPath] = <String>[mainAssetPath];
+
+      final TestAssetBundle testAssetBundle = new TestAssetBundle(
+          assetBundleMap);
+
+      final AssetImage assetImage = new AssetImage(
+          mainAssetPath,
+          bundle: new TestAssetBundle(assetBundleMap));
+
+
+      assetImage.obtainKey(const ImageConfiguration())
+          .then(expectAsync1((AssetBundleImageKey bundleKey) {
+        expect(bundleKey.name, mainAssetPath);
+        expect(bundleKey.scale, 1.0);
+      }));
+
+      assetImage.obtainKey(new ImageConfiguration(
+          bundle: testAssetBundle,
+          devicePixelRatio: 3.0))
+          .then(expectAsync1((AssetBundleImageKey bundleKey) {
+        expect(bundleKey.name, mainAssetPath);
+        expect(bundleKey.scale, 1.0);
+      }));
+    });
+  });
+
+  group(
+      'Regression - When assets available are 1.0 and 3.0 check devices with a range of scales', () {
+    const String mainAssetPath = 'assets/normalFolder/normalFile.png';
+    const String variantPath = 'assets/normalFolder/3.0x/normalFile.png';
+
+
+    void _buildBundleAndTestVariantLogic(double deviceRatio, double chosenAssetRatio,
+        String expectedAssetPath) {
+      final Map<String, List<String>> assetBundleMap =
+      <String, List<String>>{};
+
+      assetBundleMap[mainAssetPath] = <String>[mainAssetPath, variantPath];
+
+      final TestAssetBundle testAssetBundle = new TestAssetBundle(
+          assetBundleMap);
+
+      final AssetImage assetImage = new AssetImage(
+          mainAssetPath,
+          bundle: testAssetBundle);
+
+      // we have 1.0 and 3.0, asking for 1.5 should give
+      assetImage.obtainKey(new ImageConfiguration(
+          bundle: testAssetBundle,
+          devicePixelRatio: deviceRatio))
+          .then(expectAsync1((AssetBundleImageKey bundleKey) {
+        expect(bundleKey.name, expectedAssetPath);
+        expect(bundleKey.scale, chosenAssetRatio);
+      }));
+    }
+
+    test('Obvious case 1.0 - we have exact asset', () {
+      _buildBundleAndTestVariantLogic(1.0, 1.0, mainAssetPath);
+    });
+
+    test('Obvious case 3.0 - we have exact asset', () {
+      _buildBundleAndTestVariantLogic(3.0, 3.0, variantPath);
+    });
+
+    test('Typical case 2.0', () {
+      _buildBundleAndTestVariantLogic(2.0, 1.0, mainAssetPath);
+    });
+
+    test('Borderline case 2.01', () {
+      _buildBundleAndTestVariantLogic(2.01, 3.0, variantPath);
+    });
+    test('Borderline case 2.9', () {
+      _buildBundleAndTestVariantLogic(2.9, 3.0, variantPath);
+    });
+
+    test('Typical case 4.0', () {
+      _buildBundleAndTestVariantLogic(4.0, 3.0, variantPath);
+    });
+  });
+
+}