Teach Icon to use an AssetBundle

Currently this asset bundle is based on the network, but soon we'll be able to
use a local asset bundle.

R=jackson@google.com

Review URL: https://codereview.chromium.org/1217593004.

sdk/lib/mojo/asset_bundle.dart

@@ -8,31 +8,25 @@ import 'dart:sky' as sky;
 import 'package:mojo/core.dart' as core;
 import 'package:mojom/mojo/asset_bundle/asset_bundle.mojom.dart';
 
-import 'shell.dart' as shell;
 import 'net/fetch.dart';
-
-Future<sky.Image> _decodeImage(core.MojoDataPipeConsumer assetData) {
-  Completer<sky.Image> completer = new Completer<sky.Image>();
-  new sky.ImageDecoder(assetData.handle.h, completer.complete);
-  return completer.future;
-}
+import 'net/image_cache.dart' as image_cache;
+import 'shell.dart' as shell;
 
 abstract class AssetBundle {
   void close();
-  Future<sky.Image> fetchImage(String key);
+  Future<sky.Image> loadImage(String key);
 }
 
 class NetworkAssetBundle extends AssetBundle {
-  NetworkAssetBundle(Uri base_url) : _base_url = base_url;
+  NetworkAssetBundle(Uri baseUrl) : _baseUrl = baseUrl;
 
-  final Uri _base_url;
+  final Uri _baseUrl;
 
   void close() { }
 
-  Future<sky.Image> fetchImage(String name) async {
-    Uri url = _base_url.resolve(name);
-    core.MojoDataPipeConsumer assetData = (await fetchUrl(url.toString())).body;
-    return await _decodeImage(assetData);
+  Future<sky.Image> loadImage(String name) {
+    Uri url = _baseUrl.resolve(name);
+    return image_cache.load(url.toString());
   }
 }
 
@@ -50,19 +44,25 @@ class MojoAssetBundle extends AssetBundle {
   factory MojoAssetBundle.fromNetwork(String relativeUrl) {
     AssetBundleProxy bundle = new AssetBundleProxy.unbound();
     _fetchAndUnpackBundle(relativeUrl, bundle);
-    return new AssetBundle(bundle);
+    return new MojoAssetBundle(bundle);
   }
 
   AssetBundleProxy _bundle;
+  Map<String, Future<sky.Image>> _imageCache = new Map<String, Future<sky.Image>>();
 
   void close() {
     _bundle.close();
     _bundle = null;
+    _imageCache = null;
   }
 
-  Future<sky.Image> fetchImage(String name) async {
-    core.MojoDataPipeConsumer assetData =
-        (await _bundle.ptr.getAsStream(name)).assetData;
-    return await _decodeImage(assetData);
+  Future<sky.Image> loadImage(String name) {
+    return _imageCache.putIfAbsent(name, () {
+      Completer<sky.Image> completer = new Completer<sky.Image>();
+      _bundle.ptr.getAsStream(name).then((response) {
+        new sky.ImageDecoder(response.assetData.handle.h, completer.complete);
+      });
+      return completer.future;
+    });
   }
 }

sdk/lib/widgets/basic.dart

@@ -7,6 +7,7 @@ import 'dart:sky' as sky;
 
 import 'package:vector_math/vector_math.dart';
 
+import '../mojo/asset_bundle.dart';
 import '../mojo/net/image_cache.dart' as image_cache;
 import '../painting/text_style.dart';
 import '../rendering/block.dart';
@@ -550,6 +551,19 @@ class NetworkImage extends Component {
   }
 }
 
+class AssetImage extends Component {
+  AssetImage({ this.bundle, String name, this.size })
+    : name = name, super(key: name);
+
+  final AssetBundle bundle;
+  final String name;
+  final Size size;
+
+  Widget build() {
+    return new FutureImage(image: bundle.loadImage(name), size: size);
+  }
+}
+
 class WidgetToRenderBoxAdapter extends LeafRenderObjectWrapper {
 
   WidgetToRenderBoxAdapter(RenderBox renderBox)

sdk/lib/widgets/icon.dart

@@ -2,18 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import '../mojo/asset_bundle.dart';
 import 'basic.dart';
 
-// TODO(eseidel): This should use package:.
-const String kAssetBase = '/packages/sky/assets/material-design-icons';
+const String _kAssetBase = '/packages/sky/assets/material-design-icons/';
+final AssetBundle _iconBundle = new NetworkAssetBundle(Uri.base.resolve(_kAssetBase));
 
 class Icon extends Component {
-
-  Icon({
-    String key,
-    this.size,
-    this.type: ''
-  }) : super(key: key);
+  Icon({ String key, this.size, this.type: '' }) : super(key: key);
 
   final int size;
   final String type;
@@ -29,10 +25,10 @@ class Icon extends Component {
     // TODO(eseidel): This clearly isn't correct.  Not sure what would be.
     // Should we use the ios images on ios?
     String density = 'drawable-xxhdpi';
-    return new NetworkImage(
-      size: new Size(size.toDouble(), size.toDouble()),
-      src: '${kAssetBase}/${category}/${density}/ic_${subtype}_${size}dp.png'
+    return new AssetImage(
+      bundle: _iconBundle,
+      name: '${category}/${density}/ic_${subtype}_${size}dp.png',
+      size: new Size(size.toDouble(), size.toDouble())
     );
   }
-
 }