Add flutter_web samples (#75)

web/charts/example/lib/legends/legends_gallery.dart

@@ -0,0 +1,80 @@
+// Copyright 2018 the Charts project authors. Please see the AUTHORS file
+// for details.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import 'package:flutter_web/material.dart';
+import '../gallery_scaffold.dart';
+import 'datum_legend_options.dart';
+import 'datum_legend_with_measures.dart';
+import 'default_hidden_series_legend.dart';
+import 'legend_custom_symbol.dart';
+import 'series_legend_options.dart';
+import 'series_legend_with_measures.dart';
+import 'simple_datum_legend.dart';
+import 'simple_series_legend.dart';
+
+List<GalleryScaffold> buildGallery() {
+  return [
+    new GalleryScaffold(
+      listTileIcon: new Icon(Icons.insert_chart),
+      title: 'Series Legend',
+      subtitle: 'A series legend for a bar chart with default settings',
+      childBuilder: () => new SimpleSeriesLegend.withRandomData(),
+    ),
+    new GalleryScaffold(
+      listTileIcon: new Icon(Icons.insert_chart),
+      title: 'Series Legend Options',
+      subtitle:
+          'A series legend with custom positioning and spacing for a bar chart',
+      childBuilder: () => new LegendOptions.withRandomData(),
+    ),
+    new GalleryScaffold(
+      listTileIcon: new Icon(Icons.insert_chart),
+      title: 'Series Legend Custom Symbol',
+      subtitle: 'A series legend using a custom symbol renderer',
+      childBuilder: () => new LegendWithCustomSymbol.withRandomData(),
+    ),
+    new GalleryScaffold(
+      listTileIcon: new Icon(Icons.insert_chart),
+      title: 'Default Hidden Series Legend',
+      subtitle: 'A series legend showing a series hidden by default',
+      childBuilder: () => new DefaultHiddenSeriesLegend.withRandomData(),
+    ),
+    new GalleryScaffold(
+      listTileIcon: new Icon(Icons.insert_chart),
+      title: 'Series legend with measures',
+      subtitle: 'Series legend with measures and measure formatting',
+      childBuilder: () => new LegendWithMeasures.withRandomData(),
+    ),
+    new GalleryScaffold(
+      listTileIcon: new Icon(Icons.pie_chart),
+      title: 'Datum Legend',
+      subtitle: 'A datum legend for a pie chart with default settings',
+      childBuilder: () => new SimpleDatumLegend.withRandomData(),
+    ),
+    new GalleryScaffold(
+      listTileIcon: new Icon(Icons.pie_chart),
+      title: 'Datum Legend Options',
+      subtitle:
+          'A datum legend with custom positioning and spacing for a pie chart',
+      childBuilder: () => new DatumLegendOptions.withRandomData(),
+    ),
+    new GalleryScaffold(
+      listTileIcon: new Icon(Icons.pie_chart),
+      title: 'Datum legend with measures',
+      subtitle: 'Datum legend with measures and measure formatting',
+      childBuilder: () => new DatumLegendWithMeasures.withRandomData(),
+    ),
+  ];
+}