Add flutter_web samples (#75)

web/charts/example/lib/behaviors/selection_user_managed.dart

@@ -0,0 +1,164 @@
+// 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.
+
+/// Example of using user managed state to programmatically set selection.
+///
+/// In this example, clicking the "clear selection" button sets the selection
+/// to an empty selection. This example also shows that initial selection
+/// behavior can still be used with user managed state.
+///
+/// Note that the picture in this example is not interactive, please run the
+/// gallery app to try out using the button to clear selection.
+///
+// EXCLUDE_FROM_GALLERY_DOCS_START
+import 'dart:math';
+// EXCLUDE_FROM_GALLERY_DOCS_END
+import 'package:charts_flutter/flutter.dart' as charts;
+import 'package:flutter_web/material.dart';
+
+class SelectionUserManaged extends StatefulWidget {
+  final List<charts.Series> seriesList;
+  final bool animate;
+
+  SelectionUserManaged(this.seriesList, {this.animate});
+
+  /// Creates a [BarChart] with sample data and no transition.
+  factory SelectionUserManaged.withSampleData() {
+    return new SelectionUserManaged(
+      _createSampleData(),
+      // Disable animations for image tests.
+      animate: false,
+    );
+  }
+
+  // EXCLUDE_FROM_GALLERY_DOCS_START
+  // This section is excluded from being copied to the gallery.
+  // It is used for creating random series data to demonstrate animation in
+  // the example app only.
+  factory SelectionUserManaged.withRandomData() {
+    return new SelectionUserManaged(_createRandomData());
+  }
+
+  /// Create random data.
+  static List<charts.Series<OrdinalSales, String>> _createRandomData() {
+    final random = new Random();
+
+    final data = [
+      new OrdinalSales('2014', random.nextInt(100)),
+      new OrdinalSales('2015', random.nextInt(100)),
+      new OrdinalSales('2016', random.nextInt(100)),
+      new OrdinalSales('2017', random.nextInt(100)),
+    ];
+
+    return [
+      new charts.Series<OrdinalSales, String>(
+        id: 'Sales',
+        colorFn: (_, __) => charts.MaterialPalette.blue.shadeDefault,
+        domainFn: (OrdinalSales sales, _) => sales.year,
+        measureFn: (OrdinalSales sales, _) => sales.sales,
+        data: data,
+      )
+    ];
+  }
+  // EXCLUDE_FROM_GALLERY_DOCS_END
+
+  /// Create one series with sample hard coded data.
+  static List<charts.Series<OrdinalSales, String>> _createSampleData() {
+    final data = [
+      new OrdinalSales('2014', 5),
+      new OrdinalSales('2015', 25),
+      new OrdinalSales('2016', 100),
+      new OrdinalSales('2017', 75),
+    ];
+
+    return [
+      new charts.Series<OrdinalSales, String>(
+        id: 'Sales',
+        colorFn: (_, __) => charts.MaterialPalette.blue.shadeDefault,
+        domainFn: (OrdinalSales sales, _) => sales.year,
+        measureFn: (OrdinalSales sales, _) => sales.sales,
+        data: data,
+      )
+    ];
+  }
+
+  @override
+  SelectionUserManagedState createState() {
+    return new SelectionUserManagedState();
+  }
+}
+
+class SelectionUserManagedState extends State<SelectionUserManaged> {
+  final _myState = new charts.UserManagedState<String>();
+
+  @override
+  Widget build(BuildContext context) {
+    final chart = new charts.BarChart(
+      widget.seriesList,
+      animate: false, //widget.animate,
+      selectionModels: [
+        new charts.SelectionModelConfig(
+            type: charts.SelectionModelType.info,
+            updatedListener: _infoSelectionModelUpdated)
+      ],
+      // Pass in the state you manage to the chart. This will be used to
+      // override the internal chart state.
+      userManagedState: _myState,
+      // The initial selection can still be optionally added by adding the
+      // initial selection behavior.
+      behaviors: [
+        new charts.InitialSelection(selectedDataConfig: [
+          new charts.SeriesDatumConfig<String>('Sales', '2016')
+        ])
+      ],
+    );
+
+    final clearSelection = new MaterialButton(
+        onPressed: _handleClearSelection, child: new Text('Clear Selection'));
+
+    return new Column(
+        children: [new SizedBox(child: chart, height: 150.0), clearSelection]);
+  }
+
+  void _infoSelectionModelUpdated(charts.SelectionModel<String> model) {
+    // If you want to allow the chart to continue to respond to select events
+    // that update the selection, add an updatedListener that saves off the
+    // selection model each time the selection model is updated, regardless of
+    // if there are changes.
+    //
+    // This also allows you to listen to the selection model update events and
+    // alter the selection.
+    _myState.selectionModels[charts.SelectionModelType.info] =
+        new charts.UserManagedSelectionModel(model: model);
+  }
+
+  void _handleClearSelection() {
+    // Call set state to request a rebuild, to pass in the modified selection.
+    // In this case, passing in an empty [UserManagedSelectionModel] creates a
+    // no selection model to clear all selection when rebuilt.
+    setState(() {
+      _myState.selectionModels[charts.SelectionModelType.info] =
+          new charts.UserManagedSelectionModel();
+    });
+  }
+}
+
+/// Sample ordinal data type.
+class OrdinalSales {
+  final String year;
+  final int sales;
+
+  OrdinalSales(this.year, this.sales);
+}