web/charts: Migrate to null safety (#921)

web/charts/lib/behaviors/chart_title.dart

@@ -23,10 +23,10 @@ import 'package:flutter/material.dart';
 /// A series of [ChartTitle] behaviors are used to render titles, one per
 /// margin.
 class ChartTitleLine extends StatelessWidget {
-  final List<charts.Series> seriesList;
-  final bool animate;
+  final List<charts.Series<dynamic, num>> seriesList;
+  final bool? animate;
 
-  const ChartTitleLine(this.seriesList, {this.animate, Key key})
+  const ChartTitleLine(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/behaviors/initial_hint_animation.dart

@@ -48,10 +48,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class InitialHintAnimation extends StatelessWidget {
-  final List<charts.Series> seriesList;
-  final bool animate;
+  final List<charts.Series<dynamic, String>> seriesList;
+  final bool? animate;
 
-  const InitialHintAnimation(this.seriesList, {this.animate, Key key})
+  const InitialHintAnimation(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with sample data and no transition.

web/charts/lib/behaviors/initial_selection.dart

@@ -31,10 +31,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class InitialSelection extends StatelessWidget {
-  final List<charts.Series> seriesList;
-  final bool animate;
+  final List<charts.Series<dynamic, String>> seriesList;
+  final bool? animate;
 
-  const InitialSelection(this.seriesList, {this.animate, Key key})
+  const InitialSelection(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with initial selection behavior.

web/charts/lib/behaviors/percent_of_domain.dart

@@ -24,10 +24,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class PercentOfDomainBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
-  final bool animate;
+  final List<charts.Series<dynamic, String>> seriesList;
+  final bool? animate;
 
-  const PercentOfDomainBarChart(this.seriesList, {this.animate, Key key})
+  const PercentOfDomainBarChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a stacked [BarChart] with sample data and no transition.

web/charts/lib/behaviors/percent_of_domain_by_category.dart

@@ -25,11 +25,11 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class PercentOfDomainByCategoryBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
-  final bool animate;
+  final List<charts.Series<dynamic, String>> seriesList;
+  final bool? animate;
 
   const PercentOfDomainByCategoryBarChart(this.seriesList,
-      {this.animate, Key key})
+      {this.animate, Key? key})
       : super(key: key);
 
   factory PercentOfDomainByCategoryBarChart.withSampleData() {

web/charts/lib/behaviors/percent_of_series.dart

@@ -22,10 +22,10 @@ import 'package:flutter/material.dart';
 import 'package:charts_flutter/flutter.dart' as charts;
 
 class PercentOfSeriesBarChart extends StatelessWidget {
-  final List<charts.Series> seriesList;
-  final bool animate;
+  final List<charts.Series<dynamic, String>> seriesList;
+  final bool? animate;
 
-  const PercentOfSeriesBarChart(this.seriesList, {this.animate, Key key})
+  const PercentOfSeriesBarChart(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a stacked [BarChart] with sample data and no transition.

web/charts/lib/behaviors/selection_bar_highlight.dart

@@ -19,10 +19,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SelectionBarHighlight extends StatelessWidget {
-  final List<charts.Series> seriesList;
-  final bool animate;
+  final List<charts.Series<dynamic, String>> seriesList;
+  final bool? animate;
 
-  const SelectionBarHighlight(this.seriesList, {this.animate, Key key})
+  const SelectionBarHighlight(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with sample data and no transition.

web/charts/lib/behaviors/selection_callback_example.dart

@@ -33,10 +33,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SelectionCallbackExample extends StatefulWidget {
-  final List<charts.Series> seriesList;
-  final bool animate;
+  final List<charts.Series<dynamic, DateTime>> seriesList;
+  final bool? animate;
 
-  const SelectionCallbackExample(this.seriesList, {this.animate, Key key})
+  const SelectionCallbackExample(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [charts.TimeSeriesChart] with sample data and no transition.
@@ -130,8 +130,8 @@ class SelectionCallbackExample extends StatefulWidget {
 }
 
 class _SelectionCallbackState extends State<SelectionCallbackExample> {
-  DateTime _time;
-  Map<String, num> _measures;
+  DateTime? _time;
+  Map<String?, num?>? _measures;
 
   // Listens to the underlying selection changes, and updates the information
   // relevant to building the primitive legend like information under the
@@ -139,8 +139,8 @@ class _SelectionCallbackState extends State<SelectionCallbackExample> {
   _onSelectionChanged(charts.SelectionModel model) {
     final selectedDatum = model.selectedDatum;
 
-    DateTime time;
-    final measures = <String, num>{};
+    DateTime? time;
+    final measures = <String?, num?>{};
 
     // We get the model that updated with a list of [SeriesDatum] which is
     // simply a pair of series & datum.
@@ -185,7 +185,7 @@ class _SelectionCallbackState extends State<SelectionCallbackExample> {
           padding: const EdgeInsets.only(top: 5.0),
           child: Text(_time.toString())));
     }
-    _measures?.forEach((String series, num value) {
+    _measures?.forEach((String? series, num? value) {
       children.add(Text('$series: $value'));
     });
 

web/charts/lib/behaviors/selection_line_highlight.dart

@@ -19,10 +19,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SelectionLineHighlight extends StatelessWidget {
-  final List<charts.Series> seriesList;
-  final bool animate;
+  final List<charts.Series<dynamic, num>> seriesList;
+  final bool? animate;
 
-  const SelectionLineHighlight(this.seriesList, {this.animate, Key key})
+  const SelectionLineHighlight(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/behaviors/selection_line_highlight_custom_shape.dart

@@ -19,11 +19,11 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SelectionLineHighlightCustomShape extends StatelessWidget {
-  final List<charts.Series> seriesList;
-  final bool animate;
+  final List<charts.Series<dynamic, num>> seriesList;
+  final bool? animate;
 
   const SelectionLineHighlightCustomShape(this.seriesList,
-      {this.animate, Key key})
+      {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.

web/charts/lib/behaviors/selection_scatter_plot_highlight.dart

@@ -38,10 +38,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SelectionScatterPlotHighlight extends StatelessWidget {
-  final List<charts.Series> seriesList;
-  final bool animate;
+  final List<charts.Series<dynamic, num>> seriesList;
+  final bool? animate;
 
-  const SelectionScatterPlotHighlight(this.seriesList, {this.animate, Key key})
+  const SelectionScatterPlotHighlight(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [ScatterPlotChart] with sample data and no transition.
@@ -225,9 +225,9 @@ class LinearSales {
   final int year;
   final int sales;
   final double radius;
-  final String shape;
-  final charts.Color fillColor;
-  final double strokeWidth;
+  final String? shape;
+  final charts.Color? fillColor;
+  final double? strokeWidth;
 
   LinearSales(this.year, this.sales, this.radius, this.shape, this.fillColor,
       this.strokeWidth);

web/charts/lib/behaviors/selection_user_managed.dart

@@ -29,10 +29,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SelectionUserManaged extends StatefulWidget {
-  final List<charts.Series> seriesList;
-  final bool animate;
+  final List<charts.Series<dynamic, String>> seriesList;
+  final bool? animate;
 
-  const SelectionUserManaged(this.seriesList, {this.animate, Key key})
+  const SelectionUserManaged(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with sample data and no transition.

web/charts/lib/behaviors/slider.dart

@@ -33,10 +33,10 @@ import 'package:flutter/scheduler.dart';
 /// [Slider.moveSliderToDomain] can be called to programmatically position the
 /// slider. This is useful for synchronizing the slider with external elements.
 class SliderLine extends StatefulWidget {
-  final List<charts.Series> seriesList;
-  final bool animate;
+  final List<charts.Series<dynamic, num>> seriesList;
+  final bool? animate;
 
-  const SliderLine(this.seriesList, {this.animate, Key key}) : super(key: key);
+  const SliderLine(this.seriesList, {this.animate, Key? key}) : super(key: key);
 
   /// Creates a [LineChart] with sample data and no transition.
   factory SliderLine.withSampleData() {
@@ -103,9 +103,9 @@ class SliderLine extends StatefulWidget {
 }
 
 class _SliderCallbackState extends State<SliderLine> {
-  num _sliderDomainValue;
-  String _sliderDragState;
-  Point<int> _sliderPosition;
+  num? _sliderDomainValue;
+  String? _sliderDragState;
+  Point<int>? _sliderPosition;
 
   // Handles callbacks when the user drags the slider.
   _onSliderChange(Point<int> point, dynamic domain, String roleId,
@@ -119,7 +119,7 @@ class _SliderCallbackState extends State<SliderLine> {
       });
     }
 
-    SchedulerBinding.instance.addPostFrameCallback(rebuild);
+    SchedulerBinding.instance!.addPostFrameCallback(rebuild);
   }
 
   @override
@@ -175,7 +175,7 @@ class _SliderCallbackState extends State<SliderLine> {
       children.add(Padding(
           padding: const EdgeInsets.only(top: 5.0),
           child: Text(
-              'Slider position: ${_sliderPosition.x}, ${_sliderPosition.y}')));
+              'Slider position: ${_sliderPosition!.x}, ${_sliderPosition!.y}')));
     }
     if (_sliderDragState != null) {
       children.add(Padding(

web/charts/lib/behaviors/sliding_viewport_on_selection.dart

@@ -22,10 +22,10 @@ import 'package:charts_flutter/flutter.dart' as charts;
 import 'package:flutter/material.dart';
 
 class SlidingViewportOnSelection extends StatelessWidget {
-  final List<charts.Series> seriesList;
-  final bool animate;
+  final List<charts.Series<dynamic, String>> seriesList;
+  final bool? animate;
 
-  const SlidingViewportOnSelection(this.seriesList, {this.animate, Key key})
+  const SlidingViewportOnSelection(this.seriesList, {this.animate, Key? key})
       : super(key: key);
 
   /// Creates a [BarChart] with sample data and no transition.