Feature: Add StackedPieChart

example/lib/presentation/resources/app_assets.dart

@@ -15,6 +15,9 @@ class AppAssets {
         return 'assets/icons/ic_radar_chart.svg';
       case ChartType.candlestick:
         return 'assets/icons/ic_candle_chart.svg';
+      case ChartType.stackedPie:
+        // TODO: Add new icon
+        return 'assets/icons/ic_pie_chart.svg';
     }
   }
 

example/lib/presentation/samples/chart_sample.dart

@@ -46,3 +46,9 @@ class CandlestickChartSample extends ChartSample {
   @override
   ChartType get type => ChartType.candlestick;
 }
+
+class StackedPieChartSample extends ChartSample {
+  StackedPieChartSample(super.number, super.builder);
+  @override
+  ChartType get type => ChartType.stackedPie;
+}

example/lib/presentation/samples/chart_samples.dart

@@ -1,4 +1,5 @@
 import 'package:fl_chart_app/presentation/samples/candlestick/candlestick_chart_sample1.dart';
+import 'package:fl_chart_app/presentation/samples/stacked_pie/stacked_pie_chart_sample1.dart';
 import 'package:fl_chart_app/util/app_helper.dart';
 
 import 'bar/bar_chart_sample1.dart';
@@ -71,6 +72,9 @@ class ChartSamples {
     ],
     ChartType.candlestick: [
       CandlestickChartSample(1, (context) => const CandlestickChartSample1()),
+    ],
+    ChartType.stackedPie: [
+      StackedPieChartSample(1, (context) => const StackedPieChartSample1()),
     ]
   };
 }

example/lib/presentation/samples/stacked_pie/stacked_pie_chart_sample1.dart

@@ -0,0 +1,27 @@
+import 'package:fl_chart_app/presentation/samples/stacked_pie/stacked_pie_demo.dart';
+import 'package:flutter/material.dart';
+
+class StackedPieChartSample1 extends StatefulWidget {
+  const StackedPieChartSample1({super.key});
+
+  @override
+  State<StackedPieChartSample1> createState() => _StackedPieChartSample1State();
+}
+
+class _StackedPieChartSample1State extends State<StackedPieChartSample1> {
+  @override
+  Widget build(BuildContext context) {
+    return const AspectRatio(
+      aspectRatio: 1.0,
+      child: Column(
+        children: <Widget>[
+          SizedBox(height: 28),
+          Expanded(
+            child: StackedPieDemo(),
+          ),
+          SizedBox(height: 28),
+        ],
+      ),
+    );
+  }
+}

example/lib/presentation/samples/stacked_pie/stacked_pie_demo.dart

@@ -0,0 +1,81 @@
+import 'package:fl_chart/fl_chart.dart';
+import 'package:flutter/material.dart';
+
+class StackedPieDemo extends StatefulWidget {
+  const StackedPieDemo({super.key});
+
+  @override
+  State<StackedPieDemo> createState() => _StackedPieDemoState();
+}
+
+class _StackedPieDemoState extends State<StackedPieDemo> {
+  int _touchedIndex = -1;
+  int hacky = 0;
+
+  Color _getSegmentColor(int index, Color color) =>
+      _touchedIndex == -1 || _touchedIndex == index
+          ? color
+          : color.withValues(alpha: 0.5);
+
+  StackedPieChartSectionData createSectionData(
+    int index,
+    double weight,
+    double a,
+    double b, {
+    double radius = 100,
+  }) =>
+      StackedPieChartSectionData(
+        weight: weight,
+        segments: [
+          StackedPieChartSegmentData(
+            value: a,
+            color: _getSegmentColor(index, Colors.lightBlue),
+          ),
+          StackedPieChartSegmentData(
+            value: b,
+            color: _getSegmentColor(index, Colors.redAccent),
+          ),
+        ],
+        radius: radius,
+      );
+
+  @override
+  Widget build(BuildContext context) {
+    return StackedPieChart(
+      StackedPieChartData(
+        pieTouchData: StackedPieTouchData(
+          enabled: true,
+          touchCallback: (event, response) {
+            setState(() {
+              if (!event.isInterestedForInteractions ||
+                  event is! FlTapDownEvent) {
+                return;
+              }
+
+              final userSelectedIndex =
+                  response?.touchedSection?.touchedSectionIndex ?? -1;
+
+              if (_touchedIndex == userSelectedIndex) {
+                _touchedIndex = -1;
+                return;
+              } else {
+                _touchedIndex = userSelectedIndex;
+              }
+            });
+          },
+        ),
+        sections: [
+          createSectionData(1, 60, 90, 10),
+          createSectionData(2, 60, 70, 30),
+          createSectionData(3, 60, 100, 0),
+          createSectionData(4, 30, 90, 10),
+          createSectionData(5, 30, 60, 40),
+          createSectionData(6, 30, 100, 0),
+          createSectionData(7, 30, 10, 90),
+          createSectionData(8, 30, 60, 40),
+          createSectionData(9, 30, 0, 100),
+        ],
+      ),
+    );
+  }
+}

example/lib/util/app_helper.dart

@@ -1,7 +1,7 @@
 import 'package:fl_chart_app/presentation/resources/app_resources.dart';
 import 'package:fl_chart_app/urls.dart';
 
-enum ChartType { line, bar, pie, scatter, radar, candlestick }
+enum ChartType { line, bar, pie, scatter, radar, candlestick, stackedPie }
 
 extension ChartTypeExtension on ChartType {
   String get displayName => '$simpleName Chart';
@@ -13,6 +13,7 @@ extension ChartTypeExtension on ChartType {
         ChartType.scatter => 'Scatter',
         ChartType.radar => 'Radar',
         ChartType.candlestick => 'Candlestick',
+        ChartType.stackedPie => 'Stacked Pie',
       };
 
   String get documentationUrl => Urls.getChartDocumentationUrl(this);

lib/fl_chart.dart

@@ -16,3 +16,5 @@ export 'src/chart/radar_chart/radar_chart.dart';
 export 'src/chart/radar_chart/radar_chart_data.dart';
 export 'src/chart/scatter_chart/scatter_chart.dart';
 export 'src/chart/scatter_chart/scatter_chart_data.dart';
+export 'src/chart/stacked_pie_chart/stacked_pie_chart.dart';
+export 'src/chart/stacked_pie_chart/stacked_pie_chart_data.dart';

lib/src/chart/stacked_pie_chart/stacked_pie_chart.dart

@@ -0,0 +1,72 @@
+import 'package:fl_chart/src/chart/stacked_pie_chart/stacked_pie_chart_data.dart';
+import 'package:fl_chart/src/chart/stacked_pie_chart/stacked_pie_chart_renderer.dart';
+import 'package:flutter/material.dart';
+
+/// Renders a stacked pie chart as a widget, using provided [StackedPieChartData].
+class StackedPieChart extends ImplicitlyAnimatedWidget {
+  /// [data] defines the look of [StackedPieChart].
+  /// When you make any change in the [StackedPieChartData], it updates
+  /// new values with animation, and duration is [duration].
+  /// also you can change the [curve]
+  /// which default is [Curves.linear].
+  const StackedPieChart(
+    this.data, {
+    super.key,
+    super.duration = const Duration(milliseconds: 150),
+    super.curve = Curves.linear,
+  });
+
+  /// Default duration to reuse externally.
+  static const defaultDuration = Duration(milliseconds: 150);
+
+  /// Determines how the [StackedPieChart] should be look like.
+  final StackedPieChartData data;
+
+  /// Creates a [_StackedPieChartState]
+  @override
+  _StackedPieChartState createState() => _StackedPieChartState();
+}
+
+class _StackedPieChartState extends AnimatedWidgetBaseState<StackedPieChart> {
+  StackedPieChartDataTween? _stackedPieChartDataTween;
+
+  @override
+  void initState() {
+    /// Make sure that [_widgetsPositionHandler] is updated.
+    WidgetsBinding.instance.addPostFrameCallback((timeStamp) {
+      if (mounted) {
+        setState(() {});
+      }
+    });
+
+    super.initState();
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final showingData = _getData();
+
+    return StackedPieChartLeaf(
+      data: _stackedPieChartDataTween!.evaluate(animation),
+      targetData: showingData,
+    );
+  }
+
+  /// if builtIn touches are enabled, we should recreate our [pieChartData]
+  /// to handle built in touches
+  StackedPieChartData _getData() {
+    return widget.data;
+  }
+
+  @override
+  void forEachTween(TweenVisitor<dynamic> visitor) {
+    _stackedPieChartDataTween = visitor(
+      _stackedPieChartDataTween,
+      widget.data,
+      (dynamic value) => StackedPieChartDataTween(
+          begin: value as StackedPieChartData, end: widget.data),
+    ) as StackedPieChartDataTween?;
+  }
+}
+
+// TODO: implement BadgeWidgetsDelegate?