Add PieChart

 include: package:pedantic/analysis_options.yaml
-
-analyzer:
-  strong-mode:
-    implicit-dynamic: false
-  errors:
-    missing_required_param: warning
-    missing_return: warning
-
-linter:
-  rules:
-    - always_put_control_body_on_new_line
-    - avoid_as
-    - avoid_bool_literals_in_conditional_expressions
-    - avoid_classes_with_only_static_members
-    - avoid_field_initializers_in_const_classes
-    - avoid_function_literals_in_foreach_calls
-    - avoid_renaming_method_parameters
-    - avoid_returning_null_for_void
-    - avoid_slow_async_io
-    - avoid_unused_constructor_parameters
-    - avoid_void_async
-    - await_only_futures
-    - camel_case_types
-    - cancel_subscriptions
-    - control_flow_in_finally
-    - directives_ordering
-    - empty_statements
-    - flutter_style_todos
-    - hash_and_equals
-    - implementation_imports
-    - iterable_contains_unrelated_type
-    - list_remove_unrelated_type
-    - no_adjacent_strings_in_list
-    - non_constant_identifier_names
-    - omit_local_variable_types
-    - overridden_fields
-    - package_api_docs
-    - package_names
-    - package_prefixed_library_names
-    - prefer_asserts_in_initializer_lists
-    - prefer_const_constructors
-    - prefer_const_constructors_in_immutables
-    - prefer_const_declarations
-    - prefer_const_literals_to_create_immutables
-    - prefer_final_locals
-    - prefer_foreach
-    - prefer_if_elements_to_conditional_expressions
-    - prefer_initializing_formals
-    - prefer_inlined_adds
-    - prefer_typing_uninitialized_variables
-    - prefer_void_to_null
-    - sort_constructors_first
-    - sort_pub_dependencies
-    - sort_unnamed_constructors_first
-    - test_types_in_equals
-    - throw_in_finally
-    - unnecessary_brace_in_string_interps
-    - unnecessary_getters_setters
-    - unnecessary_null_aware_assignments
-    - unnecessary_overrides
-    - unnecessary_parenthesis
-    - unnecessary_statements
-    - use_full_hex_values_for_flutter_colors

@@ -25,29 +25,40 @@ Future<Uint8List> generateReport(PdfPageFormat pageFormat) async {
   const tableHeaders = ['Category', 'Budget', 'Expense', 'Result'];
 
   const dataTable = [
-    ['Phone', 80, 95, -15],
-    ['Internet', 250, 230, 20],
-    ['Electricity', 300, 375, -75],
-    ['Movies', 85, 80, 5],
-    ['Food', 300, 350, -50],
-    ['Fuel', 650, 550, 100],
-    ['Insurance', 250, 310, -60],
+    ['Phone', 80, 95],
+    ['Internet', 250, 230],
+    ['Electricity', 300, 375],
+    ['Movies', 85, 80],
+    ['Food', 300, 350],
+    ['Fuel', 650, 550],
+    ['Insurance', 250, 310],
   ];
 
+  // Some summary maths
+  final budget = dataTable
+      .map((e) => e[1] as num)
+      .reduce((value, element) => value + element);
+  final expense = dataTable
+      .map((e) => e[2] as num)
+      .reduce((value, element) => value + element);
+
   final baseColor = PdfColors.cyan;
 
   // Create a PDF document.
   final document = pw.Document();
 
+  final theme = pw.ThemeData.withFont(
+    base: pw.Font.ttf(await rootBundle.load('assets/open-sans.ttf')),
+    bold: pw.Font.ttf(await rootBundle.load('assets/open-sans-bold.ttf')),
+  );
+
   // Add page to the PDF
   document.addPage(
     pw.Page(
       pageFormat: pageFormat,
-      theme: pw.ThemeData.withFont(
-        base: pw.Font.ttf(await rootBundle.load('assets/open-sans.ttf')),
-        bold: pw.Font.ttf(await rootBundle.load('assets/open-sans-bold.ttf')),
-      ),
+      theme: theme,
       build: (context) {
+        // Top bar chart
         final chart1 = pw.Chart(
           left: pw.Container(
             alignment: pw.Alignment.topCenter,
@@ -117,6 +128,7 @@ Future<Uint8List> generateReport(PdfPageFormat pageFormat) async {
           ],
         );
 
+        // Left curved line chart
         final chart2 = pw.Chart(
           grid: pw.CartesianGrid(
             xAxis: pw.FixedAxis([0, 1, 2, 3, 4, 5, 6]),
@@ -143,10 +155,19 @@ Future<Uint8List> generateReport(PdfPageFormat pageFormat) async {
           ],
         );
 
+        // Data table
         final table = pw.Table.fromTextArray(
           border: null,
           headers: tableHeaders,
-          data: dataTable,
+          data: List<List<dynamic>>.generate(
+            dataTable.length,
+            (index) => <dynamic>[
+              dataTable[index][0],
+              dataTable[index][1],
+              dataTable[index][2],
+              (dataTable[index][1] as num) - (dataTable[index][2] as num),
+            ],
+          ),
           headerStyle: pw.TextStyle(
             color: PdfColors.white,
             fontWeight: pw.FontWeight.bold,
@@ -162,8 +183,11 @@ Future<Uint8List> generateReport(PdfPageFormat pageFormat) async {
               ),
             ),
           ),
+          cellAlignment: pw.Alignment.centerRight,
+          cellAlignments: {0: pw.Alignment.centerLeft},
         );
 
+        // Page layout
         return pw.Column(
           children: [
             pw.Text('Budget Report',
@@ -223,7 +247,7 @@ Future<Uint8List> generateReport(PdfPageFormat pageFormat) async {
                         ),
                       ),
                       pw.Text(
-                        'Budget was originally \$1915. A total of \$1990 was spent on the month of January which exceeded the overall budget by \$75',
+                        'Budget was originally \$$budget. A total of \$$expense was spent on the month of January which exceeded the overall budget by \$${expense - budget}',
                         textAlign: pw.TextAlign.justify,
                       )
                     ],
@@ -237,6 +261,55 @@ Future<Uint8List> generateReport(PdfPageFormat pageFormat) async {
     ),
   );
 
+  // Second page with a pie chart
+  document.addPage(
+    pw.Page(
+      pageFormat: pageFormat,
+      theme: theme,
+      build: (context) {
+        const chartColors = [
+          PdfColors.blue300,
+          PdfColors.green300,
+          PdfColors.amber300,
+          PdfColors.pink300,
+          PdfColors.cyan300,
+          PdfColors.purple300,
+          PdfColors.lime300,
+        ];
+
+        return pw.SizedBox(
+          height: 400,
+          child: pw.Chart(
+            title: pw.Text(
+              'Expense breakdown',
+              style: pw.TextStyle(
+                color: baseColor,
+                fontSize: 20,
+              ),
+            ),
+            grid: pw.PieGrid(),
+            datasets: List<pw.Dataset>.generate(dataTable.length, (index) {
+              final data = dataTable[index];
+              final color = chartColors[index % chartColors.length];
+              final textColor =
+                  color.luminance < 0.2 ? PdfColors.white : PdfColors.black;
+
+              final value = (data[2] as num).toDouble();
+              final pct = (value / expense * 100).round();
+
+              return pw.PieDataSet(
+                legend: '${data[0]}\n$pct%',
+                value: value,
+                color: color,
+                legendStyle: pw.TextStyle(fontSize: 10, color: textColor),
+              );
+            }),
+          ),
+        );
+      },
+    ),
+  );
+
   // Return the PDF file content
   return document.save();
 }

 # Changelog
 
-## 3.0.2
+## 3.1.0
 
 - Fix some linting issues
 - Add PdfPage.rotate attribute
 - Add RadialGrid for charts with polar coordinates
+- Add PieChart
 
 ## 3.0.1
 

@@ -35,6 +35,7 @@ class ChartLegend extends StatelessWidget {
     this.direction = Axis.vertical,
     this.decoration,
     this.padding = const EdgeInsets.all(5),
+    this.maxWidth = 200,
   });
 
   final TextStyle? textStyle;
@@ -47,6 +48,8 @@ class ChartLegend extends StatelessWidget {
 
   final EdgeInsets padding;
 
+  final double maxWidth;
+
   Widget _buildLegend(Context context, Dataset dataset) {
     final style = Theme.of(context).defaultTextStyle.merge(textStyle);
 
@@ -59,10 +62,14 @@ class ChartLegend extends StatelessWidget {
           margin: const EdgeInsets.only(right: 5),
           child: dataset.legendShape(),
         ),
-        Text(
-          dataset.legend!,
-          style: textStyle,
-        )
+        ConstrainedBox(
+          constraints: BoxConstraints(maxWidth: maxWidth),
+          child: Text(
+            dataset.legend!,
+            style: textStyle,
+            softWrap: false,
+          ),
+        ),
       ],
     );
   }

+// ignore_for_file: public_member_api_docs
+
+import 'dart:math';
+
+import 'package:pdf/pdf.dart';
+import 'package:pdf/widgets.dart';
+import 'package:vector_math/vector_math_64.dart';
+
+class PieGrid extends ChartGrid {
+  PieGrid();
+
+  late PdfRect gridBox;
+
+  late double total;
+
+  late double unit;
+
+  late double pieSize;
+
+  @override
+  void layout(Context context, BoxConstraints constraints,
+      {bool parentUsesSize = false}) {
+    super.layout(context, constraints, parentUsesSize: parentUsesSize);
+
+    final datasets = Chart.of(context).datasets;
+    final size = constraints.biggest;
+
+    gridBox = PdfRect(0, 0, size.x, size.y);
+
+    total = 0.0;
+
+    for (final dataset in datasets) {
+      assert(dataset is PieDataSet, 'Use only PieDataSet with a PieGrid');
+      if (dataset is PieDataSet) {
+        total += dataset.value;
+      }
+    }
+
+    unit = pi / total * 2;
+    var angle = 0.0;
+
+    for (final dataset in datasets) {
+      if (dataset is PieDataSet) {
+        dataset.angleStart = angle;
+        angle += dataset.value * unit;
+        dataset.angleEnd = angle;
+      }
+    }
+
+    pieSize = min(gridBox.width / 2, gridBox.height / 2);
+    var reduce = false;
+
+    do {
+      reduce = false;
+      for (final dataset in datasets) {
+        if (dataset is PieDataSet) {
+          dataset.layout(context, BoxConstraints.tight(gridBox.size));
+          assert(dataset.box != null);
+          if (pieSize > 20 &&
+              (dataset.box!.width > gridBox.width ||
+                  dataset.box!.height > gridBox.height)) {
+            pieSize -= 10;
+            reduce = true;
+            break;
+          }
+        }
+      }
+    } while (reduce);
+  }
+
+  @override
+  PdfPoint toChart(PdfPoint p) {
+    return p;
+  }
+
+  void clip(Context context, PdfPoint size) {}
+
+  @override
+  void paint(Context context) {
+    super.paint(context);
+
+    final datasets = Chart.of(context).datasets;
+
+    context.canvas
+      ..saveContext()
+      ..setTransform(
+        Matrix4.translationValues(box!.width / 2, box!.height / 2, 0),
+      );
+
+    for (var dataSet in datasets) {
+      if (dataSet is PieDataSet) {
+        dataSet.paintBackground(context);
+      }
+    }
+
+    for (var dataSet in datasets) {
+      if (dataSet is PieDataSet) {
+        dataSet.paint(context);
+      }
+    }
+
+    for (var dataSet in datasets) {
+      if (dataSet is PieDataSet) {
+        dataSet.paintLegend(context);
+      }
+    }
+
+    context.canvas.restoreContext();
+  }
+}
+
+enum PieLegendPosition { none, auto, inside }
+
+class PieDataSet extends Dataset {
+  PieDataSet({
+    required this.value,
+    String? legend,
+    required PdfColor color,
+    this.borderColor = PdfColors.white,
+    this.borderWidth = 1.5,
+    bool? drawBorder,
+    this.drawSurface = true,
+    this.surfaceOpacity = 1,
+    this.offset = 0,
+    this.legendStyle,
+    this.legendPosition = PieLegendPosition.auto,
+  })  : drawBorder = drawBorder ?? borderColor != null && color != borderColor,
+        assert((drawBorder ?? borderColor != null && color != borderColor) ||
+            drawSurface),
+        super(
+          legend: legend,
+          color: color,
+        );
+
+  final double value;
+
+  late double angleStart;
+
+  late double angleEnd;
+
+  final bool drawBorder;
+  final PdfColor? borderColor;
+  final double borderWidth;
+
+  final bool drawSurface;
+
+  final double surfaceOpacity;
+
+  final double offset;
+
+  final TextStyle? legendStyle;
+
+  final PieLegendPosition legendPosition;
+
+  @override
+  void layout(Context context, BoxConstraints constraints,
+      {bool parentUsesSize = false}) {
+    // final size = constraints.biggest;
+
+    // ignore: avoid_as
+    final grid = Chart.of(context).grid as PieGrid;
+    final len = grid.pieSize + offset;
+
+    box = PdfRect(-len, -len, len * 2, len * 2);
+  }
+
+  void _shape(Context context) {
+    // ignore: avoid_as
+    final grid = Chart.of(context).grid as PieGrid;
+
+    final bisect = (angleStart + angleEnd) / 2;
+
+    final cx = sin(bisect) * offset;
+    final cy = cos(bisect) * offset;
+
+    final sx = cx + sin(angleStart) * grid.pieSize;
+    final sy = cy + cos(angleStart) * grid.pieSize;
+    final ex = cx + sin(angleEnd) * grid.pieSize;
+    final ey = cy + cos(angleEnd) * grid.pieSize;
+
+    context.canvas
+      ..moveTo(cx, cy)
+      ..lineTo(sx, sy)
+      ..bezierArc(sx, sy, grid.pieSize, grid.pieSize, ex, ey,
+          large: angleEnd - angleStart > pi);
+  }
+
+  @override
+  void paintBackground(Context context) {
+    super.paint(context);
+
+    if (drawSurface) {
+      _shape(context);
+      if (surfaceOpacity != 1) {
+        context.canvas
+          ..saveContext()
+          ..setGraphicState(
+            PdfGraphicState(opacity: surfaceOpacity),
+          );
+      }
+
+      context.canvas
+        ..setFillColor(color)
+        ..fillPath();
+
+      if (surfaceOpacity != 1) {
+        context.canvas.restoreContext();
+      }
+    }
+  }
+
+  @override
+  void paint(Context context) {
+    super.paint(context);
+
+    if (drawBorder) {
+      _shape(context);
+      context.canvas
+        ..setLineWidth(borderWidth)
+        ..setLineJoin(PdfLineJoin.round)
+        ..setStrokeColor(borderColor ?? color)
+        ..strokePath(close: true);
+    }
+  }
+
+  void paintLegend(Context context) {
+    if (legendPosition != PieLegendPosition.none && legend != null) {
+      // ignore: avoid_as
+      final grid = Chart.of(context).grid as PieGrid;
+
+      final bisect = (angleStart + angleEnd) / 2;
+
+      final o = grid.pieSize * 2 / 3;
+      final cx = sin(bisect) * (offset + o);
+      final cy = cos(bisect) * (offset + o);
+
+      Widget.draw(
+        Text(legend!, style: legendStyle, textAlign: TextAlign.center),
+        offset: PdfPoint(cx, cy),
+        context: context,
+        alignment: Alignment.center,
+        constraints: const BoxConstraints(maxWidth: 200, maxHeight: 200),
+      );
+    }
+  }
+}

@@ -28,6 +28,7 @@ export 'src/widgets/chart/grid_cartesian.dart';
 export 'src/widgets/chart/grid_radial.dart';
 export 'src/widgets/chart/legend.dart';
 export 'src/widgets/chart/line_chart.dart';
+export 'src/widgets/chart/pie_chart.dart';
 export 'src/widgets/clip.dart';
 export 'src/widgets/container.dart';
 export 'src/widgets/content.dart';

@@ -4,7 +4,7 @@ description: A pdf producer for Dart. It can create pdf files for both web or fl
 homepage: https://github.com/DavBfr/dart_pdf/tree/master/pdf
 repository: https://github.com/DavBfr/dart_pdf
 issue_tracker: https://github.com/DavBfr/dart_pdf/issues
-version: 3.0.2
+version: 3.1.0
 
 environment:
   sdk: ">=2.12.0-0 <3.0.0"