Add edgeStyle to AnimatedCircularChart and CircularChart

lib/src/animated_circular_chart.dart

@@ -14,6 +14,15 @@ enum CircularChartType {
   Radial,
 }
 
+/// Determines how the ends of a chart's segments should be drawn.
+enum SegmentEdgeStyle {
+  /// Segments begin and end with a flat edge.
+  Flat,
+
+  /// Segments begin and end with a semi-circle.
+  Round,
+}
+
 class AnimatedCircularChart extends StatefulWidget {
   AnimatedCircularChart({
     Key key,
@@ -26,8 +35,8 @@ class AnimatedCircularChart extends StatefulWidget {
     this.startAngle = _kStartAngle,
     this.holeLabel,
     this.labelStyle,
-  })
-      : assert(size != null),
+    this.edgeStyle = SegmentEdgeStyle.Flat,
+  })  : assert(size != null),
         super(key: key);
 
   /// The size of the bounding box this chart will be constrained to.
@@ -91,6 +100,11 @@ class AnimatedCircularChart extends StatefulWidget {
   /// [ThemeData.textTheme.body2] text style.
   final TextStyle labelStyle;
 
+  /// The type of segment edges to be drawn.
+  ///
+  /// Defaults to [SegmentEdgeStyle.Flat].
+  final SegmentEdgeStyle edgeStyle;
+
   /// The state from the closest instance of this class that encloses the given context.
   ///
   /// This method is typically used by [AnimatedCircularChart] item widgets that insert or
@@ -165,6 +179,7 @@ class AnimatedCircularChartState extends State<AnimatedCircularChart>
         percentageValues: widget.percentageValues,
         holeRadius: widget.holeRadius,
         startAngle: widget.startAngle,
+        edgeStyle: widget.edgeStyle,
       ),
     );
     _animation.forward();
@@ -231,6 +246,7 @@ class AnimatedCircularChartState extends State<AnimatedCircularChart>
           percentageValues: widget.percentageValues,
           holeRadius: widget.holeRadius,
           startAngle: widget.startAngle,
+          edgeStyle: widget.edgeStyle,
         ),
       );
       _animation.forward(from: 0.0);

lib/src/circular_chart.dart

@@ -9,10 +9,15 @@ import 'package:flutter_circular_chart/src/tween.dart';
 class CircularChart {
   static const double _kStackWidthFraction = 0.75;
 
-  CircularChart(this.stacks, this.chartType);
+  CircularChart(
+    this.stacks,
+    this.chartType, {
+    this.edgeStyle = SegmentEdgeStyle.Flat,
+  });
 
   final List<CircularChartStack> stacks;
   final CircularChartType chartType;
+  final SegmentEdgeStyle edgeStyle;
 
   factory CircularChart.empty({@required CircularChartType chartType}) {
     return new CircularChart(<CircularChartStack>[], chartType);
@@ -27,6 +32,7 @@ class CircularChart {
     Map<String, int> stackRanks,
     Map<String, int> entryRanks,
     double holeRadius,
+    SegmentEdgeStyle edgeStyle,
   }) {
     final double _holeRadius = holeRadius ?? size.width / (2 + data.length);
     final double stackDistance =
@@ -47,7 +53,7 @@ class CircularChart {
           ),
     );
 
-    return new CircularChart(stacks, chartType);
+    return new CircularChart(stacks, chartType, edgeStyle: edgeStyle);
   }
 }
 
@@ -63,5 +69,6 @@ class CircularChartTween extends Tween<CircularChart> {
   CircularChart lerp(double t) => new CircularChart(
         _stacksTween.lerp(t),
         begin.chartType,
+        edgeStyle: end.edgeStyle,
       );
 }