Initial commit

lib/src/segment.dart

@@ -0,0 +1,45 @@
+import 'dart:ui';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_circular_chart/src/tween.dart';
+
+class CircularChartSegment extends MergeTweenable<CircularChartSegment> {
+  CircularChartSegment(this.rank, this.sweepAngle, this.color);
+
+  final int rank;
+  final double sweepAngle;
+  final Color color;
+
+  @override
+  CircularChartSegment get empty => new CircularChartSegment(rank, 0.0, color);
+
+  @override
+  bool operator <(CircularChartSegment other) => rank < other.rank;
+
+  @override
+  Tween<CircularChartSegment> tweenTo(CircularChartSegment other) =>
+      new CircularChartSegmentTween(this, other);
+
+  static CircularChartSegment lerp(
+      CircularChartSegment begin, CircularChartSegment end, double t) {
+    assert(begin.rank == end.rank);
+
+    return new CircularChartSegment(
+      begin.rank,
+      lerpDouble(begin.sweepAngle, end.sweepAngle, t),
+      Color.lerp(begin.color, end.color, t),
+    );
+  }
+}
+
+class CircularChartSegmentTween extends Tween<CircularChartSegment> {
+  CircularChartSegmentTween(
+      CircularChartSegment begin, CircularChartSegment end)
+      : super(begin: begin, end: end) {
+    assert(begin.rank == end.rank);
+  }
+
+  @override
+  CircularChartSegment lerp(double t) =>
+      CircularChartSegment.lerp(begin, end, t);
+}