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[Gallery] Fix directory structure (#312)
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Pierre-Louis
GitHub
278
gallery/lib/studies/rally/charts/pie_chart.dart
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278
gallery/lib/studies/rally/charts/pie_chart.dart
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// Copyright 2019 The Flutter team. All rights reserved.
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// Use of this source code is governed by a BSD-style license that can be
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// found in the LICENSE file.
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import 'dart:math' as math;
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import 'package:flutter/material.dart';
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import 'package:gallery/data/gallery_options.dart';
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import 'package:gallery/layout/text_scale.dart';
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import 'package:gallery/studies/rally/colors.dart';
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import 'package:gallery/studies/rally/data.dart';
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import 'package:gallery/studies/rally/formatters.dart';
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/// A colored piece of the [RallyPieChart].
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class RallyPieChartSegment {
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const RallyPieChartSegment({this.color, this.value});
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final Color color;
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final double value;
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}
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/// The max height and width of the [RallyPieChart].
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const pieChartMaxSize = 500.0;
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List<RallyPieChartSegment> buildSegmentsFromAccountItems(
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List<AccountData> items) {
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return List<RallyPieChartSegment>.generate(
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items.length,
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(i) {
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return RallyPieChartSegment(
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color: RallyColors.accountColor(i),
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value: items[i].primaryAmount,
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);
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},
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);
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}
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List<RallyPieChartSegment> buildSegmentsFromBillItems(List<BillData> items) {
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return List<RallyPieChartSegment>.generate(
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items.length,
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(i) {
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return RallyPieChartSegment(
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color: RallyColors.billColor(i),
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value: items[i].primaryAmount,
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);
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},
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);
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}
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List<RallyPieChartSegment> buildSegmentsFromBudgetItems(
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List<BudgetData> items) {
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return List<RallyPieChartSegment>.generate(
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items.length,
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(i) {
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return RallyPieChartSegment(
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color: RallyColors.budgetColor(i),
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value: items[i].primaryAmount - items[i].amountUsed,
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);
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},
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);
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}
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/// An animated circular pie chart to represent pieces of a whole, which can
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/// have empty space.
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class RallyPieChart extends StatefulWidget {
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const RallyPieChart(
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{this.heroLabel, this.heroAmount, this.wholeAmount, this.segments});
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final String heroLabel;
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final double heroAmount;
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final double wholeAmount;
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final List<RallyPieChartSegment> segments;
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@override
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_RallyPieChartState createState() => _RallyPieChartState();
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}
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class _RallyPieChartState extends State<RallyPieChart>
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with SingleTickerProviderStateMixin {
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AnimationController controller;
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Animation<double> animation;
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@override
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void initState() {
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super.initState();
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controller = AnimationController(
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duration: const Duration(milliseconds: 600),
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vsync: this,
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);
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animation = CurvedAnimation(
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parent: TweenSequence<double>(<TweenSequenceItem<double>>[
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TweenSequenceItem<double>(
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tween: Tween<double>(begin: 0, end: 0),
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weight: 1,
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),
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TweenSequenceItem<double>(
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tween: Tween<double>(begin: 0, end: 1),
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weight: 1.5,
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),
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]).animate(controller),
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curve: Curves.decelerate);
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controller.forward();
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}
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@override
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void dispose() {
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controller.dispose();
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super.dispose();
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}
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@override
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Widget build(BuildContext context) {
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return MergeSemantics(
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child: _AnimatedRallyPieChart(
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animation: animation,
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centerLabel: widget.heroLabel,
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centerAmount: widget.heroAmount,
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total: widget.wholeAmount,
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segments: widget.segments,
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),
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);
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}
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}
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class _AnimatedRallyPieChart extends AnimatedWidget {
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const _AnimatedRallyPieChart({
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Key key,
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this.animation,
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this.centerLabel,
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this.centerAmount,
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this.total,
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this.segments,
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}) : super(key: key, listenable: animation);
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final Animation<double> animation;
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final String centerLabel;
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final double centerAmount;
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final double total;
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final List<RallyPieChartSegment> segments;
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@override
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Widget build(BuildContext context) {
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final textTheme = Theme.of(context).textTheme;
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final labelTextStyle = textTheme.body1.copyWith(
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fontSize: 14,
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letterSpacing: 0.5,
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);
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return LayoutBuilder(builder: (context, constraints) {
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// When the widget is larger, we increase the font size.
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TextStyle headlineStyle = constraints.maxHeight >= pieChartMaxSize
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? textTheme.headline.copyWith(fontSize: 70)
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: textTheme.headline;
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// With a large text scale factor, we set a max font size.
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if (GalleryOptions.of(context).textScaleFactor(context) > 1.0) {
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headlineStyle = headlineStyle.copyWith(
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fontSize: (headlineStyle.fontSize / reducedTextScale(context)),
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);
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}
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return DecoratedBox(
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decoration: _RallyPieChartOutlineDecoration(
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maxFraction: animation.value,
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total: total,
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segments: segments,
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),
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child: Container(
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height: constraints.maxHeight,
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alignment: Alignment.center,
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child: Column(
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mainAxisAlignment: MainAxisAlignment.center,
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children: [
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Text(
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centerLabel,
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style: labelTextStyle,
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),
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Text(
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usdWithSignFormat(context).format(centerAmount),
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style: headlineStyle,
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),
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],
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),
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),
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);
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});
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}
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}
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class _RallyPieChartOutlineDecoration extends Decoration {
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const _RallyPieChartOutlineDecoration(
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{this.maxFraction, this.total, this.segments});
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final double maxFraction;
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final double total;
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final List<RallyPieChartSegment> segments;
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@override
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BoxPainter createBoxPainter([VoidCallback onChanged]) {
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return _RallyPieChartOutlineBoxPainter(
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maxFraction: maxFraction,
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wholeAmount: total,
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segments: segments,
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);
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}
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}
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class _RallyPieChartOutlineBoxPainter extends BoxPainter {
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_RallyPieChartOutlineBoxPainter(
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{this.maxFraction, this.wholeAmount, this.segments});
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final double maxFraction;
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final double wholeAmount;
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final List<RallyPieChartSegment> segments;
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static const double wholeRadians = 2 * math.pi;
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static const double spaceRadians = wholeRadians / 180;
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@override
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void paint(Canvas canvas, Offset offset, ImageConfiguration configuration) {
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// Create two padded reacts to draw arcs in: one for colored arcs and one for
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// inner bg arc.
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const strokeWidth = 4.0;
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final outerRadius = math.min(
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configuration.size.width,
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configuration.size.height,
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) /
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2;
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final outerRect = Rect.fromCircle(
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center: configuration.size.center(offset),
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radius: outerRadius - strokeWidth * 3,
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);
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final innerRect = Rect.fromCircle(
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center: configuration.size.center(offset),
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radius: outerRadius - strokeWidth * 4,
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);
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// Paint each arc with spacing.
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double cumulativeSpace = 0;
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double cumulativeTotal = 0;
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for (RallyPieChartSegment segment in segments) {
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final paint = Paint()..color = segment.color;
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final startAngle = _calculateStartAngle(cumulativeTotal, cumulativeSpace);
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final sweepAngle = _calculateSweepAngle(segment.value, 0);
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canvas.drawArc(outerRect, startAngle, sweepAngle, true, paint);
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cumulativeTotal += segment.value;
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cumulativeSpace += spaceRadians;
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}
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// Paint any remaining space black (e.g. budget amount remaining).
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final remaining = wholeAmount - cumulativeTotal;
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if (remaining > 0) {
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final paint = Paint()..color = Colors.black;
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final startAngle =
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_calculateStartAngle(cumulativeTotal, spaceRadians * segments.length);
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final sweepAngle = _calculateSweepAngle(remaining, -spaceRadians);
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canvas.drawArc(outerRect, startAngle, sweepAngle, true, paint);
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}
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// Paint a smaller inner circle to cover the painted arcs, so they are
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// display as segments.
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final bgPaint = Paint()..color = RallyColors.primaryBackground;
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canvas.drawArc(innerRect, 0, 2 * math.pi, true, bgPaint);
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}
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double _calculateAngle(double amount, double offset) {
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final wholeMinusSpacesRadians =
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wholeRadians - (segments.length * spaceRadians);
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return maxFraction *
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(amount / wholeAmount * wholeMinusSpacesRadians + offset);
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}
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double _calculateStartAngle(double total, double offset) =>
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_calculateAngle(total, offset) - math.pi / 2;
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double _calculateSweepAngle(double total, double offset) =>
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_calculateAngle(total, offset);
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}
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