✨ Function chart
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@@ -2,6 +2,8 @@ import 'package:flutter/material.dart';
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import 'package:latext/latext.dart';
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import 'package:simple_math_calc/models/calculation_step.dart';
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import 'package:simple_math_calc/solver.dart';
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import 'package:fl_chart/fl_chart.dart';
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import 'package:math_expressions/math_expressions.dart' as math_expressions;
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import 'dart:math';
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class CalculatorHomePage extends StatefulWidget {
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@@ -18,19 +20,141 @@ class _CalculatorHomePageState extends State<CalculatorHomePage> {
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CalculationResult? _result;
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bool _isLoading = false;
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double _zoomFactor = 1.0;
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@override
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void initState() {
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super.initState();
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_focusNode = FocusNode();
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_controller.addListener(_onTextChanged);
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}
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@override
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void dispose() {
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_controller.removeListener(_onTextChanged);
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_focusNode.dispose();
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super.dispose();
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}
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void _onTextChanged() {
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setState(() {});
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}
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/// 生成函数图表的点
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List<FlSpot> _generatePlotPoints(String expression, double zoomFactor) {
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try {
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// 如果是方程，取左边作为函数
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String functionExpr = expression;
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if (expression.contains('=')) {
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functionExpr = expression.split('=')[0].trim();
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}
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// 如果表达式不包含 x，返回空列表
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if (!functionExpr.contains('x') && !functionExpr.contains('X')) {
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return [];
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}
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// 预处理表达式，确保格式正确
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functionExpr = functionExpr.replaceAll(' ', '');
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// 在数字和变量之间插入乘号
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functionExpr = functionExpr.replaceAllMapped(
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RegExp(r'(\d)([a-zA-Z])'),
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(match) => '${match.group(1)}*${match.group(2)}',
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);
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// 在变量和数字之间插入乘号 (如 x2 -> x*2)
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functionExpr = functionExpr.replaceAllMapped(
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RegExp(r'([a-zA-Z])(\d)'),
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(match) => '${match.group(1)}*${match.group(2)}',
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);
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// 解析表达式
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final parser = math_expressions.ShuntingYardParser();
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final expr = parser.parse(functionExpr);
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// 创建变量 x
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final x = math_expressions.Variable('x');
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// 根据缩放因子动态调整范围和步长
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final range = 10.0 * zoomFactor;
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final step = max(0.05, 0.2 / zoomFactor); // 缩放时步长更小，放大时步长更大
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// 生成点
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List<FlSpot> points = [];
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for (double i = -range; i <= range; i += step) {
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try {
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final context = math_expressions.ContextModel()
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..bindVariable(x, math_expressions.Number(i));
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final evaluator = math_expressions.RealEvaluator(context);
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final y = evaluator.evaluate(expr);
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if (y.isFinite && !y.isNaN) {
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points.add(FlSpot(i, y.toDouble()));
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}
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} catch (e) {
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// 跳过无法计算的点
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continue;
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}
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}
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// 如果没有足够的点，返回空列表
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if (points.length < 2) {
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debugPrint('Generated ${points.length} dots');
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return [];
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}
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// 排序点按 x 值
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points.sort((a, b) => a.x.compareTo(b.x));
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debugPrint(
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'Generated ${points.length} dots with zoom factor $zoomFactor',
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);
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return points;
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} catch (e) {
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debugPrint('Error generating plot points: $e');
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return [];
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}
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}
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/// 计算图表的数据范围
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({double minX, double maxX, double minY, double maxY}) _calculateChartBounds(
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List<FlSpot> points,
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double zoomFactor,
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) {
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if (points.isEmpty) {
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return (
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minX: -10 * zoomFactor,
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maxX: 10 * zoomFactor,
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minY: -50 * zoomFactor,
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maxY: 50 * zoomFactor,
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);
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}
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double minX = points.first.x;
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double maxX = points.first.x;
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double minY = points.first.y;
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double maxY = points.first.y;
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for (final point in points) {
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minX = min(minX, point.x);
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maxX = max(maxX, point.x);
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minY = min(minY, point.y);
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maxY = max(maxY, point.y);
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}
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// 添加边距
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final xPadding = (maxX - minX) * 0.1;
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final yPadding = (maxY - minY) * 0.1;
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return (
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minX: minX - xPadding,
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maxX: maxX + xPadding,
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minY: minY - yPadding,
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maxY: maxY + yPadding,
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);
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}
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void _solveEquation() {
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if (_controller.text.isEmpty) {
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return;
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@@ -61,6 +185,18 @@ class _CalculatorHomePageState extends State<CalculatorHomePage> {
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}
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}
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void _zoomIn() {
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setState(() {
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_zoomFactor = (_zoomFactor * 0.8).clamp(0.1, 10.0);
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});
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}
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void _zoomOut() {
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setState(() {
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_zoomFactor = (_zoomFactor * 1.25).clamp(0.1, 10.0);
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});
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}
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@override
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Widget build(BuildContext context) {
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return Scaffold(
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@@ -218,6 +354,101 @@ class _CalculatorHomePageState extends State<CalculatorHomePage> {
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),
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),
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),
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const SizedBox(height: 16),
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Card(
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child: Padding(
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padding: const EdgeInsets.all(16.0),
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child: Column(
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children: [
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Row(
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mainAxisAlignment: MainAxisAlignment.spaceBetween,
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children: [
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Padding(
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padding: const EdgeInsets.only(left: 4),
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child: Text(
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'函数图像',
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style: Theme.of(context).textTheme.titleMedium,
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),
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),
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Row(
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mainAxisAlignment: MainAxisAlignment.center,
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children: [
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IconButton(
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onPressed: _zoomIn,
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icon: Icon(Icons.zoom_in),
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tooltip: '放大',
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padding: EdgeInsets.zero,
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visualDensity: VisualDensity.compact,
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),
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IconButton(
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onPressed: _zoomOut,
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icon: Icon(Icons.zoom_out),
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tooltip: '缩小',
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padding: EdgeInsets.zero,
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visualDensity: VisualDensity.compact,
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),
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],
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),
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],
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),
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const SizedBox(height: 24),
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SizedBox(
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height: 300,
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child: Builder(
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builder: (context) {
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final points = _generatePlotPoints(
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_controller.text,
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_zoomFactor,
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);
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final bounds = _calculateChartBounds(points, _zoomFactor);
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return LineChart(
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LineChartData(
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gridData: FlGridData(show: true),
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titlesData: FlTitlesData(
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leftTitles: AxisTitles(
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sideTitles: SideTitles(
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showTitles: true,
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reservedSize: 40,
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),
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),
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bottomTitles: AxisTitles(
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sideTitles: SideTitles(
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showTitles: true,
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reservedSize: 30,
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),
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),
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topTitles: AxisTitles(
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sideTitles: SideTitles(showTitles: false),
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),
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rightTitles: AxisTitles(
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sideTitles: SideTitles(showTitles: false),
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),
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),
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borderData: FlBorderData(show: true),
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lineBarsData: [
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LineChartBarData(
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spots: points,
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isCurved: true,
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color: Theme.of(context).colorScheme.primary,
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barWidth: 3,
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belowBarData: BarAreaData(show: false),
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dotData: FlDotData(show: false),
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),
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],
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minX: bounds.minX,
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maxX: bounds.maxX,
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minY: bounds.minY,
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maxY: bounds.maxY,
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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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),
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],
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);
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}
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