281 lines
9.4 KiB
Dart
281 lines
9.4 KiB
Dart
import 'package:flutter/material.dart';
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import 'package:fl_chart/fl_chart.dart';
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import 'package:simple_math_calc/parser.dart';
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import 'package:simple_math_calc/calculator.dart';
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import 'package:simple_math_calc/solver.dart';
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import 'dart:math';
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class GraphCard extends StatefulWidget {
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final String expression;
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final double zoomFactor;
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final VoidCallback onZoomIn;
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final VoidCallback onZoomOut;
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const GraphCard({
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super.key,
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required this.expression,
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required this.zoomFactor,
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required this.onZoomIn,
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required this.onZoomOut,
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});
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@override
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State<GraphCard> createState() => _GraphCardState();
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}
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class _GraphCardState extends State<GraphCard> {
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final SolverService _solverService = SolverService();
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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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// 使用solver准备函数表达式（展开因式形式）
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String functionExpr = _solverService.prepareFunctionForGraphing(
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expression,
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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 = Parser(functionExpr);
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final expr = parser.parse();
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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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// 替换变量 x 为当前值
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final substituted = expr.substitute('x', DoubleExpr(i));
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final evaluated = substituted.evaluate();
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if (evaluated is DoubleExpr) {
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final y = evaluated.value;
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if (y.isFinite && !y.isNaN) {
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points.add(FlSpot(i, y));
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}
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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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@override
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Widget build(BuildContext context) {
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return ListView(
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padding: EdgeInsets.only(
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left: 16,
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right: 16,
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bottom: MediaQuery.of(context).padding.bottom + 16,
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top: 16,
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),
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children: [
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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: widget.onZoomIn,
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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: widget.onZoomOut,
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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: 340,
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child: Builder(
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builder: (context) {
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final points = _generatePlotPoints(
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widget.expression,
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widget.zoomFactor,
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);
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final bounds = _calculateChartBounds(
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points,
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widget.zoomFactor,
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);
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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: 80,
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getTitlesWidget: (value, meta) =>
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SideTitleWidget(
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axisSide: meta.axisSide,
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child: Text(value.toStringAsFixed(2)),
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),
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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: 24,
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getTitlesWidget: (value, meta) =>
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SideTitleWidget(
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axisSide: meta.axisSide,
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child: Text(value.toStringAsFixed(2)),
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),
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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(
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show: true,
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border: Border.all(
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color: Theme.of(context).colorScheme.outline,
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),
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),
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lineTouchData: LineTouchData(
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enabled: true,
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touchTooltipData: LineTouchTooltipData(
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getTooltipItems: (touchedSpots) {
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return touchedSpots.map((spot) {
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return LineTooltipItem(
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'x = ${spot.x.toStringAsFixed(2)}\ny = ${spot.y.toStringAsFixed(2)}',
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const TextStyle(color: Colors.white),
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);
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}).toList();
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},
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),
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),
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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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}
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