✨ Seprate calculate, 反比例函数
This commit is contained in:
@@ -28,9 +28,14 @@ class GraphCard extends StatefulWidget {
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class _GraphCardState extends State<GraphCard> {
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final SolverService _solverService = SolverService();
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FlSpot? _currentTouchedPoint;
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final TextEditingController _xController = TextEditingController();
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double? _manualY;
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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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({List<FlSpot> leftPoints, List<FlSpot> rightPoints}) _generatePlotPoints(
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String expression,
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double zoomFactor,
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) {
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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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@@ -39,7 +44,7 @@ class _GraphCardState extends State<GraphCard> {
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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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return (leftPoints: [], rightPoints: []);
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}
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// 预处理表达式，确保格式正确
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@@ -69,11 +74,15 @@ class _GraphCardState extends State<GraphCard> {
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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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final step = max(0.01, 0.05 / zoomFactor); // 更小的步长以获得更好的分辨率
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// 生成点
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List<FlSpot> points = [];
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List<FlSpot> leftPoints = [];
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List<FlSpot> rightPoints = [];
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for (double i = -range; i <= range; i += step) {
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// 跳过 x = 0 以避免在 y=1/x 等函数中的奇点
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if (i.abs() < 1e-10) continue;
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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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@@ -81,8 +90,12 @@ class _GraphCardState extends State<GraphCard> {
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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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if (y.isFinite && y.abs() <= 100.0) {
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if (i < 0) {
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leftPoints.add(FlSpot(i, y));
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} else {
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rightPoints.add(FlSpot(i, y));
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}
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}
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}
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} catch (e) {
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@@ -91,22 +104,17 @@ class _GraphCardState extends State<GraphCard> {
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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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leftPoints.sort((a, b) => a.x.compareTo(b.x));
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rightPoints.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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'Generated ${leftPoints.length} left dots and ${rightPoints.length} right dots with zoom factor $zoomFactor',
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);
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return points;
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return (leftPoints: leftPoints, rightPoints: rightPoints);
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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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return (leftPoints: [], rightPoints: []);
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}
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}
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@@ -136,6 +144,11 @@ class _GraphCardState extends State<GraphCard> {
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maxY = max(maxY, point.y);
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}
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// Limit y range to prevent extreme values from making the chart unreadable
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const double maxYRange = 100.0;
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if (maxY > maxYRange) maxY = maxYRange;
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if (minY < -maxYRange) minY = -maxYRange;
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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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@@ -161,6 +174,61 @@ class _GraphCardState extends State<GraphCard> {
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return value.toStringAsFixed(4);
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}
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double? _calculateYForX(double x) {
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try {
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String functionExpr = _solverService.prepareFunctionForGraphing(
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widget.expression,
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);
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if (!functionExpr.contains('x') && !functionExpr.contains('X')) {
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return null;
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}
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functionExpr = functionExpr.replaceAll(' ', '');
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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)}*${match.group(2)}',
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);
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functionExpr = functionExpr.replaceAllMapped(
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RegExp(r'([a-zA-Z])(\d)'),
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(match) => '${match.group(1)}*${match.group(2)}',
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);
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functionExpr = functionExpr.replaceAllMapped(
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RegExp(r'%([a-zA-Z\d])'),
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(match) => '%*${match.group(1)}',
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);
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final parser = Parser(functionExpr);
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final expr = parser.parse();
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final substituted = expr.substitute('x', DoubleExpr(x));
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final evaluated = substituted.evaluate();
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if (evaluated is DoubleExpr &&
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evaluated.value.isFinite &&
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!evaluated.value.isNaN) {
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return evaluated.value;
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}
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} catch (e) {
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// Handle error
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}
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return 0 / 0;
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}
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void _performCalculation() {
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final x = double.tryParse(_xController.text);
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if (x != null) {
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setState(() {
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_manualY = _calculateYForX(x);
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});
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} else {
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ScaffoldMessenger.of(
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context,
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).showSnackBar(SnackBar(content: Text('请输入有效的数字')));
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}
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}
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@override
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void dispose() {
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_xController.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 ListView(
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@@ -212,12 +280,13 @@ class _GraphCardState extends State<GraphCard> {
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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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final (:leftPoints, :rightPoints) = _generatePlotPoints(
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widget.expression,
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widget.zoomFactor,
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);
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final allPoints = [...leftPoints, ...rightPoints];
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final bounds = _calculateChartBounds(
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points,
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allPoints,
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widget.zoomFactor,
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);
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@@ -315,14 +384,24 @@ class _GraphCardState extends State<GraphCard> {
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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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if (leftPoints.isNotEmpty)
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LineChartBarData(
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spots: leftPoints,
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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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if (rightPoints.isNotEmpty)
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LineChartBarData(
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spots: rightPoints,
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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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@@ -355,6 +434,51 @@ class _GraphCardState extends State<GraphCard> {
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],
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),
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),
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const SizedBox(height: 16),
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Row(
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children: [
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Expanded(
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child: TextField(
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controller: _xController,
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decoration: InputDecoration(
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labelText: '输入 x 值',
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border: OutlineInputBorder(),
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isDense: true,
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),
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keyboardType: TextInputType.numberWithOptions(
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decimal: true,
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signed: true,
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),
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onSubmitted: (_) => _performCalculation(),
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onTapOutside: (_) =>
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FocusManager.instance.primaryFocus?.unfocus(),
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),
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),
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const SizedBox(width: 8),
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IconButton(
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onPressed: _performCalculation,
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icon: Icon(Icons.calculate_outlined),
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tooltip: '计算 y',
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),
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],
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),
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if (_manualY != null)
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Container(
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margin: const EdgeInsets.only(top: 16),
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padding: const EdgeInsets.all(12),
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decoration: BoxDecoration(
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color: Theme.of(
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context,
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).colorScheme.surfaceContainerHighest,
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borderRadius: BorderRadius.circular(8),
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),
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child: LaTexT(
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laTeXCode: Text(
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'\$\$x = ${double.parse(_xController.text).toStringAsFixed(4)},\\quad y = ${_manualY!.toStringAsFixed(4)}\$\$',
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style: Theme.of(context).textTheme.bodyLarge,
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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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