💄 Better graph card

lib/widgets/graph_card.dart

@@ -1,5 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:fl_chart/fl_chart.dart';
+import 'package:google_fonts/google_fonts.dart';
+import 'package:latext/latext.dart';
 import 'package:simple_math_calc/parser.dart';
 import 'package:simple_math_calc/calculator.dart';
 import 'package:simple_math_calc/solver.dart';
@@ -25,6 +27,7 @@ class GraphCard extends StatefulWidget {
 
 class _GraphCardState extends State<GraphCard> {
   final SolverService _solverService = SolverService();
+  FlSpot? _currentTouchedPoint;
 
   /// 生成函数图表的点
   List<FlSpot> _generatePlotPoints(String expression, double zoomFactor) {
@@ -145,6 +148,19 @@ class _GraphCardState extends State<GraphCard> {
     );
   }
 
+  String _formatAxisValue(double value) {
+    if (value.abs() < 1e-10) return "0";
+    if ((value - value.roundToDouble()).abs() < 1e-10) {
+      return value.round().toString();
+    }
+    double absVal = value.abs();
+    if (absVal >= 100) return value.toStringAsFixed(0);
+    if (absVal >= 10) return value.toStringAsFixed(1);
+    if (absVal >= 1) return value.toStringAsFixed(2);
+    if (absVal >= 0.1) return value.toStringAsFixed(3);
+    return value.toStringAsFixed(4);
+  }
+
   @override
   Widget build(BuildContext context) {
     return ListView(
@@ -212,22 +228,52 @@ class _GraphCardState extends State<GraphCard> {
                             leftTitles: AxisTitles(
                               sideTitles: SideTitles(
                                 showTitles: true,
-                                reservedSize: 80,
+                                reservedSize: 60,
+                                interval: (bounds.maxY - bounds.minY) / 8,
                                 getTitlesWidget: (value, meta) =>
                                     SideTitleWidget(
                                       axisSide: meta.axisSide,
-                                      child: Text(value.toStringAsFixed(2)),
+                                      child: Text(
+                                        _formatAxisValue(value),
+                                        style: GoogleFonts.robotoFlex(),
+                                      ),
                                     ),
                               ),
                             ),
                             bottomTitles: AxisTitles(
                               sideTitles: SideTitles(
                                 showTitles: true,
-                                reservedSize: 24,
+                                reservedSize: 80,
-                                getTitlesWidget: (value, meta) =>
+                                interval: (bounds.maxX - bounds.minX) / 10,
-                                    SideTitleWidget(
+                                getTitlesWidget: (value, meta) => SideTitleWidget(
                                   axisSide: meta.axisSide,
-                                      child: Text(value.toStringAsFixed(2)),
+                                  child: Column(
+                                    mainAxisSize: MainAxisSize.min,
+                                    children: _formatAxisValue(value)
+                                        .split('')
+                                        .map(
+                                          (char) => ['-', '.'].contains(char)
+                                              ? Transform.rotate(
+                                                  angle: pi / 2,
+                                                  child: Text(
+                                                    char,
+                                                    style:
+                                                        GoogleFonts.robotoFlex(
+                                                          height: char == '.'
+                                                              ? 0.7
+                                                              : 0.9,
+                                                        ),
+                                                  ),
+                                                )
+                                              : Text(
+                                                  char,
+                                                  style: GoogleFonts.robotoFlex(
+                                                    height: 0.9,
+                                                  ),
+                                                ),
+                                        )
+                                        .toList(),
+                                  ),
                                 ),
                               ),
                             ),
@@ -246,6 +292,17 @@ class _GraphCardState extends State<GraphCard> {
                           ),
                           lineTouchData: LineTouchData(
                             enabled: true,
+                            touchCallback: (event, response) {
+                              if (response != null &&
+                                  response.lineBarSpots != null &&
+                                  response.lineBarSpots!.isNotEmpty) {
+                                setState(() {
+                                  _currentTouchedPoint =
+                                      response.lineBarSpots!.first;
+                                });
+                              }
+                              // Keep the last touched point visible
+                            },
                             touchTooltipData: LineTouchTooltipData(
                               getTooltipItems: (touchedSpots) {
                                 return touchedSpots.map((spot) {
@@ -276,6 +333,28 @@ class _GraphCardState extends State<GraphCard> {
                     },
                   ),
                 ),
+                if (_currentTouchedPoint != null)
+                  Container(
+                    margin: const EdgeInsets.only(top: 16),
+                    padding: const EdgeInsets.all(12),
+                    decoration: BoxDecoration(
+                      color: Theme.of(
+                        context,
+                      ).colorScheme.surfaceContainerHighest,
+                      borderRadius: BorderRadius.circular(8),
+                    ),
+                    child: Column(
+                      mainAxisAlignment: MainAxisAlignment.center,
+                      children: [
+                        LaTexT(
+                          laTeXCode: Text(
+                            '\$\$x = ${_currentTouchedPoint!.x.toStringAsFixed(4)},\\quad y = ${_currentTouchedPoint!.y.toStringAsFixed(4)}\$\$',
+                            style: Theme.of(context).textTheme.bodyLarge,
+                          ),
+                        ),
+                      ],
+                    ),
+                  ),
               ],
             ),
           ),