feat: add current time indicator.

assets/flutter_i18n/en_US.yaml

@@ -154,6 +154,8 @@ classtable:
       output_to_system: "Export to system calendar"
       refresh_classtable: "Refresh schedule"
       switch_semester: "Switch classtable semester"
+      enable_current_time_indicator: "Show current time indicator"
+      disable_current_time_indicator: "Hide current time indicator"
    class_change_page:
       title: "Schedule Changes"
       empty_message: "Currently there's no class schedule changes"

assets/flutter_i18n/zh_CN.yaml

@@ -153,6 +153,8 @@ classtable:
         output_to_system: "导出到系统日历"
         refresh_classtable: "刷新日程表"
         switch_semester: "切换课程表学期"
+        enable_current_time_indicator: "显示当前时间指示条"
+        disable_current_time_indicator: "隐藏当前时间指示条"
     class_change_page:
         title: "课程调整"
         empty_message: "目前没有调课信息"

assets/flutter_i18n/zh_TW.yaml

@@ -127,6 +127,8 @@ classtable:
     output_to_system: 導出到系統日曆
     refresh_classtable: 刷新日程表
     switch_semester: 切換課程表學期
+    enable_current_time_indicator: 顯示當前時間指示條
+    disable_current_time_indicator: 隱藏當前時間指示條
   class_change_page:
     title: 課程調整
     empty_message: 目前沒有調課信息

lib/page/classtable/class_page/content_classtable_page.dart

@@ -239,6 +239,19 @@ class _ContentClassTablePageState extends State<ContentClassTablePage> {
                   ),
                 ),
               ),
+              PopupMenuItem<String>(
+                value: 'J',
+                child: Text(
+                  FlutterI18n.translate(
+                    context,
+                    preference.getBool(
+                      preference.Preference.enableCurrentTimeIndicator,
+                    )
+                        ? "classtable.popup_menu.disable_current_time_indicator"
+                        : "classtable.popup_menu.enable_current_time_indicator",
+                  ),
+                ),
+              ),
             ],
             onSelected: (String action) async {
               final box = context.findRenderObject() as RenderBox?;
@@ -485,6 +498,18 @@ class _ContentClassTablePageState extends State<ContentClassTablePage> {
                       }
                     });
                   }
+                  break;
+                case 'J':
+                  bool currentValue = preference.getBool(
+                    preference.Preference.enableCurrentTimeIndicator,
+                  );
+                  await preference.setBool(
+                    preference.Preference.enableCurrentTimeIndicator,
+                    !currentValue,
+                  );
+                  if (context.mounted) {
+                    setState(() {});
+                  }
               }
             },
           ),

lib/page/classtable/class_table_view/class_organized_data.dart

@@ -6,6 +6,7 @@
 // Removed left/right, only use stack.
 
 import 'package:flutter/material.dart';
+import 'package:watermeter/model/time_list.dart';
 import 'package:watermeter/model/xidian_ids/exam.dart';
 import 'package:watermeter/model/xidian_ids/classtable.dart';
 import 'package:watermeter/model/xidian_ids/experiment.dart';
@@ -121,7 +122,7 @@ class ClassOrgainzedData {
     this.place,
   });
 
-  static double _transferIndex(DateTime time) {
+  static double transferIndex(DateTime time) {
     int timeInMin = time.hour * 60 + time.minute;
     int previous = 0;
     // Start from the second element.
@@ -162,6 +163,46 @@ class ClassOrgainzedData {
     return 61;
   }
 
+  static double transferIndexForIndicator(DateTime time) {
+    int minutesOfDay(String value) {
+      final timeParts = value.split(":");
+      return int.parse(timeParts[0]) * 60 + int.parse(timeParts[1]);
+    }
+
+    double indexOfMinute(int value) {
+      return transferIndex(
+        DateTime(time.year, time.month, time.day, value ~/ 60, value % 60),
+      );
+    }
+
+    final timeInMin = time.hour * 60 + time.minute;
+
+    for (int i = 0; i < timeList.length; i += 2) {
+      final start = minutesOfDay(timeList[i]);
+      final stop = minutesOfDay(timeList[i + 1]);
+      final nextStart = i + 2 < timeList.length
+          ? minutesOfDay(timeList[i + 2])
+          : null;
+      final isSmallBreak = nextStart != null && nextStart - stop <= 20;
+      final visualStop = isSmallBreak ? nextStart : stop;
+
+      // During class, map the elapsed class time across the visual block including the following small break.
+      if (timeInMin >= start && timeInMin < stop) {
+        final startIndex = indexOfMinute(start);
+        final stopIndex = indexOfMinute(visualStop);
+        return startIndex +
+            (stopIndex - startIndex) * (timeInMin - start) / (stop - start);
+      }
+
+      // During a small break, show the indicator at the end of the class.
+      if (isSmallBreak && timeInMin >= stop && timeInMin < visualStop) {
+        return indexOfMinute(visualStop);
+      }
+    }
+
+    return transferIndex(time);
+  }
+
   ClassOrgainzedData._({
     required this.data,
     required DateTime start,
@@ -170,7 +211,7 @@ class ClassOrgainzedData {
     required this.name,
     this.place,
   }) {
-    this.start = _transferIndex(start);
-    this.stop = _transferIndex(stop);
+    this.start = transferIndex(start);
+    this.stop = transferIndex(stop);
   }
 }

lib/page/classtable/class_table_view/class_table_view.dart

@@ -164,19 +164,28 @@ class _ClassTableViewState extends State<ClassTableView> {
     }
   }
 
+  /// This function will be triggered every minute to refresh the time indicator.
+  void _reloadTimeIndicator() {
+    if (mounted && classTableState.currentWeek == widget.index) {
+      setState(() {});
+    }
+  }
+
   void updateSize() => size = ClassTableState.of(context)!.constraints;
 
   @override
   void didChangeDependencies() {
     super.didChangeDependencies();
     classTableState = ClassTableState.of(context)!.controllers;
     classTableState.addListener(_reload);
+    classTableState.currentTimeNotifier.addListener(_reloadTimeIndicator);
     updateSize();
   }
 
   @override
   void dispose() {
     classTableState.removeListener(_reload);
+    classTableState.currentTimeNotifier.removeListener(_reloadTimeIndicator);
     super.dispose();
   }
 
@@ -186,6 +195,31 @@ class _ClassTableViewState extends State<ClassTableView> {
     updateSize();
   }
 
+  Widget _buildCurrentTimeIndicator() {
+    if (classTableState.currentWeek != widget.index) {
+      return const SizedBox.shrink();
+    }
+    if (!preference.getBool(preference.Preference.enableCurrentTimeIndicator)) {
+      return const SizedBox.shrink();
+    }
+    // Keep the indicator correct during short breaks between classes.
+    final timeIndex = ClassOrgainzedData.transferIndexForIndicator(
+      classTableState.currentTimeNotifier.value,
+    );
+    if (timeIndex <= 0 || timeIndex >= 61) {
+      return const SizedBox.shrink();
+    }
+    return Positioned(
+      top: blockheight(timeIndex) - 1,
+      left: leftRow,
+      width: size.maxWidth - leftRow,
+      height: 2,
+      child: Container(
+        color: Theme.of(context).colorScheme.primary.withValues(alpha: 0.5),
+      ),
+    );
+  }
+
   @override
   Widget build(BuildContext context) {
     return [
@@ -208,6 +242,7 @@ class _ClassTableViewState extends State<ClassTableView> {
                 .constrained(width: leftRow)
                 .positioned(left: 0),
             ...classSubRow(true),
+            _buildCurrentTimeIndicator(),
           ]
           .toStack()
           .constrained(height: blockheight(61), width: size.maxWidth)

lib/page/classtable/classtable_state.dart

@@ -2,6 +2,7 @@
 // Copyright 2025 Traintime PDA authors.
 // SPDX-License-Identifier: MPL-2.0 OR Apache-2.0
 
+import 'dart:async';
 import 'dart:math' as math;
 
 import 'package:device_calendar/device_calendar.dart';
@@ -54,8 +55,15 @@ class ClassTableWidgetState with ChangeNotifier {
   ///*******************************************************************///
   bool _disposed = false;
 
+  /// A notifier that fires every minute with the current time.
+  final ValueNotifier<DateTime> currentTimeNotifier =
+      ValueNotifier(DateTime.now());
+  Timer? _currentTimeTimer;
+
   @override
   void dispose() {
+    _currentTimeTimer?.cancel();
+    currentTimeNotifier.dispose();
     _disposed = true;
     super.dispose();
   }
@@ -461,6 +469,9 @@ END:VTIMEZONE
     } else {
       _chosenWeek = currentWeek;
     }
+    _currentTimeTimer = Timer.periodic(const Duration(minutes: 1), (_) {
+      currentTimeNotifier.value = DateTime.now();
+    });
   }
 
   bool _checkIsOverlapping(

lib/repository/preference.dart

@@ -89,7 +89,8 @@ enum Preference {
   ), // 上次通知使用的语言
   dormWaterToken(key: "dorm_water_token", type: "String"), // 宿舍水机登录 token
   dormWaterUid(key: "dorm_water_uid", type: "String"), // 宿舍水机用户 uid
-  dormWaterEid(key: "dorm_water_eid", type: "String"); // 宿舍水机用户 eid
+  dormWaterEid(key: "dorm_water_eid", type: "String"), // 宿舍水机用户 eid
+  enableCurrentTimeIndicator(key: "enableCurrentTimeIndicator", type: "bool"); // 是否启用当前时间指示条
 
   const Preference({required this.key, this.type = "String"});