refactor(homepage): add tab state persistence and fix multiple issues

- auto run decode/format action when page loads with non-empty input
- add null check for process main module in settings page
- reduce balloon tip display time for API server startup
- add tab selection state save/restore functionality
- fix nullable warning for selected tab variable

Author: sunquakes

CHANGELOG.md

@@ -4,6 +4,25 @@ All notable changes to this project will be documented in this file.
 
 ---
 
+## [2.3.1] - 2026-07-06
+
+### Added
+- **Tab State Persistence** - Return to previously selected tab after navigating back from a tool
+- **Auto-Execute on Entry** - Automatically process content when entering pages
+  - Base64 to Image: auto-generates image if textbox contains content
+  - JSON Format: auto-formats if textbox contains content
+
+### Changed
+- **Notification Duration** - Reduced popup notification time from 3 seconds to 1 second
+
+### Fixed
+- **Compilation Warnings** - Resolved null reference warnings in multiple pages
+  - HomePage: nullable type annotations for TabItem variables
+  - Base64ImagePage/JsonFormatPage: named parameters for null arguments
+  - SettingsPage: null check for MainModule before accessing
+
+---
+
 ## [2.3.0] - 2026-06-25
 
 ### Added

MainWindow.xaml.cs

@@ -130,7 +130,7 @@ private void InitializeNotifyIcon()
 
             if (_apiServerEnabled)
             {
-                _notifyIcon.ShowBalloonTip(3000, "Toolbox", "API Server starting...", ToolTipIcon.Info);
+                _notifyIcon.ShowBalloonTip(1000, "Toolbox", "API Server starting...", ToolTipIcon.Info);
             }
         }
 
@@ -155,7 +155,7 @@ private async void InitializeApiServer()
                 {
                     if (_notifyIcon != null)
                     {
-                        _notifyIcon.ShowBalloonTip(3000, "Toolbox", $"API Server started on port {port}", ToolTipIcon.Info);
+                        _notifyIcon.ShowBalloonTip(1000, "Toolbox", $"API Server started on port {port}", ToolTipIcon.Info);
                     }
                 }
                 else

Pages/Base64ImagePage.xaml.cs

@@ -57,6 +57,10 @@ private void LoadState()
             {
                 InputText.Text = state.GetValueOrDefault("InputText", string.Empty);
             }
+            if (!string.IsNullOrWhiteSpace(InputText.Text))
+            {
+                Decode_Click(sender: null, e: null);
+            }
         }
 
         private void Decode_Click(object sender, RoutedEventArgs e)

Pages/HomePage.xaml

@@ -158,8 +158,8 @@
                  IsUndoEnabled="True"
                  UndoLimit="20"/>
 
-        <TabControl Style="{StaticResource ModernTabControl}" 
-                    Margin="20,60,20,20">
+        <TabControl x:Name="MainTabControl" Style="{StaticResource ModernTabControl}" 
+                    Margin="20,60,20,20" SelectionChanged="MainTabControl_SelectionChanged">
 
             <!-- 编码工具 -->
             <TabItem Header="{x:Static resources:Strings.CategoryEncoding}" Tag="&#xf121;" Style="{StaticResource ModernTabItem}">

Pages/HomePage.xaml.cs

@@ -5,6 +5,7 @@
 using System.Windows.Media;
 using System.Windows.Media.Media3D;
 using System.Windows.Threading;
+using DevTools.Helpers;
 
 namespace DevTools.Pages
 {
@@ -19,13 +20,36 @@ public HomePage()
             // Initialize search debounce timer
             _searchTimer = new System.Windows.Threading.DispatcherTimer
             {
-                Interval = TimeSpan.FromMilliseconds(300) // 300ms delay
+                Interval = TimeSpan.FromMilliseconds(300)
             };
             _searchTimer.Tick += (s, e) =>
             {
                 _searchTimer.Stop();
                 FilterTools(SearchBox.Text);
             };
+
+            LoadTabState();
+        }
+
+        private void LoadTabState()
+        {
+            var state = PageStateManager.GetPageState(this);
+            if (state != null && state.TryGetValue("SelectedTabIndex", out var indexStr) && int.TryParse(indexStr, out var index))
+            {
+                if (index >= 0 && index < MainTabControl.Items.Count)
+                {
+                    MainTabControl.SelectedIndex = index;
+                }
+            }
+        }
+
+        private void MainTabControl_SelectionChanged(object sender, SelectionChangedEventArgs e)
+        {
+            var state = new Dictionary<string, string>
+            {
+                { "SelectedTabIndex", MainTabControl.SelectedIndex.ToString() }
+            };
+            PageStateManager.SavePageState(this, state);
         }
 
         private void BtnMd5_Click(object sender, RoutedEventArgs e)
@@ -121,7 +145,7 @@ private void FilterTools(string searchText)
 
             // Get TabControl and current selected tab first
             var tabControl = FindVisualChildren<System.Windows.Controls.TabControl>(this).FirstOrDefault();
-            TabItem currentSelectedTab = tabControl?.SelectedItem as TabItem;
+            var currentSelectedTab = tabControl?.SelectedItem as TabItem;
 
             // Filter buttons in all tabs
             var allButtons = FindVisualChildren<System.Windows.Controls.Button>(this);
@@ -142,8 +166,8 @@ private void FilterTools(string searchText)
             }
 
             // Filter tabs and find first visible tab
-            var allTabs = FindVisualChildren<TabItem>(this);
-            TabItem firstVisibleTab = null;
+            var allTabs = FindVisualChildren<TabItem>(this).ToList();
+            TabItem? firstVisibleTab = null;
 
             foreach (var tab in allTabs)
             {

Pages/JsonFormatPage.xaml.cs

@@ -53,6 +53,10 @@ private void LoadState()
                 InputText.Text = state.GetValueOrDefault("InputText", string.Empty);
                 _lastFormattedJson = state.GetValueOrDefault("LastFormattedJson", string.Empty);
             }
+            if (!string.IsNullOrWhiteSpace(InputText.Text))
+            {
+                Format_Click(sender: null, e: null);
+            }
         }
 
         private async void Format_Click(object sender, RoutedEventArgs e)

Pages/SettingsPage.xaml.cs

@@ -98,8 +98,11 @@ private void LanguageComboBox_SelectionChanged(object sender, SelectionChangedEv
 
                 // Restart to apply changes
                     var currentProcess = System.Diagnostics.Process.GetCurrentProcess();
-                    var startInfo = new System.Diagnostics.ProcessStartInfo(currentProcess.MainModule.FileName);
-                    System.Diagnostics.Process.Start(startInfo);
+                    if (currentProcess.MainModule != null)
+                    {
+                        var startInfo = new System.Diagnostics.ProcessStartInfo(currentProcess.MainModule.FileName);
+                        System.Diagnostics.Process.Start(startInfo);
+                    }
                     Application.Current.Shutdown();
                 }
             }