Bug fix related to closing windows

MainWindow.xaml.cs

@@ -26,23 +26,35 @@ namespace IPClab1;
 public sealed partial class MainWindow : Window
 {
     private readonly DispatcherTimer timer = new() { Interval = TimeSpan.FromMilliseconds(100) };
+    private bool IsClosed;
 
     public MainWindowViewModel ViewModel;
     public MainWindow(MainWindowViewModel viewModel)
     {
         InitializeComponent();
+
+        IsClosed = false;
+        Closed += MainWindow_Closed;
+
         ViewModel = viewModel;
+
         ExtendsContentIntoTitleBar = true;
         SetTitleBar(AppTitleBar);
+
         timer.Tick += Timer_Tick;
         timer.Start();
     }
 
+    private void MainWindow_Closed(object sender, WindowEventArgs args) => IsClosed = true;
+
     private void Timer_Tick(object? sender, object e)
+    {
+        if (!IsClosed)
         {
             AppTitleBar.Title = Title;
             ViewModel.RefreshInfo();
         }
+    }
 
     private void GridView_SizeChanged(object sender, SizeChangedEventArgs e)
     {

Properties/AssemblyInfo.cs

@@ -0,0 +1 @@
+[assembly: System.Runtime.CompilerServices.DisableRuntimeMarshalling]

Services/WindowInteractionService.cs

@@ -8,7 +8,7 @@ using IPClab1.Enums;
 
 namespace IPClab1.Services;
 
-public class WindowInteractionService
+public partial class WindowInteractionService
 {
     private const uint WM_MOUSEMOVE = 0x0200;
     private const uint WM_LBUTTONDOWN = 0x0201;
@@ -21,22 +21,22 @@ public class WindowInteractionService
     private const int SC_MAXIMIZE = 0xF030;
     private const int SC_RESTORE = 0xF120;
 
-    [DllImport("user32.dll", CharSet = CharSet.Auto)]
-    private static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, string lParam);
+    [LibraryImport("user32.dll", StringMarshalling = StringMarshalling.Utf16)]
+    private static partial IntPtr SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, string lParam);
 
-    [DllImport("user32.dll", CharSet = CharSet.Auto)]
-    private static extern bool PostMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);
-    // 1. Get Class Name
-    [DllImport("user32.dll", SetLastError = true, CharSet = CharSet.Auto)]
-    private static extern int GetClassName(IntPtr hWnd, StringBuilder lpClassName, int nMaxCount);
+    [LibraryImport("user32.dll", EntryPoint = "PostMessageW")]
+    [return: MarshalAs(UnmanagedType.Bool)]
+    private static partial bool PostMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);
 
-    // 2. Get Geometry
-    [DllImport("user32.dll", SetLastError = true)]
-    private static extern bool GetWindowRect(IntPtr hWnd, out RECT lpRect);
+    [LibraryImport("user32.dll", EntryPoint = "GetClassNameW", SetLastError = true)]
+    private static partial int GetClassName(IntPtr hWnd, [Out] char[] lpClassName, int nMaxCount);
 
-    // 3. Get Parent
-    [DllImport("user32.dll", ExactSpelling = true, CharSet = CharSet.Auto)]
-    private static extern IntPtr GetParent(IntPtr hWnd);
+    [LibraryImport("user32.dll", SetLastError = true)]
+    [return: MarshalAs(UnmanagedType.Bool)]
+    private static partial bool GetWindowRect(IntPtr hWnd, out RECT lpRect);
+
+    [LibraryImport("user32.dll")]
+    private static partial IntPtr GetParent(IntPtr hWnd);
 
     public void SimulateClick(IntPtr hwnd, int x, int y)
     {
@@ -81,9 +81,9 @@ public class WindowInteractionService
 
     public string GetWindowDetails(IntPtr hwnd)
     {
-        StringBuilder classNameBuffer = new StringBuilder(256);
-        GetClassName(hwnd, classNameBuffer, classNameBuffer.Capacity);
-        string className = classNameBuffer.ToString();
+        char[] classNameBuffer = new char[256];
+        int length = GetClassName(hwnd, classNameBuffer, classNameBuffer.Length);
+        string className = length > 0 ? new string(classNameBuffer, 0, length) : string.Empty;
 
         GetWindowRect(hwnd, out RECT rect);
 

Services/WindowListService.cs

@@ -13,7 +13,7 @@ using Windows.Graphics.Imaging;
 
 namespace IPClab1.Services;
 
-public class WindowListService
+public partial class WindowListService
 {
     #region Win32 P/Invoke Declarations
 
@@ -27,34 +27,34 @@ public class WindowListService
 
     private delegate bool EnumWindowsProc(IntPtr hWnd, IntPtr lParam);
 
-    [DllImport("user32.dll")]
+    [LibraryImport("user32.dll")]
     [return: MarshalAs(UnmanagedType.Bool)]
-    private static extern bool EnumWindows(EnumWindowsProc lpEnumFunc, IntPtr lParam);
+    private static partial bool EnumWindows(EnumWindowsProc lpEnumFunc, IntPtr lParam);
 
-    [DllImport("user32.dll")]
+    [LibraryImport("user32.dll")]
     [return: MarshalAs(UnmanagedType.Bool)]
-    private static extern bool IsWindowVisible(IntPtr hWnd);
+    private static partial bool IsWindowVisible(IntPtr hWnd);
 
-    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
-    private static extern int GetWindowText(IntPtr hWnd, StringBuilder lpString, int nMaxCount);
+    [LibraryImport("user32.dll", EntryPoint = "GetWindowTextW", SetLastError = true)]
+    private static partial int GetWindowText(IntPtr hWnd, [Out] char[] lpString, int nMaxCount);
 
-    [DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
-    private static extern int GetWindowTextLength(IntPtr hWnd);
+    [LibraryImport("user32.dll", EntryPoint = "GetWindowTextLengthW", SetLastError = true)]
+    private static partial int GetWindowTextLength(IntPtr hWnd);
 
-    [DllImport("user32.dll", CharSet = CharSet.Auto)]
-    private static extern IntPtr SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);
+    [LibraryImport("user32.dll", EntryPoint = "SendMessageW")]
+    private static partial IntPtr SendMessage(IntPtr hWnd, uint Msg, IntPtr wParam, IntPtr lParam);
 
-    [DllImport("user32.dll", EntryPoint = "GetClassLongPtr", CharSet = CharSet.Auto)]
-    private static extern IntPtr GetClassLongPtr64(IntPtr hWnd, int nIndex);
+    [LibraryImport("user32.dll", EntryPoint = "GetClassLongPtrW")]
+    private static partial IntPtr GetClassLongPtr64(IntPtr hWnd, int nIndex);
 
-    [DllImport("user32.dll", EntryPoint = "GetClassLong", CharSet = CharSet.Auto)]
-    private static extern uint GetClassLong32(IntPtr hWnd, int nIndex);
+    [LibraryImport("user32.dll", EntryPoint = "GetClassLongW")]
+    private static partial uint GetClassLong32(IntPtr hWnd, int nIndex);
 
-    [DllImport("user32.dll", SetLastError = true)]
-    private static extern uint GetWindowThreadProcessId(IntPtr hWnd, out uint lpdwProcessId);
+    [LibraryImport("user32.dll", SetLastError = true)]
+    private static partial uint GetWindowThreadProcessId(IntPtr hWnd, out uint lpdwProcessId);
 
-    [DllImport("shell32.dll", CharSet = CharSet.Auto)]
-    private static extern IntPtr ExtractIcon(IntPtr hInst, string lpszExeFileName, int nIconIndex);
+    [LibraryImport("shell32.dll", EntryPoint = "ExtractIconW", StringMarshalling = StringMarshalling.Utf16)]
+    private static partial IntPtr ExtractIcon(IntPtr hInst, string lpszExeFileName, int nIconIndex);
 
     private IntPtr GetClassLongPtr(IntPtr hWnd, int nIndex)
     {
@@ -85,13 +85,14 @@ public class WindowListService
         foreach (var hWnd in handles)
         {
             // Fetch window text title cleanly
-            int length = GetWindowTextLength(hWnd);
-            var builder = new StringBuilder(length + 1);
-            GetWindowText(hWnd, builder, builder.Capacity);
-            string title = builder.ToString();
+            var length = GetWindowTextLength(hWnd);
+            var titleBuffer = new char[length + 1];
+
+            var actualLength = GetWindowText(hWnd, titleBuffer, titleBuffer.Length);
+            var title = actualLength > 0 ? new string(titleBuffer, 0, actualLength) : string.Empty;
 
             // Fetch numeric process identifier
-            GetWindowThreadProcessId(hWnd, out uint processId);
+            GetWindowThreadProcessId(hWnd, out var processId);
 
             // Fetch and map the icon image synchronously/asynchronously into WinUI structures
             SoftwareBitmapSource iconSource = await GetWinUi3IconAsync(hWnd);
@@ -110,7 +111,7 @@ public class WindowListService
 
     private Icon GetIconFromHwnd(IntPtr hWnd)
     {
-        IntPtr hIcon = SendMessage(hWnd, WM_GETICON, ICON_BIG, IntPtr.Zero);
+        var hIcon = SendMessage(hWnd, WM_GETICON, ICON_BIG, IntPtr.Zero);
 
         if (hIcon == IntPtr.Zero)
             hIcon = SendMessage(hWnd, WM_GETICON, ICON_SMALL2, IntPtr.Zero);

ViewModels/MainWindowViewModel.cs

@@ -48,6 +48,7 @@ public partial class MainWindowViewModel(WindowListService windowListService, Wi
 
     partial void OnSelectedWindowChanged(WindowInfo value)
     {
+        if (value != null) 
             (Width, Height) = _windowInteractionService.GetWindowSize(value.Hwnd);
     }