Add screen blur option

src/InvLock/BlurWindow.xaml

@@ -0,0 +1,15 @@
+<Window x:Class="InvLock.BlurWindow"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        xmlns:local="clr-namespace:InvLock"
+        mc:Ignorable="d"
+        Loaded="Window_Loaded"
+        WindowStyle="None"
+        MouseDown="Window_MouseDown"
+        AllowsTransparency="True"
+        Background="Black"
+        Opacity="0"
+        Title="BlurWindow" Height="450" Width="800">
+</Window>

src/InvLock/BlurWindow.xaml.cs

@@ -0,0 +1,26 @@
+using InvLock.Utilities;
+
+using System.Windows;
+
+namespace InvLock;
+
+/// <summary>
+/// Interaction logic for BlurWindow.xaml
+/// </summary>
+public partial class BlurWindow : Window
+{
+    public BlurWindow()
+    {
+        InitializeComponent();
+    }
+
+    private void Window_Loaded(object sender, RoutedEventArgs e)
+    {
+        WindowsApi.EnableBlur(this);
+    }
+
+    private void Window_MouseDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
+    {
+        DragMove();
+    }
+}

src/InvLock/LockWindow.xaml.cs

@@ -19,7 +19,9 @@ public partial class LockWindow : Window
     private readonly SimpleGlobalHook hook = new SimpleGlobalHook();
     private readonly Dictionary<KeyCode, DateTime> pressedKeys = [];
     private readonly Settings settings;
+    private readonly List<BlurWindow> blurWindows = [];
     private List<IntPtr> windows = [];
+    private Point lastMousePosition;
     private bool isOpen = true;
     private bool suppressInput = false;
 
@@ -120,11 +122,32 @@ public partial class LockWindow : Window
             MinimizeWindows();
         }
 
-        isOpen = true;
-        suppressInput = true;
-
         Dispatcher.Invoke(() =>
         {
+            lastMousePosition = WpfScreenHelper.MouseHelper.MousePosition;
+
+            if (settings.BlurScreen)
+            {
+                foreach (Rect bounds in WpfScreenHelper.Screen.AllScreens.Select(s => s.WpfBounds))
+                {
+                    BlurWindow blurWindow = new()
+                    {
+                        Width = bounds.Width,
+                        Height = bounds.Height,
+                        Left = bounds.Left,
+                        Top = bounds.Top,
+                    };
+
+                    blurWindows.Add(blurWindow);
+                    blurWindow.Show();
+                }
+
+                _ = WindowsApi.SetCursorPosition(new Point(100000, 100000));
+            }
+
+            isOpen = true;
+            suppressInput = true;
+
             _ = Activate();
 
             textBlock.Text = settings.LockText;
@@ -155,6 +178,9 @@ public partial class LockWindow : Window
 
                 isOpen = true;
 
+                _ = WindowsApi.SetCursorPosition(lastMousePosition);
+                blurWindows.ForEach(w => w.Close());
+
                 textBlock.Text = settings.UnlockText;
                 textBlock.Stroke = (Brush)FindResource("PaletteGreenBrush");
 
@@ -203,6 +229,9 @@ public partial class LockWindow : Window
 
             isOpen = true;
 
+            _ = WindowsApi.SetCursorPosition(lastMousePosition);
+            blurWindows.ForEach(w => w.Close());
+
             _ = Activate();
 
             await Task.Delay(500);

src/InvLock/MainWindow.xaml

@@ -79,6 +79,20 @@
                     </ComboBox>
                 </ui:CardControl>
 
+                <ui:CardControl Margin="0,0,0,12" Icon="{ui:SymbolIcon Symbol=Clock24}" Height="75">
+                    <ui:CardControl.Header>
+                        <Grid>
+                            <Grid.RowDefinitions>
+                                <RowDefinition Height="Auto" />
+                                <RowDefinition Height="Auto" />
+                            </Grid.RowDefinitions>
+                            <ui:TextBlock Grid.Row="0" FontTypography="Body" Text="Run at startup" />
+                            <ui:TextBlock Grid.Row="1" Foreground="{ui:ThemeResource TextFillColorTertiaryBrush}" FontSize="12" Text="Start InvLock when you sign in to Windows" />
+                        </Grid>
+                    </ui:CardControl.Header>
+                    <ui:ToggleSwitch Grid.Column="1" IsChecked="{Binding IsAutoStartEnabled}" OffContent="Off" OnContent="On" />
+                </ui:CardControl>
+
                 <ui:CardControl Margin="0,0,0,12" Icon="{ui:SymbolIcon Symbol=Window24}" Height="75">
                     <ui:CardControl.Header>
                         <ui:TextBlock Grid.Row="0" FontTypography="Body" Text="Show desktop while locked" />
@@ -86,6 +100,13 @@
                     <ui:ToggleSwitch Grid.Column="1" IsChecked="{Binding Settings.HideWindows}" OffContent="Off" OnContent="On" />
                 </ui:CardControl>
 
+                <ui:CardControl Margin="0,0,0,12" Icon="{ui:SymbolIcon Symbol=Blur24}" Height="75">
+                    <ui:CardControl.Header>
+                        <ui:TextBlock Grid.Row="0" FontTypography="Body" Text="Blur screen while locked" />
+                    </ui:CardControl.Header>
+                    <ui:ToggleSwitch Grid.Column="1" IsChecked="{Binding Settings.BlurScreen}" OffContent="Off" OnContent="On" />
+                </ui:CardControl>
+
                 <ui:CardControl Margin="0,0,0,12" Icon="{ui:SymbolIcon Symbol=WindowShield24}" Height="75">
                     <ui:CardControl.Header>
                         <ui:TextBlock Grid.Row="0" FontTypography="Body" Text="Use windows lock screen to unlock" />

src/InvLock/Settings.cs

@@ -17,6 +17,7 @@ public class Settings : INotifyPropertyChanged
     private static readonly string settingsPath = Path.Combine(App.ApplicationDataPath, "settings.json");
     private bool useWindowsLockScreen = true;
     private bool hideWindows = false;
+    private bool blurScreen = false;
     private string lockText = "Lock Screen Active";
     private string theme = "Windows default";
     private HashSet<KeyCode> lockShortcut = [KeyCode.VcLeftControl, KeyCode.VcLeftShift, KeyCode.VcL];
@@ -34,6 +35,16 @@ public class Settings : INotifyPropertyChanged
         }
     }
 
+    public bool BlurScreen
+    {
+        get => blurScreen;
+        set
+        {
+            blurScreen = value;
+            OnPropertyChanged();
+        }
+    }
+
     public bool UseWindowsLockScreen
     {
         get => useWindowsLockScreen;

src/InvLock/Utilities/WindowsApi.cs

@@ -1,6 +1,8 @@
 using System.Diagnostics;
 using System.Runtime.InteropServices;
 using System.Text;
+using System.Windows;
+using System.Windows.Interop;
 
 namespace InvLock.Utilities;
 
@@ -70,12 +72,46 @@ public static class WindowsApi
         _ = ShowWindow(hWnd, show ? SW_SHOW : SW_HIDE);
     }
 
+    public static bool SetCursorPosition(Point point)
+    {
+        return SetCursorPos((int)point.X, (int)point.Y);
+    }
+
+    public static void EnableBlur(Window window)
+    {
+        WindowInteropHelper windowHelper = new WindowInteropHelper(window);
+
+        AccentPolicy accent = new AccentPolicy
+        {
+            AccentState = AccentState.ACCENT_ENABLE_BLURBEHIND
+        };
+
+        int accentStructSize = Marshal.SizeOf(accent);
+
+        nint accentPtr = Marshal.AllocHGlobal(accentStructSize);
+        Marshal.StructureToPtr(accent, accentPtr, false);
+
+        WindowCompositionAttributeData data = new WindowCompositionAttributeData
+        {
+            Attribute = WindowCompositionAttribute.WCA_ACCENT_POLICY,
+            SizeOfData = accentStructSize,
+            Data = accentPtr
+        };
+
+        _ = SetWindowCompositionAttribute(windowHelper.Handle, ref data);
+
+        Marshal.FreeHGlobal(accentPtr);
+    }
+
     [DllImport("user32.dll")]
     internal static extern bool LockWorkStation();
 
     [DllImport("user32.dll")]
     internal static extern bool ShowWindow(IntPtr hWnd, int nCmdShow);
 
+    [DllImport("user32.dll")]
+    internal static extern int SetWindowCompositionAttribute(IntPtr hwnd, ref WindowCompositionAttributeData data);
+
     [DllImport("user32.dll")]
     private static extern bool EnumWindows(EnumWindowsProc enumFunc, int lParam);
 
@@ -102,4 +138,41 @@ public static class WindowsApi
 
     [DllImport("user32.dll")]
     private static extern bool IsIconic(IntPtr hWnd);
+
+    [DllImport("user32.dll")]
+    private static extern bool SetCursorPos(int x, int y);
+
+    internal enum AccentState
+    {
+        ACCENT_DISABLED = 1,
+        ACCENT_ENABLE_GRADIENT = 0,
+        ACCENT_ENABLE_TRANSPARENTGRADIENT = 2,
+        ACCENT_ENABLE_BLURBEHIND = 3,
+        ACCENT_INVALID_STATE = 4
+    }
+
+    internal enum WindowCompositionAttribute
+    {
+        // ...
+        WCA_ACCENT_POLICY = 19
+
+        // ...
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    internal struct AccentPolicy
+    {
+        public AccentState AccentState;
+        public int AccentFlags;
+        public int GradientColor;
+        public int AnimationId;
+    }
+
+    [StructLayout(LayoutKind.Sequential)]
+    internal struct WindowCompositionAttributeData
+    {
+        public WindowCompositionAttribute Attribute;
+        public IntPtr Data;
+        public int SizeOfData;
+    }
 }