Use PInvoke instead of DllImport & Several adjustments

Author: Jack251970

Flow.Launcher.Infrastructure/NativeMethods.txt

@@ -46,4 +46,9 @@ GetMonitorInfo
 MONITORINFOEXW
 
 WM_ENTERSIZEMOVE
-WM_EXITSIZEMOVE
+WM_EXITSIZEMOVE
+
+GetKeyboardLayout
+GetWindowThreadProcessId
+ActivateKeyboardLayout
+GetKeyboardLayoutList

Flow.Launcher.Infrastructure/Win32Helper.cs

@@ -1,14 +1,17 @@
 using System;
 using System.ComponentModel;
+using System.Linq;
 using System.Runtime.InteropServices;
 using System.Windows;
 using System.Windows.Interop;
 using System.Windows.Media;
 using Windows.Win32;
 using Windows.Win32.Foundation;
 using Windows.Win32.Graphics.Dwm;
+using Windows.Win32.UI.Input.KeyboardAndMouse;
 using Windows.Win32.UI.WindowsAndMessaging;
 using Flow.Launcher.Infrastructure.UserSettings;
+using Point = System.Windows.Point;
 
 namespace Flow.Launcher.Infrastructure
 {
@@ -317,5 +320,81 @@ internal static HWND GetWindowHandle(Window window, bool ensure = false)
         }
 
         #endregion
+
+        #region Keyboard Layout
+
+        // https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-lcid/70feba9f-294e-491e-b6eb-56532684c37f
+        private static readonly uint[] EnglishLanguageIds =
+        {
+            0x0009, 0x0409, 0x0809, 0x0C09, 0x1000, 0x1009, 0x1409, 0x1809, 0x1C09, 0x2009, 0x2409, 0x2809, 0x2C09,
+            0x3009, 0x3409, 0x3C09, 0x4009, 0x4409, 0x4809, 0x4C09,
+        };
+
+        // Store the previous keyboard layout
+        private static HKL _previousLayout;
+
+        private static unsafe HKL FindEnglishKeyboardLayout()
+        {
+            // Get the number of keyboard layouts
+            int count = PInvoke.GetKeyboardLayoutList(0, null);
+            if (count <= 0) return HKL.Null;
+
+            // Get all keyboard layouts
+            var handles = new HKL[count];
+            fixed (HKL* h = handles)
+            {
+                _ = PInvoke.GetKeyboardLayoutList(count, h);
+            }
+
+            // Look for any English keyboard layout
+            foreach (var hkl in handles)
+            {
+                // The lower word contains the language identifier
+                var langId = (uint)hkl.Value & 0xFFFF;
+
+                // Check if it's an English layout
+                if (EnglishLanguageIds.Contains(langId))
+                {
+                    return hkl;
+                }
+            }
+
+            return HKL.Null;
+        }
+
+        public static unsafe void SetEnglishKeyboardLayout(bool backupPrevious)
+        {
+            // Find an installed English layout
+            var enHKL = FindEnglishKeyboardLayout();
+
+            // No installed English layout found
+            if (enHKL == HKL.Null) return;
+
+            // Get the current window thread ID
+            uint threadId = 0;
+            var result = PInvoke.GetWindowThreadProcessId(PInvoke.GetForegroundWindow(), &threadId);
+            if (result == 0 || threadId == 0) throw new Win32Exception(Marshal.GetLastWin32Error());
+
+            // Backup current keyboard layout
+            if (backupPrevious)
+            {
+                _previousLayout = PInvoke.GetKeyboardLayout(threadId);
+            }
+
+            // Switch to English layout
+            PInvoke.ActivateKeyboardLayout(enHKL, 0);
+        }
+
+        public static void SetPreviousKeyboardLayout()
+        {
+            if (_previousLayout != HKL.Null)
+            {
+                PInvoke.ActivateKeyboardLayout(_previousLayout, 0);
+
+                _previousLayout = HKL.Null;
+            }
+        }
+
+        #endregion
     }
 }

Flow.Launcher/Helper/KeyboardLayoutHelper.cs

@@ -14,7 +14,6 @@
 using CommunityToolkit.Mvvm.DependencyInjection;
 using CommunityToolkit.Mvvm.Input;
 using Flow.Launcher.Core.Plugin;
-using Flow.Launcher.Helper;
 using Flow.Launcher.Infrastructure;
 using Flow.Launcher.Infrastructure.Hotkey;
 using Flow.Launcher.Infrastructure.Image;
@@ -1377,7 +1376,7 @@ public void Show()
 
                 if (StartWithEnglishMode)
                 {
-                    KeyboardLayoutHelper.SetEnglishKeyboardLayout();
+                    Win32Helper.SetEnglishKeyboardLayout(true);
                 }
             });
         }
@@ -1450,7 +1449,7 @@ public async void Hide()
 
             if (StartWithEnglishMode)
             {
-                KeyboardLayoutHelper.SetPreviousKeyboardLayout();
+                Win32Helper.SetPreviousKeyboardLayout();
             }
 
             await Task.Delay(50);