From 81a46327223596a9cff55bd8ad4e1b332237d997 Mon Sep 17 00:00:00 2001
From: Yusyuriv <Yusyuriv@users.noreply.github.com>
Date: Sat, 22 Mar 2025 00:27:03 +0600
Subject: [PATCH] Implement auto-switching to English when the option is
 enabled

---
 Flow.Launcher/Helper/KeyboardLayoutHelper.cs | 95 ++++++++++++++++++++
 Flow.Launcher/ViewModel/MainViewModel.cs     | 13 ++-
 2 files changed, 107 insertions(+), 1 deletion(-)
 create mode 100644 Flow.Launcher/Helper/KeyboardLayoutHelper.cs

diff --git a/Flow.Launcher/Helper/KeyboardLayoutHelper.cs b/Flow.Launcher/Helper/KeyboardLayoutHelper.cs
new file mode 100644
index 000000000..db62ef783
--- /dev/null
+++ b/Flow.Launcher/Helper/KeyboardLayoutHelper.cs
@@ -0,0 +1,95 @@
+using System;
+using System.Runtime.InteropServices;
+using System.Text;
+
+namespace Flow.Launcher.Helper;
+
+public static class KeyboardLayoutHelper
+{
+    #region Windows API
+
+    [DllImport("user32.dll")]
+    private static extern IntPtr GetKeyboardLayout(uint idThread);
+
+    [DllImport("user32.dll")]
+    private static extern uint GetWindowThreadProcessId(IntPtr hWnd, IntPtr lpdwProcessId);
+
+    [DllImport("user32.dll")]
+    private static extern IntPtr ActivateKeyboardLayout(IntPtr hkl, uint flags);
+
+    [DllImport("user32.dll")]
+    private static extern int GetKeyboardLayoutList(int nBuff, [Out] IntPtr[] lpList);
+
+    [DllImport("kernel32.dll")]
+    private static extern int GetLocaleInfoA(uint Locale, uint LCType, StringBuilder lpLCData, int cchData);
+
+    [DllImport("user32.dll")]
+    private static extern IntPtr GetForegroundWindow();
+
+    // Used to get the language name of the keyboard layout
+    private const uint LOCALE_SLANGUAGE = 0x00000002;
+
+    // The string to search for in the language name of a keyboard layout
+    private const string LAYOUT_ENGLISH_SEARCH = "english";
+
+    private static IntPtr FindEnglishKeyboardLayout()
+    {
+        // Get the number of keyboard layouts
+        var count = GetKeyboardLayoutList(0, null);
+        if (count <= 0) return IntPtr.Zero;
+
+        // Get all keyboard layouts
+        var keyboardLayouts = new IntPtr[count];
+        GetKeyboardLayoutList(count, keyboardLayouts);
+
+        // Look for any English keyboard layout
+        foreach (var layout in keyboardLayouts)
+        {
+            // The lower word contains the language identifier
+            var langId = (uint)layout.ToInt32() & 0xFFFF;
+
+            // Get language name for the layout
+            var sb = new StringBuilder(256);
+            GetLocaleInfoA(langId, LOCALE_SLANGUAGE, sb, sb.Capacity);
+            var langName = sb.ToString().ToLowerInvariant();
+
+            // Check if it's an English layout
+            if (langName.Contains(LAYOUT_ENGLISH_SEARCH))
+            {
+                return layout;
+            }
+        }
+
+        return IntPtr.Zero;
+    }
+
+    #endregion
+
+    // Query textbox keyboard layout
+    private static IntPtr _previousLayout;
+
+    public static void SetEnglishKeyboardLayout()
+    {
+        // Find an installed English layout
+        var englishLayout = FindEnglishKeyboardLayout();
+
+        // No installed English layout found
+        if (englishLayout == IntPtr.Zero) return;
+
+        var hwnd = GetForegroundWindow();
+        var threadId = GetWindowThreadProcessId(hwnd, IntPtr.Zero);
+
+        // Store current keyboard layout
+        _previousLayout = GetKeyboardLayout(threadId) & 0xFFFF;
+
+        // Switch to English layout
+        ActivateKeyboardLayout(englishLayout, 0);
+    }
+
+    public static void SetPreviousKeyboardLayout()
+    {
+        if (_previousLayout == IntPtr.Zero) return;
+        ActivateKeyboardLayout(_previousLayout, 0);
+        _previousLayout = IntPtr.Zero;
+    }
+}
diff --git a/Flow.Launcher/ViewModel/MainViewModel.cs b/Flow.Launcher/ViewModel/MainViewModel.cs
index 46970a6a1..641825ec6 100644
--- a/Flow.Launcher/ViewModel/MainViewModel.cs
+++ b/Flow.Launcher/ViewModel/MainViewModel.cs
@@ -14,6 +14,7 @@ using System.Windows.Threading;
 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;
@@ -1373,6 +1374,11 @@ namespace Flow.Launcher.ViewModel
                 MainWindowOpacity = 1;
                 MainWindowVisibilityStatus = true;
                 VisibilityChanged?.Invoke(this, new VisibilityChangedEventArgs { IsVisible = true });
+
+                if (StartWithEnglishMode)
+                {
+                    KeyboardLayoutHelper.SetEnglishKeyboardLayout();
+                }
             });
         }
 
@@ -1441,7 +1447,12 @@ namespace Flow.Launcher.ViewModel
                 // 📌 Apply DWM Cloak (Completely hide the window)
                 Win32Helper.DWMSetCloakForWindow(mainWindow, true);
             }
-            
+
+            if (StartWithEnglishMode)
+            {
+                KeyboardLayoutHelper.SetPreviousKeyboardLayout();
+            }
+
             await Task.Delay(50);
 
             // Update WPF properties