From fb2033aa7a91c727d806be9d590a7c60330bbffd Mon Sep 17 00:00:00 2001
From: Alex Maitland <amaitland@users.noreply.github.com>
Date: Thu, 16 Mar 2023 13:17:17 +1000
Subject: [PATCH] WPF - Use WpfImeKeyboardHandler for supported
 KeyboardLayoutIds

---
 CefSharp.Wpf/ChromiumWebBrowser.cs            | 55 ++++++++++++++++++-
 .../Experimental/WpfIMEKeyboardHandler.cs     | 22 +++++++-
 2 files changed, 75 insertions(+), 2 deletions(-)

diff --git a/CefSharp.Wpf/ChromiumWebBrowser.cs b/CefSharp.Wpf/ChromiumWebBrowser.cs
index b7a2f8cd00..325332ec9b 100644
--- a/CefSharp.Wpf/ChromiumWebBrowser.cs
+++ b/CefSharp.Wpf/ChromiumWebBrowser.cs
@@ -608,7 +608,7 @@ private void NoInliningConstructor()
 
             browserSettings = Core.ObjectFactory.CreateBrowserSettings(autoDispose: true);
 
-            WpfKeyboardHandler = new WpfKeyboardHandler(this);
+            SetupWpfKeyboardHandler();
 
             PresentationSource.AddSourceChangedHandler(this, PresentationSourceChangedHandler);
 
@@ -753,6 +753,13 @@ private void InternalDispose(bool disposing)
                 // is called.
                 LifeSpanHandler = null;
 
+                var inputLangManager = InputLanguageManager.Current;
+
+                if (inputLangManager != null)
+                { 
+                    inputLangManager.InputLanguageChanged -= OnInputLangageChanged;
+                }
+
                 WpfKeyboardHandler?.Dispose();
                 WpfKeyboardHandler = null;
 
@@ -769,6 +776,32 @@ private void InternalDispose(bool disposing)
             Cef.RemoveDisposable(this);
         }
 
+        private void SetupWpfKeyboardHandler()
+        {
+            try
+            {
+                var inputLang = InputLanguageManager.Current.CurrentInputLanguage;
+
+                var useImeKeyboardHandler = WpfImeKeyboardHandler.UseImeKeyboardHandler(inputLang.KeyboardLayoutId);
+
+                if (useImeKeyboardHandler)
+                {
+                    WpfKeyboardHandler = new WpfImeKeyboardHandler(this);
+                }
+                else
+                {
+                    InputLanguageManager.Current.InputLanguageChanged += OnInputLangageChanged;
+
+                    WpfKeyboardHandler = new WpfKeyboardHandler(this);
+                }
+            }
+            catch (Exception)
+            {
+                // For now we'll ignore any errors and just use the default keyboard handler
+                WpfKeyboardHandler = new WpfKeyboardHandler(this);
+            }
+        }
+
         /// <summary>
         /// Gets the ScreenInfo - currently used to get the DPI scale factor.
         /// </summary>
@@ -1719,6 +1752,26 @@ private void OnDragEnter(object sender, DragEventArgs e)
             }
         }
 
+        private void OnInputLangageChanged(object sender, InputLanguageEventArgs e)
+        {
+            // If we are already using the WpfImeKeyboardHandler then we'll ignore any changes
+            if (WpfKeyboardHandler?.GetType() == typeof(WpfImeKeyboardHandler))
+            {
+                return;
+            }
+
+            var useImeKeyboardHandler = WpfImeKeyboardHandler.UseImeKeyboardHandler(e.NewLanguage.KeyboardLayoutId);
+
+            if (useImeKeyboardHandler)
+            {
+                var oldKeyboardHandler = WpfKeyboardHandler;
+                WpfKeyboardHandler = new WpfImeKeyboardHandler(this);
+                oldKeyboardHandler?.Dispose();                
+
+                InputLanguageManager.Current.InputLanguageChanged -= OnInputLangageChanged;
+            }
+        }
+
         /// <summary>
         /// PresentationSource changed handler.
         /// </summary>
diff --git a/CefSharp.Wpf/Experimental/WpfIMEKeyboardHandler.cs b/CefSharp.Wpf/Experimental/WpfIMEKeyboardHandler.cs
index a5b1c05bcb..432e490cd5 100644
--- a/CefSharp.Wpf/Experimental/WpfIMEKeyboardHandler.cs
+++ b/CefSharp.Wpf/Experimental/WpfIMEKeyboardHandler.cs
@@ -346,7 +346,7 @@ private void CreateImeWindow(IntPtr hwnd)
             }
         }
 
-        private int PrimaryLangId(int lgid)
+        private static int PrimaryLangId(int lgid)
         {
             return lgid & 0x3ff;
         }
@@ -440,5 +440,25 @@ private void UpdateCaretPosition(int index)
         {
             MoveImeWindow(source.Handle);
         }
+
+        /// <summary>
+        /// Based on the <paramref name="keyboardLayoutId"/> determine if we
+        /// should be using IME.
+        /// </summary>
+        /// <param name="keyboardLayoutId">Keyboard Layout Id (obtained from <see cref="System.Globalization.CultureInfo.KeyboardLayoutId"/></param>
+        /// <returns>
+        /// returns true if the keyboard layout matches one of our listed that support IME, otherwise false.
+        /// </returns>
+        public static bool UseImeKeyboardHandler(int keyboardLayoutId)
+        {
+            var langId = PrimaryLangId(keyboardLayoutId);
+
+            if (langId == ImeNative.LANG_KOREAN || langId == ImeNative.LANG_JAPANESE || langId == ImeNative.LANG_CHINESE)
+            {
+                return true;
+            }
+
+            return false;
+        }
     }
 }