Cleanup code around checking the IME status on Windows

We shouldn't allow for partial initialization of the User32
function pointers, since they should never be accessed on
anything other than Windows 2000 or later.

Mod code also should not call directly into platform code
where possible, so introduce a helper method that dispatches
to the correct platform code.

Author: jellysquid3

common/src/boot/java/net/caffeinemc/mods/sodium/client/platform/PlatformHelper.java

@@ -1,5 +1,7 @@
 package net.caffeinemc.mods.sodium.client.platform;
 
+import net.caffeinemc.mods.sodium.client.compatibility.environment.OsUtils;
+import net.caffeinemc.mods.sodium.client.platform.windows.api.Imm32;
 import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.Nullable;
 import org.slf4j.Logger;
@@ -26,4 +28,13 @@ public static void showCriticalErrorAndClose(
         MessageBox.showMessageBox(window, MessageBox.IconType.ERROR, messageTitle, messageBody, helpUrl);
         System.exit(1 /* failure code */);
     }
+
+    public static boolean isUsingIME() {
+        if (OsUtils.getOs() == OsUtils.OperatingSystem.WIN) {
+            return Imm32.checkIMEStatus();
+        }
+
+        // Not handled on other platforms, so just assume we are not using an IME.
+        return false;
+    }
 }

common/src/boot/java/net/caffeinemc/mods/sodium/client/platform/windows/api/Imm32.java

@@ -1,23 +1,26 @@
 package net.caffeinemc.mods.sodium.client.platform.windows.api;
 
 public class Imm32 {
-   //private static final MethodHandle IsIME;
+    public static boolean checkIMEStatus() {
+        long hkl = User32.callGetKeyboardLayout(0);
 
-    static {
-        //Linker linker = Linker.nativeLinker();
-        //SymbolLookup imm32 = SymbolLookup.libraryLookup("imm32", Arena.global());
-        //IsIME = linker.downcallHandle(imm32.find("ImmIsIME").orElseThrow(), FunctionDescriptor.of(ValueLayout.JAVA_INT, ValueLayout.ADDRESS));
-    }
+        if (hkl == 0) {
+            // Assume English keyboard layout.
+            return false;
+        }
 
-    public static boolean CheckIMEStatus() {
-        long handle = User32.callGetKeyboardLayout(0);
-        int langId = (int)(handle & 0xFFFF);
+        int langId = (int)(hkl & 0xFFFF);
 
         // ImmIsIME does not return a sensible result for this, sadly. Maybe it will some day. But it returns true almost all the time right now.
         return isImeLanguage(langId);
     }
 
-    public static boolean isImeLanguage(int langId) {
-        return langId == 2052 /* zh-CN */ || langId == 1028 /* zh-TW */ || langId == 3076 /* zh-HK */ || langId == 4100 /* zh-SG */ || langId == 1041 /* ja-JP */ || langId == 1042 /* ko-KR */;
+    private static boolean isImeLanguage(int langId) {
+        return  langId == 2052 /* zh-CN */ ||
+                langId == 1028 /* zh-TW */ ||
+                langId == 3076 /* zh-HK */ ||
+                langId == 4100 /* zh-SG */ ||
+                langId == 1041 /* ja-JP */ ||
+                langId == 1042 /* ko-KR */;
     }
 }

common/src/boot/java/net/caffeinemc/mods/sodium/client/platform/windows/api/User32.java

@@ -8,38 +8,32 @@
 
 import static org.lwjgl.system.APIUtil.apiGetFunctionAddress;
 import static org.lwjgl.system.APIUtil.apiGetFunctionAddressOptional;
+import static org.lwjgl.system.MemoryUtil.NULL;
 
 public class User32 {
     private static final SharedLibrary LIBRARY;
 
     static {
-        if (OsUtils.getOs() == OsUtils.OperatingSystem.WIN) {
-            LIBRARY = APIUtil.apiCreateLibrary("user32");
-
-            PFN_MessageBoxIndirectW = apiGetFunctionAddress(LIBRARY, "MessageBoxIndirectW");
-            PFN_GetKeyboardLayout = apiGetFunctionAddressOptional(LIBRARY, "GetKeyboardLayout");
-        } else {
-            LIBRARY = null;
-            PFN_GetKeyboardLayout = -1;
-            PFN_MessageBoxIndirectW = -1;
-        }
+        LIBRARY = APIUtil.apiCreateLibrary("user32");
+
+        PFN_MessageBoxIndirectW = apiGetFunctionAddress(LIBRARY, "MessageBoxIndirectW");
+        PFN_GetKeyboardLayout = apiGetFunctionAddress(LIBRARY, "GetKeyboardLayout");
     }
 
     private static final long PFN_MessageBoxIndirectW;
     private static final long PFN_GetKeyboardLayout;
 
     /**
-     * @see <a href="https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-messageboxw>Winuser.h Documentation</a>
+     * @see <a href="https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-messageboxw">Winuser.h Documentation</a>
      */
     public static void callMessageBoxIndirectW(MsgBoxParamSw params) {
-        if (PFN_MessageBoxIndirectW == -1) return;
-
         JNI.callPI(params.address(), PFN_MessageBoxIndirectW);
     }
 
+    /**
+     * @see <a href="https://learn.microsoft.com/en-us/windows/win32/api/winuser/nf-winuser-getkeyboardlayout">Winuser.h Documentation</a>
+     */
     public static long callGetKeyboardLayout(int thread) {
-        if (PFN_GetKeyboardLayout == -1) return 0;
-
         return JNI.callPI(thread, PFN_GetKeyboardLayout);
     }
 }

common/src/main/java/net/caffeinemc/mods/sodium/mixin/core/MinecraftMixin.java

@@ -8,7 +8,7 @@
 import net.caffeinemc.mods.sodium.client.config.ConfigManager;
 import net.caffeinemc.mods.sodium.client.gui.SodiumConfigBuilder;
 import net.caffeinemc.mods.sodium.client.gui.SodiumOptions;
-import net.caffeinemc.mods.sodium.client.platform.windows.api.Imm32;
+import net.caffeinemc.mods.sodium.client.platform.PlatformHelper;
 import net.minecraft.client.GameLoadCookie;
 import net.minecraft.client.Minecraft;
 import net.minecraft.client.main.GameConfig;
@@ -67,7 +67,7 @@ private void setFullscreen(GameConfig gameConfig, CallbackInfo ci) {
                 return; // Do not get stuck in a loop of setting exclusive fullscreen! That'd be very annoying.
             }
 
-            var hasIME = OsUtils.getOs() == OsUtils.OperatingSystem.WIN && Imm32.CheckIMEStatus();
+            var hasIME = PlatformHelper.isUsingIME();
             Minecraft.getInstance().options.exclusiveFullscreen().set(!hasIME);
 
             if (hasIME) {