move SDL_HelperWindow outside of video

move to SDL_window.c to prevent relying on SDL_VIDEO

(cherry picked from commit a190e3b5149e736919715264502fba6574ed9720)

src/core/windows/SDL_windows.c

@@ -53,6 +53,78 @@ typedef enum RO_INIT_TYPE
 #define WC_ERR_INVALID_CHARS 0x00000080
 #endif
 
+// Fake window to help with DirectInput events.
+HWND SDL_HelperWindow = NULL;
+static const TCHAR *SDL_HelperWindowClassName = TEXT("SDLHelperWindowInputCatcher");
+static const TCHAR *SDL_HelperWindowName = TEXT("SDLHelperWindowInputMsgWindow");
+static ATOM SDL_HelperWindowClass = 0;
+
+/*
+ * Creates a HelperWindow used for DirectInput.
+ */
+bool SDL_HelperWindowCreate(void)
+{
+    HINSTANCE hInstance = GetModuleHandle(NULL);
+    WNDCLASS wce;
+
+    // Make sure window isn't created twice.
+    if (SDL_HelperWindow != NULL) {
+        return true;
+    }
+
+    // Create the class.
+    SDL_zero(wce);
+    wce.lpfnWndProc = DefWindowProc;
+    wce.lpszClassName = SDL_HelperWindowClassName;
+    wce.hInstance = hInstance;
+
+    // Register the class.
+    SDL_HelperWindowClass = RegisterClass(&wce);
+    if (SDL_HelperWindowClass == 0 && GetLastError() != ERROR_CLASS_ALREADY_EXISTS) {
+        return WIN_SetError("Unable to create Helper Window Class");
+    }
+
+    // Create the window.
+    SDL_HelperWindow = CreateWindowEx(0, SDL_HelperWindowClassName,
+                                      SDL_HelperWindowName,
+                                      WS_OVERLAPPED, CW_USEDEFAULT,
+                                      CW_USEDEFAULT, CW_USEDEFAULT,
+                                      CW_USEDEFAULT, HWND_MESSAGE, NULL,
+                                      hInstance, NULL);
+    if (!SDL_HelperWindow) {
+        UnregisterClass(SDL_HelperWindowClassName, hInstance);
+        return WIN_SetError("Unable to create Helper Window");
+    }
+
+    return true;
+}
+
+/*
+ * Destroys the HelperWindow previously created with SDL_HelperWindowCreate.
+ */
+void SDL_HelperWindowDestroy(void)
+{
+    HINSTANCE hInstance = GetModuleHandle(NULL);
+
+    // Destroy the window.
+    if (SDL_HelperWindow != NULL) {
+        if (DestroyWindow(SDL_HelperWindow) == 0) {
+            WIN_SetError("Unable to destroy Helper Window");
+            return;
+        }
+        SDL_HelperWindow = NULL;
+    }
+
+    // Unregister the class.
+    if (SDL_HelperWindowClass != 0) {
+        if ((UnregisterClass(SDL_HelperWindowClassName, hInstance)) == 0) {
+            WIN_SetError("Unable to destroy Helper Window Class");
+            return;
+        }
+        SDL_HelperWindowClass = 0;
+    }
+}
+
 // Sets an error message based on an HRESULT
 bool WIN_SetErrorFromHRESULT(const char *prefix, HRESULT hr)
 {

src/video/windows/SDL_windowswindow.c

@@ -92,12 +92,6 @@ typedef void (NTAPI *RtlGetVersion_t)(NT_OSVERSIONINFOW *);
 
 // #define HIGHDPI_DEBUG
 
-// Fake window to help with DirectInput events.
-HWND SDL_HelperWindow = NULL;
-static const TCHAR *SDL_HelperWindowClassName = TEXT("SDLHelperWindowInputCatcher");
-static const TCHAR *SDL_HelperWindowName = TEXT("SDLHelperWindowInputMsgWindow");
-static ATOM SDL_HelperWindowClass = 0;
-
 /* For borderless Windows, still want the following flag:
    - WS_MINIMIZEBOX: window will respond to Windows minimize commands sent to all windows, such as windows key + m, shaking title bar, etc.
    Additionally, non-fullscreen windows can add:
@@ -1510,72 +1504,6 @@ void WIN_DestroyWindow(SDL_VideoDevice *_this, SDL_Window *window)
     CleanupWindowData(_this, window);
 }
 
-/*
- * Creates a HelperWindow used for DirectInput.
- */
-bool SDL_HelperWindowCreate(void)
-{
-    HINSTANCE hInstance = GetModuleHandle(NULL);
-    WNDCLASS wce;
-
-    // Make sure window isn't created twice.
-    if (SDL_HelperWindow != NULL) {
-        return true;
-    }
-
-    // Create the class.
-    SDL_zero(wce);
-    wce.lpfnWndProc = DefWindowProc;
-    wce.lpszClassName = SDL_HelperWindowClassName;
-    wce.hInstance = hInstance;
-
-    // Register the class.
-    SDL_HelperWindowClass = RegisterClass(&wce);
-    if (SDL_HelperWindowClass == 0 && GetLastError() != ERROR_CLASS_ALREADY_EXISTS) {
-        return WIN_SetError("Unable to create Helper Window Class");
-    }
-
-    // Create the window.
-    SDL_HelperWindow = CreateWindowEx(0, SDL_HelperWindowClassName,
-                                      SDL_HelperWindowName,
-                                      WS_OVERLAPPED, CW_USEDEFAULT,
-                                      CW_USEDEFAULT, CW_USEDEFAULT,
-                                      CW_USEDEFAULT, HWND_MESSAGE, NULL,
-                                      hInstance, NULL);
-    if (!SDL_HelperWindow) {
-        UnregisterClass(SDL_HelperWindowClassName, hInstance);
-        return WIN_SetError("Unable to create Helper Window");
-    }
-
-    return true;
-}
-
-/*
- * Destroys the HelperWindow previously created with SDL_HelperWindowCreate.
- */
-void SDL_HelperWindowDestroy(void)
-{
-    HINSTANCE hInstance = GetModuleHandle(NULL);
-
-    // Destroy the window.
-    if (SDL_HelperWindow != NULL) {
-        if (DestroyWindow(SDL_HelperWindow) == 0) {
-            WIN_SetError("Unable to destroy Helper Window");
-            return;
-        }
-        SDL_HelperWindow = NULL;
-    }
-
-    // Unregister the class.
-    if (SDL_HelperWindowClass != 0) {
-        if ((UnregisterClass(SDL_HelperWindowClassName, hInstance)) == 0) {
-            WIN_SetError("Unable to destroy Helper Window Class");
-            return;
-        }
-        SDL_HelperWindowClass = 0;
-    }
-}
-
 #if !defined(SDL_PLATFORM_XBOXONE) && !defined(SDL_PLATFORM_XBOXSERIES)
 void WIN_OnWindowEnter(SDL_VideoDevice *_this, SDL_Window *window)
 {