Fix cannot input Chinese after restarting the input method on X11

Register a callback via `XRegisterIMInstantiateCallback()` to detect
whether the input method is available again.

platform/linuxbsd/x11/display_server_x11.cpp

@@ -4143,7 +4143,6 @@ void DisplayServerX11::_xim_preedit_caret_callback(::XIM xim, ::XPointer client_
 
 void DisplayServerX11::_xim_destroy_callback(::XIM im, ::XPointer client_data,
 		::XPointer call_data) {
-	WARN_PRINT("Input method stopped");
 	DisplayServerX11 *ds = reinterpret_cast<DisplayServerX11 *>(client_data);
 	ds->xim = nullptr;
 
@@ -6047,6 +6046,73 @@ DisplayServer *DisplayServerX11::create_func(const String &p_rendering_driver, W
 	return ds;
 }
 
+void DisplayServerX11::_create_xic(WindowData &wd) {
+	if (xim && xim_style) {
+		// Block events polling while changing input focus
+		// because it triggers some event polling internally.
+		MutexLock mutex_lock(events_mutex);
+
+		// Force on-the-spot for the over-the-spot style.
+		if ((xim_style & XIMPreeditPosition) != 0) {
+			xim_style &= ~XIMPreeditPosition;
+			xim_style |= XIMPreeditCallbacks;
+		}
+		if ((xim_style & XIMPreeditCallbacks) != 0) {
+			::XIMCallback preedit_start_callback;
+			preedit_start_callback.client_data = (::XPointer)(this);
+			preedit_start_callback.callback = (::XIMProc)(void *)(_xim_preedit_start_callback);
+
+			::XIMCallback preedit_done_callback;
+			preedit_done_callback.client_data = (::XPointer)(this);
+			preedit_done_callback.callback = (::XIMProc)(_xim_preedit_done_callback);
+
+			::XIMCallback preedit_draw_callback;
+			preedit_draw_callback.client_data = (::XPointer)(this);
+			preedit_draw_callback.callback = (::XIMProc)(_xim_preedit_draw_callback);
+
+			::XIMCallback preedit_caret_callback;
+			preedit_caret_callback.client_data = (::XPointer)(this);
+			preedit_caret_callback.callback = (::XIMProc)(_xim_preedit_caret_callback);
+
+			::XVaNestedList preedit_attributes = XVaCreateNestedList(0,
+					XNPreeditStartCallback, &preedit_start_callback,
+					XNPreeditDoneCallback, &preedit_done_callback,
+					XNPreeditDrawCallback, &preedit_draw_callback,
+					XNPreeditCaretCallback, &preedit_caret_callback,
+					(char *)nullptr);
+
+			wd.xic = XCreateIC(xim,
+					XNInputStyle, xim_style,
+					XNClientWindow, wd.x11_xim_window,
+					XNFocusWindow, wd.x11_xim_window,
+					XNPreeditAttributes, preedit_attributes,
+					(char *)nullptr);
+			XFree(preedit_attributes);
+		} else {
+			wd.xic = XCreateIC(xim,
+					XNInputStyle, xim_style,
+					XNClientWindow, wd.x11_xim_window,
+					XNFocusWindow, wd.x11_xim_window,
+					(char *)nullptr);
+		}
+
+		long im_event_mask = 0;
+		if (XGetICValues(wd.xic, XNFilterEvents, &im_event_mask, nullptr) != nullptr) {
+			WARN_PRINT("XGetICValues couldn't obtain XNFilterEvents value.");
+			XDestroyIC(wd.xic);
+			wd.xic = nullptr;
+		}
+		if (wd.xic) {
+			XUnsetICFocus(wd.xic);
+		} else {
+			WARN_PRINT("XCreateIC couldn't create wd.xic.");
+		}
+	} else {
+		wd.xic = nullptr;
+		WARN_PRINT("XCreateIC couldn't create wd.xic.");
+	}
+}
+
 DisplayServerX11::WindowID DisplayServerX11::_create_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect, Window p_parent_window) {
 	//Create window
 
@@ -6252,70 +6318,7 @@ DisplayServerX11::WindowID DisplayServerX11::_create_window(WindowMode p_mode, V
 			XChangeProperty(x11_display, wd.x11_window, xdnd_aware, XA_ATOM, 32, PropModeReplace, (unsigned char *)&xdnd_version, 1);
 		}
 
-		if (xim && xim_style) {
+		_create_xic(wd);
-			// Block events polling while changing input focus
-			// because it triggers some event polling internally.
-			MutexLock mutex_lock(events_mutex);
-
-			// Force on-the-spot for the over-the-spot style.
-			if ((xim_style & XIMPreeditPosition) != 0) {
-				xim_style &= ~XIMPreeditPosition;
-				xim_style |= XIMPreeditCallbacks;
-			}
-			if ((xim_style & XIMPreeditCallbacks) != 0) {
-				::XIMCallback preedit_start_callback;
-				preedit_start_callback.client_data = (::XPointer)(this);
-				preedit_start_callback.callback = (::XIMProc)(void *)(_xim_preedit_start_callback);
-
-				::XIMCallback preedit_done_callback;
-				preedit_done_callback.client_data = (::XPointer)(this);
-				preedit_done_callback.callback = (::XIMProc)(_xim_preedit_done_callback);
-
-				::XIMCallback preedit_draw_callback;
-				preedit_draw_callback.client_data = (::XPointer)(this);
-				preedit_draw_callback.callback = (::XIMProc)(_xim_preedit_draw_callback);
-
-				::XIMCallback preedit_caret_callback;
-				preedit_caret_callback.client_data = (::XPointer)(this);
-				preedit_caret_callback.callback = (::XIMProc)(_xim_preedit_caret_callback);
-
-				::XVaNestedList preedit_attributes = XVaCreateNestedList(0,
-						XNPreeditStartCallback, &preedit_start_callback,
-						XNPreeditDoneCallback, &preedit_done_callback,
-						XNPreeditDrawCallback, &preedit_draw_callback,
-						XNPreeditCaretCallback, &preedit_caret_callback,
-						(char *)nullptr);
-
-				wd.xic = XCreateIC(xim,
-						XNInputStyle, xim_style,
-						XNClientWindow, wd.x11_xim_window,
-						XNFocusWindow, wd.x11_xim_window,
-						XNPreeditAttributes, preedit_attributes,
-						(char *)nullptr);
-				XFree(preedit_attributes);
-			} else {
-				wd.xic = XCreateIC(xim,
-						XNInputStyle, xim_style,
-						XNClientWindow, wd.x11_xim_window,
-						XNFocusWindow, wd.x11_xim_window,
-						(char *)nullptr);
-			}
-
-			if (XGetICValues(wd.xic, XNFilterEvents, &im_event_mask, nullptr) != nullptr) {
-				WARN_PRINT("XGetICValues couldn't obtain XNFilterEvents value");
-				XDestroyIC(wd.xic);
-				wd.xic = nullptr;
-			}
-			if (wd.xic) {
-				XUnsetICFocus(wd.xic);
-			} else {
-				WARN_PRINT("XCreateIC couldn't create wd.xic");
-			}
-		} else {
-			wd.xic = nullptr;
-			WARN_PRINT("XCreateIC couldn't create wd.xic");
-		}
-
 		_update_context(wd);
 
 		if (p_flags & WINDOW_FLAG_BORDERLESS_BIT) {
@@ -6471,6 +6474,54 @@ static ::XIMStyle _get_best_xim_style(const ::XIMStyle &p_style_a, const ::XIMSt
 	return p_style_a;
 }
 
+void DisplayServerX11::_xim_instantiate_callback(::Display *display, ::XPointer client_data,
+		::XPointer call_data) {
+	DisplayServerX11 *ds = reinterpret_cast<DisplayServerX11 *>(client_data);
+
+	ds->xim = XOpenIM(display, nullptr, nullptr, nullptr);
+
+	if (ds->xim == nullptr) {
+		WARN_PRINT("XOpenIM failed.");
+		ds->xim_style = 0L;
+	} else {
+		::XIMCallback im_destroy_callback;
+		im_destroy_callback.client_data = client_data;
+		im_destroy_callback.callback = (::XIMProc)(_xim_destroy_callback);
+		if (XSetIMValues(ds->xim, XNDestroyCallback, &im_destroy_callback,
+					nullptr) != nullptr) {
+			WARN_PRINT("Error setting XIM destroy callback.");
+		}
+
+		::XIMStyles *xim_styles = nullptr;
+		ds->xim_style = 0L;
+		char *imvalret = XGetIMValues(ds->xim, XNQueryInputStyle, &xim_styles, nullptr);
+		if (imvalret != nullptr || xim_styles == nullptr) {
+			fprintf(stderr, "Input method doesn't support any styles\n");
+		}
+
+		if (xim_styles) {
+			ds->xim_style = 0L;
+			for (int i = 0; i < xim_styles->count_styles; i++) {
+				const ::XIMStyle &style = xim_styles->supported_styles[i];
+
+				if (!_is_xim_style_supported(style)) {
+					continue;
+				}
+
+				ds->xim_style = _get_best_xim_style(ds->xim_style, style);
+			}
+
+			XFree(xim_styles);
+		}
+		XFree(imvalret);
+	}
+
+	// The input method has been (re)started.
+	for (KeyValue<WindowID, WindowData> &E : ds->windows) {
+		ds->_create_xic(E.value);
+	}
+}
+
 DisplayServerX11::DisplayServerX11(const String &p_rendering_driver, WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Vector2i *p_position, const Vector2i &p_resolution, int p_screen, Context p_context, int64_t p_parent_window, Error &r_error) {
 	KeyMappingX11::initialize();
 
@@ -6663,10 +6714,10 @@ DisplayServerX11::DisplayServerX11(const String &p_rendering_driver, WindowMode
 
 	if (modifiers == nullptr) {
 		if (OS::get_singleton()->is_stdout_verbose()) {
-			WARN_PRINT("IME is disabled");
+			WARN_PRINT("IME is disabled.");
 		}
 		XSetLocaleModifiers("@im=none");
-		WARN_PRINT("Error setting locale modifiers");
+		WARN_PRINT("Error setting locale modifiers.");
 	}
 
 	const char *err;
@@ -6711,42 +6762,9 @@ DisplayServerX11::DisplayServerX11(const String &p_rendering_driver, WindowMode
 		return;
 	}
 
-	xim = XOpenIM(x11_display, nullptr, nullptr, nullptr);
+	if (!XRegisterIMInstantiateCallback(x11_display, nullptr, nullptr, nullptr, (::XIDProc)(_xim_instantiate_callback), (::XPointer)this)) {
-
+		WARN_PRINT("Error registering XIM instantiate callback.");
-	if (xim == nullptr) {
+		_xim_instantiate_callback(x11_display, (::XPointer)this, nullptr);
-		WARN_PRINT("XOpenIM failed");
-		xim_style = 0L;
-	} else {
-		::XIMCallback im_destroy_callback;
-		im_destroy_callback.client_data = (::XPointer)(this);
-		im_destroy_callback.callback = (::XIMProc)(_xim_destroy_callback);
-		if (XSetIMValues(xim, XNDestroyCallback, &im_destroy_callback,
-					nullptr) != nullptr) {
-			WARN_PRINT("Error setting XIM destroy callback");
-		}
-
-		::XIMStyles *xim_styles = nullptr;
-		xim_style = 0L;
-		char *imvalret = XGetIMValues(xim, XNQueryInputStyle, &xim_styles, nullptr);
-		if (imvalret != nullptr || xim_styles == nullptr) {
-			fprintf(stderr, "Input method doesn't support any styles\n");
-		}
-
-		if (xim_styles) {
-			xim_style = 0L;
-			for (int i = 0; i < xim_styles->count_styles; i++) {
-				const ::XIMStyle &style = xim_styles->supported_styles[i];
-
-				if (!_is_xim_style_supported(style)) {
-					continue;
-				}
-
-				xim_style = _get_best_xim_style(xim_style, style);
-			}
-
-			XFree(xim_styles);
-		}
-		XFree(imvalret);
 	}
 
 	/* Atom internment */

platform/linuxbsd/x11/display_server_x11.h

@@ -236,6 +236,7 @@ class DisplayServerX11 : public DisplayServer {
 	WindowID last_focused_window = INVALID_WINDOW_ID;
 
 	WindowID window_id_counter = MAIN_WINDOW_ID;
+	void _create_xic(WindowData &wd);
 	WindowID _create_window(WindowMode p_mode, VSyncMode p_vsync_mode, uint32_t p_flags, const Rect2i &p_rect, Window p_parent_window);
 
 	String internal_clipboard;
@@ -246,7 +247,7 @@ class DisplayServerX11 : public DisplayServer {
 	int xmblen = 0;
 	unsigned long last_timestamp = 0;
 	::Time last_keyrelease_time = 0;
-	::XIM xim;
+	::XIM xim = nullptr;
 	::XIMStyle xim_style;
 
 	static int _xim_preedit_start_callback(::XIM xim, ::XPointer client_data,
@@ -259,6 +260,8 @@ class DisplayServerX11 : public DisplayServer {
 			::XIMPreeditCaretCallbackStruct *call_data);
 	static void _xim_destroy_callback(::XIM im, ::XPointer client_data,
 			::XPointer call_data);
+	static void _xim_instantiate_callback(::Display *display, ::XPointer client_data,
+			::XPointer call_data);
 
 	Point2i last_mouse_pos;
 	bool last_mouse_pos_valid = false;