load translation based on OS language

main.py

@@ -213,11 +213,13 @@ def change_lang_callback(self, enabled:bool):
         if(not enabled):  # Language not selected
             return
 
-        app.removeTranslator(translator)
-
         user_lang_id = self.language_action_group.checkedAction().data()
-        self.profile_ui.set_global_setting("language",user_lang_id) # store language setting
 
+        if user_lang_id == self.profile_ui.get_global_setting("language",DEFAULTLANG): # If user selected language same as current language
+            return 
+
+        app.removeTranslator(translator)
+        self.profile_ui.set_global_setting("language",user_lang_id) # store language setting
         self.languagechanged.emit() # loading in next start
 
     def restart_app(self):

profile_ui.py

@@ -152,22 +152,37 @@ def load_profiles_from_file(self):
         if self.ui_initialized:
             self.refresh_combox_list()
 
-    def create_or_update_profile_file(self, create: bool = False):
-        """Create a profile file if not exist, else update the existing one."""
+    def create_or_update_profile_file(self, create: bool = False) -> bool:
+        """Create a new profile file or update existing one
+
+        Args:
+            create: Whether to create a new file
+
+        Returns:
+            bool: Whether operation succeeded
+        """
         if create:
             self.profiles = self.__PROFILES_TEMPLATE
+            os_lang = PyQt6.QtCore.QLocale.system().name() # get system language, such as zh_CN
+            lang_file = os.path.join("translations", f"{os_lang}.qm")
+
+            # Use system language if translation exists, otherwise use English
+            if os.path.exists(lang_file):
+                default_lang = os_lang
+            else:
+                default_lang = "en_US"
+
+            self.profiles['global']['language'] = default_lang
+            self.log(f"Profile: use {default_lang} as default language")
             self.log("Profile: profile file created")
 
         try:
-            file = open(self.__PROFILES_FILENAME, "w", encoding="utf_8")
+            with open(self.__PROFILES_FILENAME, "w", encoding="utf_8") as f:
+                json.dump(self.profiles, f)
+            return True
         except OSError:
             return False
 
-        with file as profile_file:
-            json.dump(self.profiles, profile_file)
-
-        return True
-
     def get_global_setting(self,key : str, default = None):
         """Returns an entry of the global section or saves a default if set and not found"""
         if "global" in self.profiles:

translations/README.md

@@ -23,7 +23,7 @@ In PyQt6, internationalization (i18n) typically involves translating the text of
    - Use Linguist to create a translation file (.ts file). This file will contain all the text in your application that needs to be translated.
 
 2. Use Translation Files in the Application:
-   - In your PyQt6 application, use `QtCore.QLocale` to determine the user's preferred language.
+   - In your PyQt6 application, use `PyQt6.QtCore.QLocale.system().name()` to determine the user's preferred language.
    - Use `QtCore.QTranslator` to load the appropriate translation file based on the user's preferred language setting.
 
 3. Mark Text for Translation in the User Interface: