GUI: added more verbose error handling to JFJochDbusClient

gui/src/aaregui/threads/jfjoch_viewer.py

@@ -7,14 +7,26 @@ class JFJochDBusClient(QObject):
 
         self.__session_bus = QDBusConnection.sessionBus()
         self.__interface = None
+        self.__dbus_available = False
 
-        if not self.__session_bus.isConnected():
-            print("Failed to connect to session bus")
-            return
+        try:
+            self.__session_bus = QDBusConnection.sessionBus()
+            if self.__session_bus.isConnected():
+                self.__dbus_available = True
+                print("D-Bus session bus connected")
+            else:
+                print("D-Bus not available")
+
+        except Exception as e:
+            print(f"D-Bus not available: {e}.")
 
 
     def _ensure_interface(self):
         """Ensure we have a valid interface, creating one if needed."""
+        if not self.__dbus_available:
+            print("D-Bus not available, cannot connect to JFJoch viewer")
+            return False
+
         if self.__interface is None or not self.__interface.isValid():
             if not self.__session_bus.isConnected():
                 print("Session bus not connected")
@@ -35,6 +47,10 @@ class JFJochDBusClient(QObject):
 #TODO tidy up load functions
     @Slot(str)
     def load_file(self, name: str):
+        if not self.__dbus_available:
+            print("D-Bus not available, cannot load file in JFJoch viewer")
+            return
+
         if name.startswith("http://"):
             path = name
         else:
@@ -45,6 +61,10 @@ class JFJochDBusClient(QObject):
 
     @Slot(str, int)
     def load_image(self, name: str, number: int):
+        if not self.__dbus_available:
+            print("D-Bus not available, cannot load image in JFJoch viewer")
+            return
+
         if name.startswith("http://"):
             path = name
         else:
@@ -55,6 +75,10 @@ class JFJochDBusClient(QObject):
 
     @Slot()
     def load_online(self):
+        if not self.__dbus_available:
+            print("D-Bus not available, cannot load online data in JFJoch viewer")
+            return
+
         if self._ensure_interface():
             reply = self.__interface.call("LoadFile", "http://sls-gpu-001:8080", -1, 1)