Python GUI: Switching layouts

python/gui_view.py

@@ -8,7 +8,13 @@ import signal
 import sys
 
 # Async worker thread
-class AsyncWorker(QRunnable):
+class AsyncWorker(QRunnable, QObject):
+    def __init__(self):
+        QRunnable.__init__(self)
+        QObject.__init__(self)
+
+    exception_signal = Signal(Exception)
+
     @Slot()
     def run(self):
         self.loop = asyncio.new_event_loop()
@@ -20,48 +26,83 @@ class AsyncWorker(QRunnable):
     async def _stop_internal(self):
         self.loop.stop()
 
+    async def dispatch_and_check_exception(coro):
+        try:
+            await coro
+        except Exception as e:
+            AsyncWorker.worker.exception_happened.emit(e)
+
     def dispatch(coro):
-        asyncio.run_coroutine_threadsafe(coro, AsyncWorker.worker.loop)
+        asyncio.run_coroutine_threadsafe(AsyncWorker.dispatch_and_check_exception(coro), AsyncWorker.worker.loop)
 
 if not hasattr(AsyncWorker, "worker"):
     AsyncWorker.worker = AsyncWorker()
 
 
-class MainWindow(QMainWindow):
-
-    start_signal = Signal()
-    done_signal = Signal()
+class InitialLayout(QWidget):
+    connected_signal = Signal(BIRD)
 
     def __init__(self):
         super().__init__()
 
-        self.bird = BIRD("/run/bird/bird.ctl")
-        self.initial_layout()
-
-    def initial_layout(self):
-        widget = QWidget()
-        self.setCentralWidget(widget)
-
-        layout = QVBoxLayout(widget)
+        self.layout = QVBoxLayout(self)
 
         self.text = QLabel("No connection to BIRD.")
-        layout.addWidget(self.text, alignment=Qt.AlignmentFlag.AlignCenter)
+        self.layout.addWidget(self.text, alignment=Qt.AlignmentFlag.AlignCenter)
 
         async_trigger = QPushButton(text="Connect")
-        async_trigger.clicked.connect(self.connect)
-        layout.addWidget(async_trigger, alignment=Qt.AlignmentFlag.AlignCenter)
+        async_trigger.clicked.connect(self.connect_slot)
+        self.layout.addWidget(async_trigger, alignment=Qt.AlignmentFlag.AlignCenter)
 
     @Slot()
-    def connect(self):
+    def connect_slot(self):
+        self.bird = BIRD("/run/bird/bird.ctl")
+
         async def f():
             async with self.bird as b:
                 await b.version.update()
                 await b.status.update()
 
-                self.text.setText(f"Connected to {b.version.name} {b.version.version}")
+                self.connected_signal.emit(b)
 
         AsyncWorker.dispatch(f())
 
+
+class ConnectedLayout(QWidget):
+    def __init__(self, bird):
+        super().__init__()
+        self.bird = bird
+
+        self.layout = QVBoxLayout(self)
+
+        self.main_info = QLabel(f"Connected to {bird.version.name} {bird.version.version}")
+        self.layout.addWidget(self.main_info)
+
+        self.status = QLabel(f"Status: {bird.status.status}")
+        self.layout.addWidget(self.status)
+
+class MainWindow(QMainWindow):
+    def __init__(self):
+        super().__init__()
+
+        AsyncWorker.worker.exception_signal.connect(self.exception_slot)
+
+        self.set_layout(InitialLayout())
+        self.layout.connected_signal.connect(self.connected_slot)
+
+    def set_layout(self, layout):
+        self.setCentralWidget(layout)
+        self.layout = layout
+
+    @Slot(Exception)
+    def exception_slot(self, e):
+        print("got exception")
+        raise Exception() from e
+
+    @Slot(BIRD)
+    def connected_slot(self, bird):
+        self.set_layout(ConnectedLayout(bird))
+
 if __name__ == "__main__":
     app = QApplication(sys.argv)
     threadpool = QThreadPool()