Repaired the monitor icon not being updated

CL-541

plugins/MonitorStage/MonitorMainView.qml

@@ -16,7 +16,6 @@ Item
         color: UM.Theme.getColor("viewport_overlay")
         width: parent.width
         height: parent.height
-        visible: monitorViewComponent.sourceComponent == null ? 1 : 0
 
         MouseArea
         {

plugins/MonitorStage/MonitorStage.py

@@ -14,26 +14,79 @@ class MonitorStage(CuraStage):
         super().__init__(parent)
 
         # Wait until QML engine is created, otherwise creating the new QML components will fail
-        Application.getInstance().engineCreatedSignal.connect(self._setComponents)
+        Application.getInstance().engineCreatedSignal.connect(self._onEngineCreated)
+        self._printer_output_device = None
 
-        # Update the status icon when the output device is changed
-        Application.getInstance().getOutputDeviceManager().activeDeviceChanged.connect(self._setIconSource)
+        self._active_print_job = None
+        self._active_printer = None
 
-    def _setComponents(self):
-        self._setMainOverlay()
-        self._setSidebar()
-        self._setIconSource()
+    def _setActivePrintJob(self, print_job):
+        if self._active_print_job != print_job:
+            if self._active_print_job:
+                self._active_printer.stateChanged.disconnect(self._updateIconSource)
+            self._active_print_job = print_job
+            if self._active_print_job:
+                self._active_print_job.stateChanged.connect(self._updateIconSource)
 
-    def _setMainOverlay(self):
+            # Ensure that the right icon source is returned.
+            self._updateIconSource()
+
+    def _setActivePrinter(self, printer):
+        if self._active_printer != printer:
+            if self._active_printer:
+                self._active_printer.activePrintJobChanged.disconnect(self._onActivePrintJobChanged)
+            self._active_printer = printer
+            if self._active_printer:
+                self._setActivePrintJob(self._active_printer.activePrintJob)
+                # Jobs might change, so we need to listen to it's changes.
+                self._active_printer.activePrintJobChanged.connect(self._onActivePrintJobChanged)
+            else:
+                self._setActivePrintJob(None)
+
+            # Ensure that the right icon source is returned.
+            self._updateIconSource()
+
+    def _onActivePrintJobChanged(self):
+        self._setActivePrintJob(self._active_printer.activePrintJob)
+
+    def _onActivePrinterChanged(self):
+        self._setActivePrinter(self._printer_output_device.activePrinter)
+
+    def _onOutputDevicesChanged(self):
+        try:
+            # We assume that you are monitoring the device with the highest priority.
+            new_output_device = Application.getInstance().getMachineManager().printerOutputDevices[0]
+            if new_output_device != self._printer_output_device:
+                if self._printer_output_device:
+                    self._printer_output_device.acceptsCommandsChanged.disconnect(self._updateIconSource)
+                    self._printer_output_device.printersChanged.disconnect(self._onActivePrinterChanged)
+
+                self._printer_output_device = new_output_device
+
+                self._printer_output_device.acceptsCommandsChanged.connect(self._updateIconSource)
+                self._printer_output_device.printersChanged.connect(self._onActivePrinterChanged)
+                self._setActivePrinter(self._printer_output_device.activePrinter)
+
+        except IndexError:
+            pass
+
+    def _onEngineCreated(self):
+        # We can only connect now, as we need to be sure that everything is loaded (plugins get created quite early)
+        Application.getInstance().getMachineManager().outputDevicesChanged.connect(self._onOutputDevicesChanged)
+        self._updateMainOverlay()
+        self._updateSidebar()
+        self._updateIconSource()
+
+    def _updateMainOverlay(self):
         main_component_path = os.path.join(PluginRegistry.getInstance().getPluginPath("MonitorStage"), "MonitorMainView.qml")
         self.addDisplayComponent("main", main_component_path)
 
-    def _setSidebar(self):
+    def _updateSidebar(self):
         # TODO: currently the sidebar component for prepare and monitor stages is the same, this will change with the printer output device refactor!
         sidebar_component_path = os.path.join(Resources.getPath(Application.getInstance().ResourceTypes.QmlFiles), "Sidebar.qml")
         self.addDisplayComponent("sidebar", sidebar_component_path)
 
-    def _setIconSource(self):
+    def _updateIconSource(self):
         if Application.getInstance().getTheme() is not None:
             icon_name = self._getActiveOutputDeviceStatusIcon()
             self.setIconSource(Application.getInstance().getTheme().getIcon(icon_name))
@@ -56,25 +109,22 @@ class MonitorStage(CuraStage):
         if output_device.activePrinter.state == "maintenance":
             return "tab_status_busy"
 
-        if output_device.state == "maintenance":
-            return "tab_status_busy"
-
-        if output_device.activePrinter.activeJob is None:
+        if output_device.activePrinter.activePrintJob is None:
             return "tab_status_connected"
 
-        if output_device.activePrinter.activeJob.state in ["printing", "pre_print", "pausing", "resuming"]:
+        if output_device.activePrinter.activePrintJob.state in ["printing", "pre_print", "pausing", "resuming"]:
             return "tab_status_busy"
 
-        if output_device.activePrinter.activeJob.state == "wait_cleanup":
+        if output_device.activePrinter.activePrintJob.state == "wait_cleanup":
             return "tab_status_finished"
 
-        if output_device.activePrinter.activeJob.state in ["ready", ""]:
+        if output_device.activePrinter.activePrintJob.state in ["ready", ""]:
             return "tab_status_connected"
 
-        if output_device.activePrinter.activeJob.state == "paused":
+        if output_device.activePrinter.activePrintJob.state == "paused":
             return "tab_status_paused"
 
-        if output_device.activePrinter.activeJob.state == "error":
+        if output_device.activePrinter.activePrintJob.state == "error":
             return "tab_status_stopped"
 
         return "tab_status_unknown"