Change the Open File(s) option according to the file providers count

When there is only one file provider (i.e. the local file provider), the Open File(s) will be a
simple item in the File menu.
When there are more than one file providers, the Open File(s) will become a submenu in the File
menu, which will contain all the file providers as submenu items.

CURA-7868

cura/CuraApplication.py

@@ -30,6 +30,7 @@ from UM.Operations.SetTransformOperation import SetTransformOperation
 from UM.Platform import Platform
 from UM.PluginError import PluginNotFoundError
 from UM.Preferences import Preferences
+from UM.Qt.Bindings.FileProviderModel import FileProviderModel
 from UM.Qt.QtApplication import QtApplication  # The class we're inheriting from.
 from UM.Resources import Resources
 from UM.Scene.Camera import Camera
@@ -822,6 +823,9 @@ class CuraApplication(QtApplication):
         self._add_printer_pages_model_without_cancel.initialize(cancellable = False)
         self._whats_new_pages_model.initialize()
 
+        # Initialize the FileProviderModel
+        self._file_provider_model.initialize(self._onFileProviderEnabledChanged)
+
         # Detect in which mode to run and execute that mode
         if self._is_headless:
             self.runWithoutGUI()
@@ -1051,6 +1055,13 @@ class CuraApplication(QtApplication):
             self._simple_mode_settings_manager = SimpleModeSettingsManager()
         return self._simple_mode_settings_manager
 
+    @pyqtSlot(result = QObject)
+    def getFileProviderModel(self) -> FileProviderModel:
+        return self._file_provider_model
+
+    def _onFileProviderEnabledChanged(self):
+        self._file_provider_model.update()
+
     def event(self, event):
         """Handle Qt events"""
 

resources/qml/Menus/FileMenu.qml

@@ -22,11 +22,23 @@ Menu
     {
         id: openMenu
         action: Cura.Actions.open
-        visible: CuraApplication.fileProviders.length > 0 // DEBUG: It's > 0 so that both options are visible for debugging purposes
+        visible: (CuraApplication.getFileProviderModel().count == 1)
     }
 
-    OpenFilesMenu {
+    OpenFilesMenu
-        visible: CuraApplication.fileProviders.length > 0 // DEBUG: It's > 0 so that both options are visible for debugging purposes
+    {
+        id: openFilesMenu
+        visible: (CuraApplication.getFileProviderModel().count > 1)
+    }
+
+    Connections
+    {
+        target: CuraApplication.getFileProviderModel()
+        onItemsChanged:
+        {
+            openMenu.visible = (CuraApplication.getFileProviderModel().count == 1) // 1 because the open local files menu should always exist in the model
+            openFilesMenu.visible = (CuraApplication.getFileProviderModel().count > 1)
+        }
     }
 
     RecentFilesMenu { }

resources/qml/Menus/OpenFilesMenu.qml

@@ -11,15 +11,14 @@ import "../Dialogs"
 
 Menu
 {
-    id: menu
+    id: openFilesMenu
     title: catalog.i18nc("@title:menu menubar:file", "Open File(s)...")
     iconName: "document-open-recent";
 
-
     Instantiator
     {
         id: fileProviders
-        model: UM.FileProviderModel { }
+        model: CuraApplication.getFileProviderModel()
         MenuItem
         {
             text:
@@ -34,12 +33,12 @@ Menu
                 }
                 else
                 {
-                    fileProviders.model.trigger(model.name);
+                    CuraApplication.getFileProviderModel().trigger(model.name);
                 }
             }
             shortcut: model.shortcut
         }
-        onObjectAdded: menu.insertItem(index, object)
+        onObjectAdded: openFilesMenu.insertItem(index, object)
-        onObjectRemoved: menu.removeItem(object)
+        onObjectRemoved: openFilesMenu.removeItem(object)
     }
 }