Add API abstraction layer

Contributes to CURA-5595

cura/API/SidebarContextMenu.py

@@ -0,0 +1,34 @@
+# Copyright (c) 2018 Ultimaker B.V.
+# Cura is released under the terms of the LGPLv3 or higher.
+
+from cura.CuraApplication import CuraApplication
+
+##  The back-ups API provides a version-proof bridge between Cura's
+#   Sidebar Context Menu and plug-ins that hook into it.
+#
+#   Usage:
+#       ``from cura.API import CuraAPI
+#       api = CuraAPI()
+#       api.sidebar_context_menu.getSidebarMenuItems()
+#       menu_actions = []
+#       menu_actions.append("sidebarMenuItemOnClickHander")
+#       data = {
+#           "name": "My Plugin Action",
+#           "iconName": "my-plugin-icon",
+#           "actions": menu_actions,
+#           "menu_item": MyPluginAction(self)
+#       }
+#       api.sidebar_context_menu.addSidebarMenuItems([])``
+class SidebarContextMenu:
+
+    _application = CuraApplication.getInstance()  # type: CuraApplication
+
+    ##  Add items to the sidebar context menu.
+    #   \param menu_item dict containing the menu item to add.
+    def addSidebarMenuItem(self, menu_items: dict) -> None:
+        self._application.addSidebarCustomMenuItem(menu_items)
+
+    ##  Get all custom items currently added to the sidebar context menu.
+    #   \return List containing all custom context menu items.
+    def getSidebarMenuItems(self) -> list:
+        return self._application.getSidebarCustomMenuItems()

cura/API/__init__.py

@@ -2,6 +2,7 @@
 # Cura is released under the terms of the LGPLv3 or higher.
 from UM.PluginRegistry import PluginRegistry
 from cura.API.Backups import Backups
+from cura.API.SidebarContextMenu import SidebarContextMenu
 
 ##  The official Cura API that plug-ins can use to interact with Cura.
 #
@@ -16,3 +17,6 @@ class CuraAPI:
 
     # Backups API.
     backups = Backups()
+
+    # Sidebar Context Menu API
+    sidebar_context_menu = SidebarContextMenu()