Draft: minor improvements for gui_edit.py (#17970)

* Draft: minor improvements for gui_edit.py

* Fix error...

src/Mod/Draft/draftguitools/gui_edit.py

@@ -364,17 +364,15 @@ class Edit(gui_base_original.Modifier):
         """
         register editing callbacks (former action function)
         """
-        viewer = Gui.ActiveDocument.ActiveView.getViewer()
-        self.render_manager = viewer.getSoRenderManager()
-        view = Gui.ActiveDocument.ActiveView
+        self.render_manager = self.view.getViewer().getSoRenderManager()
         if self._keyPressedCB is None:
-            self._keyPressedCB = view.addEventCallbackPivy(
+            self._keyPressedCB = self.view.addEventCallbackPivy(
             coin.SoKeyboardEvent.getClassTypeId(), self.keyPressed)
         if self._mouseMovedCB is None:
-            self._mouseMovedCB = view.addEventCallbackPivy(
+            self._mouseMovedCB = self.view.addEventCallbackPivy(
             coin.SoLocation2Event.getClassTypeId(), self.mouseMoved)
         if self._mousePressedCB is None:
-            self._mousePressedCB = view.addEventCallbackPivy(
+            self._mousePressedCB = self.view.addEventCallbackPivy(
             coin.SoMouseButtonEvent.getClassTypeId(), self.mousePressed)
         #App.Console.PrintMessage("Draft edit callbacks registered \n")
 
@@ -382,17 +380,16 @@ class Edit(gui_base_original.Modifier):
         """
         remove callbacks used during editing if they exist
         """
-        view = Gui.ActiveDocument.ActiveView
         if self._keyPressedCB:
-            view.removeEventCallbackSWIG(coin.SoKeyboardEvent.getClassTypeId(), self._keyPressedCB)
+            self.view.removeEventCallbackSWIG(coin.SoKeyboardEvent.getClassTypeId(), self._keyPressedCB)
             self._keyPressedCB = None
             #App.Console.PrintMessage("Draft edit keyboard callback unregistered \n")
         if self._mouseMovedCB:
-            view.removeEventCallbackSWIG(coin.SoLocation2Event.getClassTypeId(), self._mouseMovedCB)
+            self.view.removeEventCallbackSWIG(coin.SoLocation2Event.getClassTypeId(), self._mouseMovedCB)
             self._mouseMovedCB = None
             #App.Console.PrintMessage("Draft edit location callback unregistered \n")
         if self._mousePressedCB:
-            view.removeEventCallbackSWIG(coin.SoMouseButtonEvent.getClassTypeId(), self._mousePressedCB)
+            self.view.removeEventCallbackSWIG(coin.SoMouseButtonEvent.getClassTypeId(), self._mousePressedCB)
             self._mousePressedCB = None
             #App.Console.PrintMessage("Draft edit mouse button callback unregistered \n")
 
@@ -572,18 +569,25 @@ class Edit(gui_base_original.Modifier):
                 index, obj.ViewObject.LineColor, marker=marker))
 
     def removeTrackers(self, obj=None):
-        """Remove Edit Trackers."""
-        if obj:
-            if obj.Name in self.trackers:
-                for t in self.trackers[obj.Name]:
-                    t.finalize()
-            self.trackers[obj.Name] = []
-        else:
-            for key in self.trackers.keys():
+        """Remove Edit Trackers.
+
+        Attributes
+        ----------
+        obj: FreeCAD object
+            Removes trackers only for given object,
+            if obj is None, removes all trackers
+        """
+        if obj is None:
+            for key in self.trackers:
                 for t in self.trackers[key]:
                     t.finalize()
             self.trackers = {'object': []}
-
+        else:
+            key = obj.Name
+            if key in self.trackers:
+                for t in self.trackers[key]:
+                    t.finalize()
+            self.trackers[key] = []
 
     def hideTrackers(self, obj=None):
         """Hide Edit Trackers.
@@ -810,15 +814,18 @@ class Edit(gui_base_original.Modifier):
         """Restore objects style during editing mode.
         """
         for obj in objs:
+            if not obj.isAttachedToDocument():
+                # Object has been deleted.
+                continue
             obj_gui_tools = self.get_obj_gui_tools(obj)
-            if obj_gui_tools and obj.isAttachedToDocument():
+            if obj_gui_tools:
                 obj_gui_tools.restore_object_style(obj, self.objs_formats[obj.Name])
 
 
     def get_specific_object_info(self, obj, pos):
         """Return info of a specific object at a given position.
         """
-        selobjs = Gui.ActiveDocument.ActiveView.getObjectsInfo((pos[0],pos[1]))
+        selobjs = self.view.getObjectsInfo((pos[0],pos[1]))
         if not selobjs:
             return
         for info in selobjs:
@@ -834,7 +841,7 @@ class Edit(gui_base_original.Modifier):
 
         If object is one of the edited objects (self.edited_objects).
         """
-        selobjs = Gui.ActiveDocument.ActiveView.getObjectsInfo((pos[0],pos[1]))
+        selobjs = self.view.getObjectsInfo((pos[0],pos[1]))
         if not selobjs:
             return
         for info in selobjs: