Network: Add add node command.

src/Model/Network/Graph.py

@@ -81,22 +81,32 @@ class Graph(object):
 
         return edge[0]
 
-    def _add_node(self, node):
-        self._nodes.append(node)
-        self._nodes_ids += 1
-
-        self._status.modified()
-        return node
-
-    def add_node(self, x:float = 0.0, y:float = 0.0):
+    def _create_node(self, x:float, y:float):
         node = self._node_ctor(
             self._nodes_ids,
             f"Node {self._nodes_ids}",
             x = x, y = y,
             status = self._status
         )
+        self._nodes_ids += 1
+        return node
+
+    def _add_node(self, node):
+        self._nodes.append(node)
+        self._status.modified()
+        return node
+
+    def add_node(self, x:float = 0.0, y:float = 0.0):
+        node = self._create_node(x, y)
         return self._add_node(node)
 
+    def insert_node(self, node):
+        self._add_node(node)
+
+    def create_node(self, x:float = 0.0, y:float = 0.0):
+        node = self._create_node(x, y)
+        return node
+
     def _add_edge(self, edge):
         # This edge already exists ?
         if any(filter(lambda e: (e.node1 == edge.node1 and

src/View/Network/GraphWidget.py

@@ -376,7 +376,12 @@ class GraphWidget(QGraphicsView):
         Returns:
             Nothing
         """
-        node = self.graph.add_node(pos.x(), pos.y())
+        node = self.graph.create_node(pos.x(), pos.y())
+        self._undo.push(
+            AddNodeCommand(
+                self.graph, node
+            )
+        )
         inode = NodeItem(node, self)
         self.scene().addItem(inode)
         self.node_items.append(inode)

src/View/Network/UndoCommand.py

@@ -11,6 +11,20 @@ from Model.Network.Node import Node
 from Model.Network.Edge import Edge
 from Model.Network.Graph import Graph
 
+class AddNodeCommand(QUndoCommand):
+    def __init__(self, graph, node):
+        QUndoCommand.__init__(self)
+
+        self._graph = graph
+        self._node = node
+
+    def undo(self):
+        self._graph.remove_node(self._node.name)
+
+    def redo(self):
+        self._graph.insert_node(self._node)
+
+
 class SetCommand(QUndoCommand):
     def __init__(self, element, column, new_value):
         QUndoCommand.__init__(self)