[ui] Paste a node on the mouse's position

When creating a node with a "paste" operation, place the node
on the mouse's position in the graph instead of default position (0,0).

If the mouse is placed on an existing node, the pasted node will be
placed on the mouse's position plus an offset so that the pasted node
does not directly overlap with the existing node.

meshroom/ui/commands.py

@@ -199,14 +199,15 @@ class PasteNodeCommand(GraphCommand):
     """
     Handle node pasting in a Graph.
     """
-    def __init__(self, graph, nodeType, parent=None, **kwargs):
+    def __init__(self, graph, nodeType, position=None, parent=None, **kwargs):
         super(PasteNodeCommand, self).__init__(graph, parent)
         self.nodeType = nodeType
+        self.position = position
         self.nodeName = None
         self.kwargs = kwargs
 
     def redoImpl(self):
-        node = self.graph.pasteNode(self.nodeType, **self.kwargs)
+        node = self.graph.pasteNode(self.nodeType, self.position, **self.kwargs)
         self.nodeName = node.name
         self.setText("Paste Node {}".format(self.nodeName))
         return node