def _OnDown(self, event):
# calculate distance of mouse to all points
p = Point(event.x, event.y)
dists = p.distance( self._nodes * Point(self.position.size) )
# is one close enough?
i = -1
if self._nodes: # or .min() will not work
tmp = dists.min()
if tmp <= self._snapWidth:
i, = np.where(dists==tmp)
# if so, store that point
if i>= 0:
self._selectedNode = i
else:
self._selectedNode = None
