#!/usr/bin/env python

# coding: utf-8

from PyQt4.QtGui import *

from PyQt4.QtCore import *

rad = 5

class Node(QGraphicsEllipseItem):

def __init__(self, path, index):

super(Node, self).__init__(-rad, -rad, 2*rad, 2*rad)

self.rad = rad

self.path = path

self.index = index

self.setZValue(1)

self.setFlag(QGraphicsItem.ItemIsMovable)

self.setFlag(QGraphicsItem.ItemSendsGeometryChanges)

self.setBrush(Qt.green)

def itemChange(self, change, value):

if change == QGraphicsItem.ItemPositionChange:

self.path.updateElement(self.index, value.toPointF())

return QGraphicsEllipseItem.itemChange(self, change, value)

class Path(QGraphicsPathItem):

def __init__(self, path, scene):

super(Path, self).__init__(path)

for i in xrange(path.elementCount()):

node = Node(self, i)

node.setPos(QPointF(path.elementAt(i)))

scene.addItem(node)

self.setPen(QPen(Qt.red, 1.75))

def updateElement(self, index, pos):

path.setElementPositionAt(index, pos.x(), pos.y())

self.setPath(path)

if __name__ == "__main__":

app = QApplication([])

path = QPainterPath()

path.moveTo(0,0)

path.cubicTo(-30, 70, 35, 115, 100, 100);

path.lineTo(200, 100);

path.cubicTo(200, 30, 150, -35, 60, -30);

scene = QGraphicsScene()

scene.addItem(Path(path, scene))

view = QGraphicsView(scene)

view.setRenderHint(QPainter.Antialiasing)

view.resize(600, 400)

view.show()

app.exec_()