Simple graph

simplegraph.kv

#:kivy 1.5.1

<MainView>:
    newdot: graphdot

    size: root.size

    GraphDot:
        center: 0, self.center_y
        id: graphdot


<GraphDot>:
    size: 20,20
    canvas:
        Ellipse:
            size: self.size
            pos: self.center

simplegraph.py

import kivy
kivy.require('1.5.1')

from kivy.app import App
from kivy.clock import Clock
from kivy.uix.floatlayout import FloatLayout
from kivy.uix.widget import Widget
from kivy.properties import ObjectProperty, ReferenceListProperty, NumericProperty, ListProperty
from kivy.vector import Vector
from kivy.graphics import Color, Ellipse, Line

import math

class MainView(Widget):

    newdot = ObjectProperty()

    old_position = [0,0]
    counter = 0.0

    def update(self,dt):
        self.counter += 0.2
        new_point = [self.counter*5, 50*math.sin(self.counter) + self.height/2]
        self.add_point(new_point)

    def add_point(self, new_position):
        self.newdot.center_y = new_position[1]
        self.newdot.center_x = new_position[0]

        position = self.old_position + new_position

        self.old_position = new_position[:]

        print position

        with self.newdot.canvas:
            Color(1,0,1)
            self.line = Line(points=self.old_position + new_position, width=2)

        if new_position[0] > self.width:
            self.counter = 0.0
            self.old_position = [0,0]
            self.canvas.clear()


class GraphDot(Widget):

    pass


class SimpleGraphApp(App):

    starting_point = [0,0]

    def build(self):
        parent = MainView()
        Clock.schedule_interval(parent.update,1/5)

        return parent

if __name__=='__main__':
    SimpleGraphApp().run()