Kivy: Rotation in Python

rotpy.py

'''
Rotation Example
================

This example rotates a button using PushMatrix and PopMatrix. You should see
a static button with the words 'hello world' rotated at a 45 degree angle.
'''


from kivy.app import App
from kivy.lang import Builder
from kivy.graphics import *

kv = '''
FloatLayout:

    Button:
        text: 'hello world'
        size_hint: None, None
        pos_hint: {'center_x': .5, 'center_y': .5}
        #canvas.before:
        #   PushMatrix
        #   Rotate:
        #       angle: 45
        #       origin: self.center
        #canvas.after:
        #   PopMatrix
'''


class RotationApp(App):
    def build(self):
        root = Builder.load_string(kv)
        btn = root.children[0]
        with btn.canvas.before:
            PushMatrix()
            rotate = Rotate(angle=45)
        with btn.canvas.after:
            PopMatrix()
        def update_rotate(w, center):
            rotate.origin = center
        btn.bind(center=update_rotate)
        return root

RotationApp().run()

Excellent, thanks!!!