Added Scale instruction example including origin

examples/canvas/scale.py

@@ -0,0 +1,36 @@
+'''
+Scaling Example
+================
+
+This example scales a button using PushMatrix and PopMatrix. It shows
+a static button with the words 'hello world', stretched about its centre by
+a factor of 1.5 horizontally and 5 vertically.
+'''
+
+
+from kivy.app import App
+from kivy.lang import Builder
+
+kv = '''
+FloatLayout:
+
+    Button:
+        text: 'hello world'
+        size_hint: None, None
+        pos_hint: {'center_x': .5, 'center_y': .5}
+        canvas.before:
+            PushMatrix
+            Scale:
+                x: 1.5
+                y: 5
+                origin: self.center
+        canvas.after:
+            PopMatrix
+'''
+
+
+class ScalingApp(App):
+    def build(self):
+        return Builder.load_string(kv)
+
+ScalingApp().run()