add touchdebug app to show everytouch with id, pos and class.

examples/touchdebug.py

@@ -0,0 +1,50 @@
+from kivy.app import App
+from kivy.uix.widget import Widget
+from kivy.uix.label import Label
+from kivy.graphics import Color, Rectangle
+
+class Touchdebug(Widget):
+    def on_touch_down(self, touch):
+        win = self.get_parent_window()
+        ud = touch.userdata
+        with self.canvas:
+            ud['color'] = Color(1, 1, 1)
+            ud['lines'] = (
+                Rectangle(pos=(touch.x, 0), size=(1, win.height)),
+                Rectangle(pos=(0, touch.y), size=(win.width, 1)))
+
+        ud['label'] = Label()
+        self.update_touch_label(ud['label'], touch)
+        self.add_widget(ud['label'])
+
+    def on_touch_move(self, touch):
+        ud = touch.userdata
+        ud['lines'][0].pos = touch.x, 0
+        ud['lines'][1].pos = 0, touch.y
+        ud['label'].pos = touch.pos
+        self.update_touch_label(ud['label'], touch)
+
+    def on_touch_up(self, touch):
+        ud = touch.userdata
+        self.canvas.remove(ud['color'])
+        self.canvas.remove(ud['lines'][0])
+        self.canvas.remove(ud['lines'][1])
+        self.remove_widget(ud['label'])
+
+    def update_touch_label(self, label, touch):
+        label.text = 'ID: %s\nPos: (%d, %d)\nClass: %s' % (
+            touch.id,
+            touch.x,
+            touch.y,
+            touch.__class__.__name__
+        )
+        label.pos = touch.pos
+        label.size = label.texture_size[0] + 20, label.texture_size[1] + 20
+
+
+class TouchdebugApp(App):
+    def build(self):
+        return Touchdebug()
+
+if __name__ == '__main__':
+    TouchdebugApp().run()