added drawing polygon example

Demos/draw_polygon/draw_polygon.py

@@ -0,0 +1,22 @@
+#!/usr/bin/env python
+import Image
+import ImageDraw
+
+BLACK = "#000000"
+WHITE = "#ffffff"
+RED = "#ff0000"
+bg_color = WHITE
+
+
+canvas_w, canvas_h = 100, 100
+im = Image.new(mode = "RGB", size = (canvas_w, canvas_h), color = bg_color)
+
+draw = ImageDraw.Draw(im = im)
+
+#xy = (p1_x, p1_y)
+#or
+#xy = (p1_x, p1_y, p2_x, p2_y, p3_x, p3_y)
+
+xy = ((10, 10), (40, 10), (55, 35), (40,50))
+draw.polygon(xy = xy, fill = RED, outline = BLACK)
+im.save("draw_polygon.jpeg")