gistfile1.py

def draw_tile(x, y, z):
	# Create a blank, transparent tile
	tile = Image.new("RGBA", (gmap.TILE_SIZE, gmap.TILE_SIZE), (0, 0, 0, 0))
	
	# Query for Zipcodess within bounding box
	rect = gmap.getTileRect(x, y, z)
	bbox = Polygon.from_bbox((rect.x, rect.y, (rect.x + rect.width), (rect.y + rect.height)))
	zipcodes = Zipcode.objects.filter(geom__intersects=bbox)
	
	# Draw polygons on tile
	for zipcode in zipcodes:
		# Set the color for this tile
		color = zipcode.color
		draw = ImageDraw.Draw(tile)
		for poly in zipcode.geom.coords[0]:
			def pixel_coords(coords):
				point = gmap.toZoomedPixelCoords(coords[1], coords[0], z)
				point.x = point.x - (gmap.TILE_SIZE * x)
				point.y = point.y - (gmap.TILE_SIZE * y)
				return (int(point.x), int(point.y))
			poly = map(pixel_coords, poly)
			draw.polygon(poly, fill=color, outline=settings.TILE_OUTLINE)
		del draw
	
	# Set opacity
	alpha = tile.split()[0]
	alpha = ImageEnhance.Brightness(alpha).enhance(settings.TILE_OPACITY)
	tile.putalpha(alpha)
	
	# Save file
	filename = "%d-%d-%d.png" % (x, y, z)
	filename = os.path.join(settings.WEB_ROOT, "tile", filename)
	tile.save(filename, "PNG")
	
	# Save tile to database
	tile = Tile(filename=filename)
	tile.save()
	if len(zipcodes) > 0:
		tile.zipcodes.add(list(zipcodes))
	tile.save()
	
	return filename