Added script which shows simulation of ledbar

* depends on pygame, which is something like wrapper around SDL
 * it gets its input from stdin, displays it and sends it to stdout, so some other script can work with it further

host_python/demo.py

@@ -0,0 +1,75 @@
+#!/usr/bin/python
+# vim:et:sw=4:ts=4:sts=4
+
+import sys
+import getopt
+import pygame
+
+def print_usage():
+    print '''\
+USAGE:
+    %s [-n number] [-h]
+OPTIONS:
+    -n number       number of controlled boxes
+    -h --help       show this help
+''' % sys.argv[0]
+
+def read_byte():
+    r = sys.stdin.read(1)
+    if len(r) == 0: raise EOFError
+    return ord(r)
+
+def write_byte(b):
+    sys.stdout.write(chr(b))
+
+def main():
+    try:
+        opts, args = getopt.getopt(sys.argv[1:], 'n:h', ['help'])
+    except getopt.GetOptError:
+        print_usage()
+        return 1
+    if len(args):
+        print_usage()
+        return 1
+    number = 10
+    show_help = False
+    for k, v in opts:
+        if k == '-n':
+            if not v.isdigit():
+                print_usage()
+                return 1
+            number = int(v)
+        elif k == '-h' or k == '--help': show_help = True
+    if show_help:
+        print_usage()
+        return 0
+
+    pygame.init()
+    screen_size = [800, 600]
+    screen = pygame.display.set_mode(screen_size)
+    pygame.display.set_caption("ledbar demo viewer")
+    offset = 5
+    pixel_width = (screen_size[0]-offset) / number
+    try:
+        exit = False
+        while not exit:
+            for event in pygame.event.get():
+                if event.type == pygame.QUIT:
+                    exit = True
+                    continue
+            screen.fill([0, 0, 0])
+            for i in xrange(number):
+                r = read_byte()
+                g = read_byte()
+                b = read_byte()
+                pygame.draw.rect(screen, [r, g, b], [pixel_width*i, 0, pixel_width-offset, pixel_width-offset])
+                write_byte(r); write_byte(g); write_byte(b)
+            pygame.display.flip()
+    except EOFError:
+        pass
+    finally:
+        pygame.quit()
+
+    return 0
+
+sys.exit(main())