#
# hello.light.45.py
#
# receive and display light level
#
# Neil Gershenfeld
# CBA MIT 10/24/07
#
# Modified by Kate Hollenbach -- uses light level to control reading lights
# for a cartoon character.
#
# (c) Massachusetts Institute of Technology 2007
# Permission granted for experimental and personal use;
# license for commercial sale available from MIT
#

from Tkinter import *
import serial

WINDOW = 600
eps = 0.1
saveflag = 0
filter = 0.0


def idle(parent,canvas):
   global saveflag, filter, eps
   #
   # idle routine
   #
   byte2 = 0
   byte3 = 0
   byte4 = 0
   ser.flush()
   while 1:
      #
      # find framing 
      #
      byte1 = byte2
      byte2 = byte3
      byte3 = byte4
      byte4 = ord(ser.read())
      if ((byte1 == 1) & (byte2 == 2) & (byte3 == 3) & (byte4 == 4)):
         break
   low = ord(ser.read())
   high = ord(ser.read())
   value = 256*high + low
   filter = (1-eps)*filter + eps*value
   x = int(.2*WINDOW + (.9-.2)*WINDOW*filter/1024.0)
   canvas.itemconfigure("text",text="%.1f"%filter)
   # set background color.
   # white for white light is very bright.
   # black when not bright. 
   # and shades of gray in between.
   grey = 255 - filter/4.0
   if (grey < 0):
      grey = 0
   elif (grey > 255):
      grey = 255
   colorstring = "#%(val)X%(val)X%(val)X" % {'val':grey}
   canvas.itemconfig('rect1', fill=colorstring)
   canvas.update()
   parent.after_idle(idle,parent,canvas)

#
# open serial port
#
ser = serial.Serial('/dev/ttyS0',9600)
ser.setDTR()
#
# set up GUI
#
root = Tk()
root.title('hello.light.45.py (q to exit)')
root.bind('q','exit')
canvas = Canvas(root, width=WINDOW, height=WINDOW, background='white')
canvas.create_text(.1*WINDOW,.125*WINDOW,text=".33",font=("Helvetica", 24),tags="text",fill="black")
canvas.create_rectangle(25,0,WINDOW, WINDOW, tags='rect1', fill='#b00000')
photo = PhotoImage(file="bear.gif")
canvas.create_image(0, 0, anchor=NW, image=photo)

canvas.pack()
#
# start idle loop
#
root.after(100,idle,root,canvas)
root.mainloop()