pc-pygame.py

import threading
import time
import serial
import sys
import pygame

class FeederThread(threading.Thread):
  running = True
  addPoint = None
  average = 40
  
  def getReading(self):
    x = self.s.readline()
    k = x.split()
    if len(k)<2:
      print "yuck, got", x
      return self.getReading()

    try:
      return int(k[0]) - int(k[1])
    except ValueError:
      print "yuck, got ", x
      return self.getReading()  

  def averageReadings(self, average):
    sum = 0.0
    for i in xrange(average):
      sum += self.getReading()
    return sum / average

  zero = 132.201
  slope = 1.5465

  def readingToPounds(self, x):
    return (x - self.zero)/self.slope

  def run(self):
    self.s = serial.Serial("/dev/ttyUSB0", 115200)
    self.s.readline()
    
    print "Measuring zero..."
    self.zero = self.averageReadings(1000)
    print "OK, zero = ", self.zero
    
    while self.running:
      k = self.averageReadings(self.average)
      k = self.readingToPounds(k)
      
      if self.addPoint:
        self.addPoint(k)






class Plotter:
  bgcolor = (255,255,255)
  linecolor = (0,0,255)
  linewidth = 3
  textcolor = (0,0,0)
  textsize = 30
  
  def handleEvents(self):
    for event in pygame.event.get():
      if event.type is pygame.QUIT:
        self.feeder.running = False
        sys.exit()
      elif event.type is pygame.MOUSEBUTTONDOWN:
        self.clearHistory()

  def clearHistory(self):
    self.history = [0.0 for x in xrange(self.width)]

  def generatePoints(self):
    history = self.history
    return [(i, self.verticalTransform(history[i])) for i in xrange(len(history))]

  def addPoint(self, q):
    if self.history:
      self.history.pop(0)
      self.history.append(q)

  def __init__(self, feeder):
    self.size = self.width, self.height = 640,480
    self.feeder = feeder
    self.clearHistory()
    self.feeder.addPoint = self.addPoint

  def calculateVerticalScale(self):
    self.top = max(max(self.history), 0)
    self.bot = min(min(self.history), 0)
    rg = (self.top-self.bot) * 1.2
    
    if rg > 0:
      self.vscale = self.height / rg
      self.vzero = int(self.height *((self.top-0)/(self.top-self.bot) + 0.1)/1.2)
    else:
      self.vscale = 1
      self.vzero = self.height / 2


  def verticalTransform(self, q):
    return self.vzero - self.vscale * q

  ### Main init code
  def main(self):
    # set up display
    pygame.init()
    pygame.font.init()
    screen = pygame.display.set_mode(self.size)

    # set up feeder
    self.feeder.start()
    
    #background = pygame.Surface(self.size).convert_alpha()
    #background.fill(self.bgcolor)
    background = pygame.image.load("background.jpg").convert_alpha()
    
    font = pygame.font.SysFont("Verdana", self.textsize)
    
    k = 0
    while True:
      # set up axes
      self.calculateVerticalScale()
      
      # draw stuff to screen
      #   background
      screen.blit(background, (0,0))
      #   data points
      pygame.draw.lines(screen, self.linecolor, False, self.generatePoints(), self.linewidth)
      #   text
      content = "Current reading: %.2f pounds" % self.history[-1]
      text = font.render(content, True, self.textcolor)
      textsize0 = font.size(content)
      screen.blit(text, ((self.width - textsize0[0])/2,10))

      content = "Peak reading: %.2f pounds" % max(self.history)
      text = font.render(content, True, self.textcolor)
      textsize1 = font.size(content)
      screen.blit(text, ((self.width - textsize1[0])/2,10 + textsize0[1] + 10))

      content = "Click anywhere to clear history!"
      text = font.render(content, True, self.textcolor)
      textsize2 = font.size(content)
      screen.blit(text, ((self.width - textsize2[0])/2,self.height-textsize2[1]-10))
      
      # done drawing... doublebuffer!
      pygame.display.flip()
      
      self.handleEvents()




    
if __name__ == "__main__":
  feeder = FeederThread()
  if len(sys.argv)>1:
    feeder.average = int(sys.argv[1])
  plotter = Plotter(feeder)
  plotter.main()