ImageTrace.py

#==============================================================================
#
#					Image Tracer Python Program 
#					Written by Dom Amato 9/3/2015
#
#==============================================================================

#==============================================================================
# import all our modules

import pygame.display as disp
import pygame.image as img
import pygame.color as color
from time import sleep
import RPi.GPIO as GPIO
from sys import exit
import xml.etree.ElementTree as ET
from threading import Timer
import glob
import os

#==============================================================================
# our board numbering, we should use BCM to preserve things across hardware
GPIO.setmode(GPIO.BCM)

#==============================================================================
# heres all the XML settings lets break them out into parts
print "Parsing XML"
tree = ET.parse('/boot/images/settings.xml')
root = tree.getroot()
setup = root.find('setup_IO_pins')
input = setup.find('input')
output = setup.find('output')
control = root.find('Control')


#==============================================================================
# all our dictionaries and lists
input_pins = [] #we dont have to search these so lists are good
output_pins = []


#these need to be searchable so we make them dictionaries 
controls = {}

cur_pos = 0
next_img = 0
prev_img = 0
img_files = glob.glob("/boot/Images/*.jpeg") + glob.glob("/boot/Images/*.jpg")
print "Images: "
print img_files

#==============================================================================
# setup our display and images
disp.init()
d_surf = disp.set_mode((0, 0))

i_surf = img.load(img_files[cur_pos])


#==============================================================================
# take the settings and make it usable 
print "Parsing Input Pins"
for pins in input.findall('pin'):
	#this is ugly but it gives us a list of tuples of the pin and its state
	input_pins.append((int(pins.text), pins.get('type')))
	#what are the buttons  
	if (pins.get('next') != None):
		next_img = int(pins.text)
	if (pins.get('previous') != None):
		prev_img = int(pins.text)
	print "\t{}, {}".format(int(pins.text), pins.get('type'))

print "Buttons - Next:{} Previous: {}".format(next_img, prev_img)
	
print "Parsing Output Pins"	
for pins in output.findall('pin'):
	#this is ugly but it gives us a list of tuples of the pin and its state
	output_pins.append((int(pins.text), pins.get('state')))
	print "\t{}, {}".format(int(pins.text), pins.get('state'))

print "Parsing Output Pin Control"	
for outputs in control.findall('Output'):
	#a dictionary that holds a tuple/pair 
	controls[int(outputs.get('trigger'))] = (int(outputs.find('pin').text),(int(outputs.find('duration').text) if int(outputs.find('duration').text) > 0 else 0))
	print "\tOutput {}, duration {}, trigger {}".format(int(outputs.find('pin').text), (int(outputs.find('duration').text) if int(outputs.find('duration').text) > 0 else 0), int(outputs.get('trigger')))

	
#=============================================================================   
# we need to handle the threaded callbacks here   

def input_callback(channel):
	global cur_pos
	print "{}, {}".format("Pin triggered", channel)
	
	if(channel == next_img):
		cur_pos = (cur_pos+1) % len(img_files)
		
	if(channel == prev_img):
		cur_pos = (cur_pos-1) % len(img_files)
	
	i_surf = img.load(img_files[cur_pos])
	d_surf.fill(color.Color(0,0,0))
	d_surf.blit(i_surf,(0,0))
	
	disp.update()
	
	#check if its an output pin
	if(channel in controls):
		#get the current state of the pin and invert it
		state = GPIO.input(controls[channel][0])
		GPIO.output(controls[channel][0], not(state))
		if(controls[channel][1] > 0):
			#check if the pin isn't a toggle
			Timer(controls[channel][1]/1000.0, reset_pin, [controls[channel][0], state]).start()
			
def reset_pin(channel, state):
	GPIO.output(channel, state)

#==============================================================================
#setup pins here
print "Setting up input pins"
for pins in input_pins:
   if (pins[1].upper() == 'PULLUP'):
		GPIO.setup(pins[0], GPIO.IN, pull_up_down=GPIO.PUD_UP)
		GPIO.add_event_detect(pins[0], GPIO.FALLING, callback=input_callback, bouncetime=200) 
		
   else: #we just assume if not declared its a pull down pin 
		GPIO.setup(pins[0], GPIO.IN, pull_up_down=GPIO.PUD_DOWN)
		GPIO.add_event_detect(pins[0], GPIO.RISING, callback=input_callback, bouncetime=200) 

print "Setting up output pins"
for pins in output_pins:
	if (pins[1].upper() == 'HIGH'):
		GPIO.setup(pins[0], GPIO.OUT, initial=GPIO.HIGH)
	else:
		GPIO.setup(pins[0], GPIO.OUT, initial=GPIO.LOW)
   
			
#==============================================================================
#our infinite loop to run everything
print "Starting infinite loop"
#we have to change the working directory or 
#it defaults to wherever called the script
os.chdir("/boot/images")
print "{}: {}".format("Current Directory", os.getcwd())

d_surf.blit(i_surf,(0,0))
disp.toggle_fullscreen()
disp.update()

while True:
	try:   
		#button presses are threaded so not handled in main loop
		#same with image and updates
		sleep(.01)
	except KeyboardInterrupt:
		GPIO.cleanup()
		disp.quit()
		exit()