Programme pour caméra sur raspberry pi ne fonctionne pas

# Point-and-shoot camera for Raspberry Pi w/camera and Adafruit PiTFT.
# This must run as root (sudo python cam.py) due to framebuffer, etc.
#
# Adafruit invests time and resources providing this open source code, 
# please support Adafruit and open-source development by purchasing 
# products from Adafruit, thanks!
#
# http://www.adafruit.com/products/998  (Raspberry Pi Model B)
# http://www.adafruit.com/products/1367 (Raspberry Pi Camera Board)
# http://www.adafruit.com/products/1601 (PiTFT Mini Kit)
# This can also work with the Model A board and/or the Pi NoIR camera.
#
# Prerequisite tutorials: aside from the basic Raspbian setup and
# enabling the camera in raspi-config, you should configure WiFi (if
# using wireless with the Dropbox upload feature) and read these:
# PiTFT setup (the tactile switch buttons are not required for this
# project, but can be installed if you want them for other things):
# http://learn.adafruit.com/adafruit-pitft-28-inch-resistive-touchscreen-display-raspberry-pi
# Dropbox setup (if using the Dropbox upload feature):
# http://raspi.tv/2013/how-to-use-dropbox-with-raspberry-pi
#
# Written by Phil Burgess / Paint Your Dragon for Adafruit Industries.
# BSD license, all text above must be included in any redistribution.

import atexit
import cPickle as pickle
import errno
import fnmatch
import io
import os
import os.path
import picamera
import pygame
import stat
import threading
import time
import yuv2rgb
from pygame.locals import *
from subprocess import call  



# UI classes ---------------------------------------------------------------

# Small resistive touchscreen is best suited to simple tap interactions.
# Importing a big widget library seemed a bit overkill.  Instead, a couple
# of rudimentary classes are sufficient for the UI elements:

# Icon is a very simple bitmap class, just associates a name and a pygame
# image (PNG loaded from icons directory) for each.
# There isn't a globally-declared fixed list of Icons.  Instead, the list
# is populated at runtime from the contents of the 'icons' directory.

class Icon:

    def __init__(self, name):
      self.name = name
      try:
        self.bitmap = pygame.image.load(iconPath + '/' + name + '.png')
      except:
        pass

# Button is a simple tappable screen region.  Each has:
#  - bounding rect ((X,Y,W,H) in pixels)
#  - optional background color and/or Icon (or None), always centered
#  - optional foreground Icon, always centered
#  - optional single callback function
#  - optional single value passed to callback
# Occasionally Buttons are used as a convenience for positioning Icons
# but the taps are ignored.  Stacking order is important; when Buttons
# overlap, lowest/first Button in list takes precedence when processing
# input, and highest/last Button is drawn atop prior Button(s).  This is
# used, for example, to center an Icon by creating a passive Button the
# width of the full screen, but with other buttons left or right that
# may take input precedence (e.g. the Effect labels & buttons).
# After Icons are loaded at runtime, a pass is made through the global
# buttons[] list to assign the Icon objects (from names) to each Button.

class Button:

    def __init__(self, rect, **kwargs):
      self.rect     = rect # Bounds
      self.color    = None # Background fill color, if any
      self.iconBg   = None # Background Icon (atop color fill)
      self.iconFg   = None # Foreground Icon (atop background)
      self.bg       = None # Background Icon name
      self.fg       = None # Foreground Icon name
      self.callback = None # Callback function
      self.value    = None # Value passed to callback
      for key, value in kwargs.iteritems():
        if   key == 'color': self.color    = value
        elif key == 'bg'   : self.bg       = value
        elif key == 'fg'   : self.fg       = value
        elif key == 'cb'   : self.callback = value
        elif key == 'value': self.value    = value

    def selected(self, pos):
      x1 = self.rect[0]
      y1 = self.rect[1]
      x2 = x1 + self.rect[2] - 1
      y2 = y1 + self.rect[3] - 1
      if ((pos[0] >= x1) and (pos[0] <= x2) and
          (pos[1] >= y1) and (pos[1] <= y2)):
        if self.callback:
          if self.value is None: self.callback()
          else:                  self.callback(self.value)
        return True
      return False

    def draw(self, screen):
      if self.color:
        screen.fill(self.color, self.rect)
      if self.iconBg:
        screen.blit(self.iconBg.bitmap,
          (self.rect[0]+(self.rect[2]-self.iconBg.bitmap.get_width())/2,
           self.rect[1]+(self.rect[3]-self.iconBg.bitmap.get_height())/2))
      if self.iconFg:
        screen.blit(self.iconFg.bitmap,
          (self.rect[0]+(self.rect[2]-self.iconFg.bitmap.get_width())/2,
           self.rect[1]+(self.rect[3]-self.iconFg.bitmap.get_height())/2))

    def setBg(self, name):
      if name is None:
        self.iconBg = None
      else:
        for i in icons:
          if name == i.name:
            self.iconBg = i
            break


# UI callbacks -------------------------------------------------------------
# These are defined before globals because they're referenced by items in
# the global buttons[] list.

def isoCallback(n): # Pass 1 (next ISO) or -1 (prev ISO)
    global isoMode
    setIsoMode((isoMode + n) % len(isoData))

def settingCallback(n): # Pass 1 (next setting) or -1 (prev setting)
    global screenMode
    screenMode += n
    if screenMode < 4:               screenMode = len(buttons) - 1
    elif screenMode >= len(buttons): screenMode = 4

def fxCallback(n): # Pass 1 (next effect) or -1 (prev effect)
    global fxMode
    setFxMode((fxMode + n) % len(fxData))

def quitCallback(): # Quit confirmation button
    saveSettings()
    raise SystemExit

def viewCallback(n): # Viewfinder buttons
    global loadIdx, scaled, screenMode, screenModePrior, settingMode, storeMode

    if n is 0:   # Gear icon (settings)
      screenMode = settingMode # Switch to last settings mode
    elif n is 1: # Play icon (image playback)
      if scaled: # Last photo is already memory-resident
        loadIdx         = saveIdx
        screenMode      =  0 # Image playback
        screenModePrior = -1 # Force screen refresh
      else:      # Load image
        r = imgRange(pathData[storeMode])
        if r: showImage(r[1]) # Show last image in directory
        else: screenMode = 2  # No images
    else: # Rest of screen = shutter
      takePicture()

def doneCallback(): # Exit settings
    global screenMode, settingMode
    if screenMode > 3:
      settingMode = screenMode
      saveSettings()
    screenMode = 3 # Switch back to viewfinder mode

def imageCallback(n): # Pass 1 (next image), -1 (prev image) or 0 (delete)
    global screenMode
    if n is 0:
      screenMode = 1 # Delete confirmation
    else:
      showNextImage(n)

def deleteCallback(n): # Delete confirmation
    global loadIdx, scaled, screenMode, storeMode
    screenMode      =  0
    screenModePrior = -1
    if n is True:
      os.remove(pathData[storeMode] + '/IMG_' + '%04d' % loadIdx + '.JPG')
      if(imgRange(pathData[storeMode])):
        screen.fill(0)
        pygame.display.update()
        showNextImage(-1)
      else: # Last image deleteted; go to 'no images' mode
        screenMode = 2
        scaled     = None
        loadIdx    = -1

def storeModeCallback(n): # Radio buttons on storage settings screen
    global storeMode
    buttons[4][storeMode + 3].setBg('radio3-0')
    storeMode = n
    buttons[4][storeMode + 3].setBg('radio3-1')

def sizeModeCallback(n): # Radio buttons on size settings screen
    global sizeMode
    buttons[5][sizeMode + 3].setBg('radio3-0')
    sizeMode = n
    buttons[5][sizeMode + 3].setBg('radio3-1')
    camera.resolution = sizeData[sizeMode][1]
#   camera.crop       = sizeData[sizeMode][2]


# Global stuff -------------------------------------------------------------

screenMode      =  3      # Current screen mode; default = viewfinder
screenModePrior = -1      # Prior screen mode (for detecting changes)
settingMode     =  4      # Last-used settings mode (default = storage)
storeMode       =  0      # Storage mode; default = Photos folder
storeModePrior  = -1      # Prior storage mode (for detecting changes)
sizeMode        =  0      # Image size; default = Large
fxMode          =  0      # Image effect; default = Normal
isoMode         =  0      # ISO settingl default = Auto
iconPath        = 'icons' # Subdirectory containing UI bitmaps (PNG format)
saveIdx         = -1      # Image index for saving (-1 = none set yet)
loadIdx         = -1      # Image index for loading
scaled          = None    # pygame Surface w/last-loaded image

# To use Dropbox uploader, must have previously run the dropbox_uploader.sh
# script to set up the app key and such.  If this was done as the normal pi
# user, set upconfig to the .dropbox_uploader config file in that account's
# home directory.  Alternately, could run the setup script as root and
# delete the upconfig line below.
uploader        = '/home/pi/Dropbox-Uploader/dropbox_uploader.sh'
upconfig        = '/home/pi/.dropbox_uploader'

sizeData = [ # Camera parameters for different size settings
 # Full res      Viewfinder  Crop window
 [(2592, 1944), (320, 240), (0.0   , 0.0   , 1.0   , 1.0   )], # Large
 [(1920, 1080), (320, 180), (0.1296, 0.2222, 0.7408, 0.5556)], # Med
 [(1440, 1080), (320, 240), (0.2222, 0.2222, 0.5556, 0.5556)]] # Small

isoData = [ # Values for ISO settings [ISO value, indicator X position]
 [  0,  27], [100,  64], [200,  97], [320, 137],
 [400, 164], [500, 197], [640, 244], [800, 297]]

# A fixed list of image effects is used (rather than polling
# camera.IMAGE_EFFECTS) because the latter contains a few elements
# that aren't valid (at least in video_port mode) -- e.g. blackboard,
# whiteboard, posterize (but posterise, British spelling, is OK).
# Others have no visible effect (or might require setting add'l
# camera parameters for which there's no GUI yet) -- e.g. saturation,
# colorbalance, colorpoint.
fxData = [
  'none', 'sketch', 'gpen', 'pastel', 'watercolor', 'oilpaint', 'hatch',
  'negative', 'colorswap', 'posterise', 'denoise', 'blur', 'film',
  'washedout', 'emboss', 'cartoon', 'solarize' ]

pathData = [
  '/home/pi/Photos',     # Path for storeMode = 0 (Photos folder)
  '/boot/DCIM/CANON999', # Path for storeMode = 1 (Boot partition)
  '/home/pi/Photos']     # Path for storeMode = 2 (Dropbox)

icons = [] # This list gets populated at startup

# buttons[] is a list of lists; each top-level list element corresponds
# to one screen mode (e.g. viewfinder, image playback, storage settings),
# and each element within those lists corresponds to one UI button.
# There's a little bit of repetition (e.g. prev/next buttons are
# declared for each settings screen, rather than a single reusable
# set); trying to reuse those few elements just made for an ugly
# tangle of code elsewhere.

buttons = [
  # Screen mode 0 is photo playback
  [Button((  0,188,320, 52), bg='done' , cb=doneCallback),
   Button((  0,  0, 80, 52), bg='prev' , cb=imageCallback, value=-1),
   Button((240,  0, 80, 52), bg='next' , cb=imageCallback, value= 1),
   Button(( 88, 70,157,102)), # 'Working' label (when enabled)
   Button((148,129, 22, 22)), # Spinner (when enabled)
   Button((121,  0, 78, 52), bg='trash', cb=imageCallback, value= 0)],

  # Screen mode 1 is delete confirmation
  [Button((  0,35,320, 33), bg='delete'),
   Button(( 32,86,120,100), bg='yn', fg='yes',
    cb=deleteCallback, value=True),
   Button((168,86,120,100), bg='yn', fg='no',
    cb=deleteCallback, value=False)],

  # Screen mode 2 is 'No Images'
  [Button((0,  0,320,240), cb=doneCallback), # Full screen = button
   Button((0,188,320, 52), bg='done'),       # Fake 'Done' button
   Button((0, 53,320, 80), bg='empty')],     # 'Empty' message

  # Screen mode 3 is viewfinder / snapshot
  [Button((  0,188,156, 52), bg='gear', cb=viewCallback, value=0),
   Button((164,188,156, 52), bg='play', cb=viewCallback, value=1),
   Button((  0,  0,320,240)           , cb=viewCallback, value=2),
   Button(( 88, 51,157,102)),  # 'Working' label (when enabled)
   Button((148, 110,22, 22))], # Spinner (when enabled)

  # Remaining screens are settings modes

  # Screen mode 4 is storage settings
  [Button((  0,188,320, 52), bg='done', cb=doneCallback),
   Button((  0,  0, 80, 52), bg='prev', cb=settingCallback, value=-1),
   Button((240,  0, 80, 52), bg='next', cb=settingCallback, value= 1),
   Button((  2, 60,100,120), bg='radio3-1', fg='store-folder',
    cb=storeModeCallback, value=0),
   Button((110, 60,100,120), bg='radio3-0', fg='store-boot',
    cb=storeModeCallback, value=1),
   Button((218, 60,100,120), bg='radio3-0', fg='store-dropbox',
    cb=storeModeCallback, value=2),
   Button((  0, 10,320, 35), bg='storage')],

  # Screen mode 5 is size settings
  [Button((  0,188,320, 52), bg='done', cb=doneCallback),
   Button((  0,  0, 80, 52), bg='prev', cb=settingCallback, value=-1),
   Button((240,  0, 80, 52), bg='next', cb=settingCallback, value= 1),
   Button((  2, 60,100,120), bg='radio3-1', fg='size-l',
    cb=sizeModeCallback, value=0),
   Button((110, 60,100,120), bg='radio3-0', fg='size-m',
    cb=sizeModeCallback, value=1),
   Button((218, 60,100,120), bg='radio3-0', fg='size-s',
    cb=sizeModeCallback, value=2),
   Button((  0, 10,320, 29), bg='size')],

  # Screen mode 6 is graphic effect
  [Button((  0,188,320, 52), bg='done', cb=doneCallback),
   Button((  0,  0, 80, 52), bg='prev', cb=settingCallback, value=-1),
   Button((240,  0, 80, 52), bg='next', cb=settingCallback, value= 1),
   Button((  0, 70, 80, 52), bg='prev', cb=fxCallback     , value=-1),
   Button((240, 70, 80, 52), bg='next', cb=fxCallback     , value= 1),
   Button((  0, 67,320, 91), bg='fx-none'),
   Button((  0, 11,320, 29), bg='fx')],

  # Screen mode 7 is ISO
  [Button((  0,188,320, 52), bg='done', cb=doneCallback),
   Button((  0,  0, 80, 52), bg='prev', cb=settingCallback, value=-1),
   Button((240,  0, 80, 52), bg='next', cb=settingCallback, value= 1),
   Button((  0, 70, 80, 52), bg='prev', cb=isoCallback    , value=-1),
   Button((240, 70, 80, 52), bg='next', cb=isoCallback    , value= 1),
   Button((  0, 79,320, 33), bg='iso-0'),
   Button((  9,134,302, 26), bg='iso-bar'),
   Button(( 17,157, 21, 19), bg='iso-arrow'),
   Button((  0, 10,320, 29), bg='iso')],

  # Screen mode 8 is quit confirmation
  [Button((  0,188,320, 52), bg='done'   , cb=doneCallback),
   Button((  0,  0, 80, 52), bg='prev'   , cb=settingCallback, value=-1),
   Button((240,  0, 80, 52), bg='next'   , cb=settingCallback, value= 1),
   Button((110, 60,100,120), bg='quit-ok', cb=quitCallback),
   Button((  0, 10,320, 35), bg='quit')]
]


# Assorted utility functions -----------------------------------------------

def setFxMode(n):
    global fxMode
    fxMode = n
    camera.image_effect = fxData[fxMode]
    buttons[6][5].setBg('fx-' + fxData[fxMode])

def setIsoMode(n):
    global isoMode
    isoMode    = n
    camera.ISO = isoData[isoMode][0]
    buttons[7][5].setBg('iso-' + str(isoData[isoMode][0]))
    buttons[7][7].rect = ((isoData[isoMode][1] - 10,) +
      buttons[7][7].rect[1:])

def saveSettings():
    try:
      outfile = open('cam.pkl', 'wb')
      # Use a dictionary (rather than pickling 'raw' values) so
      # the number & order of things can change without breaking.
      d = { 'fx'    : fxMode,
            'iso'   : isoMode,
            'size'  : sizeMode,
            'store' : storeMode }
      pickle.dump(d, outfile)
      outfile.close()
    except:
      pass

def loadSettings():
    try:
      infile = open('cam.pkl', 'rb')
      d      = pickle.load(infile)
      infile.close()
      if 'fx'    in d: setFxMode(   d['fx'])
      if 'iso'   in d: setIsoMode(  d['iso'])
      if 'size'  in d: sizeModeCallback( d['size'])
      if 'store' in d: storeModeCallback(d['store'])
    except:
      pass

# Scan files in a directory, locating JPEGs with names matching the
# software's convention (IMG_XXXX.JPG), returning a tuple with the
# lowest and highest indices (or None if no matching files).
def imgRange(path):
    min = 9999
    max = 0
    try:
      for file in os.listdir(path):
        if fnmatch.fnmatch(file, 'IMG_[0-9][0-9][0-9][0-9].JPG'):
          i = int(file[4:8])
          if(i < min): min = i
          if(i > max): max = i
    finally:
      return None if min > max else (min, max)

# Busy indicator.  To use, run in separate thread, set global 'busy'
# to False when done.
def spinner():
    global busy, screenMode, screenModePrior

    buttons[screenMode][3].setBg('working')
    buttons[screenMode][3].draw(screen)
    pygame.display.update()

    busy = True
    n    = 0
    while busy is True:
      buttons[screenMode][4].setBg('work-' + str(n))
      buttons[screenMode][4].draw(screen)
      pygame.display.update()
      n = (n + 1) % 5
      time.sleep(0.15)

    buttons[screenMode][3].setBg(None)
    buttons[screenMode][4].setBg(None)
    screenModePrior = -1 # Force refresh

def takePicture():
    global busy, gid, loadIdx, saveIdx, scaled, sizeMode, storeMode, storeModePrior, uid

    if not os.path.isdir(pathData[storeMode]):
      try:
        os.makedirs(pathData[storeMode])
        # Set new directory ownership to pi user, mode to 755
        os.chown(pathData[storeMode], uid, gid)
        os.chmod(pathData[storeMode],
          stat.S_IRUSR | stat.S_IWUSR | stat.S_IXUSR |
          stat.S_IRGRP | stat.S_IXGRP |
          stat.S_IROTH | stat.S_IXOTH)
      except OSError as e:
        # errno = 2 if can't create folder
        print errno.errorcode[e.errno]
        return

    # If this is the first time accessing this directory,
    # scan for the max image index, start at next pos.
    if storeMode != storeModePrior:
      r = imgRange(pathData[storeMode])
      if r is None:
        saveIdx = 1
      else:
        saveIdx = r[1] + 1
        if saveIdx > 9999: saveIdx = 0
      storeModePrior = storeMode

    # Scan for next available image slot
    while True:
      filename = pathData[storeMode] + '/IMG_' + '%04d' % saveIdx + '.JPG'
      if not os.path.isfile(filename): break
      saveIdx += 1
      if saveIdx > 9999: saveIdx = 0

    t = threading.Thread(target=spinner)
    t.start()

    scaled = None
    camera.resolution = sizeData[sizeMode][0]
    camera.crop       = sizeData[sizeMode][2]
    try:
      camera.capture(filename, use_video_port=False, format='jpeg',
        thumbnail=None)
      # Set image file ownership to pi user, mode to 644
      # os.chown(filename, uid, gid) # Not working, why?
      os.chmod(filename,
        stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IROTH)
      img    = pygame.image.load(filename)
      scaled = pygame.transform.scale(img, sizeData[sizeMode][1])
      if storeMode == 2: # Dropbox
        if upconfig:
          cmd = uploader + ' -f ' + upconfig + ' upload ' + filename + ' Photos/' + os.path.basename(filename)
        else:
          cmd = uploader + ' upload ' + filename + ' Photos/' + os.path.basename(filename)
        call ([cmd], shell=True)

    finally:
      # Add error handling/indicator (disk full, etc.)
      camera.resolution = sizeData[sizeMode][1]
      camera.crop       = (0.0, 0.0, 1.0, 1.0)

    busy = False
    t.join()

    if scaled:
      if scaled.get_height() < 240: # Letterbox
        screen.fill(0)
      screen.blit(scaled,
        ((320 - scaled.get_width() ) / 2,
         (240 - scaled.get_height()) / 2))
      pygame.display.update()
      time.sleep(2.5)
      loadIdx = saveIdx

def showNextImage(direction):
    global busy, loadIdx

    t = threading.Thread(target=spinner)
    t.start()

    n = loadIdx
    while True:
      n += direction
      if(n > 9999): n = 0
      elif(n < 0):  n = 9999
      if os.path.exists(pathData[storeMode]+'/IMG_'+'%04d'%n+'.JPG'):
        showImage(n)
        break

    busy = False
    t.join()

def showImage(n):
    global busy, loadIdx, scaled, screenMode, screenModePrior, sizeMode, storeMode

    t = threading.Thread(target=spinner)
    t.start()

    img      = pygame.image.load(
                pathData[storeMode] + '/IMG_' + '%04d' % n + '.JPG')
    scaled   = pygame.transform.scale(img, sizeData[sizeMode][1])
    loadIdx  = n

    busy = False
    t.join()

    screenMode      =  0 # Photo playback
    screenModePrior = -1 # Force screen refresh


# Initialization -----------------------------------------------------------

# Init framebuffer/touchscreen environment variables
os.putenv('SDL_VIDEODRIVER', 'fbcon')
os.putenv('SDL_FBDEV'      , '/dev/fb1')
os.putenv('SDL_MOUSEDRV'   , 'TSLIB')
os.putenv('SDL_MOUSEDEV'   , '/dev/input/touchscreen')

# Get user & group IDs for file & folder creation
# (Want these to be 'pi' or other user, not root)
s = os.getenv("SUDO_UID")
uid = int(s) if s else os.getuid()
s = os.getenv("SUDO_GID")
gid = int(s) if s else os.getgid()

# Buffers for viewfinder data
rgb = bytearray(320 * 240 * 3)
yuv = bytearray(320 * 240 * 3 / 2)

# Init pygame and screen
pygame.init()
pygame.mouse.set_visible(False)
screen = pygame.display.set_mode((0,0), pygame.FULLSCREEN)

# Init camera and set up default values
camera            = picamera.PiCamera()
atexit.register(camera.close)
camera.resolution = sizeData[sizeMode][1]
#camera.crop       = sizeData[sizeMode][2]
camera.crop       = (0.0, 0.0, 1.0, 1.0)
# Leave raw format at default YUV, don't touch, don't set to RGB!

# Load all icons at startup.
for file in os.listdir(iconPath):
  if fnmatch.fnmatch(file, '*.png'):
    icons.append(Icon(file.split('.')[0]))

# Assign Icons to Buttons, now that they're loaded
for s in buttons:        # For each screenful of buttons...
  for b in s:            #  For each button on screen...
    for i in icons:      #   For each icon...
      if b.bg == i.name: #    Compare names; match?
        b.iconBg = i     #     Assign Icon to Button
        b.bg     = None  #     Name no longer used; allow garbage collection
      if b.fg == i.name:
        b.iconFg = i
        b.fg     = None

loadSettings() # Must come last; fiddles with Button/Icon states


# Main loop ----------------------------------------------------------------

while(True):

  # Process touchscreen input
  while True:
    for event in pygame.event.get():
      if(event.type is MOUSEBUTTONDOWN):
        pos = pygame.mouse.get_pos()
        for b in buttons[screenMode]:
          if b.selected(pos): break
    # If in viewfinder or settings modes, stop processing touchscreen
    # and refresh the display to show the live preview.  In other modes
    # (image playback, etc.), stop and refresh the screen only when
    # screenMode changes.
    if screenMode >= 3 or screenMode != screenModePrior: break

  # Refresh display
  if screenMode >= 3: # Viewfinder or settings modes
    stream = io.BytesIO() # Capture into in-memory stream
    camera.capture(stream, use_video_port=True, format='raw')
    stream.seek(0)
    stream.readinto(yuv)  # stream -> YUV buffer
    stream.close()
    yuv2rgb.convert(yuv, rgb, sizeData[sizeMode][1][0],
      sizeData[sizeMode][1][1])
    img = pygame.image.frombuffer(rgb[0:
      (sizeData[sizeMode][1][0] * sizeData[sizeMode][1][1] * 3)],
      sizeData[sizeMode][1], 'RGB')
  elif screenMode < 2: # Playback mode or delete confirmation
    img = scaled       # Show last-loaded image
  else:                # 'No Photos' mode
    img = None         # You get nothing, good day sir

  if img is None or img.get_height() < 240: # Letterbox, clear background
    screen.fill(0)
  if img:
    screen.blit(img,
      ((320 - img.get_width() ) / 2,
       (240 - img.get_height()) / 2))

  # Overlay buttons on display and update
  for i,b in enumerate(buttons[screenMode]):
    b.draw(screen)
  pygame.display.update()

  screenModePrior = screenMode