Slideshow for Raspberry Pi (or any other Python capable OS)

slideshow.py

# -*- coding: utf-8 -*-
import os, pygame, random

pygame.init()
pygame.mouse.set_visible(False)

BACKGROUND  = (0,0,0)
INTERVAL    = os.getenv('INTERVAL', 60)
IMAGEFOLDER = os.getenv('IMAGEFOLDER', 'images')

X = pygame.display.Info().current_w
Y = pygame.display.Info().current_h

size = (X, Y)

display = pygame.display.set_mode(size)

def scaleImage(img,(bx,by)):

    ix,iy = img.get_size()
    if ix > iy:
        scale_factor = bx/float(ix)
        sy = scale_factor * iy
        if sy > by:
            scale_factor = by/float(iy)
            sx = scale_factor * ix
            sy = by
        else:
            sx = bx
    else:
        scale_factor = by/float(iy)
        sx = scale_factor * ix
        if sx > bx:
            scale_factor = bx/float(ix)
            sx = bx
            sy = scale_factor * iy
        else:
            sy = by

    return pygame.transform.scale(img, (int(sx),int(sy)))

def fade(image, direction):
    for i in direction:
        image.set_alpha(i)
        display.fill(BACKGROUND)
        display.blit(image,  ( (0.5 * X) - (0.5 * image.get_width() ), (0.5 * Y) - (0.5 * image.get_height() ) ))
        pygame.display.flip()

def printLine(fontsize, text, position, background, foreground):
    font     = pygame.font.SysFont ( "", fontsize )
    line     = font.render(text, True, background, foreground)
    lineRect = line.get_rect()
    lineRect.center = position
    display.blit(line, lineRect)

### Preload Images from Image Directory and show progress
files   = os.listdir(IMAGEFOLDER)
process = 0
cache   = []
for i in files:
    if os.path.isfile(IMAGEFOLDER + "/" + i) and not i.endswith('.HEIC'):
        img = scaleImage(pygame.image.load(IMAGEFOLDER + "/" + i).convert(), size)
        cache.append(img)
        process += 1
        bar = 80 + ((X - 80) // len(files)) * process
        display.fill((0,255,0), pygame.Rect((X // 2) - (bar // 2) , (Y // 2) - (25 // 2) , bar ,25))
        printLine(20, "Loading...", ((X // 2), (Y // 2)), (0,0,0), (0,255,0))
        pygame.display.flip()
        pygame.time.delay(1000)

while True:

    display.fill(BACKGROUND)
    image = random.choice(cache)

    fade(image, range(50,255,3))
    pygame.time.delay(int(INTERVAL) * 1000)
    fade(image, range(255,50,-3))

    for event in pygame.event.get() :
        if event.type == pygame.QUIT :
            pygame.quit()
            quit()

Requires : PyGame
Run with : python slideshow.py
Optional : INTERVAL=30 IMAGEFOLDER=/home/pi/pictures python slideshow.py