Python: auto slideshow with PIL/TkInter with no saving images

Question

I´m designing a slideshow with no user intervention, where:

a. Every image is generated by the Python script itself

b. There´s no file saving, for performance reasons

c. Every image is shown in fullscreen for a certain time

d. It´s a loop that´s supposed to never end. There´s always going to be an image to show

So far, by adapting code found in a few pages, I have it running. But every image is shown for X time and then the desktop background appears for a second or so.

I´d like to have a smooth switching from one file to next, such as FEH does. As a matter of fact, I´m trying to replace FEH because I need finer control of the display of each file (for instance, changing the time it appears on screen).

Here´s my code:

from PIL import Image 
from PIL import ImageFont
from PIL import ImageDraw
from PIL import ImageTk
import tkinter

def show_center(pil_image, msDelay):
    root = tkinter.Tk()
    w, h = root.winfo_screenwidth(), root.winfo_screenheight()
    root.overrideredirect(1)
    root.geometry("%dx%d+0+0" % (w, h))
    root.focus_set()
    root.attributes("-topmost", True)
    canvas = tkinter.Canvas(root, width=w, height=h, highlightthickness=0)
    canvas.pack()
    canvas.configure(background='black')
    
    image = ImageTk.PhotoImage(pil_image)
    imagesprite = canvas.create_image(w / 2, h / 2, image=image)
    
    root.after(msDelay, root.destroy)
    
    root.mainloop()



### script body

while True:

    # loads common background image
    img = Image.open(baseImage)    
    draw = ImageDraw.Draw(img)
    
    # here: image customization
    draw.rectangle(....)
    draw.text(....)
    img.paste(....)
    
    # shows this file
    thisDelay = some Number Calculation
    show_center(img, thisDelay)

Any ideas on how to avoid the desktop appearing between images? This will run in a headless Raspberry. I´m using Python3 on Raspbian.

Thanks in advance!

Yes, it works fine. But I can see the desktop between files. It´s not very elegant for a slideshow :D — PiBer2, Dec 11 '20 at 20:45
If it is *headless*, that means X is not running. So how can this GUI script be executed successfully? — acw1668, Dec 12 '20 at 00:19
It has a monitor but no keyboard/mouse. So "headless" might be inaccurate, you are right. But the "slideshow" and "fullscreen" parts were clear, right? ;-) — PiBer2, Dec 12 '20 at 11:22

score 1 · Answer 1 · answered Dec 12 '20 at 14:34

You can use after() instead of the while loop and simply use Label instead of Canvas:

import tkinter as tk
from PIL import Image, ImageTk, ImageDraw, ImageFont
import time
import random

def update_image():
    # sample drawing
    image = base_image.copy()
    draw = ImageDraw.Draw(image)
    draw.rectangle((100, 100, 500, 400), outline=random.choice(('red', 'green', 'blue', 'magenta', 'gold', 'orange')))
    draw.text((120, 120), f"""{time.strftime("%F %T")}""")

    # update image
    tkimg = ImageTk.PhotoImage(image)
    label.config(image=tkimg)
    label.image = tkimg # save a reference to avoid garbage collected

    ms_delay = random.randint(1000, 9000) # sample delay calculation
    root.after(ms_delay, update_image)

root = tk.Tk()
root.attributes("-fullscreen", 1, "-topmost", 1)

base_image = Image.open("/path/to/base/image")

# label for showing image
label = tk.Label(root, bg="black")
label.pack(fill="both", expand=1)

update_image() # start the slide show
root.mainloop()

That´s nice. I like how you copy() the base image so it´s not required to reload from disk every time. I can´t see how you can interrupt or manipulate the mainloop(). I need to process external info that´s generated in real time and goes into every image, not just update the current time. Thanks. — PiBer2, Dec 12 '20 at 17:55
Oh, I have to process the external info **inside** update_image(), right? — PiBer2, Dec 12 '20 at 17:59

score 0 · Answer 2 · answered Dec 11 '20 at 23:50

Well, it´s working quite well.

The solution required a bit of logic (maybe it makes sense not to destroy the object for every image) and a bit of good old trial & error.

The changes were:

Init the canvas only once, use global vars to make it persistent
For every image, call the display function and keep calling root.update() until the required timeout is reached

So, the prior function gets divided, and it looks like:

global canvas, root
global w, h

    def init_image():
    
    global canvas, root
    global w, h 
        
    root = tkinter.Tk()
    w, h = root.winfo_screenwidth(), root.winfo_screenheight()
    root.overrideredirect(1)
    root.geometry("%dx%d+0+0" % (w, h))
    root.focus_set()
    root.attributes("-topmost", True)
    canvas = tkinter.Canvas(root, width=w, height=h, highlightthickness=0)
    canvas.pack()
    canvas.configure(background='black')
    return


def show_center(pil_image, msDelay):

    global canvas, root
    global w, h
    
    image = ImageTk.PhotoImage(pil_image)
    imagesprite = canvas.create_image(w / 2, h / 2, image=image)
    
    inicio = int(time.time() * 1000)
    
    while 1:
        root.update()
        if (int(time.time() * 1000) - inicio) > msDelay:
            break
    return

Function init_image() is called once at beginning, and function show_center() is called for every image as the original post.

I hope this can be useful to anybody trying to accomplish the same.

Python: auto slideshow with PIL/TkInter with no saving images

2 Answers2

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