Tkinter: Show slideshow for images in a given directory (recursively) in cycle

slideshow.py

#!/usr/bin/env python
"""Show slideshow for images in a given directory (recursively) in cycle.

If no directory is specified, it uses the current directory.
"""
import logging
import os
import platform
import sys
from collections import deque
from itertools import cycle

try:
    import tkinter as tk
except ImportError:  # Python 2
    import Tkinter as tk  # $ sudo apt-get install python-tk

from PIL import Image  # $ pip install pillow
from PIL import ImageTk

psutil = None  # avoid "redefinition of unused 'psutil'" warning
try:
    import psutil
except ImportError:
    pass

debug = logging.debug


class Slideshow(object):

    def __init__(self, parent, filenames, slideshow_delay=2, history_size=100):
        self.ma = parent.winfo_toplevel()
        self.filenames = cycle(filenames)  # loop forever
        self._files = deque(maxlen=history_size)  # for prev/next files
        self._photo_image = None  # must hold reference to PhotoImage
        self._id = None  # used to cancel pending show_image() callbacks
        self.imglbl = tk.Label(parent)  # it contains current image
        # label occupies all available space
        self.imglbl.pack(fill=tk.BOTH, expand=True)

        # start slideshow on the next tick
        self.imglbl.after(1, self._slideshow, slideshow_delay * 1000)

    def _slideshow(self, delay_milliseconds):
        self._files.append(next(self.filenames))
        self.show_image()
        self.imglbl.after(delay_milliseconds, self._slideshow,
                          delay_milliseconds)

    def show_image(self):
        filename = self._files[-1]
        debug("load %r", filename)
        image = Image.open(filename)  # note: let OS manage file cache

        # shrink image inplace to fit in the application window
        w, h = self.ma.winfo_width(), self.ma.winfo_height()
        if image.size[0] > w or image.size[1] > h:
            # note: ImageOps.fit() copies image
            # preserve aspect ratio
            if w < 3 or h < 3:  # too small
                return  # do nothing
            image.thumbnail((w - 2, h - 2), Image.ANTIALIAS)
            debug("resized: win %s >= img %s", (w, h), image.size)

        # note: pasting into an RGBA image that is displayed might be slow
        # create new image instead
        self._photo_image = ImageTk.PhotoImage(image)
        self.imglbl.configure(image=self._photo_image)

        # set application window title
        self.ma.wm_title(filename)

    def _show_image_on_next_tick(self):
        # cancel previous callback schedule a new one
        if self._id is not None:
            self.imglbl.after_cancel(self._id)
        self._id = self.imglbl.after(1, self.show_image)

    def next_image(self, event_unused=None):
        self._files.rotate(-1)
        self._show_image_on_next_tick()

    def prev_image(self, event_unused=None):
        self._files.rotate()
        self._show_image_on_next_tick()

    def fit_image(self, event=None, _last=[None] * 2):
        """Fit image inside application window on resize."""
        if event is not None and event.widget is self.ma and (
                _last[0] != event.width or _last[1] != event.height):
            # size changed; update image
            _last[:] = event.width, event.height
            self._show_image_on_next_tick()


def get_image_files(rootdir):
    for path, dirs, files in os.walk(rootdir):
        dirs.sort()  # traverse directory in sorted order (by name)
        files.sort()  # show images in sorted order
        for filename in files:
            if filename.lower().endswith('.jpg'):
                yield os.path.join(path, filename)


def main():
    logging.basicConfig(format="%(asctime)-15s %(message)s",
                        datefmt="%F %T",
                        level=logging.DEBUG)

    root = tk.Tk()
    if logging.getLogger().isEnabledFor(logging.DEBUG) and psutil is not None:

        def report_usage(prev_meminfo=None, p=psutil.Process(os.getpid())):
            # find max memory
            if p.is_running():
                meminfo = p.memory_info()
                if (meminfo != prev_meminfo and
                        (prev_meminfo is None or
                         meminfo.rss > prev_meminfo.rss)):
                    prev_meminfo = meminfo
                    debug(meminfo)
                root.after(500, report_usage, prev_meminfo)  # report in 0.5s

        report_usage()

    # get image filenames
    imagedir = sys.argv[1] if len(sys.argv) > 1 else '.'
    image_filenames = get_image_files(imagedir)

    # configure initial size
    if platform.system() == "Windows":
        root.wm_state('zoomed')  # start maximized
    else:
        width, height, xoffset, yoffset = 400, 300, 0, 0
        # double-click the title bar to maximize the app
        # or uncomment:

        # # remove title bar
        # root.overrideredirect(True) # <- this makes it hard to kill
        # width, height = root.winfo_screenwidth(), root.winfo_screenheight()
        root.geometry("%dx%d%+d%+d" % (width, height, xoffset, yoffset))

    try:  # start slideshow
        app = Slideshow(root, image_filenames, slideshow_delay=2)
    except StopIteration:
        sys.exit("no image files found in %r" % (imagedir, ))

    # configure keybindings
    root.bind("<Escape>", lambda _: root.destroy())  # exit on Esc
    root.bind('<Prior>', app.prev_image)
    root.bind('<Up>', app.prev_image)
    root.bind('<Left>', app.prev_image)
    root.bind('<Next>', app.next_image)
    root.bind('<Down>', app.next_image)
    root.bind('<Right>', app.next_image)

    root.bind("<Configure>", app.fit_image)  # fit image on resize
    root.focus_set()
    root.mainloop()


if __name__ == '__main__':
    main()

memory_info() is not working on Python 2.7.6 (I guess any Python 2?). To make it work in my version I had to replace it with get_memory_info(). I guess memory_info is for Python 3

@ederollora the shebang is python -- it means that the code works on Python 2 and on Python 3. There is definitely psutil.Process. memory_info() method.

get_memory_info is an old name for memory_info.
It is not about Python version. It is about psutil version. get_memory_info is deprecated since psutil 2.0 (in 2014).