Tweaking a PySimpleGUI Image viewer example

image_viewer.py

# For use with /home/villares/GitHub/sketch-a-day/2022/sketch_2022_05_29

import PySimpleGUI as sg
# import PySimpleGUIQt as sg
import os.path
import PIL.Image
import io

"""
    Based on: Demo for displaying any format of image file. 
    https://github.com/PySimpleGUI/PySimpleGUI/blob/master/DemoPrograms/Demo_Image_Elem_Image_Viewer_PIL_Based.py
    Copyright 2020 PySimpleGUI.org
    LGPLv3 https://github.com/PySimpleGUI/PySimpleGUI/blob/master/license.txt    
"""

def image_as_png_bytes(file_path, resize=None):
    '''
    Open an image file and convert it into PNG formated bytes, resize optional.
    Return tuple (bytes, <dict from PIL.Image.info>)
    '''
    img = PIL.Image.open(file_path)  
    cur_width, cur_height = img.size
    if resize:
        new_width, new_height = resize
        scale = min(new_height/cur_height, new_width/cur_width)
        img = img.resize((int(cur_width*scale), int(cur_height*scale)),
                         PIL.Image.Resampling.LANCZOS)
    with io.BytesIO() as bio:
        img.save(bio, format="PNG")
        return bio.getvalue(), img.info

# --------------------------------- Define Layout ---------------------------------
# First the window layout...
left_col = [
    [sg.Text('Folder'), sg.In(size=(25,1), enable_events=True ,key='-FOLDER-'),
     sg.FolderBrowse()],  # PSG will put FolderBrowser() result into "In" field!
    [sg.Listbox(values=[], enable_events=True, size=(40,20), key='-FILE LIST-')],
    [sg.Text('Resize to'),
     sg.In(key='-W-', size=(5,1), default_text='500'),  # I added the 500 default
     sg.In(key='-H-', size=(5,1), default_text='500')]
    ]
images_col = [
    [sg.Text('Loaded from the list:')],
    [sg.Text(size=(40,1), key='-TOUT-')],
    [sg.Image(key='-IMAGE-')]  # Produces a "no data" warning at first
    ]  
third_col = [
    [sg.Multiline(key='-CODE-', size=(50, 20), disabled=True)],
    [sg.Multiline(key='-OTHER-', size=(50, 20), disabled=True)]
    ]
# ----- Full layout -----
layout = [
    [sg.Column(left_col, element_justification='c'),
     sg.VSeperator(),
     sg.Column(images_col, element_justification='c'),
     sg.VSeperator(),
     sg.Column(third_col, element_justification='c')]
    ]
# --------------------------------- Create Window ---------------------------------
window = sg.Window('Multiple Format Image Viewer', layout,resizable=True)

while True:  # run the event loop
    event, values = window.read()
    if event in (sg.WIN_CLOSED, 'Exit'):
        break
    if event == '-FOLDER-':  # Folder name was filled in, make a list of files in the folder
        folder = values['-FOLDER-']
        try:
            file_list = os.listdir(folder)  # get list of files in folder
        except:
            file_list = []
        fnames = [f for f in file_list if os.path.isfile(os.path.join(folder, f))
                  and f.lower().endswith((".png", ".jpg", "jpeg", ".tiff", ".bmp"))]
        window['-FILE LIST-'].update(fnames)
    elif event == '-FILE LIST-' and values['-FILE LIST-']:  # A file was chosen
        try:
            filename = os.path.join(values['-FOLDER-'], values['-FILE LIST-'][0])
            window['-TOUT-'].update(filename)
            if values['-W-'] and values['-H-']:
                new_size = int(values['-W-']), int(values['-H-'])
            else:
                new_size = None
            png_bytes, metadata = image_as_png_bytes(filename, resize=new_size)  
            window['-IMAGE-'].update(data=png_bytes)
            window['-CODE-'].update(metadata.pop('code', ''))
            window['-OTHER-'].update('\n'.join(f'{k}: {v}' for k, v in metadata.items()))       
        except Exception as e:
            print(f'** Error {e} **')  # failed loading the file or updating the image

window.close() # Close & Exit