PySimpleGUI/DemoPrograms/Demo_Image_Elem_Image_Viewer_PIL_Based.py

import PySimpleGUI as sg
# import PySimpleGUIQt as sg
import os.path
import PIL.Image
import io
import base64

"""
    Demo for displaying any format of image file.
    
    Normally tkinter only wants PNG and GIF files.  This program uses PIL to convert files
    such as jpg files into a PNG format so that tkinter can use it.
    
    The key to the program is the function "convert_to_bytes" which takes a filename or a 
    bytes object and converts (with optional resize) into a PNG formatted bytes object that
    can then be passed to an Image Element's update method.  This function can also optionally
    resize the image.
    
    Copyright 2020 PySimpleGUI.org
"""



def convert_to_bytes(file_or_bytes, resize=None):
    '''
    Will convert into bytes and optionally resize an image that is a file or a base64 bytes object.
    Turns into  PNG format in the process so that can be displayed by tkinter
    :param file_or_bytes: either a string filename or a bytes base64 image object
    :type file_or_bytes:  (Union[str, bytes])
    :param resize:  optional new size
    :type resize: (Tuple[int, int] or None)
    :return: (bytes) a byte-string object
    :rtype: (bytes)
    '''
    if isinstance(file_or_bytes, str):
        img = PIL.Image.open(file_or_bytes)
    else:
        try:
            img = PIL.Image.open(io.BytesIO(base64.b64decode(file_or_bytes)))
        except Exception as e:
            dataBytesIO = io.BytesIO(file_or_bytes)
            img = PIL.Image.open(dataBytesIO)

    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.LANCZOS)
    with io.BytesIO() as bio:
        img.save(bio, format="PNG")
        del img
        return bio.getvalue()



# --------------------------------- Define Layout ---------------------------------

# First the window layout...2 columns

left_col = [[sg.Text('Folder'), sg.In(size=(25,1), enable_events=True ,key='-FOLDER-'), sg.FolderBrowse()],
            [sg.Listbox(values=[], enable_events=True, size=(40,20),key='-FILE LIST-')],
            [sg.Text('Resize to'), sg.In(key='-W-', size=(5,1)), sg.In(key='-H-', size=(5,1))]]

# For now will only show the name of the file that was chosen
images_col = [[sg.Text('You choose from the list:')],
              [sg.Text(size=(40,1), key='-TOUT-')],
              [sg.Image(key='-IMAGE-')]]

# ----- Full layout -----
layout = [[sg.Column(left_col, element_justification='c'), sg.VSeperator(),sg.Column(images_col, element_justification='c')]]

# --------------------------------- Create Window ---------------------------------
window = sg.Window('Multiple Format Image Viewer', layout,resizable=True)

# ----- Run the Event Loop -----
# --------------------------------- Event Loop ---------------------------------
while True:
    event, values = window.read()
    if event in (sg.WIN_CLOSED, 'Exit'):
        break
    if event == sg.WIN_CLOSED or event == '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-':    # A file was chosen from the listbox
        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
            window['-IMAGE-'].update(data=convert_to_bytes(filename, resize=new_size))
        except Exception as E:
            print(f'** Error {E} **')
            pass        # something weird happened making the full filename
# --------------------------------- Close & Exit ---------------------------------
window.close()