Toggle button demo using PIL to draw the button

DemoPrograms/Demo_PIL_Toggle_Button.py

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+from io import BytesIO
+from PIL import Image, ImageDraw, ImageFont
+import PySimpleGUI as sg
+
+"""
+    Demo Toggle Buttons created using PIL
+
+    A BIG thank you to @jason990420 for his talented work creating this demo.
+
+    Demonstrates how you can draw buttons rather than using the built-in buttons
+    with the help of the PIL module.
+
+    One advantage is that the buttons will match your window's theme.
+
+    You'll find more PySimpleGUI programs featured in 
+    Mike Driscoll's PIL book - "Pillow: Image Processing with Python"
+
+    Copyright 2021 PySimpleGUI, @jason990420 
+"""
+
+
+def im_to_data(im):
+    """
+    Convert a PIL.Image.Image to a bytes image
+    :param im: Image
+    :type: PIL.Image.Image object
+    :return image in bytes
+    :type: bytes
+    """
+    with BytesIO() as buffer:
+        im.save(buffer, format='PNG')
+        data = buffer.getvalue()
+    return data
+
+
+def toggle_button(button_color=None, size=(100, 40), on=True):
+    """
+
+    :return image in bytes
+    :type: bytes
+    """
+    pad, radius, spacing = 5, 10, 5
+    w, h = size
+    c1, c2 = button_color if button_color else (sg.theme_input_background_color(), sg.theme_background_color())
+    im = Image.new("RGBA", (w, h), (255, 255, 255, 0))
+    draw = ImageDraw.Draw(im)
+    draw.rounded_rectangle((0, 0, w - 1, h - 1), fill=c1, width=3, radius=radius)
+    if on:
+        draw.rounded_rectangle((2, 2, w - size[1], h - 3), fill=c2, width=3, radius=radius)
+    else:
+        draw.rounded_rectangle((size[1], 2, w - 2, h - 3), fill=c2, width=3, radius=radius)
+
+    return im_to_data(im)
+
+
+
+
+sg.theme("dark red")
+# sg.theme("dark green 7")
+# sg.theme("dark gray 13")
+button_on = toggle_button()
+button_off = toggle_button(on=False)
+layout = [[sg.T('PIL Made Toggle Buttons')],
+          [sg.T('On'), sg.Button(image_data=button_on, button_color=(sg.theme_background_color(), sg.theme_background_color()), border_width=0, k='-B1-', metadata=True), sg.T('Off')],
+          [sg.Button(image_data=button_off, button_color=(sg.theme_background_color(), sg.theme_background_color()), border_width=0,  k='-B2-', metadata=False)]]
+
+
+window = sg.Window('PIL Buttons', layout, finalize=True, element_justification='c', use_custom_titlebar=True, font='_ 18')
+
+while True:
+
+    event, values = window.read()
+    if event in (sg.WINDOW_CLOSED, "Exit"):
+        break
+    window[event].metadata = not window[event].metadata
+    if window[event].metadata:
+        window[event].update(image_data=button_on)
+    else:
+        window[event].update(image_data=button_off)
+
+window.close()