PySimpleGUI/DemoPrograms/Demo_Matplotlib_Image_Elem_Spetrogram_Animated_Threaded.py

import PySimpleGUI as sg
import numpy as np
from matplotlib.backends.backend_tkagg import FigureCanvasAgg
import matplotlib.pyplot as plt
import io
import time

"""
    Demo_Matplotlib_Image_Elem_Spetrogram_Animated_Threaded Demo

    Demo to show
        * How to use an Image element to show a Matplotlib figure
        * How to draw a Spectrogram
        * How to animate the drawing by simply erasing and drawing the entire figure
        * How to communicate between a thread and the GUI

    The point here is to keep things simple to enable you to get started.

    NOTE:
        This threaded technique with matplotlib hasn't been thoroughly tested.
        There may be resource leaks for example.  Have run for several hundred seconds
        without problems so it's perhaps safe as written.

    The example static graph can be found in the matplotlib gallery:
    https://matplotlib.org/stable/gallery/images_contours_and_fields/specgram_demo.html        

    Copyright 2021, 2022 PySimpleGUI
"""

np.random.seed(19801)


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# oooooooooooooooooooooooooooooooooooooooooo of your Matplotlib code


def the_thread(window: sg.Window):
    """
    The thread that communicates with the application through the window's events.

    Because the figure creation time is greater than the GUI drawing time, it's safe
    to send a non-regulated stream of events without fear of overrunning the communication queue
    """
    while True:
        fig = your_matplotlib_code()
        buf = draw_figure(fig)
        window.write_event_value('-THREAD-', buf)  # Data sent is a tuple of thread name and counter


def your_matplotlib_code():
    # The animated part of this is the t_lower, t_upper terms as well as the entire dataset that's graphed.
    # An entirely new graph is created from scratch every time... implying here that optimization is possible.
    if not hasattr(your_matplotlib_code, 't_lower'):
        your_matplotlib_code.t_lower = 10
        your_matplotlib_code.t_upper = 12
    else:
        your_matplotlib_code.t_lower = (your_matplotlib_code.t_lower + .5) % 18
        your_matplotlib_code.t_upper = (your_matplotlib_code.t_upper + .5) % 18

    dt = 0.0005
    t = np.arange(0.0, 20.0, dt)
    s1 = np.sin(2 * np.pi * 100 * t)
    s2 = 2 * np.sin(2 * np.pi * 400 * t)

    # create a transient "chirp"
    # s2[t <= 5] = s2[15 <= t] = 0      # original line of code (not animated)
    # If running the animation, use the t_lower and t_upper values
    s2[t <= your_matplotlib_code.t_lower] = s2[your_matplotlib_code.t_upper <= t] = 0

    # add some noise into the mix
    nse = 0.01 * np.random.random(size=len(t))

    x = s1 + s2 + nse  # the signal
    NFFT = 1024  # the length of the windowing segments
    Fs = int(1.0 / dt)  # the sampling frequency

    fig, (ax2) = plt.subplots(nrows=1)
    # ax1.plot(t, x)
    Pxx, freqs, bins, im = ax2.specgram(x, NFFT=NFFT, Fs=Fs, noverlap=900)

    return fig


#  88888888b                dP
#  88                       88
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#  88        88'  `88 88'  `88
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# ooooooooooooooooooooooooooooo of your Matplotlib code


# ooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooo


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# 88     88           88
# 88aaaaa88a .d8888b. 88  88d888b. .d8888b. 88d888b.
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# dP     dP  `88888P' dP  88Y888P' `88888P' dP
# ooooooooooooooooooooooo~88~oooooooooooooooooooooooo function starts here
#                         dP

def draw_figure(figure):
    """
    Draws the previously created "figure" in the supplied Image Element

    :param figure: a Matplotlib figure
    :return: BytesIO object
    """

    plt.close('all')  # erases previously drawn plots
    canv = FigureCanvasAgg(figure)
    buf = io.BytesIO()
    canv.print_figure(buf, format='png')
    if buf is not None:
        buf.seek(0)
        # element.update(data=buf.read())
        return buf
    else:
        return None


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# d8'   `88 88     88 88
# 88        88     88 88
# 88   YP88 88     88 88
# Y8.   .88 Y8.   .8P 88
#  `88888'  `Y88888P' dP
# ooooooooooooooooooooooo


def main():
    # define the window layout
    layout = [[sg.Text('Spectrogram Animated - Threaded', font='Helvetica 24')],
              [sg.pin(sg.Image(key='-IMAGE-'))],
              [sg.T(k='-STATS-')],
              [sg.B('Animate', focus=True, k='-ANIMATE-')]]

    # create the form and show it without the plot
    window = sg.Window('Animated Spectrogram', layout, element_justification='c', font='Helvetica 14')

    counter = start_time = delta = 0
    while True:
        event, values = window.read()
        if event == sg.WIN_CLOSED:
            break
        sg.timer_start()
        if event == '-ANIMATE-':
            window['-IMAGE-'].update(visible=True)
            start_time = time.time()
            window.start_thread(lambda: the_thread(window), '-THEAD FINISHED-')
        elif event == '-THREAD-':
            plt.close('all')  # close all plots... unclear if this is required
            window['-IMAGE-'].update(data=values[event].read())
            counter += 1
            seconds_elapsed = int(time.time() - start_time)
            fps = counter / seconds_elapsed if seconds_elapsed != 0 else 1.0
            window['-STATS-'].update(f'Frame {counter} Write Time {delta} FPS = {fps:2.2} seconds = {seconds_elapsed}')
        delta = sg.timer_stop()

    window.close()


if __name__ == '__main__':
    # Newer versions of PySimpleGUI have an alias for this method that's called "start_thread" so that it's clearer what's happening
    # In case you don't have that version installed this line of code creates the alias for you
    sg.Window.start_thread = sg.Window.perform_long_operation
    main()