Tkinter threading use of change pages in a GUI

Question

I want to have two live plots on two pages in a tkinter GUI with buttons to stop the live updating. So far I've managed to create one live plot in my first page. However, I have problems with creating threads inside other functions.

api = csb.SeaBreezeAPI()
devices = list_devices() #to get the serial number of the device

spec = sb.Spectrometer.from_serial_number("FLMS15412")

xs = spec.wavelengths()
ys = spec.intensities()

fig1 = Figure(figsize=(10,6),tight_layout=True)
ax1 = fig1.add_subplot(111)

root = tk.Tk()
root.configure(background = 'light blue')
root.geometry("1400x800")

canvas1=FigureCanvasTkAgg(fig1,master=root)
canvas1.get_tk_widget().place(x=5,y=55) 

cond = False
def starts():                 
    root.after(1,starts)

cond = False
def plot_data():
    if (cond == True):
        ax1.cla()
        ax1.plot(spec.wavelengths(),spec.intensities
        (correct_dark_counts=True),'w',linewidth=1.0)
        ax1.set_xlabel('Wavelength (nm)')
        ax1.set_ylabel('Intensity (a.u.)')
        ax1.set_xlim(200,1000)
        ax1.set_ylim(0,60000) 
        ax1.set_facecolor('#1B1B2A')
        ax1.grid(color='w',linestyle='--',linewidth=0.2)
        canvas1.draw()
    root.after(1,plot_data)    
   
def plot_start():
    global cond
    cond = True

def plot_stop():
    global cond
    cond = False

root.update()
startplot = tk.Button(root, text = "Start", font = ('calibri', 12), command = lambda: plot_start())
startplot.place(x=5,y=25)

root.update()
stopplot = tk.Button(root, text = "Stop", font = ('calibri', 12), command = lambda: plot_stop())
stopplot.place(x=65,y=25)

root.update()
start = tk.Button(root, text = "Stage", font = ('calibri', 12), 
command=threading.Thread(target=plot_data).start())
start.place(x=125,y=25)

threading.Thread(target=plot_data).start()

root.after(1,plot_data)
root.mainloop()

This is a minimal code for the live plot in a single page. I want to create another page with another live plot. How can I do that with tkinter. Any help would be appreciated.

Answer 1

Here is an example of how You can plot values to windows (not sure if this is what @TheLizzard said not to do, but this works (at least it seems so)):

from tkinter import Tk, Toplevel, Label, StringVar, Button
from _thread import start_new_thread
from time import sleep


def update_root():
    counter = 0
    while True:
        root_var.set(f'{counter}')
        sleep(0.2)
        counter += 1


def update_tp():
    counter = 0
    while True:
        tp_var.set(f'{counter}')
        sleep(0.2)
        counter += 1


def second_window():
    tp = Toplevel(root)
    tp.title('Window 2')
    tp_label = Label(tp, textvariable=tp_var, font='default 20 normal')
    tp_label.pack(padx=200, pady=50)


root = Tk()
root.title('Window 1')

root_var = StringVar()
root_label = Label(root, textvariable=root_var, font='default 20 normal')
root_label.pack(padx=200, pady=50)

Button(root, text='Open other window', command=second_window).pack()

tp_var = StringVar()

start_new_thread(update_root, ())
start_new_thread(update_tp, ())

root.mainloop()

Some of the code is just for the looks, but the main part is the two functions. They run on separate threads and just update the textvariable which makes it pretty easy. Also remember to put some pause between loops (like I have done with sleep(0.2)) otherwise running just the while loop will freeze the GUI (values will be updated but it won't be possible to interact with it)