switch frame with tkinter - python-3.x

Question

I use following code:
Switch between two frames in tkinter
import RPi.GPIO as GPIO
from threading import Timer,Thread,Event
import tkinter as tk # python 3
from tkinter import font as tkfont # python 3
#import Tkinter as tk # python 2
#import tkFont as tkfont # python 2
#----------------------------------------------------------
#Setup GPIO
#----------------------------------------------------------
GPIO.setwarnings(False)
# RPi.GPIO Layout verwenden (wie Pin-Nummern)
#GPIO.setmode(GPIO.BOARD)
GPIO.setmode(GPIO.BCM)
# (GPIO 17,27,22,5) auf Input setzen
chan_list1 = [17, 27, 22, 5]
GPIO.setup(chan_list1, GPIO.IN, pull_up_down=GPIO.PUD_UP)
# (GPIO 12,13,23,24) auf Output setzen
chan_list = [12, 13, 23, 24]
GPIO.setup(chan_list, GPIO.OUT)
#----------------------------------------------------------
#--------------------------------------------------------
#Timer
#--------------------------------------------------------
class perpetualTimer():
def __init__(self,t,hFunction):
self.t=t
self.hFunction = hFunction
self.thread = Timer(self.t,self.handle_function)
def handle_function(self):
self.hFunction()
self.thread = Timer(self.t,self.handle_function)
self.thread.start()
def start(self):
self.thread.start()
def cancel(self):
self.thread.cancel()
#--------------------------------------------------------
class SampleApp(tk.Tk):
def __init__(self, *args, **kwargs):
tk.Tk.__init__(self, *args, **kwargs)
self.overrideredirect(1) #Remove Title bar
self.geometry("480x272") #Set the window dimensions
self.title_font = tkfont.Font(family='Helvetica', size=18, weight="bold", slant="italic")
# the container is where we'll stack a bunch of frames
# on top of each other, then the one we want visible
# will be raised above the others
container = tk.Frame(self)
container.pack(side="top", fill="both", expand=True)
container.grid_rowconfigure(0, weight=1)
container.grid_columnconfigure(0, weight=1)
self.frames = {}
for F in (StartPage, PageOne, PageTwo):
page_name = F.__name__
frame = F(parent=container, controller=self)
self.frames[page_name] = frame
# put all of the pages in the same location;
# the one on the top of the stacking order
# will be the one that is visible.
frame.grid(row=0, column=0, sticky="nsew")
self.show_frame("StartPage")
def show_frame(self, page_name):
'''Show a frame for the given page name'''
frame = self.frames[page_name]
frame.tkraise()
class StartPage(tk.Frame):
def __init__(self, parent, controller):
tk.Frame.__init__(self, parent)
self.controller = controller
label = tk.Label(self, text="This is the start page", font=controller.title_font)
label.pack(side="top", fill="x", pady=10)
button1 = tk.Button(self, text="Go to Page One",
command=lambda: controller.show_frame("PageOne"))
button2 = tk.Button(self, text="Go to Page Two",
command=lambda: controller.show_frame("PageTwo"))
button1.pack()
button2.pack()
class PageOne(tk.Frame):
def __init__(self, parent, controller):
tk.Frame.__init__(self, parent)
self.controller = controller
label = tk.Label(self, text="This is page 1", font=controller.title_font)
label.pack(side="top", fill="x", pady=10)
button = tk.Button(self, text="Go to the start page",
command=lambda: controller.show_frame("StartPage"))
button.pack()
class PageTwo(tk.Frame):
def __init__(self, parent, controller):
tk.Frame.__init__(self, parent)
self.controller = controller
label = tk.Label(self, text="This is page 2", font=controller.title_font)
label.pack(side="top", fill="x", pady=10)
button = tk.Button(self, text="Go to the start page",
command=lambda: controller.show_frame("StartPage"))
button.pack()
def printer():
print ('PIT(!)')
SampleApp.show_frame('PageOne')
if __name__ == "__main__":
t = perpetualTimer(0.01,printer)
t.start()
app = SampleApp()
app.mainloop()
Is it possible to switch the frames without using buttons?
e.g. comparing a counter. if the counter value is 1 show page 1
if counter value is 2 show page 2 and so on.
If I'm honest, I do not remember exactly what I've all tried.
One thing I tried was "controller.show_frame("StartPage")" from def printer sub.
What I want to achieve is to switch the pages from the "def printer" sub,
which is called periodically.
I do not know if that's possible?

Answer 1

One thing I tried was controller.show_frame("StartPage") from def printer sub.
You have to call switch_frame on the object that has that method. This is no different than any other object or any other class in python.
In your case, since SampleApp is the class that has the method, and app is a global variable that holds an instance of the class, you would do it this way:
app.show_frame("StartPage")