I have a program that shows an image. Every time the user presses enter, I recalculate the image, what takes some time:
root = tk.Tk()
def callback_enter(e):
# Heavy computation
root.bind("<Return>", callback_enter)
root.mainloop()
The problem is, when the user presses enter multiple times, callback function will be called again and again, even when the user stopped pressing the button, since the program remembers all the key presses before. Is there a way callback_enter() removes all key presses, that have been done during its execution?
the problem here is that your program, while is busy with image computation, cannot interact with the main loop that is buffering input. One way to approach it is to filter events with a time frame criterium; here is an implementation as example:
import time
import random
import Tkinter as tk
root = tk.Tk()
LAST_CALL_TIME = 0
TIME_THRESHOLD = .1
def performHeavyComputation():
print("performHeavyComputation() START")
time.sleep(1 + random.random())
print("performHavyComputation() END")
def callback_enter(e):
global LAST_CALL_TIME
global TIME_THRESHOLD
t = time.time()
if t - LAST_CALL_TIME < TIME_THRESHOLD:
print("[%.3f] filtering event e:%s"%(t, e))
else:
LAST_CALL_TIME = t
performHeavyComputation()
t1 = time.time()
TIME_THRESHOLD = t1 - t + 0.1
root.bind("<Return>", callback_enter)
root.mainloop()
Related
I am displaying a sensor device's measurement values using the Tkinter GUI application. The sensor sends new data every second. I started a new thread and put the result in a Queue and process the queue to display the values on GUI. Now I am facing another problem. The sensor has two modes of operations. For simplicity, I have used a random generator in the program. Users should be able to switch the modes using two buttons. Button-1 for Mode-1, Button-2 for Mode-2. (say the mode-1 operation is random.randrange(0,10) and mode-2 operation is random.randrange(100, 200). How do I control these two operations through Threading? if a user started a mode-1 operation, when he presses the Button-2, the mode-1 operation should stop (thread-1) and mode-2 operation (thread-2) should start. Does it mean do I need to kill thread-1? Or is there any way to control two modes in same thread? I am totally new into threading. Any suggestions, please.
import tkinter
import threading
import queue
import time
import random
class GuiGenerator:
def __init__(self, master, queue):
self.queue = queue
# Set up the GUI
master.geometry('800x480')
self.output = tkinter.StringVar()
output_label = tkinter.Label(master, textvariable= self.output)
output_label.place(x=300, y=200)
#I haven't shown command parts in following buttons. No idea how to use it to witch modes?
mode_1_Button = tkinter.Button(master, text = "Mode-1")
mode_1_Button.place(x=600, y=300)
mode_2_Button = tkinter.Button(master, text = "Mode-2")
mode_2_Button.place(x=600, y=400)
def processQueue(self):
while self.queue.qsize():
try:
sensorOutput = self.queue.get() #Q value
self.output.set(sensorOutput) #Display Q value on GUI
except queue.Empty:
pass
class ClientClass:
def __init__(self, master):
self.master = master
# Create the queue
self.queue = queue.Queue()
# Set up the GUI part
self.myGui = GuiGenerator(master, self.queue)
#How do I switch the modes of operations? do I need some flags setting through button press?
# Set up the thread to do asynchronous I/O
self.thread1_mode1 = threading.Thread(target=self.firstModeOperation)
self.thread1_mode1.start()
# Start the periodic call in the GUI to check if the queue contains
# anything new
self.periodicCall()
def periodicCall(self):
# Check every 1000 ms if there is something new in the queue.
self.myGui.processQueue()
self.master.after(1000, self.periodicCall)
def firstModeOperation(self):
while True: #??? how do i control here through mode selection
time.sleep(1.0)
msg_mode_1= random.randrange(0,10)
self.queue.put(msg_mode_1)
def secondModeOperation(self):
while True: #??? how do i control here through mode selection
time.sleep(1.0)
msg_mode_2= random.randrange(100,200)
self.queue.put(msg_mode_2)
#Operation part
root = tkinter.Tk()
client = ClientClass(root)
root.mainloop()
1) What is my goal:
I’m creating an application that should read data every 60s from ModBusServer, append those data to Graphs and then when the app is closed save the data to excel file.
Site note:
The process of reading data from ModBusServer and appending them to graphs should start after a start button is pressed.
And end after stop button is pressed OR when ModBusServer sends a request to stop.
2) What I have so far:
I created the GUI without any major problems as a class “GUI_komora”.
Everything there works just fine.
3) What is the problem:
But now I’m lost on how to approach the “read data every 60 seconds”, and overall how to control the application.
I did some research on threading but still I’m confused how to implement this to my application.
I learned how to make functions run simultaneously in this tutorial.
And also how to call a function every few seconds using this question.
But none of them helped me to learn how to control the overall flow of the application.
If you could redirect me somewhere or tell me about a better approach I would be really glad.
Some of my code:
from tkinter import *
from GUI_komora import GUI
root = Tk()
my_gui = GUI(root) #my GUI class instance
#main loop
root.mainloop()
"""
How do I achieve something like this???
whenToEnd = False
while whenToEnd:
if step == "Inicialzation":
#inicializace the app
if step == "ReadData":
#read data every 60 seconds and append them to graphs
if step == "EndApp"
#save data to excel file and exit app
whenToEnd = True
"""
Here is an example of a loop that takes a decision (every 60 sec in your case) and pushes the outcome of the decision to tkinter GUI: https://github.com/shorisrip/PixelescoPy/blob/master/base.py
Parts:
main thread - starts tkinter window
control thread - reads some data and decides what to show in GUI
GUI class - has a method "add_image" which takes input an image and displays on GUI.(add_data_to_graph maybe in your case). This method is called everytime by the control thread.
Snippets:
def worker(guiObj, thread_dict):
# read some data and make decision here
time.sleep(60)
data_to_show = <outcome of the decision>
while some_logic:
pictureObj = Picture(chosen, timer)
pictureObj.set_control_thread_obj(thread_dict["control_thread"])
guiObj.set_picture_obj(pictureObj)
pictureObj.display(guiObj)
# do post display tasks
guiObj.quit_window()
# Keep GUI on main thread and everything else on thread
guiObj = GuiWindow()
thread_list = []
thread_dict = {}
thread_for_image_control = threading.Thread(target=worker, args=(guiObj,
thread_dict))
thread_dict["control_thread"] = thread_for_image_control
thread_list.append(thread_for_image_control)
thread_for_image_control.start()
guiObj.run_window_on_loop()
# thread_for_image_control.join()
Code for Picture class:
class Picture:
def __init__(self, path, timer):
self.path = path
self.timer = timer
self.control_thread_obj = None
def set_control_thread_obj(self, thread_obj):
self.control_thread_obj = thread_obj
def display(self, guiObj):
image_path = self.path
guiObj.add_image(image_path)
time.sleep(self.timer)
Code for GUI class
class GuiWindow():
def __init__(self):
self.picture_obj = None
self.root = Tk()
self.image_label = None
self.image = None
self.folder_path = None
self.timer = None
self.root.protocol("WM_DELETE_WINDOW", self.exit_button)
def add_image(self, image_path):
resized_img = self.resize(image_path)
image_obj = ImageTk.PhotoImage(resized_img)
image_label = Label(self.root, image=image_obj,
height=resized_img.height,
width=resized_img.width)
self.image = image_obj # DO NOT REMOVE - Garbage collector error
if self.image_label is not None:
self.remove_image()
image_label.grid(row=0, column=0, columnspan=3)
self.image_label = image_label
Here based on my control loop thread I am changing image (in your case graph data) of the tkinter GUI.
Does this help?
I like to create an object per second and make the show up one by one. However, the code below wait for 3 seconds and show them all at the same time.
from tkinter import *
import time
def create():
for i in range(3):
r4=Radiobutton(root, text="Option 1"+str(i), value=1)
r4.pack( anchor = W )
time.sleep(1)
root = Tk()
create()
root.mainloop()
Your code, as is, creates a one object per second as you desired it, but this objects need to be shown, and they're shown when code flow reaches the mainloop. Hence, for observer, it looks like there're no objects at all after one second.
Of course, you can use sleep and update, but beware - sleeping leads to unresponsive window, so it's OK option (to be honest - not OK at all), if your application isn't drawn and you're outside of mainloop, but if it's not - prepare for a "frozen" window, because GUI can redraw himself only in mainloop (an event loop, you can reach it with update as well) and sleep blocks this behaviour.
But there's a good alternative, the after method, take a look on it!
And there's a snippet, so you can see the difference:
try:
import tkinter as tk
except ImportError:
import Tkinter as tk
import time
def create_with_sleep():
for _ in range(3):
tk.Radiobutton(frame_for_sleep, text="Sleep Option").pack(anchor='w')
time.sleep(int(time_entry.get()))
root.update()
def create_with_after(times=3):
if times != 0:
tk.Radiobutton(frame_for_after, text="After Option").pack(anchor='w')
times -= 1
root.after(int(time_entry.get()) * 1000, lambda: create_with_after(times))
root = tk.Tk()
test_yard_frame = tk.Frame(root)
frame_for_sleep = tk.Frame(test_yard_frame)
frame_for_after = tk.Frame(test_yard_frame)
test_yard_frame.pack()
frame_for_sleep.pack(side='left')
frame_for_after.pack(side='left')
button_frame = tk.Frame(root)
button_for_sleep = tk.Button(button_frame, text='Create 3 radiobuttons with sleep+update', command=create_with_sleep)
button_for_after = tk.Button(button_frame, text='Create 3 radiobuttons with after', command=create_with_after)
button_frame.pack()
button_for_sleep.pack(side='left')
button_for_after.pack(side='left')
time_label = tk.Label(root, text='Time delay in seconds:')
time_label.pack(fill='x')
time_entry = tk.Entry(root)
time_entry.insert(0, 1)
time_entry.pack(fill='x')
root.mainloop()
With 1 seconds delay there's no much difference, but you can try to increase delay to understand why after option is preferable in general.
You can use update to call a refresh on your objects.
In use, you would have to add the line root.update() in your for loop.
I'm working on a program that will stop users from changing a label after a random amount of time. There are two buttons, start and next, when the user presses start the start button is destroyed but is supposed to come back after a randomly selected amount of time. I tried to have the start button trigger a flag that starts a timer. When the timer reaches a certain value (count_to+1) the flag should go to zero, the start button should reappear, and the label should read end. The flag never seems to switch and the timer never initiates though. Can anyone tell me what I did wrong? and maybe point me towards a solution? Hear is the code:
import sys
from tkinter import *
import random
import time
mGui = Tk()
mGui.geometry('450x450+200+200')
mGui.title('Letters')
stored = ['A', 'b', 'c', 'd']
count_down = [10,20,30,40,50,60]
global count_to
global countFlag
count_to = IntVar()
countFlag = 0
Sec = 0
def run_counter():
count_to = random.choice(count_down)
while countFlag == 1:
Sec+=1
print(sec)
if Sec == count_to+1:
countFlag = 0
newbutton.destroy()
startbutton.grid(row=2,column=1)
phrase.configure(text='End')
return
def change_phrase():
fish = StringVar()
fish = random.choice(stored)
stored.remove(fish)
phrase.configure(text=fish)
#to help with debug
print(countFlag)
print(Sec)
print(count_to)
return
def start_count():
countFlag = True
count_to = random.choice(count_down)
print(countFlag)
startbutton.destroy()
run_counter
return
phrase = Label(mGui,text='Letter',fg='red',bg='blue')
phrase.grid(row=0,column=0, sticky=S,columnspan=2)
startbutton =Button(mGui, text='start',fg='black',bg='green',command=start_count)
startbutton.grid(row=2,column=1)
newbutton = Button(mGui,text='NEXT',fg='black',bg='red',command=change_phrase)
newbutton.grid(row=2,column=0)
#mEntry = Entry(mGui,textvariable=ment)
#mEntry.grid(row=3,column=0)
mGui.mainloop()
Tkinter programming becomes much less messy and confusing once you learn to use classes. Use Tkinter's after() method to call a function every "x" amount of time until the allotted time has elapsed.
import random
import sys
if sys.version_info[0] < 3:
import Tkinter as tk ## Python 2.x
else:
import tkinter as tk ## Python 3.x
class ButtonDisappear():
def __init__(self, root):
self.root=root
self.startbutton=tk.Button(root, text='disappear', fg='black',
bg='green', command=self.disappear)
self.startbutton.grid(row=2,column=1)
self.lab=tk.Label(self.root, text="", bg="lightblue")
def disappear(self):
## remove button
self.startbutton.grid_forget()
## grid label for time
self.lab.grid(row=0, column=0)
## "random" number
self.stop_time=random.choice([1, 2, 3, 4, 5])*1000
self.elapsed=0
self.root.after(100, self.time_it)
def time_it(self):
self.elapsed += 100
## function calls itself until time has finished
if self.elapsed < self.stop_time:
self.lab["text"]="%d of %d" % (self.elapsed, self.stop_time)
self.root.after(100, self.time_it)
## time elapsed so remove label and restore button
else:
self.lab.grid_forget()
self.startbutton.grid(row=2,column=1)
m_gui = tk.Tk()
m_gui.geometry('450x450+200+200')
m_gui.title('Letters')
B=ButtonDisappear(m_gui)
m_gui.mainloop()
I am new to Python and Tkinter but I was wondering if I could do Multithreading in Tkinter.
I have a Restaurant Simulation program and whenever it accepts an order, this is what should happen:
1) Timer that counts down and shows how many seconds are left before the order is done
2) While the Timer is counting, I want to create another instance of the Restaurant Simulation so that it could accept another order.
This is what I have tried:
from Tkinter import *
class food():
def __init__(self):
self.inventory = []
def cookOrder(self,type):
if type is 'AA': #Cook Barf
self.inventory[0]+=1
class Restaurant():
def Callback(self,root):
if tkMessageBox.askokcancel("Quit", "Do you really wish to quit?"):
root.destroy()
def MainMenu(self):
self.Main = Tk()
self.Main.grid()
Title = Label(self.Main,text = "Welcome to Resto!",font=("Bauhaus 93",20))
Title.grid(columnspan=6)
RestoMenu = Button(self.Main,text = "Order Food",command = lambda:self.Restaurant_Menu('AA'),font=("High Tower Text",12))
RestoMenu.grid(row=2,column=0)
self.Main.mainloop()
def Restaurant_Menu(self,type):
self.Main.destroy()
self.setCookTime(type)
def setCookTime(self,type):
self.MainMenu() #This is not working as I planned it to be
self.cookTimer = Tk()
self.timeLabel = Label(text="")
self.timeLabel.pack()
if type is "AA":
self.Tick(10,type)
self.cookTimer.mainloop()
self.cookTimer.wm_protocol ("WM_DELETE_WINDOW", self.Callback(self.cookTimer)) #Getting TCL Error
def Tick(self,time,type):
time -=1
if time ==-1:
food.cookOrder(type)
self.cook.destroy()
else:
self.timeLabel.configure(text="%d" %time)
self.cookTimer.after(1000, lambda: self.Tick(time,type))
Food = food()
Resto = Restaurant()
Resto.MainMenu()
Now, the problem with the code is, it is not creating another instance of the Restaurant while the countdown is going on. Any help?
Plus, how do you ask the user for the confirmation of exiting program when he clicks the exit button while the timer is ticking, using WM_DELETE_WINDOW?