I was trying to return the result from a function after a button is triggered. But it happens that the function was called once I run the project.
def main_execute():
result = 0;
return result
# Button
main_execute_btn = tk.Button(
window,
text='Execute',
height=5,
width=15,
activebackground='grey',
activeforeground='blue',
bd=3,
command=main_execute
)
main_execute_btn.place(relx=0.8, rely=0.5, anchor=CENTER)
result_str = IntVar(window, main_execute())
# Text String
main_result_ts = tk.Label(
window,
textvariable=result_str).place(relx=0.8, rely=0.8, anchor=CENTER)
Please ignore the input boxes.
The main_result_ts shall return 1 after the main_execute_btn is clicked.
Maybe you can simply change the value of the Label main_result_ts by using the .config command in the following way:
main_result_ts.config(text = result)
Also, I think you have forgotten to write window.mainloop() at the end of your code.
According to your post, you have mentioned that you want main_result_ts to display 1 after clicking main_execute_btn. For this you have to declare result`` outside the function main_execute()``` and to change its value within the function, use the following code:
def main_execute():
global result
result += 1;
return result
Related
I have a dropdown in tkinter, that i have populated with some items.
OPTIONS = [0,1,2,3,4,5,6,7]
clicked = tk.StringVar()
clicked.set(OPTIONS[0]) # default value
drop = tk.OptionMenu(frame2, clicked, *OPTIONS)
drop.place(relx = 0.65, rely=0.25, relwidth=0.08, relheight=0.6)
However, when a user selects a value, i want other things to happen as well.
Like returning the value to a global variable, or making the state of a button normal, so it's visible again.
How can i run a function, when an item is selected, or when a different item is selected?
EDIT:
Following the suggestions of TheLizzard, i changed my code to this:
# this function is triggered, when a value is selected from the dropdown
def dropdown_selection():
global dropdown_value
dropdown_value = clicked.get()
print("You changed the selection. The new selection is %s." % dropdown_value)
button_single['state'] = 'normal'
OPTIONS = list(range(8))
clicked = tk.StringVar(master=frame2)
clicked.set(OPTIONS[0])
clicked.trace("w", dropdown_selection)
drop = tk.OptionMenu(frame2, clicked, *OPTIONS)
drop.place(relx = 0.65, rely=0.25, relwidth=0.08, relheight=0.6)
However, i get this error:
TypeError: dropdown_selection() takes 0 positional arguments but 3 were given
Try this:
import tkinter as tk
def changed(*args):
print("You changed the selection. The new selection is %s." % clicked.get())
root = tk.Tk()
OPTIONS = list(range(8))
clicked = tk.StringVar(master=root) # Always pass the `master` keyword argument
clicked.set(OPTIONS[0]) # default value
clicked.trace("w", changed)
drop = tk.OptionMenu(root, clicked, *OPTIONS)
drop.pack()
root.mainloop()
In tkinter you can add callbacks to variables like StringVar using <tkinter variable>.trace(mode, callback) for more info read this.
Also always pass in the master keyword argument to all tkinter widgets/variables. You did this with the OptionMenu (it's the first argument usually). But you didn't do it for the StringVar. If you always pass the master keyword argument, you can save yourself a headache.
Edit:
When tkinter calls the callback when the variable is changed it passes some arguments (I don't think they are useful) so make sure that the callback accepts them. Instead of having def callback() use def callback(*args).
In the code mentioned I am trying to get value of "text" which is inside the function . Outside of a function with one variable "A" but here I am not getting anything.Can anyone help me on this issue please
Also when I am writing print statement inside the function it is printing the value
enter code here
from tkinter import *
window = Tk()
window.geometry('500x500')
def callback(self):
text = No_of_chances.get()
return text
No_of_chances = Entry(window)
No_of_chances.place(x=50, y=300)
No_of_chances.bind('<Return>', callback)
A=text
print(A)
window.mainloop()
The text variable is not defined when you try to do A=text this is because the function callback() is only called when the enter button is pressed. Therefore text does not exist when you try to assign it to A
The callback function works perfectly fine, it gets the current string within the Number_of_chances Entry you have, and returns it.
That being said your question is very unclear, since you provide no context to what you want to do with the text you get from the Entry when you press enter, if you provide some context I or someone else might be able to help fix your problem better.
Here is a solution so then A will contain the value you want.
from tkinter import *
window = Tk()
window.geometry('500x500')
text = ""
def callback(event):
text = No_of_chances.get()
print(text)
return text
No_of_chances = Entry(window)
No_of_chances.place(x=50, y=300)
No_of_chances.bind('<Return>', callback)
A=text
print(A)
window.mainloop()
I know there are a lot of questions about this subject, but after long researches I didn't find any that could solve my problem.
I'm trying to display with a label (using tkinter) a variable that I get from the I²C bus. The variable is therefore updated very regularly and automatically. The rest of the window should stay available for the user.
For now, the only way I found to display the label with the updated variable and to keep the rest of the window available for the user is to do so:
window = tk.Tk()
window.title("Gestionnaire de périphériques")
window.minsize(1024,600)
labelValThermo = tk.Label(a_frame_in_the_main_window,text = "")
labelValThermo.grid(row = 1, column = 1)
while True:
if mcp.get_hot_junction_temperature() != 16.0625:
labelValThermo.configure(text = "Température thermocouple: {} °C".format(mcp.get_hot_junction_temperature()))
window.update()
time.sleep(0.75)
The variable that comes from the I²C and got updated is mcp.get_hot_junction_temperature
The fact is that I know it's not the best way to force the update in an infinite loop. This should be the role of the mainloop(). I found out that the after() method could solve my problem but I don't know how to run it. I tried the following code that didn't work:
def displayThermoTemp():
if mcp.get_hot_junction_temperature() != 16.0625:
labelValThermo.configure(text = "Température thermocouple: {} °C".format(mcp.get_hot_junction_temperature()))
labelValThermo.after(500,displayThermoTemp)
window = tk.Tk()
labelValThermo = tk.Label(thermoGraphFrame,text = "")
labelValThermo.after(500, displayThermoTemp)
labelValThermo.grid(row = 1, column = 1)
window.mainloop()
Does anyone have the right syntax ?
How To use after() ?
The after() calls the function callback after the given delay in ms. Just define it inside the given function and it'll run just like a while loop till you call after_cancel(id) .
Here is an example:
import tkinter as tk
Count = 1
root = tk.Tk()
label = tk.Label(root, text=Count, font = ('', 30))
label.pack()
def update():
global Count
Count += 1
label['text'] = Count
root.after(100, update)
update()
root.mainloop()
Update your function with this and call it once before mainloop().
def displayThermoTemp():
if mcp.get_hot_junction_temperature() != 16.0625:
labelValThermo.configure(text = "Température thermocouple: {} °C".format(mcp.get_hot_junction_temperature()))
labelValThermo.after(500,displayThermoTemp)
# 100ms = 0.1 secs
window(100, displayThermoTemp)
after has the following syntax:
after(delay_ms, callback=None, *args)
You need to place the command in your callback function and update the window on which the widget is (in your case the labelValThermo looks to be on the root window:
def displayThermoTemp():
if mcp.get_hot_junction_temperature() != 16.0625:
labelValThermo.configure(text = "Température thermocouple: {} °C".format(mcp.get_hot_junction_temperature()))
root.after(500,displayThermoTemp)
import tkinter
window = tkinter.Tk()
def abc(event):
ans=0
numberss=['7','8','9']
omenu2['menu'].delete(0, 'end')
for number in numberss:
omenu2['menu'].add_command(label=numberss[ans], command=efg)
ans=ans+1
def efg(event=None):
print('yee')
numbers = ['1','2', '3']
number=['4','5','6']
var = tkinter.StringVar(window)
var1 = tkinter.StringVar(window)
omenu = tkinter.OptionMenu(window, var, *numbers, command = abc)
omenu.grid(row=1)
omenu2 = tkinter.OptionMenu(window, var1, *number, command = efg)
omenu2.grid(row=2)
after you have entered the first option menu, it will update the second one. when you enter data into the second one, it runs the command, but doesn't show you what you entered. i do not want to include a button, and i know that the command works and not on the second
i found some code that changed the options of the second menu, however when i ran this, the command wouldn't work as it was changed to tkinter.setit (i would also like to know what is does. i do not currently understand it)
omenu2['menu'].add_command(label=numberss[ans], command=tkinter._setit(var1, number))
this has been taken from a larger piece of code, and has thrown the same error
You should set your StringVar(var1) new value.
def abc(event):
numberss=['7','8','9']
omenu2['menu'].delete(0, 'end')
for number in numberss:
omenu2['menu'].add_command(label=number, command=lambda val=number: efg(val))
def efg(val, event=None):
print('yee')
var1.set(val)
You are using for loop so you don't need ans(at least not in this code) since it iterates over items themselves.
SO I am using Python 3.4 and tkinter.
And when I call a function again n again which contains a label, the label keeps on appearing in window but previous label doesn't go away?
How can I remove any printed label from GUI window as soon as function is called and then display new one?
Here is the code:-
#def prestart():
#here I check if number of match is okay, if not, user is redirected to setting else, I call start()
def start():
#CPU Choice
cpu_choice = Label(historyframe, text = "CPU Choosed: {}".format(dict['cpu_choice']))
#Played Match
#played_num_of_match = Label(scoreframe, text = "Number of Matches Played: {}".format(int(dict['match_played'])))
#Display Status
status_disp = Label(scoreframe, text = "Current Status: {}".format(dict['status']))
if(int(dict['match_played']) < int(dict['num_of_match'])):
playframe.grid(row = 1, column = 0)
historyframe.grid(row = 2, column = 1)
status_disp.pack(fill=X)
elif(int(dict['match_played']) == int(dict['num_of_match'])):
playframe.grid(row = 1, column = 0)
historyframe.grid(row = 2, column = 1)
status_disp.pack(fill=X)
cp = dict['cpu_point']
up = dict['user_point']
result(cp, up)
cpu_choice.pack(fill = X)
scoreframe.grid(row = 2, column = 0)
This function just updates the display!
def send_value(x):
#Here I run logic of game and change value of key in dictionary and call start() at end of change.
Now, the choice buttons are not in any definition as they don't need to be called again n again. I just make playframe disappear n appear!
Here is the code for them:-
#Display Question
question = Label(playframe, text = "Rock? Paper? Scissor?")
#Rock
rock = Button(playframe, text = "Rock!", command = lambda: send_value("ROCK"))
#Paper
paper = Button(playframe, text = "Paper!", command = lambda: send_value("PAPER"))
#Scissor
scissor = Button(playframe, text = "Scissor!", command = lambda: send_value("SCISSOR"))
So when user clicks Rock/Paper/Scissor, I just change key value in dictionary! But if I keep the label outside function, it doesn't get auto updated!
Everything else is working perfectly. I'll kind of now start to make code cleaner.
Try something like this instead of creating a new label every time:
import Tkinter as tk
class Window():
def __init__(self, root):
self.frame = tk.Frame(root)
self.frame.pack()
self.i = 0
self.labelVar = tk.StringVar()
self.labelVar.set("This is the first text: %d" %self.i)
self.label = tk.Label(self.frame, text = self.labelVar.get(), textvariable = self.labelVar)
self.label.pack(side = tk.LEFT)
self.button = tk.Button(self.frame, text = "Update", command = self.updateLabel)
self.button.pack(side = tk.RIGHT)
def updateLabel(self):
self.i += 1
self.labelVar.set("This is new text: %d" %self.i)
root = tk.Tk()
window = Window(root)
root.mainloop()
Important points:
1) A class is used, as it is much easier to pass values around when all Tkinter objects and variables are member variables, accessible from all of your GUI functions.
2) updateLabel does not create a new Label. It simply updates the StringVar() object to hold new text every time you call the function. This is accomplished with the textvariable = self.labelVar keyword when creating my Label widget.
PS: This is done in Python 2.5 so for this code to work for you, change Tkinter to tkinter
EDIT 06/19/2015:
If you want to implement something similar to what I have with your code, without using a class, you'll need to pass around references to your variables.
1) Change start:
Your Labels cpu_choice, status_disp, etc. should be created outside of the function; likely in the same location as question, rock, paper, scissors, etc. You will also pack them outside of the function as well. Same with all the calls to .grid inside of start; you shouldn't need to call pack or grid more than once: right when you create the widget.
The following lines:
playframe.grid(row = 1, column = 0)
historyframe.grid(row = 2, column = 1)
status_disp.pack(fill=X)
Can be done outside of the function as well; you execute these 3 statements under both the if and the elif conditions. This means they aren't really conditional statements; they are done regardless of the validity of the condition.
2) Create a StringVar for both cpu_choice & status_disp & edit the Labels as follows (remember, outside of the function):
cpu_choice_text = StringVar()
cpu_choice_text.set("Set this to whatever is shown at the start of the game")
cpu_choice = Label(historyframe, text = cpu_choice_text.get(), textvariable = cpu_choice_text)
cpu_choice.pack(fill = X)
# And do this same thing for status_disp
3) When you call start, you will now pass it cpu_choice_text & status_disp_text (or whatever they are called). Instead of trying to change the text field of the Label frame, you may now use a set call on the StringVar which is connected to the Label & the Label will automatically update. Example:
def start(cpu_choice_text, status_disp_text):
cpu_choice.set(text = "CPU Choice: {}".format(dict['cpu_choice']))
...
Alternatively, wrap it all in a class and make it much easier for yourself by using self on every Tkinter variable & widget. In this way you won't need to pass variables to your functions, just access member variables directly as I have with self.i, self.labelVar in my example.
Each time you call start you create new labels and use grid to place them in the same spot as the old labels. The best solution is to only create the labels once, but if you insist on creating new labels each time start is called, you need to delete the old labels first.
You can use the destroy() method of a label to destroy it, though for that to work you must keep a global reference of the label.