Per the following Stackoverflow wisdom
Python/Tkinter: Trap text selection via keyboard/mouse as an event?
I tried to detect the creation of a user selection in a Text object as follows
import tkinter as tk
def handle_selection(e=None):
print('here')
try:
sel_first = input_text.index(tk.SEL_FIRST)
sel_last = input_text.index(tk.SEL_LAST)
print(sel_first, sel_last)
except:
return
def main():
window = tk.Tk()
window.title("Simple Text Editor")
input_text = tk.Text(window)
input_text.bind("<<Selection>>", handle_selection)
input_text.pack()
window.mainloop()
if __name__ == "__main__":
main()
However the event is triggered (apparently) for each horizontal pixel selected rather than when the selection is completed, which was my intention. I also tried the following
input_text.bind("<<Selection-ButtonRelease>>", handle_selection)
which wasn't triggered at all.
Is there a way to capture the event when the user releases the button after making the selection?
Related
The question is how to use the tk.menu.unpost method under windows.
The code:
if __name__ == "__main__":
from tkinter import Menu, Tk, Label
t = Tk()
label = Label(t, text="Label")
label.pack()
menu = Menu(t, tearoff=0)
menu.add_command(label="command")
def unpost(event=None):
print(event)
menu.unpost()
def post(event=None):
print(event)
menu.after(3000, unpost)
try:
menu.tk_popup(menu.winfo_pointerx(), menu.winfo_pointery())
finally:
menu.grab_release()
label.bind("<Button-3>", post)
t.bind("<u>", unpost)
label.bind("<u>", unpost)
menu.bind("<u>", unpost)
t.mainloop()
On Linux, the unpost method works when triggered by the events or via menu.after.
On the windows platform the keybindings are apparently suppressed, the function unpost is executed as desired after three seconds, nevertheless the call remains eventless.
Environment: macOS Catalina, Python 3.7.4, Tcl/Tk 8.6.9, VSC 1.39.1
I have a situation where I am using a bar/qr code scanner to provide a string to a ttk.Entry() method, which then fires off a function.
The reader is seen by the OS as an HID keyboard, so the text from the QR code is received by the ttk.Entry() widget that I give focus to during code execution. I have bound the widget to the key because the scanner sends a cr/lf at the end of the text string, which works as needed.
However, I am running into an issue where if the qr code lingers over the scanner too long it will rescan the qr code and the widget receives the qr code text again, which then causes it to be processed again.
I have tried disabling the ttk.Entry() in the function, deleting the widget contents, and removing focus to no avail. The behavior I'm seeing is occurring even though the widget is disabled and does not have focus, it is still getting input and executing the function again if the scanner rescans the qr code while the function is executing.
In this first example, I simply tried to disable the widget, but that doesn't work. The widget still gets the later scans while in the function.
# test-ttk-entry1.py
import time
import tkinter as tk
from tkinter import StringVar, ttk
root = tk.Tk()
def print_text(event):
global kbEntry
textValue = kbEntry.get()
kbEntry.configure(state="disabled")
time.sleep(2) # Add in a delay to allow for repeat scan
print(textValue)
time.sleep(2) # Add in a delay to allow for repeat scan
kbEntry.configure(state="active")
kbText = StringVar()
kbEntry = ttk.Entry(root, width=10, textvariable=kbText)
kbEntry.bind("<Return>", print_text)
kbEntry.pack()
kbEntry.focus_set()
root.mainloop()
The second attempt was to disable the entry widget and upon making it active again delete the text in the field.
# test-ttk-entry2.py
import time
import tkinter as tk
from tkinter import END, StringVar, ttk
root = tk.Tk()
def print_text(event):
global kbEntry
textValue = kbEntry.get()
kbEntry.delete(0, END)
kbEntry.configure(state="disabled")
time.sleep(2) # Add in a delay to allow for repeat scan
print(textValue)
time.sleep(2) # Add in a delay to allow for repeat scan
kbEntry.configure(state="active")
kbEntry.delete(0, END)
kbText = StringVar()
kbEntry = ttk.Entry(root, width=10, textvariable=kbText)
kbEntry.bind("<Return>", print_text)
kbEntry.pack()
kbEntry.focus_set()
root.mainloop()
And finally, I was reading about taking focus from a widget and giving focus to the root window, so I added that in and it still prints multiple times to the console like there is a keyboard buffer being read by the ttk.Entry() widget. The weird thing is it seems like widgets don't normally respond to any calls to methods when they are disabled, but it appears the ttk.Entry() widget's properties/attributes (excuse me if my OOP terms are not correct) can be manipulated while disabled.
# test-ttk-entry2.py
import time
import tkinter as tk
from tkinter import END, StringVar, ttk
root = tk.Tk()
def print_text(event):
global kbEntry
textValue = kbEntry.get()
kbEntry.delete(0, END)
kbEntry.configure(state="disabled")
root.focus_set()
time.sleep(2) # Add in a delay to allow for repeat scan
print(textValue)
time.sleep(2) # Add in a delay to allow for repeat scan
kbEntry.configure(state="active")
kbEntry.delete(0, END)
kbEntry.focus_set()
kbText = StringVar()
kbEntry = ttk.Entry(root, width=10, textvariable=kbText)
kbEntry.bind("<Return>", print_text)
kbEntry.pack()
kbEntry.focus_set()
root.mainloop()
So how can I prevent the ttk.Entry() widget from accepting any input from the HID/keyboard device while my function is executing?
Since I am unable to find a way to temporarily disable the .Entry() widget programmatically to keep it from reading successive inputs, I have come up with this solution:
# test-ttk-entry2.py
import time
import tkinter as tk
from tkinter import END, StringVar, ttk
root = tk.Tk()
tempStr = "" # Global temporary string variable to trip repeated scans
def print_text(event):
global tempStr
textValue = kbEntry.get()
if tempStr == textValue:
kbEntry.delete(0, END)
print ("Duplicate scan")
return
tempStr = textValue
kbEntry.delete(0, END)
print(textValue)
time.sleep(3) # Simulate the time it takes for the function to complete
kbEntry = ttk.Entry(root, width=10)
kbEntry.bind("<Return>", print_text)
kbEntry.grid(row=0, column=0, padx=10, pady=10)
kbEntry.focus_set()
root.mainloop()
I want to print all events that happen in my application.
I am using python 3 with pygame and I use tkinter.
import pygame
from tkinter import *
from tkinter import ttk
def main():
root = Tk()
app = soundscene(root)
while True:
for event in pygame.event.get():
print (event)
root.mainloop()
if __name__ == "__main__":
main()
This code does not run as expected because the loop blocks, which makes sense
My question is how do I make the content of the "while true" loop part of the eventloop, so it prints out all pygame events?
To receive pygame events, a pygame window / display must be initialized.
"The input queue is heavily dependent on the pygame display module. If the display has not been initialized and a video mode not set, the event queue will not really work." Pygame event documentation.
However, if you do want to use tkinter with pygame, you can embed a pygame window into a tkinter window. This however will only give pygame events when using the embedded window. Here is an example from another question:
import pygame
import tkinter as tk
from tkinter import *
import os
root = tk.Tk()
embed = tk.Frame(root, width = 500, height = 500) #creates embed frame for pygame window
embed.grid(columnspan = (600), rowspan = 500) # Adds grid
embed.pack(side = LEFT) #packs window to the left
buttonwin = tk.Frame(root, width = 75, height = 500)
buttonwin.pack(side = LEFT)
os.environ['SDL_WINDOWID'] = str(embed.winfo_id())
os.environ['SDL_VIDEODRIVER'] = 'windib'
screen = pygame.display.set_mode((500,500))
screen.fill(pygame.Color(255,255,255))
pygame.display.init()
pygame.display.update()
while True:
for event in pygame.event.get():
print(event)
pygame.display.update()
root.update()
If you are looking for a way to receive events when using tkinter widgets, you can setup bindings in tkinter. More information at this link
I'm trying make auto updating label from url.
I want to make something like pager. When file on server is changed, label should changes too. with button I can download it manually but I want to automate it. Where I'm making mistake?
from tkinter import *
import urllib.request
import time
root = Tk()
check = ""
#functions
def auto():
time.sleep(5) #becouse I don't want kill server
page = "http://howan.pl/pychal/plik.txt"
g = urllib.request.urlopen(page)
data = g.read()
g.close()
return (str(data, encoding='utf-8'))
def click():
page = "http://howan.pl/pychal/plik.txt"
g = urllib.request.urlopen(page)
data = g.read()
g.close()
label.config(text=str(data, encoding='utf-8'))
#Widgets
label = Label(root, text="zer0")
button = Button(root, text="hey", command= click)
if auto() == check:
check = auto
label.config(text=check)
print(auto())
label.pack()
button.pack()
root.mainloop()
To automate it you need to make a function that does the work, and then use root.after() to call that function on a regular basis. Since you have all the work in "click" already, you could just add:
def auto_click():
click()
root.after(5000, auto_click) # call this function again in 5,000 ms (5 seconds)
auto_click() # start the autoclick loop.
I know that it's often best practice to write Tkinter GUI code using object-oriented programming (OOP), but I'm trying to keep things simple because I'm new to Python.
I have written the following code to create a simple GUI:
#!/usr/bin/python3
from tkinter import *
from tkinter import ttk
def ChangeLabelText():
MyLabel.config(text = 'You pressed the button!')
def main():
Root = Tk()
MyLabel = ttk.Label(Root, text = 'The button has not been pressed.')
MyLabel.pack()
MyButton = ttk.Button(Root, text = 'Press Me', command = ChangeLabelText)
MyButton.pack()
Root.mainloop()
if __name__ == "__main__": main()
The GUI looks like this.
I thought the text in the GUI (MyLabel) would change to "You pressed the button!" when the button is clicked, but I get the following error when I click the button:
Exception in Tkinter callback
Traceback (most recent call last):
File "C:\Users\elsey\AppData\Local\Programs\Python\Python35-32\lib\tkinter\__init__.py", line 1549, in __call__
return self.func(*args)
File "C:/Users/elsey/Documents/question code.py", line 6, in ChangeLabelText
MyLabel.config(text = 'You pressed the button!')
NameError: name 'MyLabel' is not defined
What am I doing wrong? Any guidance would be appreciated.
MyLabel is local to main() so the way you can not access it that way from ChangeLabelText().
If you do not want to change the design of your program, then you will need to change the definition of ChangeLabelText() like what follows:
def ChangeLabelText(m):
m.config(text = 'You pressed the button!')
And withing main() you will need to pass MyLabel as an argument to ChangeLabelText().
But again, you will have a problem if you code this command = ChangeLabelText(MyLabel) when you declare and define MyButton because the program will execute directly the body of ChangeLabelText() at the start and you will not have the desired result.
To resolve this later problem, you will have to use (and may be read about) lambda
Full program
So your program becomes:
#!/usr/bin/python3
from tkinter import *
from tkinter import ttk
def ChangeLabelText(m):
m.config(text = 'You pressed the button!')
def main():
Root = Tk()
MyLabel = ttk.Label(Root, text = 'The button has not been pressed.')
MyLabel.pack()
MyButton = ttk.Button(Root, text = 'Press Me', command = lambda: ChangeLabelText(MyLabel))
MyButton.pack()
Root.mainloop()
if __name__ == "__main__":
main()
Demo
Before clicking:
After clicking:
Are your sure you don't want to do it as a class (i think it makes the code a bit more clean as your project grows)? Here is a way to accomplish what you'e looking for:
#!/usr/bin/python3
from tkinter import *
from tkinter import ttk
class myWindow:
def __init__(self, master):
self.MyLabel = ttk.Label(root, text = 'The button has not been pressed.')
self.MyLabel.pack()
self.MyButton = ttk.Button(root, text = 'Press Me', command = self.ChangeLabelText)
self.MyButton.pack()
def ChangeLabelText(self, event=None):
self.MyLabel.config(text = 'You pressed the button!')
if __name__ == "__main__":
root = Tk()
mainWindow = myWindow(root)
root.mainloop()
In a Mac, is looks like this before pressing the button:
And when you press it:
But basically, in order to be able to change the text in a Label or a button, you need to ensure it has an active reference. In this case, we are doing it by creating the window as a class and referencing the widgets in the form self. widget_name = widget().
but I'm trying to keep things simple because I'm new to Python Hopefully this helps in understanding that classes are the simple way, otherwise you have to jump through hoops and manually keep track of many variables. Also, the Python Style Guide suggests that CamelCase is used for class names and lower_case_with_underlines for variables and functions. https://www.python.org/dev/peps/pep-0008/
from tkinter import *
from tkinter import ttk
class ChangeLabel():
def __init__(self):
root = Tk()
self.my_label = ttk.Label(root, text = 'The button has not been pressed.')
self.my_label.pack()
## not necessary to keep a reference to this button
## because it is not referenced anywhere else
ttk.Button(root, text = 'Press Me',
command = self.change_label_text).pack()
root.mainloop()
def change_label_text(self):
self.my_label.config(text = 'You pressed the button!')
if __name__ == "__main__":
CL=ChangeLabel()