I have a ttk.Combobox that my users can select from a dropdown list of options, or manually type something in. I have it bound to Return, so that if my user presses return after making a change it will update, but if my user clicks in the box and accidentally types something else in, it will cause an error down the road. To be clear, I already have an event bound to a new selection, as well as pressing return.
I am asking if it is possible to check if the box value has been changed when focus leaves the box, and if so, then call a function? When I tried a FocusOut bind, everytime I click on one of the dropdowns it calls my function and doesn't let me select anything from the dropdown, so that isn't working.
selection.bind('<Return>', lambda event, entry=selection, row=row: update(
updated_entry=entry.get(), row=row, entry=entry))
selection.bind('<<ComboboxSelected>>', lambda event, entry=selection, row=row: update(
updated_entry=entry.get(), row=row, entry=entry))
edit: Here is a sample code. The way this is written, if the user selects an item from the dropdown, it updates the label. If the users types something in and presses Return, it updates the label. But if the user types something in, and clicks on the other dropdown, it does not update the label.
import tkinter as tk
from tkinter import ttk
def update(updated_entry, row, entry):
label = tk.Text(root, height=1, width=10)
label.insert(tk.END, updated_entry)
label.grid(row=row, column=2)
return 'break'
def gui(root):
root.geometry('300x150')
root.config(background='snow3')
for row in range(2):
options = ['test', 'test1', 'test2']
selection = tk.ttk.Combobox(root, value=options)
selection.bind('<Return>', lambda event, entry=selection, row=row: update(
updated_entry=entry.get(), row=row, entry=entry))
selection.bind('<<ComboboxSelected>>', lambda event, entry=selection, row=row: update(
updated_entry=entry.get(), row=row, entry=entry))
selection.grid(row=row, column=1)
label = tk.Text(root, height=1, width=10)
label.grid(row=row, column=2)
if __name__ == '__main__':
root = tk.Tk()
gui(root)
tk.mainloop()
ttk.Comboboxes are a subclass of Entry widgets, which means that you can add validation to them in the same manner as you would to their base class. Namely by using the validate= and validatecommand= options Entrys support.
The reason to do this is because "validation" will allow the contents of the associated Combobox to be checked when it loses focus—i.e. your stated goal. This should work fine in conjunction with the bound event-handling you already have. The following code, which is similar to your minimal reproducible example, illustrates how do to something like that.
Note: This approach would also allow doing some real validation of the values the user has entered to prevent problems later on if they're invalid.
import tkinter as tk
from tkinter import ttk
def update(updated_entry, entry):
''' Combobox change Callback. '''
entry.delete('1.0', tk.END)
entry.insert(tk.END, updated_entry)
def gui(root):
root.geometry('300x150')
root.config(background='snow3')
for row in range(2):
text = tk.Text(root, height=1, width=10) # Widget to be updated.
text.grid(row=row, column=2)
def check_okay(new_value, text=text):
update(new_value, text)
return True # Note: accepts anything.
combobox = ttk.Combobox(root, value=('test', 'test1', 'test2'),
validate='focusout',
validatecommand=(root.register(check_okay), '%P'))
combobox.grid(row=row, column=1)
combobox.bind('<Return>', lambda event, entry=combobox, text=text:
update(entry.get(), entry=text))
combobox.bind('<<ComboboxSelected>>', lambda event, entry=combobox, text=text:
update(entry.get(), entry=text))
if __name__ == '__main__':
root = tk.Tk()
gui(root)
tk.mainloop()
Related
I am new to tkinter application. The below code is working fine. Please help how to implement mentioned features.
The dynamic value should be displayed above clear button or below the combo box ( Used pack is bottom )- Now working
Clear the label value on combo box selection.
import tkinter as tk
from tkinter import ttk
from tkinter import *
from datetime import datetime
# root window
root = tk.Tk()
root.geometry("500x350")
root.resizable(False, False)
root.title('Test')
# Log Generator in frame
Generator = tk.Frame(root)
Generator.pack(padx=10, pady=10, fill='x', expand=True)
def clear():
combo.set('')
# Function to print the index of selected option
# in Combobox
def get_log_file_name(*arg):
date_Value = datetime.now().strftime("%Y_%m_%d_%I%M%S")
output_file_name_value = "Log_"+date_Value
if var.get() == "apple":
Label(Generator, text="The value at index: "+output_file_name_value+".txt", font=('Helvetica 12')).pack()
else:
Label(Generator, text="The value at index: "+output_file_name_value+".html", font=('Helvetica 12')).pack()
# Define Tuple of months
months = ('apple','banana')
# Create a Combobox widget
label = ttk.Label(Generator, text="Selection_Option:",font=('Helvetica', 10, 'bold'))
label.pack(fill='x', expand=True)
var = StringVar()
combo = ttk.Combobox(Generator, textvariable=var)
combo['values'] = months
combo['state'] = 'readonly'
combo.pack(padx=5, pady=5)
# Set the tracing for the given variable
var.trace('w', get_log_file_name)
# Create a button to clear the selected combobox
# text value
button = Button(Generator, text="Clear", command=clear)
button.pack(side=left)
# Make infinite loop for displaying app on
# the screen
Generator.mainloop()
Clear the label value on combo box selection.
You need to capture the ComboboxSelect event to do that and the function to execute if captured
the function should be like this
What you want to do here, is to capture the combobox event, and then, do the label configuration when capturing it,
Below is the code to do the thing. and you can add code there.
def comboboxEventCapture(e=None):
label.configure(text='')
# Your code after resetting variables!
Here's the event capturing part
combo.bind("<<ComboboxSelect>>", comboboxEventCapture)
You can name the function whatever you want though.
Note that the arguement e is needed because if the event is captured, the event itself is passed as a parameter into the function, that is of no use here (unless you are going to do something with it, then use e.objname)
The dynamic value should be displayed above clear button
The second label could be outside of get_log_file_name() function.
And also configure inside function. So you don't do duplicate Label widget, naming Label2
Also the pack() must be split to prevent an error.
To clear Label2 use .configure(text='')
We will be using ttk. So don't do this from tkinter import *
Code:
import tkinter as tk
from tkinter import ttk
from datetime import datetime
root = tk.Tk()
root.geometry("500x350")
root.resizable(False, False)
root.title('Test')
Generator = tk.Frame(root)
Generator.pack(padx=10, pady=10, fill='x', expand=True)
def clear():
label2.configure(text='')
def get_log_file_name(*arg):
date_Value = datetime.now().strftime("%Y_%m_%d_%I%M%S")
output_file_name_value = "Log_"+date_Value
if var.get() == "apple":
label2.configure(text="The value at index: "+output_file_name_value+".txt", font=('Helvetica 12'))
else:
label2.configure(text="The value at index: "+output_file_name_value+".html", font=('Helvetica 12'))
# Define Tuple of months
months = ('apple','banana')
# Create a Combobox widget
label2 = ttk.Label(Generator)
label2.pack()
label = ttk.Label(Generator, text="Selection_Option:",font=('Helvetica', 10, 'bold'))
label.pack(fill='x', expand=True)
var = tk.StringVar()
combo = ttk.Combobox(Generator, textvariable=var)
combo['values'] = months
combo['state'] = 'readonly'
combo.pack(padx=5, pady=5)
# Set the tracing for the given variable
var.trace('w', get_log_file_name)
# Create a button to clear the selected combobox
# text value
button = ttk.Button(Generator, text="Clear", command=clear)
button.pack(side='left')
# Make infinite loop for displaying app on
# the screen
Generator.mainloop()
Screenshot for apple:
Screenshot for banana:
Screenshot to clear Label2:
I'm brand new to python (started today). I'm looking to automate something I do a lot of, so far I have 40% of what I need from googling and trying things out that I have found.
I'm trying to produce a counter, when I click the button, I want the counter to increase - I have this bit working...
from tkinter import *
root = Tk()
#Definitions of the fruit, links in with buttons with e1/2/3
def Appleadd_1(event):
value = int(e1.get())
value += 1
e1.delete(0, 'end')
e1.insert(0, value)
def Pearadd_1():
value = int(e2.get())
value += 1
e2.delete(0, 'end')
e2.insert(0, value)
def Grapeadd_1():
value = int(e3.get())
value += 1
e3.delete(0, 'end')
e3.insert(0, value)
#text boxes for counts
e1 = tk.Entry(root)
e1.insert(0, 0)
e1.pack()
e2 = tk.Entry(root)
e2.insert(0, 0)
e2.pack()
e3 = tk.Entry(root)
e3.insert(0, 0)
e3.pack()
#buttons
bt1 = tk.Button(root, text="Apples", command=Appleadd_1)
bt1.bind("<q>" , )
bt1.pack()
bt2 = tk.Button(root, text="Pears", command=Pearadd_1)
bt2.pack()
bt2.bind("1", bt2)
bt3 = tk.Button(root, text="Grapes", command=Grapeadd_1)
bt3.pack()
root.mainloop()
Although it looks ugly, it works and I have just found how to place things instead of using pack()
One thing I can't get to work, is binding a keyboard key to the buttons I have created. Is it possible?
Any help would be greatly appreciated!
Thank you
First off, you'll gain a lot by rewriting your code to use OOP. Tkinter like many other toolkits work best when using inheritance and classes to group widgets together.
As for your actual question, yes you can bind functions to keystrokes in tkinter, and it's relatively easy.
import tkinter as tk
def on_button_click(self, event=None): # command= takes a function with no arguments while .bind takes a function with one argument
print("Clicked the button!")
root = tk.Tk()
button = tk.Button(root, text="Click me!", command=on_button_click)
root.bind("<Control-a>", on_button_click)
Note that you can bind more than keypresses to functions. You can also bind mouse events like scrolling, clicking, or dragging the mouse, various keybind combinations like Shift+Tab, or Ctrl+F, and other events like the <Configure> event which is triggered when the window changes size, or the <Enter> and <Leave> event which are fired when you hover over the bound widget.
You must be wary though, because by default, a new binding will replace the existing binding (unless you pass in '+' as the bind method's third argument), and will trigger the callback for the widget that is currently focused (when applicable). For general purpose bindings, you should bind them to the root widget if possible.
In python tkinter, I've got a program that generates multiple buttons with a default fg of red
from tkinter import *
root = Tk()
def dothis(i):
print(i)
button.config(fg='green')
for i in range(5):
button = Button(root, width=30, text="button{}".format(i), command=lambda i=i: dothis(i))
button.config(fg='red')
button.pack()
This creates this window:
In this program, I have attempted to make it so that once the button is pressed, the colour of the text (fg) turns green. Instead, when dothis(i) is called, it changes the colour of the last button generated to green. This is not what I want.
To summarise, when I click button3, I want to see this:
But instead, I see this (the last generated button is modified, not the one I want):
How can I work around this, while still keeping the buttons generated in a loop?
Note: The buttons must also be modifiable after changing the colour e.g. Once changed to green, it can be turned back to red.
You got the correct lambda expression, but the parameter you passed isn't related to the buttons you created. You should pass the Button widget as a parameter instead:
from tkinter import *
root = Tk()
def dothis(button):
button.config(fg='green')
for i in range(5):
button = Button(root, width=30, text="button{}".format(i))
button.config(fg='red', command=lambda i=button: dothis(i))
button.pack()
root.mainloop()
To achieve toggling between red and green, you can use ternary operator:
def dothis(button):
button.config(fg='green' if button["foreground"]=="red" else "red")
If you insist on all buttons except the last one being anonymous, and using command instead of binding events, you can use partials:
from tkinter import *
from functools import partial
root = Tk()
button_callbacks = {}
def on_click(button):
button.config(fg="green")
for i in range(5):
button = Button(root, width=30, text=f"button{i}", fg="red")
callback_name = f"on_click_{i}"
button_callbacks.update({callback_name: partial(on_click, button=button)})
button.config(command=button_callbacks[callback_name])
button.pack()
Using event binding would be a bit more straight-forward, but the behavior is not exactly the same as triggering a callback using command. Here's what that might look like:
from tkinter import *
root = Tk()
def on_click(event):
button = event.widget
button.config(fg="green")
for i in range(5):
button = Button(root, width=30, text=f"button{i}", fg="red")
button.bind("<Button-1>", on_click)
button.pack()
I'm just wondering how I can deselect from a list box in thinter. Whenever I click on something in a list box, it gets highlighted and it gets underlined, but when I click off of the screen towards the side, the list box selection stays highlighted. Even when I click a button, the selection still stays underlined. For ex: in the example code below, I can't click off of the list box selection after clicking on one of them.
from tkinter import *
def Add():
listbox.insert(END, textVar.get())
root = Tk()
textVar = StringVar()
entry = Entry(root, textvariable = textVar)
add = Button(root, text="add", command = Add)
frame = Frame(root, height=100, width=100, bg="blue")
listbox = Listbox(root, height=5)
add.grid(row=0, column=0, sticky=W)
entry.grid(row=0, column=1, sticky=E)
listbox.grid(row=1, column=0)
frame.grid(row=1, column=1)
root.mainloop()
Yes, that's the normal behavior of the listbox. If you want to change that you could call the clear function every time the listbox left focus:
listbox.bind('<FocusOut>', lambda e: listbox.selection_clear(0, END))
Use the selectmode parameter on the Listbox widget.
You can click the selected item again and it will clear the selection.
See the effbot link:
http://effbot.org/tkinterbook/listbox.htm
listbox = Listbox(root, height=5, selectmode=MULTIPLE)
I have managed to create the functionality needed within the Listbox widget so that when a user clicks either back on the same item in the Listbox or elsewhere on screen the currently selected item is deselected. The solution came out to be quite simple.
Firsly I created a binding so that when the left mouse button is pressed anywhere on the window a function to deselect the list box is executed.
root.bind('<ButtonPress-1>', deselect_item)
I then created a variable to store the value of the last listbox item to be selected and initialised its value to None
previous_selected = None
Then I defined the function to deselect the listbox as follows. Firsly the new item (what item the user has just clicked on) is selected and compared to the previously selected item. If this is true then the user has clicked on an already highlighted item in the listbox and so the listbox's selection is cleared, removing the selected item. Finally, the function updates the previously selected box to the current selected box.
def deselect_item(event):
if listbox.curselection() == previous_selected:
listbox.selection_clear(0, tkinter.END)
previous_selected = listbox.curselection()
A full working example of this (in python 3.8.0) is shown below:
import tkinter
class App(tkinter.Tk):
def __init__(self):
tkinter.Tk.__init__(self)
self.previous_selected = None
self.listbox = tkinter.Listbox(self)
self.bind('<ButtonPress-1>', self.deselect_item)
self.listbox.insert(tkinter.END, 'Apple')
self.listbox.insert(tkinter.END, 'Orange')
self.listbox.insert(tkinter.END, 'Pear')
self.listbox.pack()
def deselect_item(self, event):
if self.listbox.curselection() == self.previous_selected:
self.listbox.selection_clear(0, tkinter.END)
self.previous_selected = self.listbox.curselection()
app = App()
app.mainloop()
Yesterday I asked this question Creating elements by loop Tkinter to find out how to dynamically create some bullet points. Now I'm looking to add a clear button so when pressed, will reset the entire form. I have tried setting the list back to [] but it didn't work.
edit - So basically when I press reset I'd like it to look exactly like it did when the form was loaded.
The buttons are removed with the destroy method:
for button in self.button:
button.destroy()
import Tkinter as tk
class ButtonBlock(object):
def __init__(self, master):
self.master = master
self.button = []
self.button_val = tk.IntVar()
entry = tk.Entry()
entry.grid(row=0, column=0)
entry.bind('<Return>', self.onEnter)
entry.focus()
clear_button = tk.Button(master, text='Clear', command=self.onClear)
clear_button.grid(row=0, column=1)
def onClear(self):
for button in self.button:
button.destroy()
def onEnter(self, event):
entry = event.widget
num = int(entry.get())
self.onClear()
for i in range(1, num+1):
self.button.append(tk.Radiobutton(
self.master, text=str(i), variable=self.button_val, value=i,
command=self.onSelect))
self.button[-1].grid(sticky='WENS', row=i, column=0, padx=1, pady=1)
def onSelect(self):
print(self.button_val.get())
if __name__ == '__main__':
root = tk.Tk()
ButtonBlock(root)
root.mainloop()
Setting the list back (i.e. using self.button = []) just clears the data stored in the button variable. That action alone is not connected to the user interface (UI). You have to explicitly remove the widget objects which were created (by the onEnter method).
So the clearing feature you are looking for should be feasible by extending the answer from your previous question. Add an onClear method to the ButtonBlock class so that when your "Clear" control (i.e. using a button widget) is selected its callback function calls ButtonBlock.onClear(), similar to how your Entry widget invokes the onEnter method.
EDIT: See unutbu's answer to this question. When selected, the clear_button control calls ButtonBlock.onClear(). The for loop in onClear gets a reference to each button ojbect from the button list and calls the object's destroy method, which removes it from the UI.