Develop Reference

tkinter executes function while the button stays pressed and stop when released

I'm new to tkinter and I'm looking for a button that executes a function in loop as soon as the button is pressed; when released the button, function will no more be executed
I currently have a tk.Button(self, text="S+", command=sch_plus_callback) with
def sch_plus_callback():
self.ser.write(b'\x02\x56\x81\x80\x80\x80\x80\x80\x39\x35\x04')
Now I would like some sort of button that does
def sch_plus_callback():
while button_is_pressed:
self.ser.write(b'\x02\x56\x81\x80\x80\x80\x80\x80\x39\x35\x04')
Is there a way?
My full code is
class SampleApp(tk.Tk):
def __init__(self, *args, **kwargs):
tk.Tk.__init__(self, *args, **kwargs)
# self.insert_lengh_text_label = tk.Label(self, text="Max Packet Length")
self.sch_plus_button = tk.Button(self, text="S+", command=self.sch_plus_callback)
self.sch_plus_button.pack()
def sch_plus_callback(self):
self.ser.write(b'\x02\x56\x81\x80\x80\x80\x80\x80\x39\x35\x04')
I'm now using these methods but it's more a workaround then an actual solution
def sch_plus_stop_callback(self, event):
self.after_cancel(repeat)
def sch_plus_callback(self, *args,):
global repeat
try:
repeat = self.after(300, self.sch_plus_callback, args[0])
except:
pass
self.ser.reset_input_buffer()
self.ser.reset_output_buffer()
self.ser.write(b'\x02\x56\x81\x80\x80\x80\x80\x80\x39\x35\x04')

In the function, catch the event of releasing the left mouse button "ButtonRelease-1",using the method widget.bind(event, handler), by which you interrupt the loop.
https://python-course.eu/tkinter/events-and-binds-in-tkinter.php#:~:text=Events%20can%20be%20key%20presses,and%20methods%20to%20an%20event.&text=If%20the%20defined%20event%20occurs,called%20with%20an%20event%20object.
So that the loop does not block the tkinter, you need to run it through after(time, callback).
Tkinter loop link https://tkdocs.com/tutorial/eventloop.html.
Code as a sample:
from tkinter import *
def sch_plus_callback(event):
global repeat
repeat = root.after(500, sch_plus_callback, event)
text.insert(END, "Bye Bye.....\n")
def stop_callback(event):
root.after_cancel(repeat)
root = Tk()
text = Text(root)
text.insert(INSERT, "Hello.....\n")
text.pack()
button = Button(root, text="S+")
button.pack()
button.bind('<Button-1>', sch_plus_callback)
button.bind('<ButtonRelease-1>', stop_callback)
root.mainloop()
def sch_plus_stop_callback(self, event):
self.after_cancel(self.repeat)
def sch_plus_callback(self, event):
try:
self.repeat = self.after(300, self.sch_plus_callback, event)

Why does adding a custom menu break keyboard event binding in Python3/tkinter?

In the following code, when I press the button to add some secondary windows, and then try to close a window by using "Command-w" it does not always close the active window. But if I disable the menu creation by commenting the line self.gerar_menu(), windows are opened and closed as expected (I mean, by clicking the red 'x' button or by pressing Command-W in OS X). Any idea about what is wrong here?
Here is my current test code:
#!/usr/bin/env python3.6
# encoding: utf-8
import tkinter as tk
import tkinter.font
from tkinter import ttk
class baseApp(ttk.Frame):
"""
Parent classe for main app window (will include some aditional methods and properties).
"""
def __init__(self, master, *args, **kwargs):
super().__init__(master, *args, **kwargs)
self.master = master
self.mainframe = ttk.Frame(master)
self.mainframe.pack()
class App(baseApp):
""" Base class for the main application window """
def __init__(self, master, *args, **kwargs):
super().__init__(master, *args, **kwargs)
self.master = master
#self.gerar_menu() # This line breaks "Command-w" functionality
self.lbl_text = ttk.Label(self.mainframe, text="This is the Main Window")
self.lbl_text.pack()
self.btn = ttk.Button(self.mainframe, text="Open Second window",
command=lambda: self.create_detail_window(self, number=0))
self.btn.pack()
self.newDetailsWindow = {}
self.windows_count=0
def gerar_menu(self):
""" generate the application menu """
self.menu = tk.Menu(root)
root.config(menu=self.menu)
self.fileMenu = tk.Menu(self.menu)
self.menu.add_cascade(label="File", menu=self.fileMenu)
self.fileMenu.add_command(label="New Document", command=None, accelerator="Command+n")
def create_detail_window(self, *event, number=None):
self.windows_count += 1
self.newDetailsWindow[self.windows_count]=tk.Toplevel()
self.newDetailsWindow[self.windows_count].geometry('900x600+80+130')
self.newDetailsWindow[self.windows_count].title(f'Detail: {self.windows_count}')
self.newDetailsWindow[self.windows_count].wm_protocol("WM_DELETE_WINDOW", self.newDetailsWindow[self.windows_count].destroy)
self.newDetailsWindow[self.windows_count].bind("Command-w", lambda event: self.newDetailsWindow[-1].destroy())
self.detail_window = detailWindow(self.newDetailsWindow[self.windows_count], self.windows_count)
self.newDetailsWindow[self.windows_count].focus()
print(self.newDetailsWindow)
class detailWindow(ttk.Frame):
""" Base class for secondary windows """
def __init__(self, master, rep_num, *args,**kwargs):
super().__init__(master,*args,**kwargs)
self.num_rep = rep_num
self.master.minsize(900, 600)
self.master.maxsize(900, 600)
print(f"Showing details about nr. {self.num_rep}")
self.mainframe = ttk.Frame(master)
self.mainframe.pack()
self.lbl_text = ttk.Label(self.mainframe,
text=f"Showing details about nr. {self.num_rep}")
self.lbl_text.pack()
if __name__ == "__main__":
root = tk.Tk()
janela_principal = App(root)
root.title('Main Window')
root.bind_all("<Mod2-q>", exit)
root.mainloop()

If you want to create a binding for closing a window, you need the function to act upon the actual window that received the event. Your code is always deleting the last window that was opened no matter which window received the event.
The first step is to bind to a function rather than using lambda. While lambda has its uses, binding to a named function is much easier to debug and maintain.
Once the function is called, the event object can tell you which window got the event via the widget attribute of the event object. Given this window, you can get the toplevel window that this window is in (or itself, if it's a toplevel window) via the winfo_toplevel command.
For example:
window = tk.Toplevel(...)
...
window.bind("<Command-w>", self.destroy_window)
...
def destroy_window(self, event):
window = event.widget.winfo_toplevel()
window.destroy()

Tkinter Large Text Dialogue (save string on button click)

I am trying to make a large text-entry popup as part of a gui. The idea is to get paragraph-long user-input. The problem is that the method get_big_text() returns before the button is pushed. How can I have a separate window pop-up like this, and be able to save the user's text to a variable in my control program? Everything else in my program has been working out, until I tried to implement this. I am new to gui programming. I get the feeling that there is something fundamentally different about waiting for user input here, but I can't wrap my head around it in the functional context.
My goal is to have the line print(foo.get_big_text()) print the user's text, but of course it prints None because the get_big_text() method finishes.
I have left out the details of the rest of the gui, and wrote an __init__() that probably doesn't need to be there, but this is the basics of how my gui is coming along. The Toplevel widget is the only widget in my gui that is not somehow connected to root.
from tkinter import *
class Gui:
def __init__(self, root):
tframe = Frame(root)
tframe.pack(side='top')
bframe = Frame(root)
bframe.pack(side='bottom')
self.txt = Text(tframe)
self.txt.insert('0.0', 'Totally foobar')
self.txt.pack()
self.btn = Button(bframe, text='OK')
self.btn.pack()
def get_big_text(self, title='', text=''):
popup = Toplevel(height=160, width=180)
popup.title(title)
txtframe = Frame(popup)
txtframe.pack()
big_text = Text(txtframe)
big_text.insert('0.0',text)
big_text.pack()
btnframe = Frame(popup)
btnframe.pack()
grab_text = Button(btnframe)
grab_text.config(text="Done", command=lambda: big_text.get('0.0', 'end'))
grab_text.pack()
root=Tk()
root.title('Example')
foo = Gui(root)
print(foo.get_big_text())
root.mainloop()

You should pass the text to one function in your class and then do whatever you want with it (like printing):
from Tkinter import *
class Gui:
def __init__(self, root):
tframe = Frame(root)
tframe.pack(side='top')
bframe = Frame(root)
bframe.pack(side='bottom')
self.txt = Text(tframe)
self.txt.insert('0.0', 'Totally foobar')
self.txt.pack()
self.btn = Button(bframe, text='OK')
self.btn.pack()
def f(self, text):
print(text)
def get_big_text(self, title='', text=''):
popup = Toplevel(height=160, width=180)
popup.title(title)
txtframe = Frame(popup)
txtframe.pack()
big_text = Text(txtframe)
big_text.insert('0.0',text)
big_text.pack()
btnframe = Frame(popup)
btnframe.pack()
grab_text = Button(btnframe)
grab_text.config(text="Done", command=lambda: self.f(big_text.get('0.0', 'end')))
grab_text.pack()
root=Tk()
root.title('Example')
foo = Gui(root)
foo.get_big_text()
root.mainloop()
If you want to print the text after the gui finished you can do this modifications:
On Gui.f:
def f(self, text):
self.text = text
At the end of your code:
root.mainloop()
print(foo.text)

After some suggestions from #xndrme, and some hard thinking, I realized the solution is quite simple. It's just that I'm not used to programing in this functional style. Really fun to discover this, though.
I wanted the get_big_text() method to return the text so that I could pass it somewhere else and "do something" with it when the text comes. The solution was to pass an anonymous function to the method and "tell it" what should be done with it when it does come.
Note the new callback parameter in get_big_text()
from tkinter import *
class Gui:
def __init__(self, root):
tframe = Frame(root)
tframe.pack(side='top')
bframe = Frame(root)
bframe.pack(side='bottom')
self.txt = Text(tframe)
self.txt.insert('0.0', 'Totally foobar')
self.txt.pack()
self.btn = Button(bframe, text='OK')
self.btn.pack()
def get_big_text(self, callback, title='', text=''):
popup = Toplevel(height=160, width=180)
popup.title(title)
txtframe = Frame(popup)
txtframe.pack()
big_text = Text(txtframe)
big_text.insert('0.0',text)
big_text.pack()
btnframe = Frame(popup)
btnframe.pack()
grab_text = Button(btnframe)
grab_text.config(text="Done", command=lambda:callback(big_text.get('0.0', 'end')))
grab_text.pack()
root=Tk()
root.title('Example')
foo = Gui(root)
foo.get_big_text(lambda x:print(x))
root.mainloop()

The general flow for a dialog is to create the window, then call wait_window to wait until the window has been dismissed by the user. Your function can then return whatever you want.
There's a bit of a chicken-and-egg thing going on, in that you need to get the value from the dialog before the dialog is destroyed since the text widget will be destroyed when the toplevel is destroyed. You do this by explicitly managing the destruction of the window (read: get the value before actually destroying the window).
Here's a working example, trying to preserve as much as code as possible but without using a global import:
import Tkinter as tk
class CustomDialog(object):
def __init__(self, parent, title="Enter a paragraph", default_text=""):
self.parent = parent
self.title = title
self.default = default_text
def show(self):
self.popup = tk.Toplevel(self.parent)
self.popup.title(self.title)
txtframe = tk.Frame(self.popup)
txtframe.pack()
self.big_text = tk.Text(txtframe)
self.big_text.insert('1.0',self.default)
self.big_text.pack()
btnframe = tk.Frame(self.popup)
btnframe.pack()
grab_text = tk.Button(btnframe)
grab_text.config(text="Done", command=self.done)
grab_text.pack()
# make sure our "done" method gets called even if the
# user destroys the window
self.popup.wm_protocol("WM_DELETE_WINDOW", self.done)
# wait for the window to be destroyed
root.wait_window(self.popup)
return self.data
def done(self, *args):
# get the data from the window, then destroy
# the window and return to the caller
self.data = self.big_text.get("1.0", "end-1c")
self.popup.destroy()
class Example(tk.Frame):
def __init__(self, parent):
tk.Frame.__init__(self, parent)
b = tk.Button(self, text="Get Input", command=self.go)
b.pack()
def go(self):
dialog = CustomDialog(self, default_text="totally foobar")
result = dialog.show()
print "result:", result
if __name__ == "__main__":
root = tk.Tk()
Example(root).pack(fill="both", expand=True)
root.mainloop()
Another option that you have is to pass a callback to your dialog, and tie that callback to the "done" button. That way, whenever the user clicks the button, you execute the callback to do whatever you want with the data before destroying the window.
That is how you implement a non-modal dialog, since you don't necessarily have to destroy the window. Font dialogs are a good example of this, where you might want to keep the dialog open for quite a while, and affect whatever is currently selected.
The effbot site has a decent writeup on dialogs. See http://effbot.org/tkinterbook/tkinter-dialog-windows.htm

tkinter app adding a right click context menu?

I have a python-tkinter gui app that I've been trying to find some way to add in some functionality. I was hoping there would be a way to right-click on an item in the app's listbox area and bring up a context menu. Is tkinter able to accomplish this? Would I be better off looking into gtk or some other gui-toolkit?

You would create a Menu instance and write a function that calls
its post() or tk_popup() method.
The tkinter documentation doesn't currently have any information about tk_popup().
Read the Tk documentation for a description, or the source:
library/menu.tcl in the Tcl/Tk source:
::tk_popup --
This procedure pops up a menu and sets things up for traversing
the menu and its submenus.
Arguments:
menu - Name of the menu to be popped up.
x, y - Root coordinates at which to pop up the menu.
entry - Index of a menu entry to center over (x,y).
If omitted or specified as {}, then menu's
upper-left corner goes at (x,y).
tkinter/__init__.py in the Python source:
def tk_popup(self, x, y, entry=""):
"""Post the menu at position X,Y with entry ENTRY."""
self.tk.call('tk_popup', self._w, x, y, entry)
You associate your context menu invoking function with right-click via:
the_widget_clicked_on.bind("<Button-3>", your_function).
However, the number associated with right-click is not the same on every platform.
library/tk.tcl in the Tcl/Tk source:
On Darwin/Aqua, buttons from left to right are 1,3,2.
On Darwin/X11 with recent XQuartz as the X server, they are 1,2,3;
other X servers may differ.
Here is an example I wrote that adds a context menu to a Listbox:
import tkinter # Tkinter -> tkinter in Python 3
class FancyListbox(tkinter.Listbox):
def __init__(self, parent, *args, **kwargs):
tkinter.Listbox.__init__(self, parent, *args, **kwargs)
self.popup_menu = tkinter.Menu(self, tearoff=0)
self.popup_menu.add_command(label="Delete",
command=self.delete_selected)
self.popup_menu.add_command(label="Select All",
command=self.select_all)
self.bind("<Button-3>", self.popup) # Button-2 on Aqua
def popup(self, event):
try:
self.popup_menu.tk_popup(event.x_root, event.y_root, 0)
finally:
self.popup_menu.grab_release()
def delete_selected(self):
for i in self.curselection()[::-1]:
self.delete(i)
def select_all(self):
self.selection_set(0, 'end')
root = tkinter.Tk()
flb = FancyListbox(root, selectmode='multiple')
for n in range(10):
flb.insert('end', n)
flb.pack()
root.mainloop()
The use of grab_release() was observed in an example on effbot.
Its effect might not be the same on all systems.

I made some changes to the conext menu code above in order to adjust my demand and I think it would be useful to share:
Version 1:
import tkinter as tk
from tkinter import ttk
class Main(tk.Frame):
def __init__(self, master):
tk.Frame.__init__(self, master)
master.geometry('500x350')
self.master = master
self.tree = ttk.Treeview(self.master, height=15)
self.tree.pack(fill='x')
self.btn = tk.Button(master, text='click', command=self.clickbtn)
self.btn.pack()
self.aMenu = tk.Menu(master, tearoff=0)
self.aMenu.add_command(label='Delete', command=self.delete)
self.aMenu.add_command(label='Say Hello', command=self.hello)
self.num = 0
# attach popup to treeview widget
self.tree.bind("<Button-3>", self.popup)
def clickbtn(self):
text = 'Hello ' + str(self.num)
self.tree.insert('', 'end', text=text)
self.num += 1
def delete(self):
print(self.tree.focus())
if self.iid:
self.tree.delete(self.iid)
def hello(self):
print ('hello!')
def popup(self, event):
self.iid = self.tree.identify_row(event.y)
if self.iid:
# mouse pointer over item
self.tree.selection_set(self.iid)
self.aMenu.post(event.x_root, event.y_root)
else:
pass
root = tk.Tk()
app=Main(root)
root.mainloop()
Version 2:
import tkinter as tk
from tkinter import ttk
class Main(tk.Frame):
def __init__(self, master):
master.geometry('500x350')
self.master = master
tk.Frame.__init__(self, master)
self.tree = ttk.Treeview(self.master, height=15)
self.tree.pack(fill='x')
self.btn = tk.Button(master, text='click', command=self.clickbtn)
self.btn.pack()
self.rclick = RightClick(self.master)
self.num = 0
# attach popup to treeview widget
self.tree.bind('<Button-3>', self.rclick.popup)
def clickbtn(self):
text = 'Hello ' + str(self.num)
self.tree.insert('', 'end', text=text)
self.num += 1
class RightClick:
def __init__(self, master):
# create a popup menu
self.aMenu = tk.Menu(master, tearoff=0)
self.aMenu.add_command(label='Delete', command=self.delete)
self.aMenu.add_command(label='Say Hello', command=self.hello)
self.tree_item = ''
def delete(self):
if self.tree_item:
app.tree.delete(self.tree_item)
def hello(self):
print ('hello!')
def popup(self, event):
self.aMenu.post(event.x_root, event.y_root)
self.tree_item = app.tree.focus()
root = tk.Tk()
app=Main(root)
root.mainloop()

from tkinter import *
root=Tk()
root.geometry("500x400+200+100")
class Menu_Entry(Entry):
def __init__(self,perant,*args,**kwargs):
Entry.__init__(self,perant,*args,**kwargs)
self.popup_menu=Menu(self,tearoff=0,background='#1c1b1a',fg='white',
activebackground='#534c5c',
activeforeground='Yellow')
self.popup_menu.add_command(label="Cut ",command=self.Cut,
accelerator='Ctrl+V')
self.popup_menu.add_command(label="Copy ",command=self.Copy,compound=LEFT,
accelerator='Ctrl+C')
self.popup_menu.add_command(label="Paste ",command=self.Paste,accelerator='Ctrl+V')
self.popup_menu.add_separator()
self.popup_menu.add_command(label="Select all",command=self.select_all,accelerator="Ctrl+A")
self.popup_menu.add_command(label="Delete",command=self.delete_only,accelerator=" Delete")
self.popup_menu.add_command(label="Delete all",command=self.delete_selected,accelerator="Ctrl+D")
self.bind('<Button-3>',self.popup)
self.bind("<Control-d>",self.delete_selected_with_e1)
self.bind('<App>',self.popup)
self.context_menu = Menu(self, tearoff=0)
self.context_menu.add_command(label="Cut")
self.context_menu.add_command(label="Copy")
self.context_menu.add_command(label="Paste")
def popup(self, event):
try:
self.popup_menu.tk_popup(event.x_root, event.y_root, 0)
finally:
self.popup_menu.grab_release()
def Copy(self):
self.event_generate('<<Copy>>')
def Paste(self):
self.event_generate('<<Paste>>')
def Cut(self):
self.event_generate('<<Cut>>')
def delete_selected_with_e1(self,event):
self.select_range(0, END)
self.focus()
self.event_generate("<Delete>")
def delete_selected(self):
self.select_range(0, END)
self.focus()
self.event_generate("<Delete>")
def delete_only(self):
self.event_generate("<BackSpace>")
def select_all(self):
self.select_range(0, END)
self.focus()
ent=Menu_Entry(root)
ent.pack()
root.mainloop()

Important Caveat:
(Assuming the event argument that contains the coordinates is called "event"): Nothing will happen or be visible when you call tk_popup(...) unless you use "event.x_root" and "event.y_root" as arguments. If you do the obvious of using "event.x" and "event.y", it won't work, even though the names of the coordinates are "x" and "y" and there is no mention of "x_root" and "y_root" anywhere within it.
As for the grab_release(..), it's not necessary, anywhere. "tearoff=0" also isn't necessary, setting it to 1 (which is default), simply adds a dotted line entry to the context menu. If you click on it, it detaches the context menu and makes it its own top-level window with window decorators. tearoff=0 will hide this entry. Moreover, it doesn't matter if you set the menu's master to any specific widget or root, or anything at all.

Creating a popup message box with an Entry field

I want to create a popup message box which prompts user to enter an input. I have this method inside a class. I am basing my code on this guide by java2s.
class MyDialog:
def __init__(self, parent):
top = self.top = Toplevel(parent)
Label(top, text="Value").pack()
self.e = Entry(top)
self.e.pack(padx=5)
b = Button(top, text="OK", command=self.ok)
b.pack(pady=5)
def ok(self):
print "value is", self.e.get()
self.top.destroy()
root = Tk()
d = MyDialog(root)
root.wait_window(d.top)
But in this, top = self.top = Toplevel(parent) doesn't work for me.
I have a mockup of what I am trying to accomplish.
My program structure looks something like this:
class MainUI:
def__int__(self):
...
self.initUI()
def initUI(self):
.......
Popup = Button(self, text="Enter Value", command=self.showPopup)
def showPopup(self):
#create the popup with an Entry here
How can I create a message box in Python which accepts user input?

I'm a little confused about your two different blocks of code. Just addressing the first block of code, nothing happens because you never enter the mainloop. To do that, you need to call root.mainloop(). The typical way of doing this is to add a button to root widget and bind a callback function to the Button (which includes d=MyDialog() and root.wait_window(d.top))
Here's some basic code which I hope does what you want ...
from Tkinter import *
import sys
class popupWindow(object):
def __init__(self,master):
top=self.top=Toplevel(master)
self.l=Label(top,text="Hello World")
self.l.pack()
self.e=Entry(top)
self.e.pack()
self.b=Button(top,text='Ok',command=self.cleanup)
self.b.pack()
def cleanup(self):
self.value=self.e.get()
self.top.destroy()
class mainWindow(object):
def __init__(self,master):
self.master=master
self.b=Button(master,text="click me!",command=self.popup)
self.b.pack()
self.b2=Button(master,text="print value",command=lambda: sys.stdout.write(self.entryValue()+'\n'))
self.b2.pack()
def popup(self):
self.w=popupWindow(self.master)
self.b["state"] = "disabled"
self.master.wait_window(self.w.top)
self.b["state"] = "normal"
def entryValue(self):
return self.w.value
if __name__ == "__main__":
root=Tk()
m=mainWindow(root)
root.mainloop()
I get the value from the popupWindow and use it in the main program (take a look at the lambda function associated with b2).
Main window:
"Click me" window:
Main window while "click me" is open:

import tkinter as tk
from tkinter import simpledialog
ROOT = tk.Tk()
ROOT.withdraw()
# the input dialog
USER_INP = simpledialog.askstring(title="Test",
prompt="What's your Name?:")
# check it out
print("Hello", USER_INP)
Enjoy ...

I did it in Tkinter without any classes. I created a function that starts a new window.
popup.Tk()
popup.mainloop()
In that window there is an Entry field from where I get the text with a variable which value is: entry.get()
Then you can use that variable for whatever you need and it will take the text from that Entry field.

I just tried this:
def get_me():
s = simpledialog.askstring("input string", "please input your added text")
Source: https://www.youtube.com/watch?v=43vzP1FyAF8