Trying my first foray into Python and TkInter, and have already gotten some great help here. However, I'm hitting another wall and hoping somebody here can give me a lift to the other side.
My app is pretty simple, conceptually. Just a page with 10-20 rows of labels next to text boxes and option menus (with about 25 items, all identical).
All I want to do is add SUBMIT and QUIT buttons. But, as with most things I'm trying, I get errors every step of they way.
SubmitButton = Button(root, text="Submit", command=greetings)
SubmitButton.place(x=700, y=600)
def greetings():
print("Hello there")
The error (on this particular example) is
NameError: name 'greetings' is not defined
But isn't that what def greetings() does?
Most of the examples I'm seeing refer to things like self/master/frame, but I don't have any of that stuff in my script (at least not explicitly).
Isn't there some easy way to create a custom function and call that function on the click event? Or do I have to go back to the drawing board and try to understand how to use classes and such?
I'm using Python 3.6 and Spyder if that makes any difference.
Thank you for any guidance.
I'm not sure why it's not printing to the console on button push and without seeing your updated snippet I wouldn't be able to tell.
However, the below snippet does work for me and should demonstrate how to handle custom functions on buttons:
from tkinter import *
root = Tk()
def greetings():
print("Hello there")
SubmitButton = Button(root, text="Submit", command=greetings)
SubmitButton.pack()
Also, to answer your question. No, you don't need to use classes or any form of object orientation. However, when it comes to tkinter (and yes this is heavily opinion based) it is often easier to use classes, there are countless reasons why this is and there are plenty of questions and answers on and off this site as to why this is.
This answer probably has the best explanation as to why this is.
Related
I've been unable to successfully launch separate windows - the main window Tk, naturally, has to be the initiator of .mainloop, and originally, that was the only window in the GUI. After I completed the GUI, tested it's functionality, and was slightly proud of myself, I got all confident and decided to incorporate a user login window as well.
The program itself is just a question-and-answer quiz that randomizes a test on the 50 United State's Capital cities - an idea I'd sort of stolen from one of my Python PDF guides, however, I wrote the code independently, partly as an exercise and partly to learn hands-on for the experience. But after running into difficulties trying to get the Toplevel window to actually launch, I couldn't manage to pull it off even with every resource and guide I had for Tkinter open at the same time!
Tried wait_window... tried grab_set() and focus_set() ... and again, I know the main window has to initiate the mainloop. What in the world am I doing wrong, here?! Is it the way I have my code structured altogether?! Bad structure? Anyway, here's the code... I hope this site formats code to consolidate after a certain number of lines because it's quite long.
All that code, so little skill... LOL. Thing needs some exception handling, too... I know that. Any advise, guidance, and/or assistance towards any aspect of my code is not only welcome, it's greatly appreciated, so please, if there's something beyond this two-window dilemma I can't seem to conquer, feel free to put it on front street! Thank you in advance! :)
My Code
class MainWin(tk.Tk):
def __init__(self):
super().__init__()
self.title('Minimal Code')
class Login(tk.Toplevel):
def __init__(self, master=MainWin()):
super().__init__()
self.name = tk.StringVar()
enter code here
userlbl = tk.Label('Enter Name: ')
userent = tk.Entry(width=18, textvariable=self.name)
Ok, so for minimal coding to replicate the basic issue I'm having, please assume I've entered in the .grid() info for the label and entry widgets... ultimately, how I'd like this to work is for the login screen (Toplevel) to pop up - and if the Main window is behind it, that's no problem, just disable until the login window is closed - yet I can't, for the life of me, seem to accomplish this.
I really don't want to have to rewrite the entire thing, but I'm considering it... to see if using Canvas can more easily execute this particular action.
The order of the classes is back to front.
so the Main fails because it is initialised befor it is called:
class Login(tk.Toplevel):
def __init__(self, master=Main(), takefocus=True):
super().__init__()
I switched the order around and this error goes.
first this: class Main(tk.Tk):
then this: class Login(tk.Toplevel):
I dont know if this makes the code work, but it removes the error.
Also, when you instantiate a class it needs the brackets, so
master=Main
becomes
master=Main()
Apologies if this is a completely easy fix and I've just missed it. I am learning Python and I am trying to develop a GUI alongside my backend code using Tkinter. This is completely foreign to me and I have recently come across the problem that when I press my buttons there is a very small chance that it will make my window move behind all other open programs.
I am not entirely sure what is causing this but my guess is it stems somehow from one of two functions I have; one meant to minimise the main root window and the second to reveal it. However, these functions are not called in any place in my program that I would not expect them and the windows being minimised are not the root window (which my two functions act on).
I have both functions added below (hopefully, I am pretty new to SO) but if any additional code is needed I will supply it. I have quite a bit of code and everything else functions perfectly so I didn't want to post all my code is all.
There is no particular combination of button presses or buttons in particular which cause it, it appears to be any of them seemingly at random. It sends whatever window I have up to the taskbar.
def revealMenu():
root.update()
root.deiconify()
def hideMenu():
root.withdraw()
I designed a character creation page, and included a bit where a person can input their name with ui.input() but the problem is, they can't push any buttons or do anything at all without submitting the text first and I am trying to figure out how to turn this ui.input into a clickable so it is only active when its selected.
Then engine has a page on the ui.input (and includes explaining that the button arg is possible) but it doesn't really give me any other example other than button=None. and anything else I try, the game won't even load.
Sorry if this is a really noob question. Seems like the most simple thing.
This is what I have for that part if it helps..
ui.input('', xalign=0.5, yalign=0.5)
first_name = ui.interact()
How about creating a character creation screen and using a graphic button?
In a custom screen, you can control everything using buttons and code, which is, in some senses, outside of your story.
If there are lets say 4 buttons, all with the same Click event, how can I find out which button was pressed?
if the event looks like this def Button_Click(self, sender, e): I'm sure I can compare sender to my buttons somehow. But how?
Well, I've never used IronPython so I don't know how much help this will be, but what I usually do when trying to figure out these things in regular python is to print type(sender) , print sender and print dir(sender) to console(or output to a file if you don't have a console available).
This should help you figure out what exactly is the "sender" parameter. In the simplest case it could be the button itself so a simple == will work to know which button it was. Or it could have a method/property that gets you the button object. In which case, dir(sender) might contain an obvious one, or if not, google the class name gotten from type(sender) and see if you can find any docs.
How to suppress end user ability to edit/add/delete text in a Text widget? (Python v3.2.. and tkinter)
The point is to suppress only the ability to change/add/delete text but not to castrate other features. Perhaps a NoEdit Text widged would be a better name.
I've tried .text['state'] = 'disabled' and it works almost OK in Windows (it still allows user to select/copy text highlights the selection, page up/down and up/down buttons work. The only thing broken seems to be the cursor made invisible.)
But on MacIntosh everything is broken. No highlights, no select/copy,... UGH
Since Tkinter has practically no documentation in Python, I've searched and found some TCL advise, to derive a new class and suppress the insert and delete functions.
So, I've tried as so:
class roText(tk.Text):
def insert(self,*args,**kwargs):
print(" Hey - Im inside roText.insert")
pass
def delete(self,*args,**twargs):
pass
def pInsert(self,*args,**twargs):
super().insert(*args,**twargs)
Unfortunately it didn't work right. Apparently tkinter does not use those insert and delete functions when end user enters/deletes code. Perhaps those TCL insert/delete are something else, and I lost something in translation from TCL and Swahili. What functions does tkinter.Text use for end user editing text? Hopefully they are not internal...
So, is there a way to modify the Text widget to suppress only end user editing?
Is there a way to do it without diving inside and overriding internal Tkinter code, so the stuff doesn't get broken by next releases of Tkinter?
Looking at the Idle shell window, I see that they've managed to suppress edits (except for the last line). So there is a way. But what is it and how costly?
Sorry for bumping an old question, but I was searching for an answer to this question also and finally found a solution. The solution I found involves overriding the key bindings when the text widget has focus and is pretty simple. Found here.
To override the bindings of a widget there is a bind function where you pass a string of what is to be overridden and the new function you want it to call.
self.txtBox.bind("<Key>", self.empty)
Somewhere else in the class you'll need to define the function to handle the event.
def empty(self, event):
return "break"
By returning the string "break" the event handler knows to stop after your function, instead of continuing with the default action.
I hope this answers your question. Cheers.
The reason the disabled state doesn't seem to work on the Mac is because it turns off the binding that gives focus to the widget. Without focus, the highlighting on a Mac doesn't show up. If you set the state to disabled but then assign a binding to <ButtonPress-1> to explicitly set focus to the disabled text widget, you can then select and copy text and the highlighting will show.
As for the cursor disappearing... arguably, that's what's supposed to happen. The cursor tells the user "this is where text will get inserted". Since no text will get inserted, having that visual clue would be confusing to the user. What you could do instead, if it was really important, is to insert a small image wherever they click to simulate the cursor.
To answer your question about whether the widget actually uses the insert and delete methods: the methods on the actual underlying widget are what the default bindings use, so overriding them in a subclass has no effect. You would need to redo all the default bindings for that to work. It's doable, but a lot of work.
Unfortunately, this is one area where programming in Tcl really shines, because you can simply disable the insert and delete commands of the widget. Of course, you can do that directly in Tkinter also since ultimately it runs tcl code to do everything, but that would involve writing some tcl code which is not a very good solution from the perspective of a Python coder.
I think the best solution is to use the disabled state, then add in just enough bindings to do what you want.
Here's a simple example that works by explicitly setting focus on a mouse button click. With this code I'm able to click and swipe to select a region, or double- or triple-click to select words and lines:
import Tkinter as tk
class SampleApp(tk.Tk):
def __init__(self, *args, **kwargs):
tk.Tk.__init__(self, *args, **kwargs)
self.text = tk.Text(width=40, height=20)
self.text.bind("<1>", self.set_focus)
self.text.insert("end", "\n".join(dir(tk.Tk)))
self.text.configure(state="disabled")
self.text.pack(fill="both", expand=True)
def set_focus(self, event):
'''Explicitly set focus, so user can select and copy text'''
self.text.focus_set()
if __name__ == "__main__":
app = SampleApp()
app.mainloop()
#BryanOakley It took me a while to test your suggestion since I have no Mac.
Unfortunately Mac implementation of Python is buggy.
I've added focus, ie my disable function which I call after creating a window and inserting text, now calls first:
self.txt['state'] = 'disabled'
and then
self.txt.focus_set()
Which is what I think you've suggested.
It "kind of" worked. Ie: when selecting text (click and drag or double-click) highlighting works most of the time. Python must have some bad memory references or such bugs: Sometimes highlighting doesn't work at first, then it starts working (in the same window) after more clicking. Sometimes when program is invoked it works right of the bat. Sometimes selecting with Shift-rightArrow key will work but selecting with the mouse will not. Then starts working again. Or it will work fine in one window but not in another one (both of the same class), then starts working in all windows...etc...
The good thing is that adding focus did not affect badly Windows (ie all works fine as without focus.
I guess at this point I will just hope that future/next release of Python for Mac will fix those bugs..
BTW, it seems that Mac is a bit of an orphan for Python. Implementation is much uglier then for Windows. I mean the fonts look worse, the buttons, etc.. Or it could be due to different screen resolutions and Python ports that poorly account for those. Not sure
Anyway. Thank you for your help and suggestion to use focus for Mac.