Develop Reference

Updating a label from an entry field on button push with tkinter in Python 3.5.2

I am trying to create a window with a line label, an entry field, a current value label, and an "Update Value" button.
Here is an example:
This is what I have so far. I can get the entered value to print to console, but I can't seem to work out how to get an entered value and change the currentValue Label to reflect that value by pressing the button:
from tkinter import*
main=Tk()
#StringVar for currentValue in R0C2
currentValue = StringVar(main, "0")
#Called by the setValues button, looks for content in the entry box and updates the "current" label
def setValues():
content = entry.get()
print(content)
#This kills the program
def exitProgram():
exit()
#Title and window size
main.title("Title")
main.geometry("350x200")
#Descriptions on the far left
Label(main, text="Duration (min): ").grid(row=0, column=0)
#Entry boxes for values amidship
entry=Entry(main, width=10)
entry.grid(row=0, column=1)
#Displays what the value is currently set to.
currentValue = Label(textvariable=currentValue)
currentValue.grid(row=0,column=2)
#Takes any inputted values and sets them in the "Current" column using def setValues
setValues=Button(text='Set Values',width=30,command=setValues)
setValues.grid(row=9, column=0, columnspan=2)
#Red button to end program
exitButton=Button(main, text='Exit Program',fg='white',bg='red',width=30, height=1,command=exitProgram)
exitButton.grid(row=20, column = 0, columnspan=2)
main.mainloop()

There are a couple of problems with your code.
Firstly, you are overwriting the setValues function with the setValues Button widget, and similarly, you are overwriting the currentValue StringVar with the currentValue Label.
To set a StringVar, you use its .set method.
Don't use plain exit in a script, that's only meant to be used in an interactive interpreter session, the proper exit function is sys.exit. However, in a Tkinter program you can just call the .destroy method of the root window.
Here's a repaired version of your code.
import tkinter as tk
main = tk.Tk()
#StringVar for currentValue in R0C2
currentValue = tk.StringVar(main, "0")
#Called by the setValues button, looks for content in the entry box and updates the "current" label
def setValues():
content = entry.get()
print(content)
currentValue.set(content)
#This kills the program
def exitProgram():
main.destroy()
#Title and window size
main.title("Title")
main.geometry("350x200")
#Descriptions on the far left
tk.Label(main, text="Duration (min): ").grid(row=0, column=0)
#Entry boxes for values amidship
entry = tk.Entry(main, width=10)
entry.grid(row=0, column=1)
#Displays what the value is currently set to.
currentValueLabel = tk.Label(textvariable=currentValue)
currentValueLabel.grid(row=0,column=2)
#Takes any inputted values and sets them in the "Current" column using def setValues
setValuesButton = tk.Button(text='Set Values',width=30,command=setValues)
setValuesButton.grid(row=9, column=0, columnspan=2)
#Red button to end program
exitButton = tk.Button(main, text='Exit Program',fg='white',bg='red',width=30, height=1,command=exitProgram)
exitButton.grid(row=20, column = 0, columnspan=2)
main.mainloop()
BTW, it's a Good Idea to avoid "star" imports. Doing from tkinter import * dumps 130 names into your namespace, which is unnecessary and creates the possibility of name collisions, especially if you do star imports from several modules. It also makes the code less readable, since the reader has remember which names you defined and which ones came from the imported module(s).

In my opinion the easiest way to do this would be using an object orientated method. This way you could declare a button with a command that calls a def which runs self.label.configure(text=self.entry.get()).
This can be seen below:
import tkinter as tk
class App:
def __init__(self, master):
self.master = master
self.label = tk.Label(self.master)
self.entry = tk.Entry(self.master)
self.button = tk.Button(self.master, text="Ok", command=self.command)
self.label.pack()
self.entry.pack()
self.button.pack()
def command(self):
self.label.configure(text=self.entry.get())
root = tk.Tk()
app = App(root)
root.mainloop()
The above creates a label, entry and button. The button has a command which calls a def within the class App and updates the value of the label to be the text contained within the entry.
This all works very smoothly and cleanly and more importantly is drastically easier (in my opinion) to read and update in the future.

From your code you are setting the 'currentValue', which is a StringVar:
#StringVar for currentValue in R0C2
currentValue = StringVar(main, "0")
to an object Label further down in your code. You cannot do this!
#Displays what the value is currently set to.
currentValue = Label(textvariable=currentValue) ** this line is wrong
currentValue.grid(row=0,column=2)
You should name the label something different like:
#Displays what the value is currently set to.
lblCurrentValue = Label(textvariable=currentValue)
lblCurrentValue.grid(row=0,column=2)
Then in your "setValues" method you should use 'StringVar.set(value) to update the label like so:
def setValues():
content = entry.get()
currentValue.set(entry.get())------------------Here I set the value to the entry box value
print(content)
I tend to avoid stringVar and just use:
Label.config(text='*label's text*')
If you need more help I can post you my solution but try and solve it first becasue its the best way to learn. My tip is to make sure you are using correct naming conventions. In tkinter I tend to use lbl..., entryBox... etc before widgets so I know what they are and not to confuse them with variables.

Trying to use "grid" and "place" in one frame after using "pack" in another frame but widgets are not visible

I'm currently working on an invoice generator in python tkinter for my coursework. I am quite new to programming and I have created a basic login page so when the login button is pressed (haven't setup restraints yet) the GUI moves to the next 'screen.' I am using frames to do this. However, on the next 'page' I can only pack() widgets, if I try and place them or use a grid they simply don't appear and I get an empty GUI window.
#!/usr/bin/python
# -- coding: utf-8 --
import tkinter as tk
root = tk.Tk()
def go_to_login():
f1.pack()
f2.pack_forget()
def go_to_first():
f1.pack_forget()
f2.pack()
root.geometry('1280x800')
root.title('Invoice')
f1 = tk.Frame(root)
label_US = tk.Label(f1, text='Username')
label_US.pack()
label_PW = tk.Label(f1, text='Password')
label_PW.pack()
entry_US = tk.Entry(f1)
entry_US.pack()
entry_PW = tk.Entry(f1, show='*')
entry_PW.pack()
checkbox_LI = tk.Checkbutton(f1, text='Keep me logged in')
checkbox_LI.pack()
but_LI = tk.Button(f1, text='login', command=go_to_first)
but_LI.pack()
but_QT = tk.Button(f1, text='Quit', command=quit)
but_QT.pack()
f2 = tk.Frame(root)
but_LO = tk.Button(f2, text='Logout', command=go_to_login)
but_LO.pack() # try to change pack here
but_HP = tk.Button(f2, text='Help')
but_HP.pack() # try to change pack here
but_NX1 = tk.Button(f2, text='Next', command=quit)
but_NX1.pack() # try to change pack here
f1.pack()
root.mainloop()
What I basically want is to be able to place or use grid to set the locations of my widgets also on the second frame, but unless I use pack I get an empty GUI screen. What have I done wrong or how can I place the widgets instead to packing them?
I'm not sure if this is the best way to do things and I have no experience using classes etc but I'm open to suggestions.

As long as you specify the row and column when using .grid(), the code works fine for both 'screens'. I can think of two possible reasons why you're code wasn't working
1) If you try and use .pack and .grid for two labels in the same frame, you will get an error
2) There may be something else in your code causing your error, if so, add it to your question
Anyway, here's the code that worked for me:
f2 = tk.Frame(root)
but_LO = tk.Button(f2, text='Logout', command=go_to_login)
but_LO.grid(row = 0, column = 0) # specify row and column
but_HP = tk.Button(f2, text='Help')
but_HP.grid(row = 1, column = 0)
but_NX1 = tk.Button(f2, text='Next', command=quit)
but_NX1.grid(row = 2, column = 0)

How do you keep a widget in view while scrolling?

I am using Tix to automatically create a scroll bar as the content changes. I want to keep a button or two in the user's view while they scroll through the contents of the application.
I haven't seen this question for Tkinter/Tix yet so I thought I'd ask.
The following code will create a sample of the problem where the button is at a fixed point in the window, and is subject to being scrolled.
from Tkinter import *
import Tix
class some_GUI:
def __init__(self, root):
sw= Tix.ScrolledWindow(root, scrollbar=Tix.AUTO)
sw.pack(fill=Tix.BOTH, expand=1)
frame1 = Frame(sw.window)
frame1.grid(row = 0, column = 1)
frame2 = Frame(sw.window)
frame2.grid(row = 0, column = 2)
def quit():
root.quit()
for i in range(0,300):
label1 = Label(frame1, text = "foo")
label1.grid(row = i, column = 0)
button = Button(frame2, text = "Quit", command = quit)
button.pack()
root = Tix.Tk()
display = some_GUI(root)
root.mainloop()
I want the button(s) to be in "frame2" and centered vertically relative to the application's window. I tried using winfo_height/winfo_width to find the frame's height/ width to work with update, but these values didn't change with the addition of the labels and button.
Attempted/possible solutions:
I put frame2 in sw.subwidgets_all[1] by doing the following:
frame1.pack(side = LEFT)
frame2 = Frame(sw.subwidgets_all()[1])
frame2.pack(side = RIGHT)
button = Button(frame2, text = "Quit", command = quit)
button.pack(side = RIGHT)
This allows the fixed position relative to the application, but the window resizes relative to the button's parent instead of frame1. Another drawback is that the horizontal scrollbar is only relative to frame1.
Find the midpoint of the scrollbar and update the position of the buttons relative to those coordinates using place(maybe?) not sure how to accomplish this, and seeing SO solutions in general I think this might be an inefficient way of doing this.
EDIT: Although this isn't exactly what I had in mind, the following code works as per falsetru's suggestion in the comments:
from Tkinter import *
import Tix
class some_GUI:
def __init__(self, root):
def quit():
root.quit()
frame2 = Frame(root)
frame2.pack(side = RIGHT)
button = Button(frame2, text = "Quit", command = quit)
button.pack()
frame1 = Frame(root)
frame1.pack(side = LEFT)
sw= Tix.ScrolledWindow(frame1, scrollbar=Tix.AUTO)
sw.pack(fill=Tix.BOTH, expand=1)
for widget in sw.subwidgets_all():
print widget
for i in range(0,300):
label1 = Label(sw.window, text = "foo")
label1.grid(row = i, column = i)
print root.winfo_toplevel()
for widget in sw.subwidgets_all():
print widget
root = Tix.Tk()
display = some_GUI(root)
root.mainloop()

You can put the button out of ScrollWindows:
import Tix
from Tkinter import *
def build_ui(root):
sw = Tix.ScrolledWindow(root, scrollbar=Tix.AUTO)
sw.pack(side=LEFT, fill=Tix.BOTH, expand=1)
for i in range(300):
label1 = Label(sw.window, text="foo")
label1.grid(row=i, column=0)
button = Button(root, text="Quit", command=root.quit)
button.pack(side=RIGHT)
root = Tix.Tk()
build_ui(root)
root.mainloop()

The second option you mentioned could be the one that satisfies your situation, however that is computationally expensive as you will need to delete the button(s) and redraw them over and over relatively to the scrollbar up/down motion. Not only this is ugly by design but it can be an obstacle for any further scalability of your application or even lead to unexpected bugs if your application runs some serious operations.
The only realistic solution I see for your problem is to fix the button(s) on (for example the bottom of) the upper canvas (or whatever region you want to set) and outside the scrollable region as #falsetru commented you.

Resize entry box in tkinter

The following MWE is for a window with horizontal and vertical scrollbars. The window contains an entry box in which the current working directory is displayed. However, the text in the entry box cannot all be seen as the box is too small. I would like to be able to display more of this text as the user enlarges the window. How can I adapt the following example so that the Entry box (defined in UserFileInput) resizes with the window? I have tried using window.grid_columnconfigure (see below), however this doesn't have any effect. It seems to be a problem with using the canvas, as previously I was able to get the Entry boxes to resize, however I need the canvas in order to place the horizontal and vertical scrollbars on the window.
window.grid(row=0, column=0, sticky='ew')
window.grid_columnconfigure(0, weight=1)
(and also with column = 1) but this doesn't have an effect.
import Tkinter as tk
import tkFileDialog
import os
class AutoScrollbar(tk.Scrollbar):
def set(self, lo, hi):
if float(lo) <= 0.0 and float(hi) >= 1.0:
# grid_remove is currently missing from Tkinter!
self.tk.call("grid", "remove", self)
else:
self.grid()
tk.Scrollbar.set(self, lo, hi)
class Window(tk.Frame):
def UserFileInput(self,status,name):
row = self.row
optionLabel = tk.Label(self)
optionLabel.grid(row=row, column=0, sticky='w')
optionLabel["text"] = name
text = status#str(dirname) if dirname else status
var = tk.StringVar(root)
var.set(text)
w = tk.Entry(self, textvariable= var)
w.grid(row=row, column=1, sticky='ew')
w.grid_columnconfigure(1,weight=1)
self.row += 1
return w, var
def __init__(self,parent):
tk.Frame.__init__(self,parent)
self.row = 0
currentDirectory = os.getcwd()
directory,var = self.UserFileInput(currentDirectory, "Directory")
if __name__ == "__main__":
root = tk.Tk()
root.grid_columnconfigure(0, weight=1)
root.grid_rowconfigure(0,weight=1)
vscrollbar = AutoScrollbar(root,orient=tk.VERTICAL)
vscrollbar.grid(row=0, column=1, sticky='ns')
hscrollbar = AutoScrollbar(root, orient=tk.HORIZONTAL)
hscrollbar.grid(row=1, column=0, sticky='ew')
canvas=tk.Canvas(root,yscrollcommand=vscrollbar.set,xscrollcommand=hscrollbar.set)
canvas.grid(row=0, column=0, sticky='nsew')
vscrollbar.config(command=canvas.yview)
hscrollbar.config(command=canvas.xview)
window = Window(canvas)
canvas.create_window(0, 0, anchor=tk.NW, window=window)
window.update_idletasks()
canvas.config(scrollregion=canvas.bbox("all"))
root.mainloop()

You have several problems in your code that are getting in your way. The biggest obstacle is that you're putting a frame inside a canvas. That's rarely necessary, and it makes your code more complex than it needs to be? Is there a reason you're using a canvas, and is there a reason you're using classes for part of your code but not for everything?
Regardless, you have two problems:
the frame isn't growing when the window grows, so the contents inside the window can't grow
the label won't grow because you're using grid_columnconfigure incorrectly.
Hints for visualizing the problem
When trying to solve layout problems, a really helpful technique is to temporarily give each containing widget a unique color so you can see where each widget is. For example, coloring the canvas pink and the Window frame blue will make it clear that the Window frame is also not resizing.
Resizing the frame
Because you're choosing to embed your widget in a canvas, you are going to have to manually adjust the width of the frame when the containing canvas changes size. You can do that by setting a binding on the canvas to call a function whenever it resizes. The event you use for this is <Configure>. Note: the configure binding fires for more than just size changes, but you can safely ignore that fact.
The function needs to compute the width of the canvas, and thus the desired width of the frame (minus any padding you want). You'll then need to configure the frame to have that width. To facilitate that, you'll need to either keep a reference to the canvas id of the frame, or give the frame a unique tag.
Here is a function that assumes the frame has the tag "frame":
def on_canvas_resize(event):
padding = 8
width = canvas.winfo_width() - padding
canvas.itemconfigure("frame", width=width)
You'll need to adjust how you create the canvas item to include the tag:
canvas.create_window(..., tags=["frame"])
Finally, set a binding to fire when the widget changes size:
canvas.bind("<Configure>", on_canvas_resize)
Using grid_columnconfigure to get the label to resize
You need to use grid_columnconfigure on the containing widget. You want the columns inside the frame to grow and shrink, not the columns inside the label.
You need to change this line:
w.grid_columnconfigure(...)
to this:
self.grid_columnconfigure(...)

Change position of checkbox relative to text in Tkinter's Checkbutton

How can I change where the text is relative to the checkbox for a Tkinter Checkbutton?
By default, the text is to the right of the checkbox. I would like to change that, so the text is on the left or above of the checkbox.
I know this can be done by creating a Label with the required text and delicately positioning the two near each other, but I'd prefer to avoid that method.
Some sample code:
from Tkinter import *
root = Tk()
Checkbutton(root, text="checkButon Text").grid()
root.mainloop()

Well, I don't think you can do it directly, but you can do something that looks as it should. It is the Label-solution, but I altered it slightly, so the resulting compound of Checkbutton and Label is treated as a single Widget as wrapped in a Frame.
from Tkinter import *
class LabeledCheckbutton(Frame):
def __init__(self, root):
Frame.__init__(self, root)
self.checkbutton = Checkbutton(self)
self.label = Label(self)
self.label.grid(row=0, column=0)
self.checkbutton.grid(row=0, column=1)
root = Tk()
labeledcb = LabeledCheckbutton(root)
labeledcb.label.configure(text="checkButton Text")
labeledcb.grid(row=0, column=0)
root.mainloop()
When you create multiple frames (with their respective content - Checkbutton and Label) you can handle them easily. That way you would just have to position the Frames like you would do it with the Checkbuttons.