Learning to use Tkinter and following an online tutorial. This is an example given where text is entered and then label will update accordingly to the input text field.
I'm trying it in Python3 on Mac and on Raspberry Pi and I don't see the effect of trace, hence the label doesn't get modified by the Entry. Any help would be appreciate (or any other simple example of how to use Entry and Trace together)
Thanks.
from tkinter import *
class HelloWorld:
def __init__(self, master):
frame = Frame(master)
frame.pack()
self.button = Button(
frame, text="Hello", command=self.button_pressed
)
self.button.pack(side=LEFT, padx=5)
self.label = Label(frame, text="This is a label")
self.label.pack()
a_var = StringVar()
a_var.trace("w", self.var_changed)
self.entry = Entry(frame,textvariable=a_var)
self.entry.pack()
def button_pressed(self):
self.label.config(text="I've been pressed!")
def var_changed(self, a, b, c):
self.label.config(text=self.entry.get())
def main():
root = Tk()
root.geometry("250x150+300+300")
ex = HelloWorld(root)
root.mainloop()
if __name__ == '__main__':
main()
The problem is that you are using a local variable for a_var, and on the Mac it is getting garbage-collected. Save a reference to the variable (eg: self.a_var rather than just a_var).
self.a_var = StringVar()
self.a_var.trace("w", self.var_changed)
self.entry = Entry(frame,textvariable=self.a_var)
self.entry.pack()
Note: if all you want is to keep a label and entry in sync, you don't need to use a trace. You can link them by giving them both the same textvariable:
self.entry = Entry(frame, textvariable=self.a_var)
self.label = Label(frame, textvariable=self.a_var)
Related
I am trying to create a GUI for an auto-complete prototype and am new to tkinter. I want to get the entire input when Space is pressed but I am unable to do so. The idea is to get all the entries in the text box so that I can do some analysis inside a function call.
This is the code:
def kp(event):
app.create_widgets(1)
import random
def getFromScript(text):
#########THIS IS A PLACE HOLDER FOR ACTUAL IMPLEMENTATION
i= random.randint(1,100)
return ['hello'+str(i),'helou'+text]
from tkinter import *
class Application(Frame):
def __init__(self, master=None):
Frame.__init__(self, master)
self.pack()
self.create_widgets(0)
# Create main GUI window
def create_widgets(self,i):
self.search_var = StringVar()
self.search_var.trace("w", lambda name, index, mode: self.update_list(i))
self.lbox = Listbox(self, width=45, height=15)
if i==0:
self.entry = Entry(self, textvariable=self.search_var, width=13)
self.entry.grid(row=0, column=0, padx=10, pady=3)
self.lbox.grid(row=1, column=0, padx=10, pady=3)
# Function for updating the list/doing the search.
# It needs to be called here to populate the listbox.
self.update_list(i)
def update_list(self,i):
search_term = self.search_var.get()#### THIS LINE SHOULD READ THE TEXT
# Just a generic list to populate the listbox
if(i==0):
lbox_list = ['Excellent','Very Good','Shabby', 'Unpolite']
if(i==1):
lbox_list = getFromScript(search_term)####### PASS TEXT HERE
self.lbox.delete(0, END)
for item in lbox_list:
if search_term.lower() in item.lower():
self.lbox.insert(END, item)
root = Tk()
root.title('Filter Listbox Test')
root.bind_all('<space>', kp)
app = Application(master=root)
app.mainloop()
Any kind of help is highly appreciable. Thanks in advance
Problem is you are creating a new StringVar on each create_widgets call.
Create StringVar in your __init__.
class Application(Frame):
def __init__(self, master=None):
...
self.search_var = StringVar()
...
I'm just getting started coding in Python/Tkinter for a small Pymol plugin. Here I'm trying to have a toggle button and report its status when it is clicked. The button goes up and down, but toggleAVA never gets called. Any ideas why?
from Tkinter import *
import tkMessageBox
class AVAGnome:
def __init__(self, master):
# create frames
self.F1 = Frame(rootGnome, padx=5, pady=5, bg='red')
# checkbuttons
self.AVAselected = IntVar()
self.AVAselected.trace("w", self.toggleAVA)
self.AVAbutton = Checkbutton(self.F1, text='AVA', indicatoron=0, variable=self.AVAselected)
# start layout procedure
self.layout()
def layout(self):
self.F1.pack(side=TOP, fill=BOTH, anchor=NW)
#entry and buttons
self.AVAbutton.pack(side=LEFT)
def toggleAVA(self, *args):
if (self.AVAselected.get()):
avastatus = "selected"
else:
avastatus = "unselected"
tkMessageBox.showinfo("AVA status", avastatus)
def __init__(self):
open_GnomeUI()
def open_GnomeUI():
# initialize window
global rootGnome
rootGnome = Tk()
rootGnome.title('AVAGnome')
global gnomeUI
gnomeUI = AVAGnome(rootGnome)
I tested your code with Pymol.
Problem is because you use Tk() to create your window. You have to use Toplevel() and then it will work correctly with trace() or with command=.
Pymol is created with tkinter which can have only one window created with Tk() - it is main window in program. Every other window has to be created with Toplevel().
I have attached a working version of your code below. You can refer to it to learn where you went wrong. Generally, you have to mind how you structure your code if you are using a class format.This will help you visualize your code and debug better. You can read this discussion to help you.
from Tkinter import *
import tkMessageBox
class AVAGnome(Frame):
def __init__(self, parent):
Frame.__init__(self, parent)
# create frames
self.F1 = Frame(self, padx=5, pady=5, bg='red')
# checkbutton
self.AVAselected = IntVar()
self.AVAselected.trace("w", self.toggleAVA)
self.AVAbutton = Checkbutton(
self.F1, text='AVA', indicatoron=0, width=10,
variable=self.AVAselected)
# start layout procedure
self.F1.pack(side=TOP, fill=BOTH, anchor=NW)
self.AVAbutton.pack(side=LEFT) #entry and buttons
def toggleAVA(self, *args):
if (self.AVAselected.get()):
avastatus = "selected"
else:
avastatus = "unselected"
tkMessageBox.showinfo("AVA status", avastatus)
if __name__ == '__main__':
rootGnome = Tk()
rootGnome.title('AVAGnome')
gnomeUI = AVAGnome(rootGnome)
gnomeUI.pack(fill="both", expand=True)
gnomeUI.mainloop()
Update: The above code structure is for standalone tkinter programme. I am attempting to convert this working code to follow Pymol plugin example. Revised code is posted below and is susceptible to further revision.
# https://pymolwiki.org/index.php/Plugins_Tutorial
# I adapted from the example in the above link and converted my previous code to
#
from Tkinter import *
import tkMessageBox
def __init__(self): # The example had a self term here.
self.open_GnomeUI()
class AVAGnome(Frame):
def __init__(self, parent):
Frame.__init__(self, parent)
# create frames
self.F1 = Frame(self, padx=5, pady=5, bg='red')
# checkbutton
self.AVAselected = IntVar()
self.AVAselected.trace("w", self.toggleAVA)
self.AVAbutton = Checkbutton(
self.F1, text='AVA', indicatoron=0, width=10,
variable=self.AVAselected)
# start layout procedure
self.F1.pack(side=TOP, fill=BOTH, anchor=NW)
self.AVAbutton.pack(side=LEFT) #entry and buttons
def toggleAVA(self, *args):
if (self.AVAselected.get()):
avastatus = "selected"
else:
avastatus = "unselected"
tkMessageBox.showinfo("AVA status", avastatus)
# Note, I added a "self" term throughout function.
# Try w/ & w/o "self" to see which works.
def open_GnomeUI(self):
self.rootGnome = Tk()
self.rootGnome.title('AVAGnome')
self.gnomeUI = AVAGnome(self.rootGnome)
self.gnomeUI.pack(fill="both", expand=True)
self.gnomeUI.mainloop()
So I am currently trying to create a button on a GUI that will let the user generate a new entry field.
I have no idea how to do this. I'm guessing that it will require a lambda function, but apart from that, I have no idea.
Here's the basic code I have so far:
from tkinter import *
class prac:
def autoAddWidget(self,frame,x,y):
self.entryField = Entry(frame,text="Entry Field")
self.entryField.grid(row=x, column=y)
#lambda function?
def __init__(self, master):
frame = Frame(master, width=60, height=50)
frame.pack()
x=1
self.addWidgetButton = Button(frame, text="Add new widget", command=self.autoAddWidget(frame, x,0))
self.addWidgetButton.grid(row=0, column=0)
x+=1
root = Tk()
app = prac(root)
root.mainloop()
Would appreciate the help.
Thanks
You're passing to the command argument result from the method self.autoAddWidget(frame, x,0) not method itself. You have to pass there a reference to a callable object, a function that will be called when the event occurs. Please check a documentation next time before you ask the question.
Ok, I fixed the code, now it works:
from tkinter import *
class Prac:
def autoAddWidget(self):
self.entryField = Entry(self.frame,text="Entry Field")
self.entryField.grid(row=self.x, column=0)
self.x+=1
def __init__(self, master):
self.frame = Frame(master, width=60, height=50)
self.frame.pack()
self.x=1
self.addWidgetButton = Button(self.frame, text="Add new widget", command=self.autoAddWidget)
self.addWidgetButton.grid(row=0, column=0)
root = Tk()
app = Prac(root)
root.mainloop()
I'm just starting to learn to use tkinter with python and it seems counterintuitive that this attempt at a simple script to print whatever is entered into the entry box, doesn't work:
class App:
def __init__(self, master):
frame = Frame(master)
frame.pack()
text_write = Entry(frame)
text_write.pack()
self.button = Button(frame, text="quit", fg="red", command=frame.quit)
self.button.pack(side=LEFT)
self.hi_there = Button(frame, text='hello', fg='black', command=self.say_hi(text_write.get()))
self.hi_there.pack(side=RIGHT)
def say_hi(self, text):
print(text)
root = Tk()
app = App(root)
root.mainloop()
This does nothing and outputs no errors, but if I change it to this:
class App:
def __init__(self, master):
frame = Frame(master)
frame.pack()
self.text_write = Entry(frame)
self.text_write.pack()
self.button = Button(frame, text="quit", fg="red", command=frame.quit)
self.button.pack(side=LEFT)
self.hi_there = Button(frame, text='hello', fg='black', command=self.say_hi)
self.hi_there.pack(side=RIGHT)
def say_hi(self):
print(self.text_write.get())
then it calls the function and prints the value. Why does the 'self' need to be declared there? And why can't you pass the value of text_write as an argument to say_hi (as in the first example) and have it display? Or can you and I'm just doing it wrong?
When you do this:
self.button = Button(..., command=func())
then python will call func(), and the result of that will be assigned to the command attribute. Since your func doesn't return anything, command will be None. That's why, when you push the button, nothing happens.
Your second version seems fine. The reason self is required is that without it, text_write is a local variable only visible to to the init function. By using self, it becomes an attribute of the object and thus accessible to all of the methods of the object.
If you want to learn how to pass arguments similar to your first attempt, search this site for uses of lambda and functools.partial. This sort of question has been asked and answered several times.
I'm making a program using Tkinter where the user inputs their weight in Pound and then it outputs their weight in kilo.
I'm having problems getting the contents of the Entry from the user.
I'm calculating the pound to kilo in clicked1.
Can someone show me how I would get the Entry input there?
from Tkinter import *
import tkMessageBox
class App(object):
def __init__(self):
self.root = Tk()
self.root.wm_title("Question 7")
self.label = Label (self.root, text= "Enter your weight in pounds.")
self.label.pack()
self.entrytext = StringVar()
Entry(self.root, textvariable=self.entrytext).pack()
self.buttontext = StringVar()
self.buttontext.set("Calculate")
Button(self.root, textvariable=self.buttontext, command=self.clicked1).pack()
self.label = Label (self.root, text="")
self.label.pack()
self.root.mainloop()
def clicked1(self):
input = 3423 #I would like the user input here.
self.label.configure(text=input)
def button_click(self, e):
pass
App()
What you are looking for is [widget].get()
Text widget
In case you use the Text widget, you have to use [widget].get(1.0, END) where 1.0 means "first line, 0th character"
Code review
I've noticed a few other things in your code that could get improved:
PEP8 conformity; see pep8online.com
If you add a Shebang, Linux users will be able to execute it directly with ./script.py.
Variable naming:
input is a built-in function and you should avoid overwriting it
Use meaningful variable names (entrytext might be problematic in case you extend your program)
Avoid from Tkinter import *. This might lead to unexpected naming clashes.
Complete code
##!/usr/bin/env python
import Tkinter as Tk
class App(object):
def __init__(self):
self.root = Tk.Tk()
self.root.wm_title("Question 7")
self.label = Tk.Label(self.root, text="Enter your weight in pounds.")
self.label.pack()
self.weight_in_kg = Tk.StringVar()
Tk.Entry(self.root, textvariable=self.weight_in_kg).pack()
self.buttontext = Tk.StringVar()
self.buttontext.set("Calculate")
Tk.Button(self.root,
textvariable=self.buttontext,
command=self.clicked1).pack()
self.label = Tk.Label(self.root, text="")
self.label.pack()
self.root.mainloop()
def clicked1(self):
weight_in_kg = self.weight_in_kg.get()
self.label.configure(text=weight_in_kg)
def button_click(self, e):
pass
App()
Is this the kinda thing you are looking for?
from Tkinter import *
import tkMessageBox
class App(object):
def __init__(self):
self.root = Tk()
self.root.wm_title("Question 7")
self.label = Label (self.root, text= "Enter your weight in pounds.")
self.label.pack()
self.entrytext = StringVar()
Entry(self.root, textvariable=self.entrytext).pack()
self.buttontext = StringVar()
self.buttontext.set("Calculate")
Button(self.root, textvariable=self.buttontext, command=self.clicked1).pack()
self.label = Label (self.root, text="")
self.label.pack()
self.root.mainloop()
def clicked1(self):
input = self.entrytext.get()
result = int(input)*2
self.label.configure(text=result)
def button_click(self, e):
pass
App()
I think this is what your'e looking for, although not just times by 2.
You would probably also want to put in an exception for if the value is not a int.
As you have associated a StringVar with your Entry widget, you can easily access/manipulate the widget's text with StringVar's get and set methods.
See here for more information.