I've searched everywhere on the web but unfortunately no where did
I find an answer to this question:
after setting a tkinter Entry() widget's textvariable to a textvariable.
the text variable does not update after I have typed text into the entry.
code below:
def saveFileName(self):
if(self.save_file_name != ""):
self.window.destroy()
self.name_not_set = False
print("saving...")
else:
print("notsaving...entry empty")
pass
def cancel(self):
self.name_not_set = False
self.exit = True
self.window.destroy()
print("exiting...")
def askForFilename(self):
self.window = tk.Tk()
self.window.wm_title("enter a file name")
label = Label(self.window,text="please enter a file name:").pack(side="top")
entry = Entry(self.window,textvariable=self.save_file_name).pack()
save = Button(self.window,text="save",command=self.saveFileName).pack()
cancel = Button(self.window,text="cancel",command=self.cancel).pack()
self.window.mainloop()
The necessary variables have been defined and these methods are part
of a class which is a tk.TK() instance.
this problem is very bothersome
:( very sad :(
Thank you and merry christmas in advance!
A textvariable associated with an Entry should be a StringVar(). I don't se any such declaration in your code.
self.save_file_name = StringVar()
To set and get the value of a StringVar() you must use the set() or get() method, eg.
def saveFileName(self):
if(self.save_file_name.get() != ""):
self.window.destroy()
# etc, etc.
Also, don't create more than one instance of Tk() as in:
def askForFilename(self):
self.window = tk.Tk()
Use Toplevel() instead. Or even better: use the tkinter filedialogs.
Related
I want to write a program where after a user enters text and clicks a button, the text becomes a label and the button text is changed. My code is:
# Imports
import os, sys
import tkinter
"""
Tkinter program 1
text box + button + label
"""
# Button Entry
def enter(inputtedinfo, randvar, EnterMessage):
randvar = inputtedinfo.get()
EnterMessage = "Submitted!"
# Main Function
def main():
something = tkinter.Tk()
something.title("My First Tkinter Window")
something.geometry("600x400")
randvar = ""
EnterMessage = "Enter"
inputtedinfo = tkinter.StringVar()
userLabel = tkinter.Label(something, text = randvar)
userEntry = tkinter.Entry(something, textvariable = inputtedinfo)
userButton = tkinter.Button(something, text = EnterMessage, command = enter(inputtedinfo, randvar, EnterMessage))
userEntry.grid(row=0,column=0)
userLabel.grid(row=0,column=1)
userButton.grid(row=0,column=2)
something.mainloop()
sys.exit(0)
if(__name__ == "__main__"):
main()
The user input works, but clicking the button does nothing despite the fact that it is supposed to change the variables for the button and label displays. Did I mess up somewhere?
The command argument takes the name of a function. If you write the complete call with arguments, it's not the name of the function but whatever is returned by this exact function call. So, your button will not work. It will have the command None.
In order to do what you want to do, you have to make the StringVar()s accessible to the function you are calling. So, you can both get the contents of the entry and change the values of the button and the label. To do this, best add the string variables and the widgets as attributes to the toplevel you already created (something). So, they stay available to all functions and you can get and change information:
# Button Entry
def enter():
something.randvar.set(something.inputtedinfo.get())
something.userButton["text"] = "Submitted!"
# Main Function
def main():
global something
something = tkinter.Tk()
something.title("My First Tkinter Window")
something.geometry("600x400")
something.randvar = tkinter.StringVar()
something.randvar.set("")
EnterMessage = "Enter"
something.inputtedinfo = tkinter.StringVar()
userLabel = tkinter.Label(something, textvariable = something.randvar)
something.userEntry = tkinter.Entry(something, textvariable = something.inputtedinfo)
something.userButton = tkinter.Button(something, text = EnterMessage, command = enter)
something.userEntry.grid(row=0,column=0)
userLabel.grid(row=0,column=1)
something.userButton.grid(row=0,column=2)
something.mainloop()
if(__name__ == "__main__"):
main()
There are few issues in your code:
assign string to textvariable, should use StringVar instead
command=enter(...) will execute enter(...) immediately and then assign None to command option, should use lambda instead
updating strings inside enter() does not automatically update the label and the button, should use .set() on the StirngVar instead
Below is modified code:
def enter(inputtedinfo, randvar, EnterMessage):
# used .set() to update StringVar
randvar.set(inputtedinfo.get())
EnterMessage.set("Submitted!")
def main():
something = tkinter.Tk()
something.title("My First Tkinter Window")
something.geometry("600x400")
randvar = tkinter.StringVar() # changed to StringVar()
EnterMessage = tkinter.StringVar(value="Enter") # changed to StringVar()
inputtedinfo = tkinter.StringVar()
userLabel = tkinter.Label(something, textvariable=randvar) # used textvariable instead of text option
userEntry = tkinter.Entry(something, textvariable=inputtedinfo)
userButton = tkinter.Button(something, textvariable=EnterMessage, command=lambda: enter(inputtedinfo, randvar, EnterMessage))
userEntry.grid(row=0,column=0)
userLabel.grid(row=0,column=1)
userButton.grid(row=0,column=2)
something.mainloop()
This is a simple test script I am attempting to write which will help me teach myself about tkinter...
from tkinter import *
def hello():
print("U pressed it lol")
global window1, window2
window2 = None
window1 = None
def setWindow(windowEnter):
global window
window = windowEnter
window = Tk()
window.attributes("-fullscreen", True)
def newScreen(newScreen, screenToDelete):
setWindow(newScreen)
print("New Window Created")
screenToDelete.destroy()
print("He ded lol")
setWindow(window1)
def setStuff():
button = Button(window1, text="hey", command=hello)
label = Label(window1, text="YoYoYo My dude")
button2 = Button(window1, text="Next Page", command = lambda: newScreen(window2, window1))
button.pack()
label.pack()
button2.pack()
setStuff()
When I run this code it returns an error?
File "C:\Users\026341\Desktop\test.py", line 19, in newScreen
screenToDelete.destroy()
AttributeError: 'NoneType' object has no attribute 'destroy'
Why doesn't this work & how do i fix it?
Thanks in advance :)
(Btw I'm using python 3.6)
You set
window2 = None
window1 = None
as global variables and then define the command function for button2 to be
lambda: newScreen(window2, window1)
Which calls newScreen with the values window2 and window1 which are both None, hence the error. The underlying issue here is your setWindow function:
def setWindow(windowEnter):
global window
window = windowEnter
window = Tk()
window.attributes("-fullscreen", True)
which doesn't work the way you are using it. When you call setWindow(window1), you pass the value of window1, what the function does with the variable cannot be seen on a global scope. A quick example would be this:
def increment(a):
a +=1
x = 1
print(x)
increment(x)
print(x)
which will print 1 twice.
To achieve what you want I suggest you use a dictionary to keep track of your windows.
from tkinter import *
def hello():
print("U pressed it lol")
global window1, window2
windows = {}
def setWindow(window_name):
windows[window_name] = Tk()
windows[window_name].attributes("-fullscreen", True)
def newScreen(newScreen_name, screenToDelete_name):
setWindow(newScreen_name)
print("New Window Created")
windows[screenToDelete_name].destroy()
del windows[screenToDelete_name] #delete invalid entry from dict
print("He ded lol")
setWindow("window1")
def setStuff():
button = Button(windows["window1"], text="hey", command=hello)
label = Label(windows["window1"], text="YoYoYo My dude")
button2 = Button(windows["window1"], text="Next Page", command = lambda: newScreen("window2", "window1"))
button.pack()
label.pack()
button2.pack()
setStuff()
Note on the side: previously your function was def newScreen(newScreen, screenToDelete), which is very confusing/bad style since both the function and its first argument share the same name. I changed it anyway to highlight that it now takes strings as arguments, but keep it in mind for the furture.
I'm not able to test it right now, but I've spotted a source of error:
lambda: newScreen(window2, window1)
This creates a lambda function that doesn't take any arguments, hence window2 and window1 will be None, and None doesn't have a destroy() method, hence the error. Instead try:
lambda window2, window1: newScreen(window2, window1)
When I press the button, I want it to get the Entry and -for future things- use it in another function.
import tkinter
def ButtonAction():
MyEntry = ent.get() #this is the variable I wanna use in another function
den = tkinter.Tk()
den.title("Widget Example")
lbl = tkinter.Label(den, text="Write Something")
ent = tkinter.Entry(den)
btn = tkinter.Button(den, text="Get That Something", command = ButtonAction )
lbl.pack()
ent.pack()
btn.pack()
den.mainloop()
print MyEntry #something like this maybe. That's for just example
I will use this thing as a search tool. Entry window will appear, get that "entry" from there and search it in files like:
if MyEntry in files:
#do smth
I know I can handle the problem with using globals but from what I've read it's not recommended as a first solution.
Structure the program using class.
import tkinter
class Prompt:
def button_action(self):
self.my_entry = self.ent.get() #this is the variable I wanna use in another function
def __init__(self, den):
self.lbl = tkinter.Label(den, text="Write Something")
self.ent = tkinter.Entry(den)
self.btn = tkinter.Button(den, text="Get That Something", command=self.button_action)
self.lbl.pack()
self.ent.pack()
self.btn.pack()
den = tkinter.Tk()
den.title("Widget Example")
prompt = Prompt(den)
den.mainloop()
You can access the input using prompt.my_entry later.
I'm using Python and Tkinter, and I want the equivalent of onchange event from other toolkits/languages. I want to run code whenever the user updates the state of some widgets.
In my case, I have many Entry, Checkbutton, Spinbox and Radiobutton widgets. Whenever any one of these changes, I want to run my code (in this case, update a text box on the other panel).
(just remember that user may interact with those widgets using either mouse or keyboard, and even using Ctrl+V to paste text)
I think the correct method is to use trace on a tkinter variable that has been assigned to a widget.
For example...
import tkinter
root = tkinter.Tk()
myvar = tkinter.StringVar()
myvar.set('')
mywidget = tkinter.Entry(root,textvariable=myvar,width=10)
mywidget.pack()
def oddblue(a,b,c):
if len(myvar.get())%2 == 0:
mywidget.config(bg='red')
else:
mywidget.config(bg='blue')
mywidget.update_idletasks()
myvar.trace('w',oddblue)
root.mainloop()
The w in trace tells tkinter whenever somebody writes (updates) the variable, which would happen every time someone wrote something in the Entry widget, do oddblue. The trace always passes three values to whatever function you've listed, so you'll need to expect them in your function, hence a,b,c. I usually do nothing with them as everything I need is defined locally anyway. From what I can tell a is the variable object, b is blank (not sure why), and c is the trace mode (i.e.w).
For more info on tkinter variables check this out.
How I would solve this in Tcl would be to make sure that the checkbutton, spinbox and radiobutton widgets are all associated with an array variable. I would then put a trace on the array which would cause a function to be called each time that variable is written. Tcl makes this trivial.
Unfortunately Tkinter doesn't support working with Tcl arrays. Fortunately, it's fairly easy to hack in. If you're adventurous, try the following code.
From the full disclosure department: I threw this together this morning in about half an hour. I haven't actually used this technique in any real code. I couldn't resist the challenge, though, to figure out how to use arrays with Tkinter.
import Tkinter as tk
class MyApp(tk.Tk):
'''Example app that uses Tcl arrays'''
def __init__(self):
tk.Tk.__init__(self)
self.arrayvar = ArrayVar()
self.labelvar = tk.StringVar()
rb1 = tk.Radiobutton(text="one", variable=self.arrayvar("radiobutton"), value=1)
rb2 = tk.Radiobutton(text="two", variable=self.arrayvar("radiobutton"), value=2)
cb = tk.Checkbutton(text="checked?", variable=self.arrayvar("checkbutton"),
onvalue="on", offvalue="off")
entry = tk.Entry(textvariable=self.arrayvar("entry"))
label = tk.Label(textvariable=self.labelvar)
spinbox = tk.Spinbox(from_=1, to=11, textvariable=self.arrayvar("spinbox"))
button = tk.Button(text="click to print contents of array", command=self.OnDump)
for widget in (cb, rb1, rb2, spinbox, entry, button, label):
widget.pack(anchor="w", padx=10)
self.labelvar.set("Click on a widget to see this message change")
self.arrayvar["entry"] = "something witty"
self.arrayvar["radiobutton"] = 2
self.arrayvar["checkbutton"] = "on"
self.arrayvar["spinbox"] = 11
self.arrayvar.trace(mode="w", callback=self.OnTrace)
def OnDump(self):
'''Print the contents of the array'''
print self.arrayvar.get()
def OnTrace(self, varname, elementname, mode):
'''Show the new value in a label'''
self.labelvar.set("%s changed; new value='%s'" % (elementname, self.arrayvar[elementname]))
class ArrayVar(tk.Variable):
'''A variable that works as a Tcl array variable'''
_default = {}
_elementvars = {}
def __del__(self):
self._tk.globalunsetvar(self._name)
for elementvar in self._elementvars:
del elementvar
def __setitem__(self, elementname, value):
if elementname not in self._elementvars:
v = ArrayElementVar(varname=self._name, elementname=elementname, master=self._master)
self._elementvars[elementname] = v
self._elementvars[elementname].set(value)
def __getitem__(self, name):
if name in self._elementvars:
return self._elementvars[name].get()
return None
def __call__(self, elementname):
'''Create a new StringVar as an element in the array'''
if elementname not in self._elementvars:
v = ArrayElementVar(varname=self._name, elementname=elementname, master=self._master)
self._elementvars[elementname] = v
return self._elementvars[elementname]
def set(self, dictvalue):
# this establishes the variable as an array
# as far as the Tcl interpreter is concerned
self._master.eval("array set {%s} {}" % self._name)
for (k, v) in dictvalue.iteritems():
self._tk.call("array","set",self._name, k, v)
def get(self):
'''Return a dictionary that represents the Tcl array'''
value = {}
for (elementname, elementvar) in self._elementvars.iteritems():
value[elementname] = elementvar.get()
return value
class ArrayElementVar(tk.StringVar):
'''A StringVar that represents an element of an array'''
_default = ""
def __init__(self, varname, elementname, master):
self._master = master
self._tk = master.tk
self._name = "%s(%s)" % (varname, elementname)
self.set(self._default)
def __del__(self):
"""Unset the variable in Tcl."""
self._tk.globalunsetvar(self._name)
if __name__ == "__main__":
app=MyApp()
app.wm_geometry("400x200")
app.mainloop()
You have three different ways of doing the same:
1) Use the built-in "command" configuration, like the one you use on buttons
import tkinter as tk
from tkinter import messagebox as tk_messagebox
def spinbox1_callback():
tk_messagebox.showinfo("Spinbox callback", "You changed the spinbox.")
if __name__ == "__main__":
master = tk.Tk()
spinbox1 = tk.Spinbox(master, from_=0, to=10, command=spinbox1_callback)
spinbox1.pack()
tk.mainloop()
2) Use the event bindings to capture specific events:
http://effbot.org/tkinterbook/tkinter-events-and-bindings.htm
import tkinter as tk
from tkinter import messagebox as tk_messagebox
root = tk.Tk()
def callback(event):
tk_messagebox.showinfo("clicked at", event.x, event.y)
frame = tk.Frame(root, width=100, height=100)
frame.bind("<Button-1>", callback)
frame.pack()
root.mainloop()
3) "trace" changes on a tkinter variable classes, so if your widget uses a StringVar, BooleanVar, IntVar, or DoubleVar in the textvariable parameter, you will get a callback once it gets updated. https://effbot.org/tkinterbook/variable.htm
import tkinter as tk
from tkinter import messagebox as tk_messagebox
if __name__ == "__main__":
master = tk.Tk()
widget_contents = tk.StringVar()
widget_contents.set('')
some_entry = tk.Entry(master,textvariable=widget_contents,width=10)
some_entry.pack()
def entry1_callback(*args):
tk_messagebox.showinfo("entry callback", "You changed the entry %s" % str(args))
some_entry.update_idletasks()
widget_contents.trace('w',entry1_callback)
tk.mainloop()
It's quite late, but yet, somebody found something that might be useful.
The whole idea comes from #bryan Oakley's post
If I understand well, the main problem is to detech Entry widget's . To detect it in spinbox, Checkbutton and Radiobutton you can use command options when creating widget.
To catch the <onChange> in Entry widget you can use Bryan`s approach using Tcl, which generates this event. As I said, this is not my solution, I've only changed it slightly for this case.
For example:
import tkinter as tk
from tkinter import ttk
def generateOnChange(obj):
obj.tk.eval('''
proc widget_proxy {widget widget_command args} {
# call the real tk widget command with the real args
set result [uplevel [linsert $args 0 $widget_command]]
# generate the event for certain types of commands
if {([lindex $args 0] in {insert replace delete}) ||
([lrange $args 0 2] == {mark set insert}) ||
([lrange $args 0 1] == {xview moveto}) ||
([lrange $args 0 1] == {xview scroll}) ||
([lrange $args 0 1] == {yview moveto}) ||
([lrange $args 0 1] == {yview scroll})} {
event generate $widget <<Change>> -when tail
}
# return the result from the real widget command
return $result
}
''')
obj.tk.eval('''
rename {widget} _{widget}
interp alias {{}} ::{widget} {{}} widget_proxy {widget} _{widget}
'''.format(widget=str(obj)))
def onEntryChanged(event = None):
print("Entry changed")
def onCheckChanged(event = None):
print("Check button changed")
def onSpinboxChanged(event = None):
print("Spinbox changed")
def onRadioChanged(event = None):
print("Radio changed")
if __name__ == '__main__':
root = tk.Tk()
frame = tk.Frame(root, width=400, height=400)
entry = tk.Entry(frame, width=30)
entry.grid(row=0, column=0)
generateOnChange(entry)
entry.bind('<<Change>>', onEntryChanged)
checkbutton = tk.Checkbutton(frame, command=onCheckChanged)
checkbutton.grid(row=1, column=0)
spinbox = tk.Spinbox(frame, width=100, from_=1.0, to=100.0, command=onSpinboxChanged)
spinbox.grid(row=2, column=0)
phone = tk.StringVar()
home = ttk.Radiobutton(frame, text='Home', variable=phone, value='home', command=onRadioChanged)
home.grid(row=3, column=0, sticky=tk.W)
office = ttk.Radiobutton(frame, text='Office', variable=phone, value='office', command=onRadioChanged)
office.grid(row=3, column=0, sticky=tk.E)
frame.pack()
root.mainloop()
Of course modify it to create different callback for plenty of instances (as you mentioned in the question) is easy now.
I hope somebody will find it useful.
So far, I have not encountered any thing equivalent of onChange in Tkinter.
Widgets can be bound to the various events and I have done that explicitly.
http://effbot.org/tkinterbook/tkinter-events-and-bindings.htm
Is it possible to bind all widgets to one command, with a single line? It would be nice if I could type in one line as opposed to doing each widget individually.
You would use the bind_all method on the root window. This will then apply to all widgets (unless you remove the bindtag "all" from some widgets). Note that these bindings fire last, so you can still override the application-wide binding on specific widgets if you wish.
Here's a contrived example:
import Tkinter as tk
class App:
def __init__(self):
root = tk.Tk()
root.bind_all("<1>", self.woot)
label1 = tk.Label(text="Label 1", name="label1")
label2 = tk.Label(text="Label 2", name="label2")
entry1 = tk.Entry(name="entry1")
entry2 = tk.Entry(name="entry2")
label1.pack()
label2.pack()
entry1.pack()
entry2.pack()
root.mainloop()
def woot(self, event):
print "woot!", event.widget
app=App()
You might also be interested in my answer to the question How to bind self events in Tkinter Text widget after it will binded by Text widget? where I talk a little more about bindtags.
If you have a list that contains all your widgets, you could iterate over them and assign the events.
You mean something like this code which handles all mouse events handled with single function?
from Tkinter import *
class ButtonHandler:
def __init__(self):
self.root = Tk()
self.root.geometry('600x500+200+200')
self.mousedown = False
self.label = Label(self.root, text=str(self.mousedown))
self.can = Canvas(self.root, width='500', height='400', bg='white')
self.can.bind("<Motion>",lambda x:self.handler(x,'motion'))
self.can.bind("<Button-1>",lambda x:self.handler(x,'press'))
self.can.bind("<ButtonRelease-1>",lambda x:self.handler(x,'release'))
self.label.pack()
self.can.pack()
self.root.mainloop()
def handler(self,event,button_event):
print('Handler %s' % button_event)
if button_event == 'press':
self.mousedown = True
elif button_event == 'release':
self.mousedown = False
elif button_event == 'motion':
if self.mousedown:
r = 5
self.can.create_oval(event.x-r, event.y-r, event.x+r, event.y+r, fill="orange")
self.label.config(text=str(self.mousedown))
button_event = ButtonHandler()
You could also just define a function that calls on all your widgets, and call that function. Or better yet create a class that call on your widgets in init and import the class...