I want to delete a menu checkbutton when i right click on it.
Its usually done with bind("Mouse3", deletefunction) , BUT i need an actual instance of a checkbutton to bind it with, and the only way to add a checkbutton to a menu i know is a add_checkbutton() method (and i have no access to instance this way). Is there any way i could do this?
import tkinter as tk
root = tk.Tk()
menubar = tk.Menu(root)
view_menu = tk.Menu(menubar, tearoff=0)
view_menu.add_checkbutton(label="Right click on me to delete", onvalue=1, offvalue=False)
# I want to do something like this:
# c = Checkbutton(label="Right click on me to delete")
# c.bind("Mouse3", my_delete_function())
# view_menu.add(c)
menubar.add_cascade(label='View', menu=view_menu)
root.config(menu=menubar)
root.mainloop()
To the best of my understanding, there's essentially two parts to your question:
Can the menu bar item be assigned for manipulation after?
Can the referenced item be then bound to an event?
The first answer is, sort of. While you can't exactly assign the object, you can reference it by index like this:
view_menu.delete(0)
Since you added the checkbutton first, it'll have an index of 0. You can either keep track of the indices, or refer to the item by its label. See this related answer from Bryan Oakley. e.g.:
view_menu.delete(view_menu.index("Right click on me to delete"))
The .index() method will locate the index by the menu entry's label, which can be handy unless you have the same label more than once...
The second answer, as far as I'm aware, there doesn't seem to be any effective binding for typical events like mouse clicks. However after some search I did come across a rather hidden <<MenuSelect>> binding that at least triggers an event. That by itself is not useful to your quest, but you can combine the event state with the checkbutton's command argument as well as a boolean flag to trigger an event on click:
# Add a BooleanVar for flagging:
delete_checkbutton = tk.BooleanVar()
# Add a binding to your view_menu
view_menu.bind('<<MenuSelect>>', event_state)
# Define the callback function:
def event_state(e):
if bool(e.state & 0x0400): # watch for the Mouse Right click state
# you might opt to use 0x0004 or 0x0001 instead
# i.e. Ctrl+click or Shift+Click
delete_checkbutton.set(True)
else: # If the state is not right click, reset the flag
delete_checkbutton.set(False)
# Define a self_delete command for the checkbutton
def self_delete():
if delete_checkbutton.get():
view_menu.delete(view_menu.index("Right click on me to delete"))
# Add the command to your checkbutton
view_menu.add_checkbutton(label="Right click on me to delete", onvalue=lambda:print('hey'), offvalue=False, command=self_delete)
Note: You will actually have to hold right click and then left click on the checkbutton to delete it. Obviously the drawback is you have now triggered the on/off value, and you might need to have some additional handling on those.
If right + left click is too awkward, Ctrl/Shift is another mod state you might consider.
Another side note: I'm a proponent of OOP when it comes to tkinter, it makes accessible variables and flags much easier without needing to worry the global and nonlocal namespaces. Here since delete_checkbutton is set in the global namespace I avoied using the global keyword and accessed it via the tk.BooleanVar() object. However if you were to use a python boolean (e.g. flag = True) then it won't be as effective unless you indicate global flag in both functions. If however you took an OOP approach you can reference the flags directly via self.flag without ambiguity.
Finally, here are the comprehensive changes implemented into your code for sampling:
import tkinter as tk
def event_state(e):
if bool(e.state & 0x0400):
# you might opt to use 0x0004 or 0x0001 instead
# i.e. Ctrl+click or Shift+Click
delete_checkbutton.set(True)
else:
delete_checkbutton.set(False)
def self_delete():
if delete_checkbutton.get():
view_menu.delete(view_menu.index("Right click on me to delete"))
root = tk.Tk()
menubar = tk.Menu(root)
delete_checkbutton = tk.BooleanVar()
view_menu = tk.Menu(menubar, tearoff=0)
view_menu.add_command(label='dude', command=lambda: print('dude'))
view_menu.add_checkbutton(label="Right click on me to delete", onvalue=lambda:print('hey'), offvalue=False, command=self_delete)
menubar.add_cascade(label='View', menu=view_menu)
root.config(menu=menubar)
view_menu.bind('<<MenuSelect>>', event_state)
root.mainloop()
All that said, I am of the opinion that this is not a very smooth User Experience and is somewhat confusing. Just the permanent deletion of the menu item alone is questionable at best, combined with the method you are trying to call upon the deletion feels even more contrived. I'd suggest revisiting your UX flow to consider how to streamline this.
Related
I have 2 radiobuttons created (inside a QMainWindow class) like:
def dtype_radiobuttons(self):
layout = QHBoxLayout()
rb1 = QRadioButton("complex")
rb1.toggled.connect(lambda: self.update_image("dtype", rb1.text()))
self.real_dtype_rb = QRadioButton("real", self)
self.real_dtype_rb.toggled.connect(lambda: self.update_image("dtype", self.real_dtype_rb.text()))
self.btngroup.append(QButtonGroup())
self.btngroup[-1].addButton(self.real_dtype_rb)
self.btngroup[-1].addButton(rb1)
rb1.setChecked(True)
layout.addWidget(rb1)
layout.addWidget(self.real_dtype_rb)
layout.addStretch()
return layout
def library_radiobutton(self):
layout = QHBoxLayout()
self.cvnn_library_rb = QRadioButton("cvnn", self)
self.cvnn_library_rb.toggled.connect(lambda: self.update_image("library", self.cvnn_library_rb.text()))
rb2 = QRadioButton("tensorflow", self)
rb2.toggled.connect(lambda: self.update_image("library", rb2.text()))
self.btngroup.append(QButtonGroup())
self.btngroup[-1].addButton(rb2)
self.btngroup[-1].addButton(self.cvnn_library_rb)
self.cvnn_library_rb.setChecked(True)
layout.addWidget(self.cvnn_library_rb)
layout.addWidget(rb2)
layout.addStretch()
return layout
I want to make it impossible to select the complex option of the dtype radiobuttons group and tensorflow radiobutton of the library radiobuttons. Leaving 3 out of the 4 possible combinations. So if I select complex and library was tensorflow, I want to automatically change the library to cvnn. I tried to implement it like this:
def update_image(self, key, value):
if value == "complex":
if hasattr(self, 'cvnn_library_rb'): # It wont exists if I still didnt create the radiobutton.
self.cvnn_library_rb.setChecked(True) # Set library cvnn
elif value == "tensorflow":
if hasattr(self, 'real_dtype_rb'):
self.real_dtype_rb.setChecked(True) # Set real dtype
... Do the other stuff I need to do.
The weird thing is that it actually works in the sense that, for example, if I am on complex activated and select tensorflow, the radiobutton changes to real (what I want!) but tensorflow does not get selected! I need to select it again as if making self.real_dtype_rb.setChecked(True) cancels the selection of the radiobutton I clicked on. (Very weird if you ask me).
The hasattr is used because depending on the order I call the
functions, there are some radiobuttons that will be created before
the other, so it might not exist.
This
is an option I am considering but it's disabling the radiobutton
group instead of changing their state (not what I prefer).
The signal toggled is triggered whenever you change the state of your radio buttons. So, it will be triggered when you call setChecked (once for the radio button you toggle and once for the other you untoggle) and update_image is called is the wrong case.
You have to check the state of the radio button and call update_image only if the radio button is toggled:
rb2.toggled.connect(lambda state: state and self.update_image("library", rb2.text(), state))
I'm trying to build a listbox using Tkinter and receive the selected option by clicking it.
import Tkinter as tk
from Tkinter import *
root = tk.Tk()
lst=Listbox(root, height=30, width=50)
lst.insert(1, "hy")
lst.insert(2, "hello")
lst.insert(3, "hey")
lst.pack()
sel = lst.curselection()
print sel
root.mainloop()
However, when I run the code it prints me an empty tuple before I pressed any choise.
Does someone know how to get the selected choise after I press one and not right after I run it?
Thanks a lot :)
You are getting the selection about a millisecond after creating the widget, well before the user has a chance to see the UI much less interact with it.
GUI programs are event based, meaning that things happen in response to events. Events are things like clicking buttons, inserting data into input widgets, and selecting items from listboxes.
You need to do one of two things: create a button or other widget which will get the selected item, or configure it so that a function is called whenever an item is selected.
No matter which solution you use, you will need a function that ultimately calls the curselection method of the listbox to get a list of indices. You can then call the get method to get the selected item or items.
Here's a function definition that will print the selected item, or print "no selection" if nothing is selected. So that it can be resused without modification. we'll define it to take the listbox as an argument.
Note: this example assumes the widget only supports a single select, to keep it simple:
def print_selection(listbox):
selection = listbox.curselection()
if selection:
print(f"selected item: {listbox.get(selection[0])}")
else:
print("nothing is selected")
Using a button
To call this from a button is straight-forward. We just create a button after we create the listbox, and use the command attribute to call the function. Since the function we wrote earlier needs a parameter, we'll use lambda to create a temporary function for the button.
button = tk.Button(root, text="Print Selected Item", command=lambda: print_selection(lst))
button.pack()
Calling the function when the selection is made
To call the function whenever the user changes the selection, we can bind a function to the <<ListboxSelect>> event. We'll create a separate function for this, and then pull the widget from the event object that is automatically passed to the function.
def print_callback(event):
print_selection(event.widget)
lst.bind("<<ListboxSelect>>", print_callback)
First of all, the reason you are getting an empty tuple is because you have executed the statements:
sel = lst.curselection()
print(sel)
before you have executed the root.mainloop()
Secondly, your setup for listbox fails to include a StringVar variable to hold your list.
Once the variable has been defined, you should be able to use the .insert statements to add your list items one at a time, or you can initialize the StringVar variable using a .set('hy', 'hello', 'hey') command.
To provide a return of a selected variable, you must incorporate an event handler to determine the list position selected onclick or some other triggering method.
For a pretty clear explanation of these characteristics check here
I have an Entry widget on a simple calculator. The user can choose to enter an equation via the keypad. I was wondering if there was a way to detect a character(from the keypad in my case) being typed into the Entry widget. So, focus is on the widget, user presses '4', it comes up on the widget... can I detect this act, for basic purposes of logging the input?
Every time you press a key inside a Tkinter window, a Tkinter.Event instance is created. All you need to do is access that instance. Here is a simple script that demonstrates just how:
from Tkinter import Tk, Entry
root = Tk()
def click(key):
# print the key that was pressed
print key.char
entry = Entry()
entry.grid()
# Bind entry to any keypress
entry.bind("<Key>", click)
root.mainloop()
key (being a Tkinter.Event instance) contains many different attributes that can be used to get almost any type of data you want on the key that was pressed. I chose to use the .char attribute here, which will have the script print what each keypress is.
Yes. There are a few different ways to do this, in fact.
You can create a StringVar, attach it to the Entry, and trace it for changes; you can bind all of the relevant events; or you can add a validation command that fires at any of several different points in the sequence. They all do slightly different things.
When a user types 4, there's a key event with just the 4 in it (which doesn't let you distinguish whether the user was adding 4 to the end, or in the middle, or replacing a whole selected word, or…), and then a modification event is fired with the old text,* and then the "key" or "all" validation function is called with the (proposed) new text, and the variable is updated with the (accepted) new text (unless the validation function returned false, in which case the invalidcommand is called instead).
I don't know which one of those you want, so let's show all of them, and you can play around with them and pick the one you want.
import Tkinter as tk
root = tk.Tk()
def validate(newtext):
print('validate: {}'.format(newtext))
return True
vcmd = root.register(validate)
def key(event):
print('key: {}'.format(event.char))
def var(*args):
print('var: {} (args {})'.format(svar.get(), args))
svar = tk.StringVar()
svar.trace('w', var)
entry = tk.Entry(root,
textvariable=svar,
validate="key", validatecommand=(vcmd, '%P'))
entry.bind('<Key>', key)
entry.pack()
root.mainloop()
The syntax for variable trace callbacks is a bit complicated, and not that well documented in Tkinter; if you want to know what the first two arguments mean, you need to read the Tcl/Tk docs, and understand how Tkinter maps your particular StringVar to the Tcl name 'PY_VAR0'… Really, it's a lot easier to just build a separate function for each variable and mode you want to trace, and ignore the args.
The syntax for validation functions is even more complicated, and a lot more flexible than I've shown. For example, you can get the inserted text (which can be more than one character, in case of a paste operation), its position, and all kinds of other things… but none of this is described anywhere in the Tkinter docs, so you will need to go the Tcl/Tk docs. The most common thing you want is the proposed new text as the argument, and for that, use (vcmd, '%P').
Anyway, you should definitely play with doing a variety of different things and see what each mechanism gives you. Move the cursor around or select part of the string before typing, paste with the keyboard and with the mouse, drag and drop the selection, hit a variety of special keys, etc.
* I'm going to ignore this step, because it's different in different versions of Tk, and not very useful anyway. In cases where you really need a modified event, it's probably better to use a Text widget and bind <<Modified>>.
If you just need to do simple things without using trace module you can try
def objchangetext(self, textwidget):
print(textwidget.get()) #print text out to terminal
text1 = tk.Entry(tk.Tk())
text1.bind("<KeyRelease>", lambda event, arg=(0): objchangetext(text1))
Why doesn't clicking on a child element propagate to the parent?
from tkinter import *
root = Tk()
def handler(event):
print('clicked at', event.x, event.y)
frame = Frame(root, width=100, height=100)
label = Label(frame, text="Label")
frame.bind('<Button-1>', handler)
frame.pack()
label.pack(side=TOP)
root.mainloop()
When I run that, clicking on the label doesn't fire the handler. I've understood that events propagate to parents by default and if you didn't want that, you'd have to return "break"
You are incorrect in your original understanding that events propagate to their parent. They do not.
Admittedly, there's an edge case for widgets which are a direct descendant of a toplevel or root window. Even there, it's not that they are propagating to their parent, but rather they are being handled by other bindings as defined by the bind tags, and by default every widget has it's toplevel window as one of it's bind tags.
If you want to set a binding to work everywhere you can use the bind_all method, since each widget has an "all" bindtag by default. Another option is to give several widgets the same bindtag (using the bindtags method), then bind to that bindtag with bind_class. Which choice you make depends on what you are trying to accomplish.
bindtags are extremely powerful -- arguably more powerful than any binding mechanisms from any other toolkit. For example, if you need to have events propagate you can do that by adjusting the bindtags of every widget to include all of its ancestors. In my experience, however, such shenanigans is rarely ever needed.
You're mistaken. "break" causes that event to not propagate to other handlers for the widget that was clicked on.
In other words, if you bound your action to label and then you bound another action to the first button onto label, both callbacks will be called (unless you return "break" from the first one to be called.)
I'm not sure of a workaround though ... (We might need to wait for BryanOakley to show up ;)
Basically, what I've done is bound a click event to a function. For example:
self.button1.bind("<Button-1>",self.chooseDice)
What I want now is to access the result of chooseDice() in another function. What is the best way to go about doing that?
class GraphicsInterface:
#we want to initialize the game board here, set up the dice and buttons
def __init__(self):
self.window = Tk()
self.window.geometry("720x500")
#buttons under each die
self.clicked=[] #empty list to collect all the buttons that were clicked (see chooseDice function)
self.button1 = Button(self.window, text="Dice 1", width=13) #create the button object
self.button1.place(x=60, y=160)
#bind button click event to a function (chooseDice())
self.button1.bind("<Button-1>",self.chooseDice)
self.button2 = Button(self.window, text="Dice 2", width=13)
self.button2.place(x=185, y=160)
self.button2.bind("<Button-1>",self.chooseDice)
#using the event as an argument, append the text to the clicked list
def chooseDice(self, event):
self.clicked.append(event.widget.cget('text'))
self.diceList=[] #create a new empty list
for i in range(len(self.clicked)):
self.diceList.append(int(self.clicked[i][5])) #get just the int value of the last character (i.e. the dice number)
self.deactivate(event.widget) #deactivate the button
return self.diceList
You are already doing what you need to do. Your example code sets self.diceList to some value. Anywhere else in your code you can directly use self.diceList.
By the way -- you're writing code that is going to be hard to maintain over time. For example, what if you change the dice label to "Dice One" or simply "One" rather than "Dice 1"? Or, as your app progresses you might want graphical images instead of text on the buttons. You'll have to modify the code that parses the button name. You are essentially encoding information in a button label which is not a good idea.
A simple solution, that also makes your chooseDice method simpler and easier to understand, is to pass in the dice number in the callback. For example:
self.button1.configure(command=lambda btn=self.button1: self.chooseDice(btn, 1))
The above passes two parameters to the chooseDice method: the button instance (so you can disable it) and the button number (so you don't have to parse the button name to get it)
This also allows you to create your dice in a loop rather than hard-coding multiple copies of the same block of code. Here's a complete working example:
from Tkinter import *
class GraphicsInterface:
def __init__(self):
self.window = Tk()
self.window.geometry("720x500")
self.clicked=[]
self.buttons = []
for n in range(1, 3):
btn = Button(text="Button " + str(n))
btn.configure(command=lambda btn=btn, n=n: self.chooseDice(btn, n))
btn.pack()
self.buttons.append(btn)
btn = Button(text="Go!", command=self.go)
btn.pack()
self.window.mainloop()
def go(self):
print "buttons:", self.clicked
self.reset()
def reset(self):
'''Reset all the buttons'''
self.clicked = []
for button in self.buttons:
button.configure(state="normal")
def chooseDice(self, widget, number):
self.clicked.append(number)
widget.configure(state="disabled")
app = GraphicsInterface()
Finally, some last bits of advice:
Don't use place, it makes your GUIs harder to create, and they won't react well to changes in window size, changes in font, changes in platform, etc. Use pack and grid instead. Also, don't create fixed-width buttons. Again, this is to better handle changes in fonts. There are times when you want fixed width buttons, but it doesn't look like your code has any reason to use them.
Finally, I don't know what you're actually trying to accomplish, but usually if you're using buttons to track state (is this thing pressed or not?) you want to use checkboxes (pick N of N) or radiobuttons (pick 1 of N). You might want to consider switching to those instead of to buttons.
Refactor. Split this into two functions.
One returns the proper result, usable by other objects.
The other is bound to a GUI control, and uses the proper result to activate and deactivate GUI objects.
Indeed, you should always do this. You should always have functions that do normal Python stuff, work correctly without the GUI and can be unit tested without the GUI. Then you connect this working "model" to the GUI.
just add a self.result attribute to your class and set it at chooseDice()