CODEWITHSUNDEEP
pythontkinter
Module_art
Module_art

Reputation: 1067

Python Tkinter How use bindings correctly?

The idea was show in label where my cursor(line.column) is. Which work with .index(INSERT) well but if i bind the right mouse button with text it returns the previous cursor position not the current. It seems that callback is executed after event?

from tkinter import Tk, Text, Frame, Label, StringVar, constants, END, INSERT

EXPL_TEXT = "I know that dress is karma. Perfume regret\nYou got me thinking bout"

class App(Frame):
     def __init__(self,master):
        Frame.__init__(self,master)
        self.pack()
        self.var = StringVar()
        self.init_widgets()

    def init_widgets(self):
        self.text = Text(self)
        self.text.bind('<Button-1>',self.callback_index)
        self.text.pack()
        self.text.insert(END,EXPL_TEXT)
        self.label = Label(self, textvariable=self.var)
        self.label.pack()

    def callback_index(self,event):
        x = self.text.index(INSERT)
        self.var.set(x)

if __name__ == '__main__':
    root = Tk()
    app = App(root)
    root.mainloop()

Upvotes: 2

Views: 87

Answers (1)

Mike - SMT
Mike - SMT

Reputation: 15226

The issue I believe you are seeing is that when you click your mouse down the event fires to read INSERT. The problem is before you lift your mouse the location will still have the value of the previous INSERT. So in order for you to get the update after the event has completed we can use after() to wait for the event to finish and then set the value for self.var.

Change your callback_index method to:

def callback_index(self,event):
    root.after(0, lambda: self.var.set(self.text.index(INSERT)))

What we are doing is telling python to schedule something to happen after a set time. I believe (Correct me if I am wrong) Because an event is in progress it waits until that event finishes to perform the action in the after() method.

We use lambda to create an anonymous function to update your self.var variable and all should work as intended.

Upvotes: 1

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