Show combobox drop down while editing text using tkinter

问题

Is it possible to make Combobox editable while dropdown is opened? I haven't found any solution. I want to make it more like Google Search but using ComboBox.

回答1:

Question: Show Combobox PopdownWindow, while editing text

This example extends a ttk.Combobox to the following:

Show the PopdownWindow while typing
Open the PopdownWindow on Key-pressed '<Down>'
Close the PopdownWindow on Key-pressed '<Up', if at the first item in the Listbox

Reference:

Events and Bindings

For each widget, you can bind Python functions and methods to events.
ttk::combobox — text field with popdown selection list

The ttk::combobox uses the entry and listbox widgets internally.

Inherit from ttk.Combox

import tkinter as tk
import tkinter.ttk as ttk


class Combobox(ttk.Combobox):

Helper function, to map the internal Toplevel and Listbox to a tkinter object.

WARNING: This uses Tk/Tcl internals, which could change without notice.
This may working only with the tested Tk/Tcl version!

def _tk(self, cls, parent):
    obj = cls(parent)
    obj.destroy()
    if cls is tk.Toplevel:
        obj._w = self.tk.call('ttk::combobox::PopdownWindow', self)
    else:
        obj._w = '{}.{}'.format(parent._w, 'f.l')
    return obj

Initalize the object, get the internal references and bind to Key-press events

def __init__(self, parent, **kwargs):
    super().__init__(parent, **kwargs)
    self.popdown = self._tk(tk.Toplevel, parent)
    self.listbox = self._tk(tk.Listbox, self.popdown)

    self.bind("<KeyPress>", self.on_keypress, '+')
    self.listbox.bind("<Up>", self.on_keypress)

Key-pressed handler to show or hide the PopdownWindow and set the Keyboard focus.

def on_keypress(self, event):
    if event.widget == self:
        state = self.popdown.state()

        if state == 'withdrawn' \
                and event.keysym not in ['BackSpace', 'Up']:
            self.event_generate('<Button-1>')
            self.after(0, self.focus_set)

        if event.keysym == 'Down':
            self.after(0, self.listbox.focus_set)

    else:  # self.listbox
        curselection = self.listbox.curselection()

        if event.keysym == 'Up' and curselection[0] == 0:
            self.popdown.withdraw()

Usage:

class App(tk.Tk):
    def __init__(self):
        super().__init__()

        values = ('one', 'two', 'three', 'four', 'five', 'six', 'seven')

        self.cb = Combobox(self, value=values)
        self.cb.grid(row=0, column=0)


if __name__ == "__main__":
    App().mainloop()

Tested with Python: 3.5 - 'TclVersion': 8.6 'TkVersion': 8.6

来源：https://stackoverflow.com/questions/59763822/show-combobox-drop-down-while-editing-text-using-tkinter

标签

python

tkinter

combobox