customWidgets.py

import tkinter as tk
from tkinter import ttk

# I may have broken the unicode...
Tkinter_umlauts = [
    "odiaeresis",
    "adiaeresis",
    "udiaeresis",
    "Odiaeresis",
    "Adiaeresis",
    "Udiaeresis",
    "ssharp",
]


class AutocompleteEntry(ttk.Entry):
    """
    Subclass of Tkinter.Entry that features autocompletion.

    To enable autocompletion use set_completion_list(list) to define
    a list of possible strings to hit.
    To cycle through hits use down and up arrow keys.
    """

    def set_completion_list(self, completion_list):
        self._completion_list = sorted(
            completion_list, key=str.lower
        )  # Work with a sorted list
        self._hits = []
        self._hit_index = 0
        self.position = 0
        self.bind("<KeyRelease>", self.handle_keyrelease)

    def autocomplete(self, delta=0):
        """autocomplete the Entry, delta may be 0/1/-1 to cycle through possible hits"""
        if delta:  # need to delete selection otherwise we would fix the current position
            self.delete(self.position, tk.END)
        else:  # set position to end so selection starts where textentry ended
            self.position = len(self.get())
        # collect hits
        _hits = []
        for element in self._completion_list:
            if element.lower().startswith(self.get().lower()):  # Match case-insensitively
                _hits.append(element)
        # if we have a new hit list, keep this in mind
        if _hits != self._hits:
            self._hit_index = 0
            self._hits = _hits
        # only allow cycling if we are in a known hit list
        if _hits == self._hits and self._hits:
            self._hit_index = (self._hit_index + delta) % len(self._hits)
        # now finally perform the auto completion
        if self._hits:
            self.delete(0, tk.END)
            self.insert(0, self._hits[self._hit_index])
            self.select_range(self.position, tk.END)

    def handle_keyrelease(self, event):
        """event handler for the keyrelease event on this widget"""
        if event.keysym == "BackSpace":
            self.delete(self.index(tk.INSERT), tk.END)
            self.position = self.index(tk.END)
        if event.keysym == "Left":
            if self.position < self.index(tk.END):  # delete the selection
                self.delete(self.position, tk.END)
            else:
                self.position = self.position - 1  # delete one character
                self.delete(self.position, tk.END)
        if event.keysym == "Right":
            self.position = self.index(tk.END)  # go to end (no selection)
        if event.keysym == "Down":
            self.autocomplete(1)  # cycle to next hit
        if event.keysym == "Up":
            self.autocomplete(-1)  # cycle to previous hit
        if len(event.keysym) == 1 or event.keysym in Tkinter_umlauts:
            self.autocomplete()


class AutocompleteCombobox(ttk.Combobox):
    def set_completion_list(self, completion_list):
        """Use our completion list as our drop down selection menu, arrows move through menu."""
        self._completion_list = sorted(
            completion_list, key=str.lower
        )  # Work with a sorted list
        self._hits = []
        self._hit_index = 0
        self.position = 0
        self.bind("<KeyRelease>", self.handle_keyrelease)
        self["values"] = self._completion_list  # Setup our popup menu

    def autocomplete(self, delta=0):
        """autocomplete the Combobox, delta may be 0/1/-1 to cycle through possible hits"""
        if delta:  # need to delete selection otherwise we would fix the current position
            self.delete(self.position, tk.END)
        else:  # set position to end so selection starts where textentry ended
            self.position = len(self.get())
        # collect hits
        _hits = []
        for element in self._completion_list:
            if element.lower().startswith(self.get().lower()):  # Match case insensitively
                _hits.append(element)
        # if we have a new hit list, keep this in mind
        if _hits != self._hits:
            self._hit_index = 0
            self._hits = _hits
        # only allow cycling if we are in a known hit list
        if _hits == self._hits and self._hits:
            self._hit_index = (self._hit_index + delta) % len(self._hits)
        # now finally perform the auto completion
        if self._hits:
            self.delete(0, tk.END)
            self.insert(0, self._hits[self._hit_index])
            self.select_range(self.position, tk.END)

    def handle_keyrelease(self, event):
        """event handler for the keyrelease event on this widget"""
        if event.keysym == "BackSpace":
            self.delete(self.index(tk.INSERT), tk.END)
            self.position = self.index(tk.END)
        if event.keysym == "Left":
            if self.position < self.index(tk.END):  # delete the selection
                self.delete(self.position, tk.END)
            else:
                self.position = self.position - 1  # delete one character
                self.delete(self.position, tk.END)
        if event.keysym == "Right":
            self.position = self.index(tk.END)  # go to end (no selection)
        if len(event.keysym) == 1:
            self.autocomplete()
        # No need for up/down, we'll jump to the popup
        # list at the position of the autocompletion


def test(test_list):
    """Run a mini application to test the AutocompleteEntry Widget."""
    root = tk.Tk(className=" AutocompleteEntry demo")
    entry = AutocompleteEntry(root)
    entry.set_completion_list(test_list)
    entry.pack()
    entry.focus_set()
    combo = AutocompleteCombobox(root)
    combo.set_completion_list(test_list)
    combo.pack()
    combo.focus_set()
    # I used a tiling WM with no controls, added a shortcut to quit
    root.bind("<Control-Q>", lambda event=None: root.destroy())
    root.bind("<Control-q>", lambda event=None: root.destroy())
    root.mainloop()


if __name__ == "__main__":
    test_list = ("apple", "banana", "CranBerry", "dogwood", "alpha", "Acorn", "Anise")
    test(test_list)