Python Cookbook 2Nd Edition Jun 1002005 [Electronic resources] نسخه متنی

Recipe 11.5. Entering Accented Characters in Tkinter Widgets

Credit: Artur de Sousa
Rocha

Problem

You want your application to allow the user to easily enter accented
characters into Tkinter widgets even from a U.S.-layout keyboard.

Solution

Internationalized applications should enable the user to easily enter
letters with accents and diacritics (e.g., umlauts, and tildes) even
from a U.S.-layout keyboard. A usefully uniform convention is the
following: hitting Ctrl-accent, for any
kind of accent or diacritic, acts as a dead
key, ensuring that the next letter hit will be decorated
by that accent or diacritic. For example, Ctrl-apostrophe, followed
by a, enters an a with an
acute accent (the character á). The following classes
provide the keyboard and widget bindings that allow this
internationalized input functionality:

from Tkinter import *
from ScrolledText import ScrolledText
from unicodedata import lookup
import os
class Diacritical(object):
"" Mixin class that adds keyboard bindings for accented characters, plus
other common functionality (e.g.: Control-A == 'select all' on Windows).
""
if os.name == "nt":
stroke = '/'
else:
stroke = 'minus'
accents = (('acute', "'"), ('grave', '`'), ('circumflex', '^'),
('tilde', '='), ('diaeresis', '"'), ('cedilla', ','),
('stroke', stroke))
def _ _init_ _(self):
# Fix some non-Windows-like Tk bindings, if we're on Windows
if os.name == 'nt':
self.bind("<Control-Key-a>", self.select_all)
self.bind("<Control-Key-/>", lambda event: "break")
# Diacritical bindings
for a, k in self.accents:
self.bind("<Control-Key-%s><Key>" % k,
lambda event, a=a: self.insert_accented(event.char, a))
def insert_accented(self, c, accent):
if c.isalpha( ):
if c.isupper( ):
cap = 'capital'
else:
cap = 'small'
try:
c = lookup("latin %s letter %c with %s" % (cap, c, accent))
self.insert(INSERT, c)
return "break"
except KeyError, e:
pass
class DiacriticalEntry(Entry, Diacritical):
"" Tkinter Entry widget with some extra key bindings for
entering typical Unicode characters - with umlauts, accents, etc. ""
def _ _init_ _(self, master=None, **kwargs):
Entry._ _init_ _(self, master=None, **kwargs)
Diacritical._ _init_ _(self)
def select_all(self, event=None):
self.selection_range(0, END)
return "break"
class DiacriticalText(ScrolledText, Diacritical):
"" Tkinter ScrolledText widget with some extra key bindings for
entering typical Unicode characters - with umlauts, accents, etc. ""
def _ _init_ _(self, master=None, **kwargs):
ScrolledText._ _init_ _(self, master=None, **kwargs)
Diacritical._ _init_ _(self)
def select_all(self, event=None):
self.tag_add(SEL, "1.0", "end-1c")
self.mark_set(INSERT, "1.0")
self.see(INSERT)
return "break"

Discussion

Here is an example of use of these widget classes. We present the
example, as usual, with a guard of if _ _name_ _ ==
'_ _main_ _'; so we can make it part of
the module containing the classes and have it run when the module is
executed as a "main script":

def test( ):
frame = Frame( )
frame.pack(fill=BOTH, expand=YES)
if os.name == "nt":
frame.option_add("*font", "Tahoma 8")    # Win default, Tk uses other
# The editors
entry = DiacriticalEntry(frame)
entry.pack(fill=BOTH, expand=YES)
text = DiacriticalText(frame, width=76, height=25, wrap=WORD)
if os.name == "nt":
text.config(font="Arial 10")
text.pack(fill=BOTH, expand=YES)
text.focus( )
frame.master.title("Diacritical Editor")
frame.mainloop( )
if _ _name_ _ == "_ _main_ _":
test( )

You might want to remove the keyboard event settings that
don't really have much to do with accents and
diacritics, (e.g., Ctrl-A, meaning "select
all") to some other, separate mixin class. I keep
that functionality together with the actual handling of diacritics
basically because I always need both features anyway.

Some design choices might be altered, such as my decision to have
Ctrl-equal as the way to enter a tilde. I took that path because I
just couldn't find a way to make
Ctrl-~ work the right way, at least on my Windows
machine! Also, depending on which languages you need to support, you
might have to add other accents and diacritics, such as a-ring for
Swedish, German scharfes-s, Icelandic eth and thorn, and so forth.

See Also

Docs about the unicodedata module in the
Library Reference and Python in a
Nutshell; information about Tkinter can be obtained from
a variety of sources, such as Pythonware's
An Introduction to Tkinter, by Fredrik Lundh
(http://www.pythonware.com/library), New
Mexico Tech's Tkinter
Reference (http://www.nmt.edu/tcc/help/lang/python/docsl),
Python in a Nutshell, and various other books.