Is it possible to limit TextCtrl to accept numbers only in wxPython?

Question

I want to have a text control that only accepts numbers. (Just integer values like 45 or 366)

What is the best way to do this?

score 10 · Answer 1 · answered Oct 19 '09 at 18:13

I had to do something similar, checking for alphanumeric codes. The tip on EVT_CHAR was the right thing:

class TestPanel(wx.Panel):
    def __init__(self, parent):
        wx.Panel.__init__(self, parent, -1)
        self.entry = wx.TextCtrl(self, -1)
        self.entry.Bind(wx.EVT_CHAR, self.handle_keypress)

    def handle_keypress(self, event):
        keycode = event.GetKeyCode()
        if keycode < 255:
            # valid ASCII
            if chr(keycode).isalnum():
                # Valid alphanumeric character
                event.Skip()

how will it work for cases when user presses del button or arrow buttons? — Beliaev Maksim, Apr 12 '21 at 11:51

tom10 · Accepted Answer · 2009-09-02T22:03:38.223

6

IntCtrl, Masked Edit Control, and NumCtrl are all designed to do just this, with different levels of control. Checkout the wx demo under "More Windows/Controls" to see how they work.

(Or, if you're instead really looking forward to doing this directly with a raw TextCtrl, I think you'd want to catch EVT_CHAR events, test the characters, and call evt.Skip() if it was an allowed character.)

edited Sep 02 '09 at 22:03

answered Sep 02 '09 at 21:38

tom10

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score 1 · Answer 3 · answered Jan 07 '18 at 23:18

As other answers note, it's possible to do this with an EVT_CHAR handler. You'll want to call event.Skip() for the characters you want to let through, and not call it for the ones you want to block. One nuance is that you probably also want to call event.Skip() for tab characters; pressing tab triggers the EVT_CHAR event, and if you don't call event.Skip(), you'll effectively disable tab traversal between TextCtrls.

Here's a minimal application showing two TextCtrls that accept integer or decimal numbers, with working tab traversal:

import wx

app = wx.App()

frame = wx.Frame(None, -1, 'simple.py')
panel = wx.Panel(frame)
text_ctrl_1 = wx.TextCtrl(panel, value='123')
text_ctrl_2 = wx.TextCtrl(panel, value='456', pos=(0, 30))

def block_non_numbers(event):
    key_code = event.GetKeyCode()

    # Allow ASCII numerics
    if ord('0') <= key_code <= ord('9'):
        event.Skip()
        return

    # Allow decimal points
    if key_code == ord('.'):
        event.Skip()
        return

    # Allow tabs, for tab navigation between TextCtrls
    if key_code == ord('\t'):
        event.Skip()
        return

    # Block everything else
    return

text_ctrl_1.Bind(wx.EVT_CHAR, block_non_numbers)
text_ctrl_2.Bind(wx.EVT_CHAR, block_non_numbers)

frame.Show()
app.MainLoop()

You'll probably also want to enable backspace, del, left-right: `if key_code in (8, 127, 314, 316): event.Skip() return` Note, the values may be platform dependent. — jake77, Apr 22 '18 at 08:02
@jake77 I believe those keys don't trigger `EVT_CHAR` at all (and so checking for them in an `EVT_CHAR` handler is unnecessary), though I'll confirm later. — Mark Amery, Apr 22 '18 at 10:35

score 1 · Answer 4 · answered Apr 26 '11 at 20:53

You can try IntCtrl, EVT_CHAR, or implement a new/existing validator (like IntValidator). Validators can be used to validate a field (useful when trying to validate multiple things on a dialog/panel) and they can also be used with EVT_CHAR to restrict input in a field.

score 1 · Answer 5 · answered Oct 30 '19 at 13:28

I wanted the same but for floats, so I used the following method in the class:

 def force_numeric(self, event, edit):
    raw_value =  edit.GetValue().strip()
    keycode = event.GetKeyCode()
    if keycode < 255:
        print('keycode:', keycode,'chr(keycode) ', chr(keycode))
        if chr(keycode).isdigit() or chr(keycode)=='.' and '.' not in raw_value:
            print('skip')
            event.Skip()

to register the event in the constructor:

    item = wx.TextCtrl(self.panel, -1, str(pose_config['locref_stdev']))
    item.Bind(wx.EVT_CHAR, lambda event: self.force_numeric(event, item))

Modifying the answer above

I would add key=8 support to ablt to delete charachers ``` if chr(keycode).isdigit() or keycode == 8 or chr(keycode) == '.' and '.' not in raw_value: ``` — ekitru, Aug 02 '23 at 14:21

score 0 · Answer 6 · answered Jun 12 '18 at 02:26

NumCtrl has some weird quirks to me. Here is my attempt to create a Number control based on EVT_CHAR and keycode.

This control allow numbers as well as all special keycode (ctrl combo, arrow key, backspace etc...), so that copy-paste, undo-redo, select-all etc still works. It will only block other printable characters (using string.printable) and unicode characters (using WXK_NONE)

Another way to check and allow all special keycode can be found by this answer. This is a better approach but requires more code.

import string

MyNumCtrl = wx.TextCtrl()
MyNumCtrl.Bind(EVT_CHAR, onChar)

def onChar(self, event):
    keycode = event.GetKeyCode()
    obj = event.GetEventObject()
    val = obj.GetValue()
    # filter unicode characters
    if keycode == wx.WXK_NONE:
        pass 
    # allow digits
    elif chr(keycode) in string.digits:
        event.Skip()
    # allow special, non-printable keycodes
    elif chr(keycode) not in string.printable:
        event.Skip() # allow all other special keycode
    # allow '-' for negative numbers
    elif chr(keycode) == '-':
        if val[0] == '-':
            obj.SetValue(val[1:])
        else:
            obj.SetValue('-' + val)
    # allow '.' for float numbers
    elif chr(keycode) == '.' and '.' not in val:
        event.Skip()
    return

score -1 · Answer 7 · answered Apr 14 '14 at 06:03

-1

Please check "Validator.py" script in wxpython demo. it is exactly what you need

answered Apr 14 '14 at 06:03

alwbtc

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Is it possible to limit TextCtrl to accept numbers only in wxPython?

7 Answers7