Re: [gtkmm] Customized CellRenderers

[Roger Leigh <roger whinlatter uklinux net>]

Murray Cumming <murrayc murrayc com> writes:

> On Tue, 2004-04-20 at 14:36, Leandro Fanzone wrote:
>
>> > I'm working on writing an editable ListView, much like a database 
>> > table editing tool. I would like to implement a new CellRenderer that 
>> > prevents users from entering letters on an integer field on the fly 
>> > (instead of checking this after the editing was done),
>
> I suggest that you ask on gtk-list. You probably need to derive a new
> CellRenderer, though I think a numeric_only property would be useful on
> the regular CellRendererText.

Even better would be a regular expression used to validate/restrict
input.  For numeric types, this could be as simple as '[0-9]*', but
would give significantly more flexibility:
'[0-9][0-9]-[0-9][0-9]-[0-9][0-9]' (a simple date) and
'[0-9][0-9]:[0-9][0-9]' (time).

This need not be a large overhead: use regcomp on construction, and
regexec to validate and regfree on destruction.

You could allow different modes:
- restrict to valid input
- allow invalid input, but flag error (e.g. red background)
- validate on focus out or activation
- validate manually

This shouldn't be too difficult--I plan to derive a custom Entry and
CellRenderer when I find time.


-- 
Roger Leigh

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