Re: XForms: Test if input object has changed

From: T.C. Zhao (
Date: Wed Feb 09 2000 - 23:27:25 EST

  • Next message: T.C. Zhao: "Re: XForms: Test if input object has changed"

    # To subscribers of the xforms list from "T.C. Zhao" <> :

    The behavior you're describing sounds like v0.88 (
    input callback not called when a form is hidden). In any
    case, registering a filter probably is the cleanest way
    to go about it if you use the v_ldata field in the object
      filter_used_as_a_change_check(ob, oldbuf, newbuf, key)
            ob->u_ldata = (ob->u_ldata || key != 0);
            return FL_VALID;

    In your input callback
       input_callback(ob, data)
            ob->u_ldata = 0;

    This way, the status of the input field "hangs" on the object
    itself, and I would consider this clean.

    --- Clive A Stubbings <xforms> wrote:
    > # To subscribers of the xforms list from Clive A Stubbings
    > <> :
    > Hi,
    > Does anyone know of a clean way to test whether text in an input
    > object has been changed since the object was last set or its
    > callback was last called?
    > I need this to "work round" a quirk in the way FL_RETURN_CHANGED
    > works.
    > If you use fl_set_input_return(ob, FL_RETURN_CHANGED) on a Multiline
    > input object, the callback will be called when focus changes to
    > another
    > input object on the same form. However the callback is not called
    > when
    > you press a button or do some other action or focus on an input to
    > another form. So.. if you flip between tabs on a tabbed form, or
    > close a
    > form, the callback still isn't called. Now its easy to check whether
    > the
    > current focus object is an input object using
    > inputobj = fl_get_focus_object(form);
    > if (inputobj && (inputobj->objclass == FL_INPUT)) {
    > but what I can't see is how to then check whether the object has
    > been changed..
    > I guess there are various ways to work round this like setting a
    > callback to occur on every character typed. But I don't really want
    > to
    > read and process on every character. I suppose I could set a flag,
    > but
    > there are a number of objects spread over a number of forms and that
    > would take a lot of managing..
    > A simple
    > int fl_input_has_changed(FL_OBJECT ob);
    > function would be ideal..
    > I have a REALLY dirty way of doing this, but it is not portable
    > across
    > different versions of the library because it relies on knowing the
    > internal structure of the "spec" field in an input object.. (which is
    > not in the headers so I deduced the critical bit empirically.. ;-)
    > There
    > seems to be a field there that contains exactly this information (8th
    > int for what its worth).. I do not like this solution...
    > Anyone know of any better way?
    > Cheers
    > Clive
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