Re: XForms: more double buffering strangeness

Stephen Langer (
Thu, 10 Jul 1997 13:34:52 -0400

To subscribers of the xforms list from "Stephen Langer" <> :

> >
> Yes, it is in the FL_DRAW handler for a Free object.
> I've never had the problem you describe and, in fact, do quite a bit
> of object handling in my Canvas Expose handlers and I do force redraws
> with fl_redraw_object() or fl_redraw_form() with no difficulty
> whatsoever -- at least any that I recall.
> What difficulties have you had?

When redrawing an object sometimes another redraw event will be generated,
and I'll get recursive calls to my Expose handler. I'm a little fuzzy on the
details (this was a while ago), but I know that I was forced to avoid doing
anything that might cause a redraw while redrawing my canvas. I think what
was happening was that by redrawing other objects during the canvas redraw,
all the objects on the form (including the canvas) would be redrawn. Also, if
an error occurs during the redraw then I had to wait until after exiting the
Expose handler to call fl_show_alert, since another redraw is triggered when
the alert box is dismissed.

-- Steve

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