[Iup-users] Suggestions

[Antonio Scuri]

 Good point. IupUpdate is meant to be "update now". But a "mark for update"
is something that I should consider for IUP. Maybe a parameter for
IupUpdate. I have to think about it.

Thanks,
scuri

> -----Original Message-----
> From: iup-users-bounces at lists.luaforge.net 
> [mailto:iup-users-bounces at lists.luaforge.net] On Behalf Of 
> Otfried Cheong
> Sent: sexta-feira, 5 de outubro de 2007 10:06
> To: iup-users at lists.luaforge.net
> Subject: Re: [Iup-users] Suggestions
> 
> Antonio Scuri wrote:
> >   dpy = (Display*)IupGetAttribute(ih, "XDISPLAY");
> >   wnd = (Window)IupGetAttribute(ih, "XWINDOW");
> >   XGetWindowAttributes(dpy, wnd, &wa);
> >   visual = wa.visual;
> > 
> >   You will need only X, no need for Xt.
> 
> This works very well, thanks!
> 
> > void IupUpdate(Ihandle* ih)
> > {
> >   if (ih->handle)
> >     XmRedisplayWidget(ih->handle);
> > }
> 
> This also seems to work - but I'm surprised that it should be 
> necessary to use a function from the X Print extension for a 
> normal GUI task? 
> I've also tried XClearArea (see
> http://www.faqs.org/faqs/motif-faq/part6/section-2.html), 
> which also seems to work but sometimes flickers considerably.
> 
> I've started working with IUP about a week ago, and generally 
> found it quite pleasant and intuitive - except for the 
> updating of widgets.  This is the only thing so far that 
> caused me trouble when porting my application to Lua/IUP (from Qt).
> 
> In other toolkits, the "update" method only marks the widget 
> as 'dirty' 
> and needing a redraw.  In Qt, for instance, "update" only 
> schedules a paint event to happen when Qt returns to the main 
> event loop.  Several "update" calls therefore generate only 
> one call to the paint callback.
> 
> For instance, I have a specialized widget with several 
> methods for setting zoom, panning, changing contents, etc.  
> Each method calls "update" internally.  In my client code, I 
> would typically call several of these methods, e.g.
> 
>    canvas->setZoom(2.0);
>    canvas->setPan(300, 400);
>    canvas->setPage(...);
>    canvas->setZoom(....);
> 
> All this only causes one redraw, when the system returns to 
> the main loop.  You can imagine how astonished I was that IUP 
> immediately redraws the widget inside each of these setXXX 
> methods.  I had to take the internal "update" out of each 
> method, and call it from my client code:
> 
>    canvas->setZoom(2.0);
>    canvas->setPan(300, 400);
>    canvas->setPage(...);
>    canvas->setZoom(....);
>    canvas->update();
> 
> Even this is not optimal, since there may be further changes 
> before the program returns to the main loop, and unnecessary 
> redraws are done.
> 
> Is there a good reason why IUP does it this way?  For 
> instance, why does IupUpdate in the Windows driver use the 
> RDW_UPDATENOW flag?  (I tried to take it out and my program 
> still seems to work - but perhaps some of the 
> extra controls rely on this?)   In any case, it might be a 
> good idea to 
> mention this fact in the documentation.
> 
> Best wishes,
>   Otfried
> 
> 
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