From: Steve Tuckner <STUCKNER@...>
Date: 2003-01-28T21:47:29+09:00
Subject: Re: [FXRuby] How to force a paint on a canvas.

Thanks to both replies!

It works spiffy now and update works fine for my purposes. I guess I looked
for and invalidate (Windows/Mac background) method or a repaint method.
There was a repaint method but it didn't do any good. What is that for by
the way?

Thanks again for your help!

Steve Tuckner

> -----Original Message-----
> From: Lyle Johnson [mailto:lyle@users.sourceforge.net]
> Sent: Monday, January 27, 2003 6:19 PM
> To: ruby-talk@ruby-lang.org
> Cc: daniel@zepeda-zone.net
> Subject: Re: [FXRuby] How to force a paint on a canvas.
>
>
> Steve Tuckner wrote:
>
> > I am working on a simple turtle graphics demonstration
> program that I
> > can use to give a demonstration to several classes of 1st
> graders. The
>
> > problem I am having is that I can draw on the canvas widget, but I
> can't
> > force it repaint after I draw. The canvas code looks like below:
>
> <snip>
>
> There's a reasonably good discussion of this in the FOX FAQ:
>
> 	http://www.fox-toolkit.org/faq.html
>
> under the topic "When do I call flush(), forceRefresh(),
> refresh() and
> update() after a change?".
>
> As Daniel pointed out in his reply, the function you want to call is
> FXCanvas#update, which should mark the drawing canvas as "dirty" and
> thus make it a candidate for repainting at some point in the future.
> Usually, that time "in the future" arrives pretty quickly (as soon as
> you return to the event loop), but it's an important distinction to
> note. As the FAQ states, if you want the repaints to take place
> *immediately*, be sure to follow the call to FXCanvas#update
> with a call
>
> to FXApp#flush. Since a flush() can be expensive, I'd try it
> without it
> first to see if you're OK with the delayed results.
>
> Hope this helps,
>
> Lyle
>