Ubuntu consistency changes

[Daniel Stone]

On Thu, Oct 13, 2005 at 10:26:46AM +0200, John Nilsson wrote:
> On Thu, 2005-10-13 at 16:33 +1000, Daniel Stone wrote:
> > Secondly, assuming you want to do the compositing client-side, you need
> > to do colour transformations of 1024*768, 1600*1200, or however many,
> > pixels.  This hurts.  Doing this quickly in software is a non-trivially
> > difficult task.
> 
> This is done within gdk_pixbuf_get_from_drawable?

Uhm, I was mainly talking about if you need to combine images for pretty
effects.

> > Thirdly, you need to upload the image again.
> 
> That part isn't so bad actually.
> 
> john at newkid:~/test$ ./blur
> Pixbuf downloaded in 0.119416s
> Pixbuf blured in 0.170319s
> Pixbuf uploaded in 0.053775s

Hm, that's not too bad.  But if you're still running at 0.23 seconds per
operation, plus however much time you need for Xlib's buffering to
outwit you, it's too slow to do multiple, graduated, effects.  If you
do a single effect, that's fine.

> > This pretty much eliminates any kind of gradual fade: you'll need to do
> > that with a very good compositing manager if you want it.  The only
> > reason xscreensaver's fade works is because it does a gamma fade, which
> > is both quick and very well supported.
> 
> I kind of figured that why nothing more was done with it in this case.
> 
> I guess the right thing to do is to postpone this kind of EyeCandy(TM)
> until it can be done using OpenGL...

Indeed.  Hooray.

> By the way is there a quick way to repaint the whole screen? I was
> trying to use
> 
> 	GdkRectangle rect = {0,0,width,height};
>         gdk_window_invalidate_rect(root, &rect, TRUE);
>         gdk_window_process_all_updates();
> 
> no luck. As you see, I'm still learning all this stuff...

It's getting rather off-topic, yeah; if you need to force a repaint of
the whole screen for whatever reason, I don't think a simple
invalidation will do it; you'll probably need to map and then quickly
unmap a w x h unmanaged window.
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