Re: How did Gnome/KDE do it?

[G B <gbpublicemailaddress yahoo com>]

Tristan,
Thanks for that.
Do you mean that X composite extensions aren't
available for QT, or for QT and also for gtk?  So in
gtk, if you move the label, does it know to only
redraw (clear) the area where the label was
previously, and then redraw it in the new position, or
do you, as I suppose, have to take care of what
regions you want redrawn?  Is the same true of QT?  If
neither toolkits do this, then maybe this function can
be better done in OpenGL, since you can access the
framebuffer directly and erase only the old position
of only the text, which I read that you can't do
(can't access frame buffer directly) in, at least, QT.
 However, I've been advised not to use OpenGL in this
way on the EFNET channel.  Perhaps I misread the
advise given there.  What are your thoughts on all
this?

The answer you gave did help me understand the
situation more clearly.  

--- Tristan Van Berkom <tristan van berkom gmail com>
wrote:

> On Tue, 30 Nov 2004 12:03:02 -0800 (PST), G B
> <gbpublicemailaddress yahoo com> wrote:
> > How did Gnome/KDE make, for example, the linux
> > terminal, or any window who's background can be
> set to
> > the desktop (I'm not interested in setting the BG
> > image to the desktop in particular, but an
> arbitrary
> > image), and allow scrolling text over that image.
> >
> > Note, I don't mean tile the background of a text
> edit
> > widget and scroll down the tiles upon which the
> text
> > is permanently place, but actual scrolling text
> over a
> > non-scrolling image.
> >
> > Hint: I notice that the text scrolling is done
> line by
> > line, not by a single, or arbitrary number of
> pixels.
> > Thanks,
>
> For now, transperency in terminals is a matter of
> grabing the desktop
> image and rendering the text to that, since X
> composite extentions arent
> really available yet ;-)
>
> When rendering labels in Gtk+, labels render
> directly to the parent window
> every time the parent window recieves an expose from
> the X server... 
> So every time the background, the position of the
> label, or the alignment of
> the label changes, the label gets re-rendered.
>
> I'm not entirely sure this answers your question
> though :-/
>
> Cheers,
>                                                     
> -Tristan



                
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