Re: Is Alpha Channel support in next release plan?

On Wed, 2003-08-06 at 07:50, Owen Taylor wrote:

> It's not that translucency isn't considered interesting, but
> addressing it in GTK+ when it's not in the windowing system isn't
> particularly interesting, or, for that matter, feasible.

This isn't really the issue or the question.  What you've said here is
exactly what I said a few days ago.  But Christof's point is not
necessarily about transluscent windows or popups, but having support all
the way through gdk for alpha-channel.  That way when there is a target
that supports alpha-channel windows, we'll have already done it right.

Why are we waiting for to add alpha support to gdk?  Why not add it
right now.  Even though X11 may not have transluscent windows, we could
still use alpha-channels in gdk to composite a transluscent widget (say
a text view box) on top of some pixmap in the window.  Basically none of
this has anything to do with X11 or the underlying window system.

For example, if the gdk_draw_* methods supported alpha channel and we
used gdk_pixbuf as the backing store (gtk does do double-buffering these
days, correct?), then that's all we're asking for right now.  Then
people could do nasty hacks to get transluscent tooltips, fade-in menus,
etc.  This would be an ABI change, so I don't imagine it would happen in
this version of GTK.  To me the following things would have to change: 
GdkColor and it's descendents would have to support the alpha value. 
The backing store method and all the drawing subroutines would have to
be modified.  Other than that, the higher-level widgets could stay the
same, except to add a few calls to maybe modify the alpha channel in the
style or something.

I'm not demanding that you do something.  I'm just wondering why you're
pushing to wait until X supports alpha-channel when this issue has
nothing to do with X at all.  Does this make sense?


> Regards,
> 					Owen
> _______________________________________________
> gtk-devel-list mailing list
> gtk-devel-list gnome org
Michael L Torrie <torriem chem byu edu>

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