Re: again about "Alpha backgrounds"

["Andrea Vettorello" <andrea vettorello gmail com>]

On Jan 30, 2008 5:15 AM, Philip Langdale <philipl overt org> wrote:
> Janek Kozicki wrote:

[...]

> > can you elaborate a bit more about this patch?
>
> Well, your screenshot is unfortunately a bit of a bad example with the
> whole batman theme. When you have an app using an ARGB visual, it will
> cause sawfish to use ARGB for the frame window - and it then uses
> gdk-pixbuf to render the frame. however, gdk-pixbuf doesn't know how
> to correctly handle the visual, with the result that it clobbers
> the alpha channel to zero. Then X will render the frame elements as
> transparent (but not invisible because X uses pre-calculated alpha
> on the RGB values).
>
> So, just run gnome-terminal with transparency and you'll see the
> frame elements are transparent instead of solid, and with my patch
> they will be correctly solid.

When you say gnome-terminal transparency you don't mean the
"transparent background" option under Profile -> Effects, right?

If i use xcompmgr i've the same result with Metacity or Sawfish, the
trasparent background is done as the usual root window background
clipping, and changing opacity/transparency with transset in both WMs
affects windows and frames (you mention true transparency on the wiki
so i'm doing something wrong).

If i try with the Metacity development version and the integrated
compositor enabled, the gnome-terminal transparent background option
uses true transparency.

I was wondering, would the patch still be necessary if instead of GDK
was used XRenderComposite to render a window frame?

I would love to add compositing support to Sawfish, but every time i
look at the code i find something new that i didn't considered before
with the result of running away scared and shocked.


-- 
Andrea