compositing: agreeing on a hint name for CMs requesting to draw the desktop background

[Christian Neumair-2]

Compiz sets the _COMPIZ_WALLPAPER_SUPPORTED hint for requesting to draw
the desktop background. There is a patch against Nautilus [1] available
that uses this hint to draw the folder background with alpha=0.

I would like to bring up two issues:

1) We are a bit concerned because the hint is compiz-specific.

Maybe you could agree on a name that is used for signalling that the CM
wants to draw the desktop background? IMO *_WALLPAPER_SUPPORTED doesn't
sound very concise either.


2) Wallpaper modification application

Currently, when right-clicking the desktop one can also pick from a
popup menu to change the wallpaper using a GNOME-specific application.
This obviously is not adequate for CMs. Maybe they should be able to
give a hint about the name of the .desktop file that should be launched
to configure the desktop background?

I am not sure whether it is adequate to depend on this very specific
freedesktop.org spec, so maybe the CM should be forced to also specify a
binary basename or path. But then again, .desktop files are way more
flexible wrt startup notification, attempting to execute fallback
binaries etc.

Do we have to worry about remote sessions in this context?

Note that on top of such a hint, a xdg-* application could be written
which analyzes whether a CM is running, and runs the adequate background
change application.


best regards,
 Christian Neumair

[1] http://bugzilla.gnome.org/show_bug.cgi?id=444320

--
Christian Neumair <cneumair@...>

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[Nathaniel Smith]

On Tue, Mar 25, 2008 at 12:42:06PM +0100, Christian Neumair wrote:
> Compiz sets the _COMPIZ_WALLPAPER_SUPPORTED hint for requesting to draw
> the desktop background. There is a patch against Nautilus [1] available
> that uses this hint to draw the folder background with alpha=0.

>From your email, I can't tell what this hint actually does (or even
what window it is set on -- the root? -- or who sets it), and I can't
tell why compiz wants to do anything different with backgrounds than
other WMs (i.e., just use the window with type DESKTOP as the
background).  Could you perhaps elaborate some?

-- Nathaniel

--
Electrons find their paths in subtle ways.
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Hi,

> On Tue, Mar 25, 2008 at 12:42:06PM +0100, Christian Neumair wrote:
> > Compiz sets the _COMPIZ_WALLPAPER_SUPPORTED hint for requesting to draw
> > the desktop background. There is a patch against Nautilus [1] available
> > that uses this hint to draw the folder background with alpha=0.
>
> >From your email, I can't tell what this hint actually does (or even
> what window it is set on -- the root? -- or who sets it),

It's set by a Compiz (or better Compiz Fusion) plugin (which aims to
draw per-viewport wallpapers), and is set on the root window. This
property semantically just says "I am able to draw the wallpaper,
there's no need to have the desktop window draw the wallpaper".

> and I can't
> tell why compiz wants to do anything different with backgrounds than
> other WMs (i.e., just use the window with type DESKTOP as the
> background).  Could you perhaps elaborate some?

As said, per-viewport wallpapers or even video wallpapers or similar.
The goal is to have the desktop window draw itself transparent (and keep
only the icons opaque) so other stuff can be drawn underneath it without
losing the actual desktop functionality.

Regards,

Danny

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[Christian Neumair-2]

Am Dienstag, den 25.03.2008, 14:23 +0100 schrieb Danny Baumann:

> Hi,
>
> > On Tue, Mar 25, 2008 at 12:42:06PM +0100, Christian Neumair wrote:
> > > Compiz sets the _COMPIZ_WALLPAPER_SUPPORTED hint for requesting to draw
> > > the desktop background. There is a patch against Nautilus [1] available
> > > that uses this hint to draw the folder background with alpha=0.
> >
> > >From your email, I can't tell what this hint actually does (or even
> > what window it is set on -- the root? -- or who sets it),
>
> It's set by a Compiz (or better Compiz Fusion) plugin (which aims to
> draw per-viewport wallpapers), and is set on the root window. This
> property semantically just says "I am able to draw the wallpaper,
> there's no need to have the desktop window draw the wallpaper".
>
> > and I can't
> > tell why compiz wants to do anything different with backgrounds than
> > other WMs (i.e., just use the window with type DESKTOP as the
> > background).  Could you perhaps elaborate some?
>
> As said, per-viewport wallpapers or even video wallpapers or similar.
> The goal is to have the desktop window draw itself transparent (and keep
> only the icons opaque) so other stuff can be drawn underneath it without
> losing the actual desktop functionality.

Ping.

best regards,
 Christian Neumair

--
Christian Neumair <cneumair@...>

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