Re: Client side usage of PersistStream

On Tue, 2003-06-17 at 01:08, Martin Kretzschmar wrote:
> Hi Christian,
> 
> Am Die, 2003-06-17 um 00.13 schrieb Christian Glodt:
> > I've been looking for an example of client side
> > usage of the PersistStream interface. Specifically,
> > I want to feed a local file to a Control in the easiest
> > possible way. I've tried PersistFile, which works fine,
> > but not all Controls support PersistFile anymore as its
> > deprecated.
> 
> No, the PersistFile interface is not deprecated. Only the use of
> BonoboPersistFile for implementing PersistFile in a component is
> discouraged. Same for BonoboPersistStream.

Yes, but unfortunately some components only support PersistFile
and others only PersistStream. To support these "corner case"
components I need to be able to talk both Stream and File at
my end.

> > I'm currently blocked on the part where I need to
> > instantiate a Bonobo_Stream which I can pass to
> > Bonobo_PersistStream_load(). I've read somewhere that
> > GnomeVFS can create such a stream, but I didn't find
> > out how.
> 
> To get a (read-only) Stream, do 
> stream = bonobo_get_object (moniker, "IDL:Bonobo/Stream:1.0", &ev);
> 
> where moniker is "file:<<path to your file>>" for local files, or
> "vfs:<<vfs-uri>>" for gnome-vfs, or some other fancy moniker.

Great, I was hoping it would be that easy.

> But you really want:
> 
> control = bonobo_get_object (moniker, "IDL:Bonobo/Control:1.0", &ev);
> 
> which will return a control with the file loaded. It will use whatever
> PersistFoo the control implements.

Actually, that's what I'm currently doing. But due to specific
constraints on my project (http://www.nongnu.org/moz-bonobo/),
I can't rely on this function. The name of the file I need to
open is mangled, and GnomeVFS sometimes fails to recognize its
mime type because of this. Incidently, I know the exact mime
type of the file. So, I instantiate a control supporting that
mime type and then feed it the file via PersistFile or Persist-
Stream.

> > I'd be very grateful for any explanations or pointers
> > to sources I can study to see how this can be done.
> 
> Nautilus can use PersistStream:
> nautilus/components/adapter/nautilus-adapter-stream-load-strategy.c
> in nautilus_adapter_stream_load_strategy_load_location
> 
> And in gpdf a test uses PersistStream:
> gpdf/xpdf/tests/test-pdf-loading.cc, in load_via_bonobo_stream.
> 
> HTH,
> 	Martin

Thanks, this helps me a lot.

Cheers,

Christian Glodt