Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!usc!snorkelwacker!bloom-beacon!EXPO.LCS.MIT.EDU!keith
From: keith@EXPO.LCS.MIT.EDU (Keith Packard)
Newsgroups: comp.windows.x
Subject: Re: Pixmap serialNumber assignment
Message-ID: <9010171649.AA05267@xenon.lcs.mit.edu>
Date: 17 Oct 90 16:49:03 GMT
References: <199@thor.UUCP>
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
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> I'm in the process of implementing a server over top of another
> graphics system and I've been using serialNumber as a unique
> identifier for graphics system resources I create

serialNumber is used by DIX to tag GCs with the drawable they've been validated
against.

Whenever a window is reconfigured, it's serialNumber is changed by DIX so that
all GCs which currently are validated against it are revalidated to use the new
clipping information.

This means that serialNumbers can change (at least for windows) without DDX
ever finding out.

> ProcCreatePixmap in dix/dispatch.c calls
> the screen's CreatePixmap procedure which assigns a serial number
> to the newly-created pixmap, but then ProcCreatePixmap assigns it
> a new serial number which screws up my mapping.

Even our ddxen fill in the serialNumber field in the pixmap, so this does look
redundant.  However, I'd hate to have your DDX code rely on the fact that in
the current implementation, serialNumbers for pixmaps never change.

The pixmap does contain a devPrivate field which can be used to hook on any
device-dependent information; I'm not really sure what else you'd need.
For a unique identifier, it seems like you could easily use the pixmap address.