Path: utzoo!attcan!uunet!lll-winken!ames!pasteur!ucbvax!bloom-beacon!think!ephraim
From: ephraim@think.COM (Ephraim Vishniac)
Newsgroups: comp.sys.mac.programmer
Subject: Re: Hard Disk Icons
Keywords: Disk, Icon
Message-ID: <35424@think.UUCP>
Date: 16 Jan 89 15:08:09 GMT
References: <300@puivax.UUCP>
Sender: news@think.UUCP
Reply-To: ephraim@think.com (Ephraim Vishniac)
Organization: Thinking Machines Corporation, Cambridge MA, USA
Lines: 27

In article <300@puivax.UUCP> dave@puivax.UUCP (Dave Duffy) writes:
>I would like to be able to display the icons of any hard disks
>present on the system, and I just can't figure out how to get the
>icon.  I know it is somewhere in the driver, but since the finder is
>able to display the icon, there must be some method of asking the
>driver for the icon. I tried using the Control call documented in
>IM-4, but had no success. I know it is described as for the HD-20
>only, but I figured it couldn't hurt. It is also possible I wasn't
>setting up the parameter block properly.

When writing a driver, I followed the description given in Tech Note
#28: Finders and Foreign Drives.  "Finders 4.1 and newer issue a new
Control call and, if that fails, they issue the old Control call.  The
new call has csCode = 21, and the driver should return a pointer in
csParam.  The pointer points to an 'ICN#' followed by a 1 to 31 byte
Pascal string containing the descriptor."

Notes: the csCode is 21 decimal.  The ICN# is the actual icon image
and mask, not a resource number.  The pointer is a pointer, not a
handle.  The Pascal string is an Str31 located immediately after the
ICN# (i.e., at the end of the icon mask).

Ephraim Vishniac					  ephraim@think.com
Thinking Machines Corporation / 245 First Street / Cambridge, MA 02142-1214

	"Arlo Guthrie, it seems, has found what he was looking for:
		God, and the Macintosh." (Boston Globe)