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From: dmaustin@vivid.sun.com (Darren Austin)
Newsgroups: comp.windows.x
Subject: Re: HELP needed with BadMatch error
Message-ID: <DMAUSTIN.91Mar26141609@vivid.sun.com>
Date: 26 Mar 91 22:16:09 GMT
References: <1991Mar21.083826.6036@siesoft.co.uk>
Sender: news@exodus.Eng.Sun.COM
Distribution: comp
Organization: Sun Microsystems, Mountain View
Lines: 49
In-reply-to: huw@siesoft.co.uk's message of 21 Mar 91 08:38:26 GMT

Hi Huw,

I tried sending you mail, but I it bounced.

In article <1991Mar21.083826.6036@siesoft.co.uk> huw@siesoft.co.uk (Huw Roberts) writes:
>   The protocol error:
>   -------------------------------------------------------------------------------
>   X Error:  BadMatch, invalid parameter attributes
>     Request Major code 72 ()
>     Request Minor code
>     ResourceID 0xe00002
>     Error Serial #13
>     Current Serial #14
>
	...
>
>       maskp = XCreatePixmap(display, RootWindowOfScreen(screen), cols, rows, 1);
>       XPutImage(display, maskp, DefaultGCOfScreen(screen), mask, 0, 0, 0, 0,
>		   cols, rows);
>   }
>   -------------------------------------------------------------------------------
>   Basically the problem is with the last statement.  Note that both the Image
>   and the Pixmap have depth 1.

This is the problem.  The pixmap and the image may both be of
depth 1, but the DefaultDepth() of the server probably isn't.
GC's can only be used with drawables of the same depth that it
was created with.  The DefaultGCOfScreen() is created with the
RootWindow as the drawable (which is of depth DefaultDepth()).
Therefore if your DefaultDepth() is something other than 1 (like
it would be on a color display), you will get this BadMatch
error.

Now a solution would be to create your own GC with the pixmap
as the drawable like so:

	gc = XCreateGC(display, pixmap, 0, NULL);

This will give you the equivalent of the DefaultGC, except that
you can use it with the pixmap.

Hope this helps,
--Darren

--
Darren Austin                         |  Actually, it's a buck and a quarter
Windows and Graphics Software	      |  staff, but I'm not going to tell
Sun Microsystems, Mountain View       |  *him* that.
dmaustin@sun.com	              |