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From: randy@erik.UUCP (Randy Brown)
Newsgroups: comp.windows.x
Subject: Re:  XPutImage
Message-ID: <9103211635.AA09366@erik.uucp>
Date: 21 Mar 91 16:35:34 GMT
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
Lines: 31


	From: uunet!quisp.philips.com!bob (Robert A. Cohen)
	Message-Id: <118960@philabs.Philips.Com>

        Is there a faster way to display sequences
	than using XPutImage() in a loop?

If you have enough room in the server to create pixmaps
(off-screen drawables), you can then copy them to the 
screen with XCopyArea, which is usually much faster than
XPutImage.  If your server supports the shared memory
extension MIT-SHM (use xdpyinfo to find out) you can
allocate pixmaps in client memory and share them with 
the server, allowing both client and server to draw
quickly into the pixmap, with rapid display via a 
call to XCopyArea and no actual transmission of the
image through the client-server connection.

There is also a double-buffering and amimation extension
that I don't know anything about--I offer this only as
an exercise for the ambitious reader.  One advantage is
that timing is done in the server, which is presumably 
no less precise than timing in the client, and doesn't
get changed by variations in the connection delay.

Sequences each image of which require only a few of many
available colors can be displayed by overlaying them in
various planes of a single window and changing colormaps
to display specific planes, with "don`t care" values for
the other planes.  Changing colormaps is fast on most
 servers.