Newsgroups: comp.windows.x
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!think.com!snorkelwacker.mit.edu!bloom-beacon!dont-send-mail-to-path-lines
From: doug@genmri.UUCP (Doug Becker)
Subject: Re: XPutImage
Message-ID: <9103211808.AA24098@genmri.sane.COM>
Sender: daemon@athena.mit.edu (Mr Background)
Organization: The Internet
References: <118960@philabs.Philips.Com>
Date: 21 Mar 91 18:08:25 GMT
Lines: 31

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

That depends on your environment, your application, and on the tradeoffs
you're willing to make.  Here are two alternatives:

1.  Use pixmaps and XCopyArea.  (That is, create your image, XPutImage it
    into a pixmap, and XCopyArea the pixmap into your window.)  In my
    environment, this method can be 5-7 times faster than XPutImage.  The
    disadvantage of this approach is that it is costly in terms of server
    resources (mainly memory).  This can be a significant drawback,
    especially if your image is deep, your pixmaps are large, or server
    memory is limited.

2.  Use MIT-SHM (the shared memory extension -- XShmPutImage).  In my
    environment (and depending on the size of the image), this is only
    marginally slower than pixmaps, and consumes fewer resources (a shared
    memory segment and ID).  The major disadvantages to this method are
    that it only works locally (i.e., when the server and the client are
    running on the same machine), and that MIT-SHM is a nonstandard,
    experimental extension, which means that you cannot rely on every
    server supporting it.

A third alternative is XIE (the X Image Extension).  I've no experience
with that, so I'll leave it to an XIE expert to comment.

-- 

Doug Becker
doug@nmri.ge.com
crdgw1!sane!doug