Re: Display Memory

["Bluez Zhao" <zhyforever 263 net>]

Hi Liam,

Thanks for your help. Yes, I want to implement a screenshot and want it as
fast as quick. But as you know, if the desktop is using multiple visual
types, it will take a long time to query the window tree and determine the
area of the same visual type and get it's image. Someone told me that in the
display memory each pixel is stored as 32 bits. So I wander if I can get
that memory directly. Can you give me any suggestion?

Regards,

bluez


----- Original Message -----
From: "Liam Quin" <liam holoweb net>
To: "Bluez Zhao" <zhyforever 263 net>
Cc: "gtk-list" <gtk-list gnome org>; "gtk-devel-list"
<gtk-devel-list gnome org>; "gtk-app-devel-list"
<gtk-app-devel-list gnome org>
Sent: 2001年1月5日 4:02
Subject: Re: Display Memory


> On Thu, Jan 04, 2001 at 03:30:53PM +0800, Bluez Zhao wrote:
> > Hi everybody,
> > I want to get the image from display memory directly but not by calling
> > XGetImage.
> > Is there anyone who can tell me how can I do both on Solaris and Linux?
> In general you can't do this.
>
> Solaris OpenWindows has a direct X frame system that lets you talk to
> the video card (framebuffer) directly, uing semaphores to lock the
> X server out, but it is not easy to use.
>
> You can use the direct memory X extension to share a single image,
> using System V shared memory.  This is a limited resource, and is
> not always available (on Linux, it's a kernel option), so your
> program needs to work without it.
>
> If you are trying to implement a screenshot, look at other programs
> that do so (e.x. xwd -root).o
>
> If you are hoping for more speed, writing to video memory is not going
> to be fast on Solaris as using X; the X libraries will talk to
> the hardware directly when it would be faster, too.
>
> Lee
>
> --
> Liam Quin - Barefoot in Toronto - liam holoweb net -
http://www.holoweb.net/
> Ankh: irc.sorcery.net www.valinor.sorcery.net irc.gnome.org
www.advogato.org
> author, The Open Source XML Database Toolkit, Wiley, August 2000
> Co-author, The XML Specification Guide, Wiley, 1999
>
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