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From: tomj@snowking.ebay.sun.COM (Tom Jacobs)
Newsgroups: comp.windows.x
Subject: Re: X11 and PIXRECTS
Message-ID: <8910231837.AA14833@snowking.sun.com>
Date: 23 Oct 89 18:37:46 GMT
Sender: daemon@bloom-beacon.MIT.EDU
Organization: The Internet
Lines: 56

Andrew MacLean writes:
> I have heard that in order to use memory pixrects with X11/NeWS, I MUST use 
> the PIXWIN interface "as a compatibility veneer over Xlib."

Not necessarily true, remember Pixwin is just a windowing interface to
using Pixrects and Pixrects are just a client-side representation of
data.  XView has reimplemented the Pixwin interface by translating the
Pixwin calls to Xlib calls.  However, not all of the logic of
Pixrect/Pixwin translates well in the Xlib graphics.  This is because the
PIX_* graphics OPS made assumptions about foreground and background
colors.  The result is that pixwin (not pixrect) calls may work on one
server, but not on another.

> Is this true? Is there no way to use X windows to display a memory pixrect
> into?

No, you can do the translation of the mpr to a Pixmap by calling XCreateImage().
Below is what XView does to create a simple bitmap from a mpr...
                xv_image_1(dest_info) = r_ximage =
                    (XImage *) XCreateImage(display, visual,
                                        1, XYBitmap, 0,
                                        (char *) mpr_d(((Pixrect *) src))->md_image,
                                        0, 0, MPR_LINEBITPAD,
                                        mpr_d(((Pixrect *) src))->md_linebytes);

The above is from the XView source (usr.lib/libxvin/pw/xv_rop.c).  

...
...

> The problem that I have run into is that if I take an image contained in a
> memory pixrect, and use the pr_rop routine to display the image to the screen
> (while running X11/NeWS) the system crashes. (The system is a SPARC Station 1)

Under XView, we first create the Pixmap and then copy that into the window.

> Is there some kind of preparation of the screen that I should perform before
> displaying the pixrect image? (for example, locking the screen?) Is it
> possible to avoid using the PIXWIN interface? Does anyone have any similar
> code that they have written that I may use as an example?`

Get the XView source and look at our Pixwin compatibility code (usr.lib/libxvin/pw)

> Any information would be greatly appreciated.
> 
> Signed Frustrated!!!
> 
> Thankyou, in advance.
> -- 
> Andrew MacLean                     ...uunet!mnetor!lsuc!isgtec!andrew
> Success is a journey, not an adventure!   ...utzoo!lsuc!isgtec!andrew
> ISG Technologies Inc. 3030 Orlando Dr. Mississauga. Ont. Can. L4V 1S8

	Tom Jacobs     (tomj@sun.com     -or-   ..!sun!tomj)
	Sun Microsystems, Inc.
	Mountain View, CA  94043