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From: erc@pai.UUCP (Eric Johnson)
Newsgroups: comp.windows.x
Subject: Re: Info on: SHAPE or XINPUT or Multiple buffering with X wanted
Summary: Info on SHAPE
Keywords: SHAPE, XINPUT, BUFFER, ANIMATION X11R4
Message-ID: <1411@pai.UUCP>
Date: 31 Aug 90 15:05:02 GMT
References: <1990Aug30.094024.25974@abblund.se>
Organization: Boulware Technologies, Inc., Burnsville, MN
Lines: 82

In article <1990Aug30.094024.25974@abblund.se>, erik@abblund.se (Erik Sparre) writes:
> I need information about the following X extensions:
> 
> SHAPE - allows widgets to be non-rectangular (I think).
> XINPUT - 
> Multiple buffering - 
   [...]
> I don't know much about SHAPE and XINPUT, so every piece of information 
> is welcome.
> 
> -- 
> Erik Sparre                                  | Email erik@abblund.se
> ABB Corporate Research                       | Phone +46 46 168527
> Dept. KLL, Lab for Man-Machine Communication | Telex        33709
> IDEON Research Park, S-223 70 LUND, SWEDEN   | Fax   +46 46 145620

The SHAPE extension to X11 R4 is described in a document titled
"X11 Nonrectangular Window SHAPE Extension" v. 1.0 by Keith
Packard.  Basically skip over the text until section 7
("C language binding").  The main idea is that a window in
X can have a shape other than a rectangle.  A clock, for example,
can be round (see oclock im X11R4).  If you don't have this
extension (or another like it), all your windows in X are rectangles.

The simplest way to test this out (assuming your version of X
has this extension) is to create a bitmap and then set a window's
shape to that bitmap.  Its kind of fun. (I'm assuming you know
Xlib...)

In brief:

#include  <X11/extensions/shape.h>	/* add this include file */

        ... /* set up your display connection, create a window, etc... */

        ... /* create a depth 1 bitmap with whatever bits set you want */

        XShapeCombineMask( display, 
                window,
                ShapeBounding,
                0, 0,
                bitmap_shape,
                ShapeSet );

	XMapWindow( display, window );

Where:
        bitmap_shape is a depth 1 pixmap (in other words, a bitmap).

You can also use regions to set up the shape for a window.  (A caveat, 
though, rectangular regions work better than circular ones on
performance. A window made up of 100 filled rectangles performs much better
than one made up of 100 filled circles.)

When you link your program, link with the Xext library as well:

      cc -o foo foo.c -lXext -lX11

Or something like that.

Note: You may want to test for the existence of this extension
before trying to use it. See the XShapeQueryExtension() description.

Using the SHAPE extension proved to be really easy. It took me about five
minutes to figure out Packard's description of how the SHAPE extension
works (one of the few areas of X that was easy to figure out :-) Try
it, its fun.

Kevin Reichard and I put a brief (but less brief than this) discussion in
our latest book, _Advanced X Window Applications Programming_, which
I was told is just hitting the stores. (Call 1-800-MANUALS for more
information). 

Hope this helps, 
-Eric


-- 
Eric F. Johnson               phone: +1 612 894 0313    BTI: Industrial
Boulware Technologies, Inc.   fax:   +1 612 894 0316    automation systems
415 W. Travelers Trail        email: erc@pai.mn.org     and services
Burnsville, MN 55337 USA