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.TH DMXGetWindowAttributes __libmansuffix__ __vendorversion__

.SH NAME

DMXGetWindowAttributes \- determine back-end window attributes

.SH SYNOPSIS

.B #include <X11/extensions/dmxext.h>

.sp

.nf

.BI "Bool DMXGetWindowAttributes(Display " *dpy ,

.BI "                            Window " window ,

.BI "                            int " *screen_count ,

.BI "                            int " available_count ,

.BI "                            DMXWindowAttributes " *attr );

.fi

.SH DESCRIPTION

When calling

.BR DMXGetWindowAttributes() ,

.I window

specifies the window ID of a window on the

.BR Xdmx (1)

server and

.I available_count

specifies the length of

.I attr.

.PP

The number of screens for which information is available will be

returned in

.I screen_count

and information about those screen will be returned in

.IR attr .

If

.I screen_count

is less than

.IR available_count ,

then information for all of the screens will be returned.  Otherwise,

information for the first

.I available_count

screens will be returned.

.PP

The

.I DMXWindowAttributes

structure is:

.sp

.nf

typedef struct {

    int          screen;

    Window       window;

    XRectangle   pos, vis;

} DMXWindowAttributes;

.fi

.PP

For each back-end X server that displays a portion of

.IR window ,

this structure contains the physical

.I screen

containing that portion, the

.I window

ID on the back-end X server of the window containing that portion, the

position and dimensions of the window on the back-end

.RI ( pos ,

in screen coordinates), and the visible area of the window on the

back-end

.RI ( vis ,

in window-relative coordinates -- all zeros if the window is not visible

on the backend).

.PP

To obtain more information about the physical screen use the

.BR DMXGetScreenAttributes (__libmansuffix__)

call.

.PP

Note that DMX allows multiple back-end windows to overlap in their

view of the DMX logical window.  Further, a logical window does not

have to be completely covered by back-end windows -- there may be

gaps.

.PP

As an example, consider a 500x500 window that spans the top two

1024x768 back-end displays (A and B) of a 2048x1536 DMX display

composed of 4 1024x768 back-end displays arranged in a cube:

.sp

.nf

    A B

    C D

.fi

.sp

In this case, the DMXGetWindowAttributes call would return the

following information for the 500x500 window:

.sp

.nf

display A: 500x500 window at 1024-250,0 (relative to back end)

           with 250x500 visible at 0,0 (relative to window origin)

display B: 500x500 window at -250,0 (relative to back end)

           with 250x500 visible at 250,0 (relative to window origin)

display C: 500x500 window at 1024-250,-768 with 0x0 visible at 0,0

display D: 500x500 window at -250,-768 with 0x0 visible at 0,0

.fi

.SH "RETURN VALUE"

.B DMXGetWindowAttributes()

returns

.B True

unless there is a protocol error.

.PP

.B DMXGetWindowAttributes()

can generate

.B BadWindow

and

.B BadAlloc

errors.

.SH NOTES

Because this call transports a great deal of information over the wire,

please call

.BR DMXGetScreenCount (__libmansuffix__)

first, and make sure

.I attr

is sufficiently large.

.PP

On a particular back-end server, it is possible that the associated

window has not yet been mapped because the

.BR XMapWindow (__libmansuffix__)

call that will eventually map the window had been buffered by Xlib's

normal buffering system.  To avoid this race condition, please call

.BR DMXSync (__libmansuffix__)

before communicating directly with the back-end X server.

.SH "SEE ALSO"

.BR DMXGetScreenCount "(__libmansuffix__), "

.BR DMXSync "(__libmansuffix__), "

.BR DMXGetScreenAttributes "(__libmansuffix__), "

.BR DMX "(__libmansuffix__), " Xdmx (1)