NAME

       DMXGetWindowAttributes - determine back-end window attributes

SYNOPSIS

       #include <X11/extensions/dmxext.h>

       Bool DMXGetWindowAttributes(Display *dpy,
                                   Window window,
                                   int *screen_count,
                                   int available_count,
                                   DMXWindowAttributes *attr);

DESCRIPTION

       When  calling  DMXGetWindowAttributes(), window specifies the window ID of a window on the
       Xdmx(1) server and available_count specifies the length of attr.

       The number of screens for which information is available will be returned in  screen_count
       and information about those screen will be returned in attr.  If screen_count is less than
       available_count, then information for all of the screens  will  be  returned.   Otherwise,
       information for the first available_count screens will be returned.

       The DMXWindowAttributes structure is:

       typedef struct {
           int          screen;
           Window       window;
           XRectangle   pos, vis;
       } DMXWindowAttributes;

       For  each back-end X server that displays a portion of window, this structure contains the
       physical screen containing that portion, the 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
       (pos, in screen coordinates), and the visible area of the window on the back-end (vis,  in
       window-relative coordinates -- all zeros if the window is not visible on the backend).

       To  obtain  more  information  about the physical screen use the DMXGetScreenAttributes(3)
       call.

       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.

       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:

           A B
           C D

       In this case, the DMXGetWindowAttributes call would return the following  information  for
       the 500x500 window:

       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

RETURN VALUE

       DMXGetWindowAttributes() returns True unless there is a protocol error.

       DMXGetWindowAttributes() can generate BadWindow and BadAlloc errors.

NOTES

       Because  this  call  transports  a  great  deal  of information over the wire, please call
       DMXGetScreenCount(3) first, and make sure attr is sufficiently large.

       On a particular back-end server, it is possible that the associated  window  has  not  yet
       been  mapped  because  the XMapWindow(3) call that will eventually map the window had been
       buffered by Xlib's normal buffering system.  To avoid this  race  condition,  please  call
       DMXSync(3) before communicating directly with the back-end X server.

SEE ALSO

       DMXGetScreenCount(3), DMXSync(3), DMXGetScreenAttributes(3), DMX(3), Xdmx(1)