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DMXGetWindowAttributes(3)


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)



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