DMXGetWindowAttributeUNIX)Programmer's DMXGetWindowAttributes(3X)
DMXGetWindowAttributes - determine back-end window attri-
butes
#include <X11/extensions/dmxext.h>
Bool DMXGetWindowAttributes(Display *dpy,
Window window,
int *screen_count,
int available_count,
DMXWindowAttributes *attr);
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 win-
dow, 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(3X) 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
XFree86 Version 4.5.0 1
DMXGetWindowAttributeUNIX)Programmer's DMXGetWindowAttributes(3X)
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
DMXGetWindowAttributes() returns True unless there is a pro-
tocol error.
DMXGetWindowAttributes() can generate BadWindow and BadAlloc
errors.
Because this call transports a great deal of information
over the wire, please call DMXGetScreenCount(3X) 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(3X) call that will eventually map the window had
been buffered by Xlib's normal buffering system. To avoid
this race condition, please call DMXSync(3X) before communi-
cating directly with the back-end X server.
DMXGetScreenCount(3X), DMXSync(3X),
DMXGetScreenAttributes(3X), DMX(3X), Xdmx(1)
XFree86 Version 4.5.0 2
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