---
name: "DMXGetScreenCount"
section: "3x"
platform: "linux"
package: "libdmx-dev"
version: "1:1.0.2-2"
release: "Debian 4.0 (Etch)"
platforms: ["linux"]
url: "https://new.carta.tech/DMXGetScreenCount/3x"
---

# DMXGetScreenCount(3x)

determine number of back-end screens

## NAME

DMXGetScreenCount - determine number of back-end screens

## SYNOPSIS

**#include \<X11/extensions/dmxext.h\>**

```
Bool DMXGetScreenCount(Display *dpy,
                       int *screen_count);
```

## DESCRIPTION

**DMXGetScreenCount()** returns the number of back-end screens that a [**Xdmx**(1)](/Xdmx/1.md) server controls.  Since a DMX screen usually fills all of the available area on a back-end server, there is usually a one-to-one correspondence between DMX screens and backend servers.  However, it is also possible for a DMX screen to cover only part of the available area on a back-end server, and for more than one DMX screens to occupy different parts of the visible area on the same back-end server.

A DMX screen may be managed as a regular X screen in the [**Xdmx**(1)](/Xdmx/1.md) server or may be joined with other DMX screens using Xinerama.

## RETURN VALUE

**DMXGetScreenCount()** sets *screen\_count* and returns **True** unless there is a protocol error.

## NOTES

If Xinerama is active, only one logical screen will be available to clients of the [**Xdmx**(1)](/Xdmx/1.md) server.  However, this call will accurately reflect the number of composite back-end screens that the [**Xdmx**(1)](/Xdmx/1.md) server is using.

## SEE ALSO

**DMXGetScreenAttribtues**(3X),  **DMXChangeScreenAttributes**(3X),  **DMX**(3X), [**Xdmx**(1)](/Xdmx/1.md)