This is a tool to cheat an X11 server to believe that there are more monitors than there actually are. It hooks into libXRandR and libXinerama and replaces certain, configurable monitor configurations with multiple virtual monitors. A tool that comes with this package can be used to configure how monitors are split.
This tool used to only work with XRandR, but I found it useful to add Xinerama emulation. It can be readily removed if it isn't needed though.
Note that this tool right now only works for legacy Xlib applications. Applications using xcb will not work. See issue #22 for progress on xcb support.
Also note: With xrandr 1.5, this library shouldn't be needed anymore for most users. xrandr has an abstraction for "monitors" now which should work out of the box, at least with applications written using one of the big GUI frameworks.
You'll want to use this library if you have a multi-head setup, but a crappy video driver which tells RandR that there is only one big monitor, resulting in wrong window placement by window managers. Matrox Tripple Head 2 Go et al. are other candidates, where there really is only one big monitor, but you'd want to split it anyway. Another use case is to test multi-head behaviour without having multiple monitors.
You may use, redistribute and modify this program under the terms of the GNU General Public License (GPL) Version 3, in the version available under the URL http://www.gnu.org/licenses/gpl.html#.
- Phillip Berndt
- Geoffrey 'gnif' McRae
- Gerry Demaret
- Audrius Butkevicius
In most cases, simply run
make, then install using
make install. This will determine
where the library should be installed and where the originals reside. Pay
attention to any warnings/errors from the configure script. To compile the
library, you will need the XRandR and X11 development packages for your
In case of Ubuntu, install the following prerequisites:
sudo apt-get install xorg-dev libglu1-mesa-dev build-essential \ python3-gi python-gi-dev python-gi-cairo
After installation, use the
fakexrandr-manage tool to create a configuration (in
If you need FakeXRandR for another use case or the automated building does not work for you, here are some details:
configure script creates a
config.h header with the
path to the system's real
libXrandr.so file and a path which preceeds that of
the real library in the ld search path, where the FakeXRandR should be placed.
You can use
ldconfig -v to get a list of suitable directories, if
should fail to determine one.
libXrandr.c file only contains a initialization function which loads the
symbols from the real library and implementations of the functions that we
actually override and which require more than replacement of XIDs for fake
screens with real the one's. All other functions are automatically generated
make_skeleton.py from the default Xrandr header file.
After installation, you have a tool
fakexrandr-manage available. It starts
a GUI if you have PyGObject installed and falls back to a command line interface
elsewise. You can manually use the CLI if you run
In the GUI, use the select box at the top to choose an output that you want to
split and click "Create". It will be identified by its resolution and EDID,
which is a device specific identifier. A monitor will be drawn below.
You can add splits by drawing horizontal and vertical lines with your mouse. To split an output into top and bottom part, draw a horizontal line, i.e. use your mouse like you would use scissors to cut a sheet of paper. You can move existing lines with the left mouse button, and remove them by right-clicking. When you close the configuration tool, you will be asked whether you want to save the altered configuration. Other programs, including your window manager, might need to be restarted before they begin to use the new configuration.
- How can I see if it's working?
libXrandr.soshould show up in
/usr/local/lib. Then, start
xrandr. Any split screens should show up multiple times, with
~2, etc. appended to their names. After you restarted your X11 session, fullscreening applications using Xrandr (e.g. GTK apps) should fullscreen to the virtual screen, not the physical one.
- Changing settings of the fake screen doesn't have any effect?!
XRandR is only used to communicate information on the resolution and output settings between X11 server, graphics driver and applications. It is up to the graphics driver to actually apply any settings. Since FakeXRandR only hooks into the X11
↔application communication, attempts to change settings for fake screens won't have any effect.
- My two screens are mirrored. Does this library help?
No. See the FAQ in the Gist for FakeXinerama (see "See also" section).
The program currently relies on the OS caching the configuration file in system memory. Since many programs will read it often, it would be useful to cache it ourselfes, in XResources (see an old revision for some Python code in the management tool regarding that), via a daemon, or shared memory.
- https://gist.github.com/phillipberndt/7688785 For my version of Fake xinerama, based on Kris Maglione's version. Note that this is now included in FakeXRandR.