Many laptop owners often connect their machines to external displays, whether monitors, televisions, or projectors. For display chips that support XrandR, the setup is usually rather simple. For users with Nvidia chips, it is still easy but not quick. To switch to an external display, you either have to configure it in the xorg.conf file to automatically recognize it or use nvidia-settings and click through a series of options each time you want to use it.

With Disper, a free on-the-fly display switching utility, you can quickly and easily switch to an external display, clone your screens, extend a display, and choose from any of the supported resolutions. Disper is a command line utility, but after a few initial command entries, you can easily bind it to a shortcut key or run it from a single command by using a basic script.

Installation

The Disper website lists binary package archives for Ubuntu, ArchLinux, and OpenSUSE. Follow your distribution’s normal installation procedures to install. For all other distributions, Disper uses python and is easy to install from source. To install:

1. Download the latest version

2. Open a terminal window

3.. Extract the contents of the archive:

tar zxvf disper_0.2.3.tar.gz

4. Go to the src/ directory:

cd trunk/src

5. Type:

make install

Alternative, you can run the program without installing, directly from the src directory:

./cli.py

Initial Setup

Disper should recognize your VGA, DVI, or HDMI connection right away. The first thing to do with Disper is to identify your displays. Enter the following command:

disper –list

The output will look like this:

display DFP-0: HannStar Display Corp HSD121PHW1

resolutions: …960×540, 832×624, 1024×768, 1366×768

display DFP-1: SONY TV

resolutions: …1400×1050, 1600×1024, 1680×1050, 1280×720, 1920×1080

Note: I truncated the lower resolutions, but the full list will show all of them.

Usage

If you just want to clone your display, you can enter one command:

disper -c

Unfortunately, if your device has an odd maximum resolution like my netbook (1366×768), this will result in both screens switching to something like 1024×768. That may be fine for projectors, but if you want to play movies, TV shows, or games on your television, for example, you will want to use custom settings.

For example, if I wanted to display only on my television in 720p resolution, I would enter:

disper -S -r 1280×720

The uppercase “S” refers to the external display. To switch back to the default netbook display, I would enter:

disper -s

This will automatically detect the default resolution and return to it. (Notice the lowercase “s”).

At any time, you can have Disper display the current settings with:

disper -p

The output will look like:

backend: nvidia

associated displays: DFP-0

metamode: DFP-0: 1366×768 @1366×768 +0+0

scaling: aspect-scaled

Extending the displays takes advantage of Nvidia’s Twinview, all with a single command. For example, if I wanted two screens, with my TV screen above my laptop, I would type:

disper -e -r 1366×768,1920×1080 -t top

This would give me a normal laptop screen plus a 1080p full resolution TV screen.

Simplifying

While typing in disper commands may be simple for some, others may not see it as having much of an advantage over using nvidia-settings or a graphical frontend for XrandR. To truly make it simple, you need to create a script and/or menu shortcuts.

For switching to the Sony TV, as in the example above, the script could be as simple as:

#!/bin/sh

disper -S -r 1280×720

Make sure to make your script executable with:

chmod a+x script-name

You could also come up with something more complex that will automatically detect displays and switch back and forth. You could then bind the command to a shortcut using your desktop environment (For example, in KDE, use kmenuedit, where you can assign a keyboard shortcut to a command). You can also create a script for each setting and then easily switch to the one you need from the run command dialog (Alt+F2).

For more information about Disper and links to custom scripts to make switching displays easier, visit the project’s website.

As with all operating systems, the way a Linux game behaves on a computer is largely dependent on the design of the game, the graphics hardware and drivers the user has, and the settings one chooses. Native Linux games are typically better at supporting the computer’s default resolution without much tweaking, but the way it handles fullscreen display on a a dual-monitor system depends on the game engine employed.

After about an hour of trying to configure all of your games, you might very well find yourself drowning in sea of techno-babble and configuration files. But have no fear, MakeTechEasier has come to your rescue yet again.

This brief guide to various types of games you can run in Linux on a dual-monitor system is based on my experience with an Nvidia 3D graphics card and the accompanying proprietary drivers. Nevertheless, most of it will apply to all 3D graphics cards. This guide also assumes that you already have your dual-monitor setup functioning by utilizing Xinerama, TwinView, XRandR, or some other method. This does not apply to dual-monitor setups that use separate Xorg instances for each monitor.

The Problem

When running a game, either as a native Linux application or through Wine, you have probably encountered one of these situations:

1. The game takes over both monitors and stretches the images over both.

2. One screen goes dark, and the other screen displays the game correctly. This may be found for many users.

3. The game maximizes on one screen, but it is not the screen you want to use.

The Solutions

Unfortunately, there is no one solution for all three situations, but there are a few ways to fix them, depending on your preferences.

Windowed Play

Although this may seem like more of a workaround, you can actually have a game run in a window and then turn that window into a fullscreen one. Follow these steps:

1. Configure the game to run in a window. For many Linux games, this might involve editing the configuration file, usually found in ~/.game-name/

2. Set the game’s resolution to your desktop’s exact resolution.

3. Start the game.

4. Use your window manager to make the window full screen (In KDE, right-click on the title bar, hover over ‘Advanced’ and click ‘Fullscreen’. You can also use a shortcut key, if configured. In some games, the ‘Fullscreen’ option will be unavailable. For these, choose ‘No Border’.)

As you might have noticed, Windowed Play has its disadvantages, particularly if your window manager does not have its own fullscreen feature. The biggest advantage is that, if you are like me and are supposed to be working rather than playing games, you can still at least have a business or work app open on the other screen to offer some semblance of efficiency.

Single Full Screen

On nearly all native Linux games that I have encountered, you can achieve true fullscreen results simply by configuring the game to use the resolution of one monitor. This, however, does not guarantee that it will be on the screen you want.

A universal method is to use xrandr to turn off one of the monitors. For example, you can run the following command in a terminal:

$  xrandr --output MONITORNAME --off

There are also graphical xrandr programs available, such as krandtray (Resize and Rotate) or gnome-randr-applet (Display Geometry Switcher). In either case, simply select the monitor you want to turn off and disable it, or in the case of a large virtual display (such as the kind with TwinView), select the smaller resolution.

For SDL games, you can setup an environment variable that will force it to use the screen you want, and this will dim the unused screen as long as you are playing.

$  export SDL_VIDEO_FULLSCREEN_HEAD=2

The number indicates the display number of the monitor, so change it according to your needs. You can even plug this into the game’s startup script and make it all automatic.

Windows Games in Wine

There is an easy way to use a windowed mode in Wine:

1. Start Wine Configuration (winecfg)

2. Click on the ‘Graphics’ tab

3. Check ‘Emulate a virtual desktop’

4. Next to ‘Desktop size’ enter your exact screen resolution.

When you start Wine applications, it will have a Windows desktop in the background. When starting games, the games should go fullscreen with no window border.

This should prevent Windows games from stretching over both screens and give you a fullscreen experience.

There are other options available for fullscreen gaming on dual monitors, and the only way to find the best method for your setup is to experiment with different techniques.

Dual monitor setup in Linux has never been easier. While methods such as the xinerama extension sometimes drive people insane, using RandR (Resize and Rotate) is quick and painless. This will allow you to use both monitors as one big screen instead of two identical ones (cloning). Follow these simple steps to get started.

Note: This HOWTO assumes that you are using the opensource drivers for your video card (ATI or Intel). Nvidia and AMD proprietary drivers come with their dual screen components.

1. Setup your xorg.conf configuration file:

Edit it as root:

gksudo gedit /etc/X11/xorg.conf

(in GNOME) or

kdesudo kate /etc/X11/xorg.conf

(in KDE)

2. Create a subsection under the “Screen” section with the following.

SubSection "Display"
Depth 24
Modes "1440x900" "1440x900" #the resolutions of your monitors
Virtual 2880 800
EndSubSection

Xrandr will function without these xorg.conf lines, but it will limit the size of your desktop.

For my computer, I am using two monitors with 1440×900 resolution. If you have a different resolution, put those resolutions under “modes” and then combine the width of both for “virtual”. In other words, if you have a 1280×800 monitor, it would be “Virtual 2560 800″.

3. Save your changes, exit and restart X.

4. Now, you can setup your dual screens however you like. First find out some information about the screens. Open a terminal emulator and type:

xrandr -q

It should tell you the name of each screen and its current resolution. On my computer, my screens are “DVI-0″ and “DVI-1″.

5. To make one large desktop including both screens, run this command:

xrandr --auto --output DVI-0 --mode 1440x900 --right-of DVI-1

DVI-0 is on the right, and DVI-1 is on the left.

6. Create a script called “startxrandr” to run this command whenever you want.

#!/bin/sh
xrandr --auto --output DVI-0 --mode 1440x900 --right-of DVI-1

7. Make sure to make the script executable

chmod a+x startxrandr

That is all it takes. You can play around with it and see all of xrandr’s commands by running “xrandr -help”.

Notes:

There are also a few GUI applications that allow you to control xrandr.  Check with your Linux distribution.

You can set xrandr to run when your display manager or desktop environment starts. See the its documentation for startup applications.

KDE and GNOME will automatically configure two screens correctly so that maximizing a window will only fill one of the screens. Some desktop environments do not yet have support for this. You will have to test the one you use. You should have no problems with Compiz.

You can have two monitors with different resolutions, which is useful if you are using a laptop connected to a larger monitor.

In KDE, each screen will automatically be a different activity, and you can apply different widgets on each.

Some applications, especially those that rely on SDL (like many Linux games), may not honor your xrandr settings. If you are lucky, it will just clone the game on both screens. For applications like Boxee, you will need to set the environment variable before starting it:

export SDL_VIDEO_FULLSCREEN_HEAD=1