RandR

from Wikipedia, the free encyclopedia
RandR
Basic data

Maintainer Keith Packard , Jim Gettys
developer X.Org Foundation
Current  version 1.5.0
(May 16, 2015)
operating system Linux
category protocol
www.x.org/wiki/Projects/XRandR/

Randr (from English R ESize and R Otate ) is a communication protocol , which in form of an extension of X11 or Wayland for setting monitor settings is used. XRandR (or WRandR with Wayland) can scale, rotate and reflect windows .

To change the graphics mode, a command must be sent to the screen control unit (display controller) as well as one to the x-server (X.Org server), which sets the root window accordingly.

The modes supported by the respective screen are obtained from the graphics driver via EDID , while the modes supported by the screen control unit are contained in the driver.

The options to scale, rotate and / or reflect relate to the content of the frame buffer or the root window.

Users use RandR either via a graphical configuration program or the command line programs xrandr(X11) or weston-wrandr(Wayland).

xrandr

An example output from xrandrlooks like this: 

Screen 0: minimum 8 × 8, current 1920 × 1080, maximum 32767 × 32767
eDP1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 344mm x 194mm
   1920x1080     60.05*+  40.03
   1400x1050     59.98
   1280x1024     60.02
   1280x960      60.00
   1024x768      60.00
   800x600       60.32    56.25
   640x480       59.94
HDMI1 disconnected (normal left inverted right x axis y axis)
VGA1 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

In this example, only one monitor is connected to DisplayPort connection 1 ( labeled eDP1 ) (DisplayPort allows several screens to be connected to one connection via daisy chaining) and the signal output at the eDP1 output has the parameters Screen resolution = 1920x1080 pixels , refresh rate = 60.05 Hz. Nothing is connected to the existing HDMI and VGA connections.

The following call mirrors the output at LVDS output 1 to HDMI output 3, but scales the image. As a result, both output devices are operated with their respective native resolution: 

xrandr --fb 1600x900 --output LVDS1 --mode 1600x900 --scale 1x1 --output HDMI3 --same-as LVDS1 --mode 1920x1200 --scale-from 1600x900

Note: The designation of the individual outputs is determined in the DRM .

Screenshots

There are quite a number of graphic programs that use RandR to adjust screen settings. As can be seen from the above example, in contrast to the command line program, these offer far fewer options for configuring the screen or screens as required.

  • GNOME 3.14

  • Xfce

  • lxrandr

  • grandr

See also

Individual evidence

  1. ↑ [ANNOUNCE] randrproto 1.5.0 , May 16, 2015
  2. ↑ The X Resize, Rotate and Reflect Extension Version 1.5.0, March 14, 2015
  3. ↑ Phoronix: A Newbie's Guide To RandR 1.2 , November 26, 2007.
  4. ^ Opening a Window to a Wider World .