How to create virtual display under Raspbian using xrandr? - raspberry-pi

Question

Could anybody help me out to understand how to create virtual display for Raspberry Pi 3 B running Raspbian using xrandr?
I saw that it is possible to do this, for example, for Ubuntu and Linux Mint by executing these commands:
#!/bin/bash
xrandr --newmode "1920x1080_60.00" 173.00 1920 2048 2248 2576 1080 1083 1088 1120 -hsync +vsync
xrandr --addmode VIRTUAL1 1920x1080_60.00
sleep 2
xrandr --output VIRTUAL1 --mode 1920x1080_60.00 --left-of HDMI1 --primary
xinput map-to-output $(xinput | grep -v 'XTEST.*pointer' |grep 'slave.*pointer' | grep -o 'id=*[0-9]*[0-9]' | cut -d'=' -f2) HDMI1
But under raspberry this script is not able to find VIRTUAL1 output.
When I simply run xrandr I get the following result:
xrandr: Failed to get size of gamma for output default
Screen 0: minimum 320 x 240, current 1360 x 768, maximum 1360 x 768
default connected 1360x768+0+0 0mm x 0mm
1360x768 60.00*
1024x768 60.00
800x600 60.00 56.00
640x480 60.00
680x384 60.00
512x384 60.00
400x300 60.00 56.00
320x240 60.00
1920x1080_60.00 (0x2af) 172.800MHz -HSync +VSync
h: width 1920 start 2040 end 2248 total 2576 skew 0 clock 67.08KHz
v: height 1080 start 1081 end 1084 total 1118 clock 60.00Hz
with no VIRTUAL1 and HDMI1 listed, only default. Can't figure out what steps should be taken for these outputs to appear in the given list?
Or if it is not possible then how can I create virtual display using other tools?

Answer 1

You wont be creating a virtual display for use with RPI. What you need to do is link your display to xrandr. This is done with the following code in terminal.
DISPLAY=:0 xrandr
Once you have done this it will be linked to xrandr and you'll be able to use it as if on Linux. However, you will need to do this on every boot or create a script that will run on boot and do this for you.
Also using xrand are will not resize your frame-buffer, this will need to be done as well.