How to change resolution of one screen so that only part of it is used?

Question

I have two differently sized displays side-to-side, like this:

I would like to shrink the part of one display so that it has a black bar on the left (i.e. part of the physical screen is not used), like this:

Here's my output of xrandr:

$ xrandr
Screen 0: minimum 320 x 200, current 3520 x 1200, maximum 32767 x 32767
LVDS1 connected 1600x900+0+300 (normal left inverted right x axis y axis) 309mm x 174mm
   1600x900       60.0*+
   1440x900       59.9  
   1360x768       59.8     60.0  
   1152x864       60.0  
DP1 connected primary 1920x1200+1600+0 (normal left inverted right x axis y axis) 518mm x 324mm
   1920x1200      60.0*+
   1920x1080      60.0 +
   1600x1200      60.0  
   1680x1050      60.0  
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

What I already have

After reading this and this I came up with the following command:

xrandr --fb 3360x1200 --output LVDS1 --mode 1440x900 --pos 0x300 --output DP1 --mode 1920x1200 --pos 1440x0

Which results in this:

As you can see, the problem is that the displayed area is centered on the screen, while I want it to be aligned right. Also, it only worked with 1440x900 resolution while I want 1200x900.

Answer 1

You can move the screen right as many pixels as you want using xrandr's transform option.

# change output and display to match your system
args=" --verbose --display :0.0 "
output=" --output HDMI1"
hor="-100"
ver="0"
transform=" --transform 1,0,$hor,0,1,$ver,0,0,1"
xrandr $args $output $transform