Ubuntu – Change DPI on HiDPI laptop with two external monitors

dpiexternal-monitorubuntu-gnomexrandr

I have a Surface Pro 3 laptop (running Ubuntu Gnome) with two external monitors.
The laptop's screen has a resolution of 2160×1440, and the two monitors are 1920×1080.
The Surface Pro (eDP1) is on the left, and the two other monitors (DP1 & DP2) are on the right, with the central monitor being the primary monitor.

This causes everything on the Surface Pro display to be extremely small, so I want to change the DPI of this display to make everything a bit bigger.

However, I have no idea how to do that.
I've tried using xrandr, but I can't get it to work.

Can anyone help?

Cheers, CJ

Best Answer

Try running the following command:

xrandr --output eDP1 --auto --output DP1 --auto --scale 2x2 --right-of eDP1 --output DP2 --auto --scale 2x2 --right-of DP1

This should make the HD monitors look smaller. You can also use this in conjunction with the following:

gsettings set org.gnome.desktop.interface scaling-factor 2

After running both of these commands, the Surface Pro 3 should look larger, but the external monitors should look the same size as they did before. Try adjusting the values to 1.5 if the Surface's display looks too 'big'.

Source: https://wiki.archlinux.org/index.php/HiDPI

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Ubuntu – Is it possible to have different DPI configurations for two different screens

It seems people are still struggling trying to work with several monitors and HiDPI displays. A good workaround is described in arch wiki https://wiki.archlinux.org/index.php/HiDPI#Multiple_displays. So, I have:

laptop asus ln303ux: 3200x1800,
external monitor: 1920x1200

Now I use Ubuntu 14.10 & GNOME Shell 3.12.2 that has pretty usable HiDPI support. So I just use out-of-the-box support of HiDPI - scaling factor is 2 (it can be set up via GUI). That means that on external monitor I get everything twice bigger than acceptable. Thus, I use xrandr; but instead of downscaling laptop screen, I upscale external monitor screen:

xrandr --output HDMI1 --scale 2x2 --mode 1920x1200 --fb 3840x4200 --pos 0x0
xrandr --output eDP1 --scale 1x1 --pos 320x2400

So, one by one:

--output HDMI1 in my case is the external screen, eDP1 is the laptop screen.
--scale 2x2 - make everything on external screen twice smaller
--mode XxY - explicitly set the resolution for screen (not necessary if is already set)
--fb XxY - set size of a virtual screen (framebuffer) (important without this, you will be able to use only a fourth part of the screen). In my case one screen was on top of another, so I added up effective heights 2400+1800=4200. Also note, that maximum framebuffer size might be specified in xorg.conf - then you cannot exceed it (it is written in the first line of xrandr -q output).
--pos XxY - in my case I set absolute positioning of the screens, so my laptop screen is directly on the bottom of the external screen. The value Y here is double the external monitor height.

And this is it! Everything is as crisp as it could be.

FYI: to get the names of the screens and available resolutions, one can run xrandr --current. More information on setting the resolution an be found here: https://wiki.ubuntu.com/X/Config/Resolution .

UPDATE - OPTION 2: one more interesting workaround for applications that support GTK3. If I normally use only one application on the large screen (e.g. some IDE, like leksah), I do not resize the the screen, but run the application scaled to its original size

env GDK_SCALE=0.5 GDK_DPI_SCALE=0.5 CLUTTER_SCALE=0.5 appname

Best Answer

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Ubuntu – Is it possible to have different DPI configurations for two different screens

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