Arch Linux

frank604

Member

From: BC, Canada

Registered: 2011-04-20

Posts: 1,212

[SOLVED] Hidpi laptop with lowdpi external monitor

Trying to setup my hidpi laptop with my lowdpi external monitor. 

- Use .Xresources to set Xft.dpi = 276 (according to dpi.lv using 3200x1200 13.3")
- Run:

xrandr --output eDP-1 --scale 1x1 --pos 320x2160 --output DP-1-1 --dpi 92 --scale 2x2 --mode 1920x1080 --fb 3840x3960 --pos 0x0 --output DP-1-3 --off

This code creates a frame buffer and setting DP-1-1 on top of eDP-1. DP-1-3 is turned off for testing.
- start X with xorg-xinit using .xinitrc to launch dwm

Issue: Smaller fonts in firefox/chromium/qutebrowser are fuzzy/blurry, which I think has something to do with the scaling.  The Xft.dpi at 276 is perfect if only using the laptop and no external monitor.  My external monitor is 1920x1080.  I've also tried panning instead using:

xrandr --output eDP-1 --off --output DP-1-1 --auto --panning 3840x2160+0+0 --scale 2x2  --output DP-1-3 --off

Panning also produces the same issue. First time using an hidpi but I've been reading the hidpi archwiki as well as xorg/xrandr documentation.  Not much else in documentation.  If anyone has a good link or a suggestion on how they setup their hidpi+lowdpi monitors, please share.

In the meantime, I pkill x to get to console, comment out Xft.dpi in .Xresources and then load up output to the two external lowdpi monitors without scaling.  Then when I leave this desk I pkill x, enable the Xft.dpi and startx again.  I've looked to set different dpi per monitor but xrandr --dpi does not have an effect.  I am using intel native modesetting. 

*I should of stayed with the FHD instead of the QHD

Last edited by frank604 (2016-10-30 19:30:57)

frank604

Member

From: BC, Canada

Registered: 2011-04-20

Posts: 1,212

Re: [SOLVED] Hidpi laptop with lowdpi external monitor

The temporary conclusion to this issue is to set a lower resolution on my laptop.  Instead of 3200x1800, used 1920x1080 via xrandr.  In my case, the resolution needed to be added, where I followed the wiki and ran cvt and use cvt's output to add the new res.

xrandr --newmode "1920x1080_60.00"  173.00  1920 2048 2248 2576  1080 1083 1088 1120 -hsync +vsync
xrandr --addmode eDP-1 1920x1080_60.00   
xrandr --output eDP-1 --mode 1920x1080_60.00    

I turned off the Xft.dpi in .Xresources
I turned off any scaling whether via exporting env or xrandr.
All font is crystal clear.  And preferred system font (I set it with lxappearance) is set to 10.
When I attach lowdpi monitors, I just enable xrandr output and {left|right} of...

This isn't a perfect solution but by far it is a workaround to have crisp fonts on hidpi laptop monitor as well as lowdpi external monitor via hdmi/dp.  I'll mark it solved for now.