[Solved] Cannot effectively set DPI scaling

Mindstormscreator · 2016-02-11 05:24:47

So I just got a new Macbook Pro Retina 2015 13-inch for the sole purpose of using Arch on it, and I'm trying to find the most straightforward, uniform way to scale everything to be usable with the Macbook display's high dpi. I'm using Xfce.

I saw here in the wiki that some applications, including chromium, use the DPI X specifies to scale their UIs. After reading here that X always sets the DPI to 96 by default (and just assumes my display is much larger than it actually is) without configuration, I created /etc/X11/xorg.conf.d/90-monitor.conf as follows:

Section "Monitor"
    Identifier             "eDP1"
    DisplaySize            286 179    # In millimeters
EndSection

This specifies the actual size of the Macbook's display.

Next, I restarted the lxdm service and was greeted with what appears to be a new, scaled UI:

Notice that the font size in the text box is pretty large.

After logging in, I do see an increase in X's dpi when I run

xdpyinfo | grep -B2 resolution

however, nothing on my desktop appears to change its scaling. Chromium, which supposedly supports HiDPI on Linux by reading X settings, doesn't change in appearance at all. Eye of Gnome, a Gtk3 image viewing program, doesn't change in scaling either.

Now for the interesting part: when I log back out, I'm greeted with this login screen:

The size of the text box has decreased back to its original, smaller size! So changing the X display size in 90-display.conf seems to have affected it on first login, but it remains unchanged on each subsequent prompt.

In addition, I've tried starting my desktop from startx (with no display manager), and still experience no changes in DPI scaling in the desktop.

So, what could be going on here? How can I make the X DPI settings persistent, or what else could I try to achieve proper DPI scaling? Any help is really appreciated.

Last edited by Mindstormscreator (2016-02-13 19:09:23)

Ziusudra · 2016-02-11 06:17:11

I see some things, like Chromium, react to the Xft.dpi setting in .Xresources. https://wiki.archlinux.org/index.php/X_resources

The 90-monitor.conf file does nothing for me.

The only way I've seen a difference in the 'xdpyinfo | grep -B2 resolution' output is with xrandr: https://wiki.archlinux.org/index.php/Xo … I_manually

Head_on_a_Stick · 2016-02-11 08:44:21

Mindstormscreator wrote:

what else could I try to achieve proper DPI scaling?

If you use `startx` you can try:

startx -- -dpi xxx

Last edited by Head_on_a_Stick (2016-02-11 08:44:53)

Mindstormscreator · 2016-02-12 23:14:42

Ziusudra wrote:

I see some things, like Chromium, react to the Xft.dpi setting in .Xresources.

Sadly setting Xft.dpi in .Xresources only causes lxdm to scale up its UI for a single login like before; no other applications are affected.

Head_on_a_Stick wrote:

If you use `startx` you can try:
startx -- -dpi xxx

This also didn't seem to work.

Could something be clearing away my X dpi settings?

Last edited by Mindstormscreator (2016-02-12 23:15:02)

Head_on_a_Stick · 2016-02-13 10:53:03

Mindstormscreator wrote:

Could something be clearing away my X dpi settings?

Probably LXDM or XFCE.

Try it without a display manager and with a pure window manager (openbox is a known "good egg" you can try).

Mindstormscreator · 2016-02-13 19:09:08

So setting Xft.dpi in purely openbox worked, but then I also found that merely setting the dpi in Xfce settings -> Appearance -> Fonts -> "Custom DPI setting" works too. Funny how I didn't find this earlier.

Arch Linux

#1 2016-02-11 05:24:47

[Solved] Cannot effectively set DPI scaling

#2 2016-02-11 06:17:11

Re: [Solved] Cannot effectively set DPI scaling

#3 2016-02-11 08:44:21

Re: [Solved] Cannot effectively set DPI scaling

#4 2016-02-12 23:14:42

Re: [Solved] Cannot effectively set DPI scaling

#5 2016-02-13 10:53:03

Re: [Solved] Cannot effectively set DPI scaling

#6 2016-02-13 19:09:08

Re: [Solved] Cannot effectively set DPI scaling

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