FS#66003 - [chromium] Reading device-scale-factor from Xft.dpi or other environment variables

Attached to Project: Arch Linux
Opened by Iran (IRunArchLinuxBTW) - Saturday, 28 March 2020, 03:09 GMT
Last edited by Evangelos Foutras (foutrelis) - Monday, 30 March 2020, 17:06 GMT
Task Type Feature Request
Category Packages: Extra
Status Closed
Assigned To Evangelos Foutras (foutrelis)
Architecture All
Severity Low
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No

Details

Chromium and Chromium based applications (Electron apps like Atom, VSCode, keybase, riot) support custom DPI scale factors, but the only way to pass them certain values is through the `--force-device-scale-factor` command line option. See the [ArchWiki](https://wiki.archlinux.org/index.php/HiDPI#Chromium_/_Google_Chrome). I asked about it on Reddit a few weeks ago. See [this post](https://www.reddit.com/r/archlinux/comments/fcagfi/high_dpi_issue_96_dpi_is_too_small_128_dpi_is_too/).

Most other applications use X Resources's `Xft.dpi` variable: see the [ArchWiki](https://wiki.archlinux.org/index.php/HiDPI#X_Resources).

On my monitor I like to use `Xft.dpi: 112`, which means `--force-device-scale-factor=1.1666`.
Setting a custom DPI scale factor through the `--force-device-scale-factor` option is a pain: I have to override all the .desktop file for **every** Chromium based application and I need to remember to pass that option when running those programs via command line.

Would it be possible to modify all the Chromium based app packages so that the scale factor is read from an environmental variable, an XResource variable or something else?
I don't know whether it's possible to patch Chromium (and the various Electrons) for this. If it's not that easy, an option could be replace the binary files with a wrapper script that decides whether to pass the `--force-device-scale-factor.
This task depends upon

Closed by  Evangelos Foutras (foutrelis)
Monday, 30 March 2020, 17:06 GMT
Reason for closing:  Won't implement
Comment by Evangelos Foutras (foutrelis) - Sunday, 29 March 2020, 13:57 GMT
For Chromium only, you can add '--force-device-scale-factor=1.1666' to $HOME/.config/chromium-flags.conf; /usr/bin/chromium is a wrapper that reads custom flags from there and passes them to /usr/lib/chromium/chromium.

For Chromium-based applications with no Arch-specific custom wrapper, you can only rely on what Chromium itself does to retrieve/calculate the scale factor.

Downstream patching in order to customize the behavior of all Chromium-based applications is not feasible and/or the right thing to do.

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