Suggest a fractional scales for imperfect DPIs

[Kekun]

I have devices with DPIs imperfect for integer scaling, Dippi helps me to know that but it doesn't help me know what scaling is the best for that device, even if that means using fractional scaling which isn't perfectly supported yet.

I'd love to see the Very Low DPI, Fairly Low DPI, Potentially Problematic, Fairly High DPI and Very High DPI messages be more usful and less judgmental of my otherwise perfectly fine hardware.

E.g. I have a laptop with a 14" 3840×2160 screen, Dippi tells me its 314 DPI is fairly high, it's 16:9 and it's equivalent to 1920×1080@2x. What I'd love for Dippi to tell me in such a case is:

• the recommended logical DPI for laptops is insert target logical DPI for laptops
• I can use @2.25x for 140 logical DPI, which isn't supported by all systems and my result in some blur
• I can use @2x for 157 logical DPI, which is supported by more systems and will be sharp, but the image will be small

Of course GNOME doesn't officially support fractional scaling yet, but this isn't just about GNOME nor Linux.

[AdrianVovk]

Target logical DPI for laptops is something that's ultimately going to be DE-specific.

Anyway, for Mutter and thus GNOME you can find the target values here: https://gitlab.gnome.org/GNOME/mutter/-/blob/422ee451/src/backends/meta-monitor.c#L1845-1867

[cassidyjames]

If the complexity/purpose of the app is expanded quite significantly, then I could consider this—however, the point of the app is to help people understand the best case where it's integer scaling. Even on DEs that support fractional scaling fractions of a pixel don't exist so you will end up with some blurriness or jitter somewhere if using noninteger scales (e.g. the web, other toolkits…).

Instead, I think I'd rather update the "Potentially Problematic" case text to also suggest using a non-integer scale but warning that it may be blurry.