Re: Retina does not necessarily imply fractional
[Author here]
> Retina does not imply *fractional* scaling. In fact, historically it was kinda the opposite.
I think you are misinterpreting 2 different things here: both what I meant, and the broader Apple use of the Retina term.
Apple's Retina displays originated on the phones, remember. Specifically the iPhone 4, then later the iPad, and only some years later the Mac range.
The first one I owned personally was an iPhone 6S Plus, with a 1920x1080 LCD that it runs at 730x414. That's approximately 2.6 on-screen pixels per display pixel, with very slightly different aspect ratios in the X and Y dimensions. (!)
So, I stand by my comment: the OS *needs* to support fractional scaling to handle this well. iOS doesn't even have options for it: you get what Apple thinks best. The big-screen iPad Pro has a single option: full-size or zoomed.
MacOS has more. Using a Mac with a Retina display, Apple's UI doesn't expose scaling factors directly, but they are there. What the user sees are 5 steps, from "Larger text" to "Default" to "More space".
This is as it should be, IMHO. GNOME, for instance, optionally exposes raw percentages, and on Fedora only if you enable it from the CLI. Other distros give you an on/off switch, which should not be necessary and is bad UI for a start. I have no time for excuses about "may degrade performance". GNOME 3 came out 12 years ago (Wayland 15 years) and is backed by a multi-billion-dollar corporation. Make it work, make it work *now*, and stop whinging or making excuses.
MATE drops the screen resolution, which is an awful fix. Xfce exposes a fractional scaling factor but this don't work and you have to manually enter overrides of less than one -- which *does* work but is even worse UI.
But the point is, and that is what I am getting at here, if you have more than one display, X11 cannot handle this. It does support fractional scaling but it's global and so applies to all displays. Windows is bad at this but you can set it per-display. Only macOS handles it right: one OS-wide setting and the OS makes sure that it works right across all displays, on its own with no user intervention.
What I am getting at here is not what Apple products ship with: it is that to properly support such displays, and offer a choice of text and feature sizes on screen to suit users of different ages and eyesight abilities, the display server *must* support non-integer scaling factors, which as I said X11 does not do well. I stand by that.
And secondly, to have more than one display if they are not the same DPI, it must also support non-integer scaling factors *on a per-screen basis*, on the fly, without reboots or restarts.
And ideally, without ever showing the user a percentage or a fraction or a decimal, let alone usability nightmares such as values between 0 to 1, or worse still negative numbers.
As such, I entirely stand by my summary.
You are correct in what you say, but I don't think it's especially relevant and it neglects the devices on which the tech was introduced.