Can X11 scale to virtual resoltions on HiDPI/Retina screens the way OS X does?

Question

I've recently had the chance to use a Macbook Pro with Retina Display, and its quite clear that the display is futuristic enough to actually warrant Apple's over-the-top marketing.

I've got sensitive eyes, and I don't like looking at very small text. Apple's virtual scaling for HiDPI resolutions scales the entire screen, not just text/UI buttons. This creates a higher level of detail on a canvas encompassing a smaller virtual resolution.

Most discussions that I've found say there's no similar solution when using Linux except to change gnome DPI settings.

After some cursory research, it seems that scaled resolutions are possible under X11 (see here). The --scale feature can be used for netbooks virtualizing a larger resolution, but could inverted values emulate a 1440x900 desktop on a 2880x1800 screen? If not, why?

Solution

Why don't you try yourself?

xrandr --output LVDS-1 --scale 0.5x0.5

seems to work acceptably - but remember that it is just scaling, for example any font rendering will be blurry rather than fine and crisp (no matter what algorithm is used for the scaling it acts on bitmaps) - for that the correct solution is setting DPI of the display device and font/icon sizes.

Comments

[Tammer Ibrahim]

Thanks! I was trying to figure out why this wouldn't work, and I don't have a HiDPI device to test. The answer is, as you mention, that xrandr scaling works via bitmap. The blurriness I get on a lower DPI screen would remain. Guess we'll have to wait for a more complete solution.

[peterph]

The solution is, as I mentioned, setting appropriate DPI and using large font size and artwork. AFAIK that's exactly what Apple does.

[Greg A. Woods]

Actually Apple now does scaling. E.g. on a 32-inch XDR-Pro display with a native resolution of 6008x3384 pixels, the resolution in macOS is just 3008x1692. One visible UI pixel is 4 display panel pixels. You can force macOS to use the full resolution (which is possible in at least Monterey 12.1) by holding the "option" key while clicking on the "Scaled" button in the Displays preferences panel, and scrolling up on the list for the "hidden" full res choice. Then you'll see tiny fonts, minuscule icons, etc. X11 mostly does much better than Apple, despite needing some tricks to make it work.