Ensure text scales responsively to DPI settings

[rmol]

We should ensure we're enabling Qt's high DPI support. It might be as simple as setting QT_AUTO_SCREEN_SCALE_FACTOR=1 in the environment, and makes the client a lot more usable on high resolution displays.

Without it, text can be so small as to be nearly illegible, and is sometimes clipped -- I saw this as early as the login box.

[kushaldas]

Does Qube work on any of those high DPI systems?

[rmol]

It does. They're definitely adding support.

I think we might have some more general scaling problems; on my 1920x1080 T480 I increased Xft.dpi in ~/.Xresources and our text doesn't scale like other apps'. In fact even the solution I suggested above doesn't seem to affect the login dialog labels, though everything else scales.

Here are two instances (on my 4K Debian system), the larger one with QT_AUTO_SCREEN_SCALE_FACTOR=1 and the smaller without:

Note the clipping and smaller button text in the unscaled instance.

Once logged in, though, the text in headers and conversations is larger and much more legible.

Unfortunately, using QT_AUTO_SCREEN_SCALE_FACTOR=1 on my T480, the login dialog is blown up so big it no longer fits on my screen; the bottom controls are out of reach below the edge of the screen.

This is probably going to be more complicated than I'd hoped. :frowning_face:

[emkll]

By default, looks nice in 4k

When changing the text dpi/scaling option in appearance -> dpi (doubling from 96 to 180), only the title bar text is scaled:

[eloquence]

This should not impact most users with current recommended hardware & settings, but still worth researching longer term as we broaden hardware & display support and improve accessibility.

[sssoleileraaa]

Just some quick notes on what my dom0 Appearance config looks like on a fresh install of Qubes 4.0.4:

• Style tab
  • Clearlooks
• Icons tab
  • Adwaita - The Only One
  • HighContrast: High contrast scalable icons with black borders
• Fonts tab
  • Default Font: Sans
  • Rendering: "anti-aliasing" checked
  • Hinting: Full
  • Sub-pixel order: None
  • DPI: 96
• Settings tab
  • Toolbar Style: Icons
  • Menus and Buttons
    • "Show images on buttons" checked
    • "Show images" checked
    • everything else unchecked

I haven't looked into this as much as @rmol, but it looks like this is still open: https://github.com/QubesOS/qubes-issues/issues/1951.