Support of the fractional DPI

Hi, ALL,
Is GTK3 supports fractional DPI (125 - 150) or that is done in GTK4?

Thank you.

No, GTK3 has no support for fractional scaling.

GTK4 4.12 may support downscaling when used with compositors exposing fractional scaling on Wayland.

Additionally, DPI has nothing to do with fractional scaling.

Are you saying that by default Wayland will use 100%, 200%, 300% etc scale and not have 125%, 150%, 175% etc?

I am actually scared to ask about X now… :wink:

For the second answer - what about upscaling? Because people usually need to upscale, not downscale…

Thank you.

Wayland has integer scaling factors in the core protocol, and an additional (unstable) protocol has been introduced for fractional scaling.

With fractional scaling, Wayland compositors typically ask clients to render at a certain scale, and then scale down the output to match the desired scaling factor—e.g. for a 150% scale factor, compositors will ask the client to render at 2× the scale, and then downscale to 1.5×.

X11 works in a similar way, with the difference that only the compositor can affect the rendering, and there’s no fractional protocol like in Wayland to inform the clients.

No, “people” don’t usually need to upscale. Upscaling means making pixels up, and that will inevitably lead to awful results. Applications can render at different, higher scaling factors—2× the size, 3× the size, etc, but nothing is getting “upscaled”.


Thank you.for the explanation

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