Is there any way to set application scale from within application?

[qarmin]

Some users complain that the application’s UI elements are too small.
One possible workaround for them is to set SLINT_SCALE_FACTOR to a value greater than 1.

However, this is inconvenient for most users(to do this manually), so I’d prefer to be able to configure this from inside application, rather than via env::set_var, which is unsafe.

[ogoffart]

env::set_var is sound to use in the main function before any thread is started.

Otherwise, you can use window().dispatch_event(WindowEvent::ScaleFactorChanged{scale_factor: ...})
But in principle, the app is not supposed to do that as this should be done by the platform itself, and it will be overwritten when the scale factor actually changes (the user move window between screen or changes their display settings)

The question is also why is the scale factor not correct by default. What platform and backend are we talking about? There is maybe something wrong in their setting, but the Slint application should normally use the same scaling as all other applications on the desktop

[qarmin]

It is sound, but I still want to avoid unsafe in the codebase as much as possible.

Some users report that certain fonts are too small, even though I’m using the default font size.
To avoid adding an option to change the font size, which would break many things, since there are many places where element sizes depend on the font size, I’d like to give users the option to scale the entire application instead.