Intercepting key events regardless of focus

[etiennep249]

I'd like to be able to intercept key events without a FocusScope. With a LineEdit, for example, it steals the focus from whatever might have a FocusScope, so you can't handle keybinds while in it. Or have a "global" keybind that runs regardless of where focus might be.

I'm using winit, which has key events. However, with slint, we don't have access to this event loop and building another one is forbidden. There are some crates out there that support global keybinds, but I could not find one that supports both X11 and Wayland like winit does.

Is there something that would help me achieve this?

[hunger]

If you know that you are using Winit, then you could try to use the i-slint-nackend-winit crate (internal, so no stability guarantees!). See the docs for a way to access the winit window directly from there.

I have not tried this, but maybe you can intercept the events there :-)

[etiennep249]

I tried it, it doesn't give any access to the event loop (that I am aware of). It seems to be more to interact with the window itself.
Looking at event_loop.rs, there doesn't seem to be any external way to access it. The interface only contains the window, the proxy to send events and the clipboard. Worst case scenario, I could fork the whole crate just to be able to pass a callback to the event loop, but that seems a bit extreme.

[ogoffart]

I wonder if, in focus scope, we shouldn't maybe have a new intercept-key-pressed(KeyEvent) -> EventResult
It would work exactly like key-pressed but instead of sending event from top to bottom of the focus scope, we would send them from bottom to top, before the key-pressed. This would allow to capture shortcut.

FocusScope {
   intercept-key-pressed(event) => {  
      ... if the event is CTRL + C , send the copy() callback  and accept..
   }
   
  
   ...
        LineEdit {
        }
}

So if user press CTRL + C, then we save and nothing is sent to the line edit (so it override the LineEdit shortcut) otherwise, for other keys, the LineEdit keeps getting all the shortcut.

@tronical: what do you think?

[tronical]

Hmm, so how would "bottom to top" look like? We traverse top to bottom, collect all scopes on the way, and then invoke intercept-key-pressed in reverse order?

That said, a global key bind regardless of where the focus is, that's in my opinion a shortcut. As the name "global" implies, for the user this should always work if the window is active. I would not add tree traversal to this global phenomenon but rather have a Shortcut element, for example.

Say you have a "Ctrl+C" shortcut that should copy something depending on the rest of the application state, then I'd rather have that code in one place ("if (this_mode) copy_that() else if (that_mode) copy_something_else()") instead of relying on a reverse tree traversal that may be much harder to debug.