How to use egui + winit so I have control over the event loop?

[lolbinarycat]

I want to have direct control over the display connection and windows, but every example I can find uses some sort of callback, either through run_native or some sort of App trait.

I'm pretty sure I need to use egui_winit to translate between winit events and egui events, but i'm not sure how to.

[baltobor]

Hello everyone,

This would be very useful for me as well.
I am building a host for virtual instruments using the open source CLAP interface to make music. The clack framework opens the GUI of these instruments using winit and an event_loop. (hint: there is another framework with name clack)

I tried to open the instrument’s GUI by pushing a button in egui. Unfortunately, the plugins are encapsulated by the vendor and create their own user interface. Therefore, I need access to the event loop.

I tried the examples external_eventloop and external_eventloop_async. Unfortunately, I couldn’t successfully open both the egui and the external encapsulated view.

I like the new interface in terms of access to the event_loop, but I don’t know how to access the event_loop from inside. Typically, I would use a proxy to call a custom event. That event would then be handled within the closure of the event loop, where I have access to everything. The external_eventloop example uses an event loop bound to UserEvent (EventLoop).

It’s easy to get a proxy with event_loop.create_proxy(), but I can’t inject my custom events. I need sth like:

UserEvent::OpenPluginWindow(plugin_id) => {
    // Open external GUI-Window here
}

from inside the event_loop.

Am I missing something here, or does someone know a best practice? I’m still new to Rust, so maybe I’ve overlooked something. For now, it looks like egui is eating up the whole winit run loop. On macOS, for example, I can’t create another one — not even in another thread. Linux behaves differently. I would like to have one application which uses the event_loop to control new windows.

My goal is to:
1. Create a custom event that can be called via the proxy
2. From within the event loop, create additional windows to host the external library GUIs.

[MightyBurger]

I've needed access to the winit event loop to implement a tray icon app with egui. I found the pure_glow example particularly useful.

https://github.com/emilk/egui/blob/main/crates/egui_glow/examples/pure_glow.rs

I don't know for sure if it will meet your needs, but it is worth evaluating.

[parasyte]

Here is an example with egui-wgpu and egui-winit that you can use as a basis (it's on an old version of egui, and must be adapted to recent changes): https://github.com/parasyte/pixels/tree/main/examples/minimal-egui