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rust-native-ui / libui-rs

Rust bindings to the minimalist, native, cross-platform UI toolkit `libui`
Apache License 2.0
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unsure how to use UI::queue_main with multiple threads #55

Open Treeki opened 5 years ago

Treeki commented 5 years ago

Hey there,

I'm experimenting with iui as a new Rust programmer and I'm unsure whether I've hit upon a design issue with UI::queue_main, or if there's a solution I've just missed, as this method isn't used in any of the examples.

According to the iui documentation, UI::queue_main will queue a function to execute on the GUI thread - I assume this is the thread that called UI::init().

libui explicitly states you can call uiQueueMain from any thread, but I can't figure out how to do this with iui; it requires a UI instance which I cannot obtain in non-GUI threads as UI is neither Send nor Sync.

Is there a way to do this, or is this a bug/design flaw? Any advice would be appreciated!

For reference - I'm trying to offload ongoing USB device I/O using hidapi-rs onto a background thread and have it notify the GUI thread when data comes in or when the device is connected/disconnected.

The only method I can figure out for doing this is to have the GUI create a channel where the Sender is moved into the background thread and Reciever::try_recv is called regularly on a timer, but this feels inelegant to me and I'd much rather be able to have the background thread notify the GUI through libui's queuing mechanism so that it can update immediately.

NoraCodes commented 5 years ago

libui explicitly states you can call uiQueueMain from any thread

This is problem on our side, then, for sure. I think an API whereby we hand out a queuing token which is Send from UI and then provide queue_main on that token is the way to go here.

quickdudley commented 3 years ago

queue_main doesn't actually use the self argument.

quickdudley commented 3 years ago

I have a branch at https://github.com/quickdudley/libui-rs/tree/55-async-queue-main which might address this; but I'm still figuring out how to test it. Will submit a pull request if I can do so.