Fix missing egui file drag and drop events

[MickHarrigan]

Description

This PR adds functionality to pass bevy_window::FileDragAndDrop events down to egui. Additionally adds a bevy-ified version of the egui file_dialog example.

Changes:

• Added a log_file_dnd_events feature similar in functionality to the log_input_events feature
• Added an example of bevy events going through to egui for files being dragged and dropped onto the window
• Added new bevy systems, event, and setting for controlling event passthrough

Why this is needed:

Currently when using bevy_egui any files that get dragged and dropped (or hovered) onto the window can only be read from directly via bevy. With this it allows passing down into the egui context for usage there.

Limitations:

I don't believe that there is a concise way to handle the location of a file drop / hover, only that it exists.

This is to be fixed with the release of winit 0.31 afaik and should eventually be covered.

[vladbat00]

Hi, thank you for the PR, this is a very welcome addition! I added a minor comment, but apart from that and failing CI for some reason, the PR looks good to me.

[MickHarrigan]

Hi, thank you for the PR, this is a very welcome addition! I added a minor comment, but apart from that and failing CI for some reason, the PR looks good to me.

With regards to the CI stuff, I have a commit ready that would put the relevant code behind a cfg(...) that would maintain the current functionality on Windows and Unix but do nothing whatsoever otherwise.

Is that a preferable action for this? I am not well versed with wasm, ios, nor android (and I think the latter 2 wouldn't support file selection easily?) so I am curious to hear your opinion.

[vladbat00]

Yes, let's just disable the code for those targets with cfg(...).

[MickHarrigan]

Got CI checks just about working but running cargo test --all causes an error for running out of disk space. I am not great with CI myself and have been looking for a way around the disk usage but haven't gotten anything yet 😅

[vladbat00]

Not sure what's the best way to deal with it, but I usually go to the cache page and just nuke everything one by one :D
In your case that would be https://github.com/MickHarrigan/bevy_egui/actions/caches

[vladbat00]

Hm, I'm not sure I like adding a feature that doesn't really affect the functionality, but only brings a new dependency in, which is not used outside of the dev stuff anyway... It might be confusing to users, as they would intuitively expect that this feature should either enable or disable the associated functionality in their apps.

Is there probably another way around this?

[vladbat00]

Would this work instead? Maybe this way we can get rid of the file_browse feature: #375 (comment).

Suggested change

	# `file_browse` feature only, workaround dev-dependency
	[target.'cfg(not(any(target_os = "android", target_os = "ios", target_arch = "wasm32")))'.dependencies]
	rfd = { version = "0.13", optional = true }
	[target.'cfg(not(any(target_os = "android", target_os = "ios", target_arch = "wasm32")))'.dev-dependencies]
	rfd = "0.13"

[vladbat00]

Oh, I can see this was even your initial version. I assume you were trying to workaround the CI weirdness?..

So basically here the build was already failing due to the out of space error: https://github.com/MickHarrigan/bevy_egui/actions/runs/14431554045/job/40467118849

So maybe we can partially revert this one?

[vladbat00]

I've merged your PR via #377 - it takes your branch except for the last two commits. That's basically the code I wanted to see, sorry if I my comments were confusing 😄
Thanks a lot for your work on this!