MouseMotion not working in browser as intended

[miketwenty1]

Bevy version

main branch as of: #11231
Desktop / chrome / Wasm

What you did

Have a minimum viable system:

pub fn mouse_system(
    mut mouse_motion_events: EventReader<MouseMotion>,
    mouse: Res<ButtonInput<MouseButton>>,
) {
    for event in mouse_motion_events.read() {
        info!("1-{:#?}", event);
        if mouse.pressed(MouseButton::Middle) || mouse.pressed(MouseButton::Left) {
            info!("2-{:#?}", mouse);
        }
    }
}

This system doesn't register mouse motion until the screen has been "messed" with. Such that the screen is resized or you switch in and out of the screen after the bevy app loads.

You can see my whole code base here:
https://github.com/miketwenty1/bevy_broken

What went wrong

Here is a demo showing that I click in the button in the canvas and it still doesn't register mouse motion events.
the info!()'s only appear in the console after I resize the screen. After that I can click in the screen and then it registers the mouse motion events.
https://github.com/bevyengine/bevy/assets/7761473/cdb1f6a4-6630-4a67-b161-a77e58313d38

[alice-i-cecile]

I suspect this is related to #11052: smells like a winit / winit integration bug.

[daxpedda]

This looks like a bug in Winit.
Apparently Winit doesn't detect the canvas to be focused, which is why it doesn't send any device events.

Strangely enough I can only reproduce this in Bevy, Winit examples work fine.
But AFAICT Bevy doesn't mess with the canvas at all, so I will have to continue digging.

[daxpedda]

Should be fixed in rust-windowing/winit#3369 and will be backported to v0.29.10.

[miketwenty1]

@daxpedda how do I take advantage of this for my bevy app?

[daxpedda]

You have to wait until v0.29.10 gets released or port rust-windowing/winit#3369 yourself.
The intention is to get the next patch released soon.

[alice-i-cecile]

Going to close as fixed (since it appears to be on main). If it still doesn't work there, or after the next release, please reopen this!

[miketwenty1]

@alice-i-cecile I'm pointed to main and still have the same issue after using this commit 64a15f1

I still need to switch tabs or change change screen size in order to capture the mouse motion events for desktop/wasm.

[mockersf]

it's waiting on a patch release of winit that didn't happen yet

[miketwenty1]

@mockersf is it this one?
rust-windowing/winit@d39528a
If not could you link the PR for tracking?

[mockersf]

You have to wait until v0.29.10 gets released or port rust-windowing/winit#3369 yourself.

The intention is to get the next patch released soon.

This one

[miketwenty1]

@mockersf you rock.

Note if I point to main for winit it will break bevy_winit right now.. but doing the specific commit mockersf referenced seems to solve this issue. if anyone else wants a temporary work around, I believe it's safe to add this to your cargo toml. Only tested against bevy main though, not 0.12.1.

[patch.crates-io]
winit = { git = "https://github.com/rust-windowing/winit.git", rev = "798c205cef1aa0c92eb43bef537583ce5b1ad1fb" }

To let you know of breaking changes on main right now, as I believe they'll need to be fixed for next winit patch, hope this helps:

error[E0107]: struct takes 0 generic arguments but 1 generic argument was supplied
   --> /..../.cargo/git/checkouts/bevy-f7ffde730c324c74/5c6b7d5/crates/bevy_winit/src/lib.rs:783:18
    |
783 |     event_loop: &EventLoopWindowTarget<()>,
    |                  ^^^^^^^^^^^^^^^^^^^^^---- help: remove these generics
    |                  |
    |                  expected 0 generic arguments
    |
note: struct defined here, with 0 generic parameters
   --> /..../.cargo/git/checkouts/winit-c2fdb27092aba5a7/14b418a/src/event_loop.rs:51:12
    |
51  | pub struct EventLoopWindowTarget {
    |            ^^^^^^^^^^^^^^^^^^^^^

error[E0107]: struct takes 0 generic arguments but 1 generic argument was supplied
  --> /..../.cargo/git/checkouts/bevy-f7ffde730c324c74/5c6b7d5/crates/bevy_winit/src/system.rs:38:18
   |
38 |     event_loop: &EventLoopWindowTarget<()>,
   |                  ^^^^^^^^^^^^^^^^^^^^^---- help: remove these generics
   |                  |
   |                  expected 0 generic arguments
   |
note: struct defined here, with 0 generic parameters
  --> /..../.cargo/git/checkouts/winit-c2fdb27092aba5a7/14b418a/src/event_loop.rs:51:12
   |
51 | pub struct EventLoopWindowTarget {
   |            ^^^^^^^^^^^^^^^^^^^^^

error[E0107]: struct takes 0 generic arguments but 1 generic argument was supplied
  --> /..../.cargo/git/checkouts/bevy-f7ffde730c324c74/5c6b7d5/crates/bevy_winit/src/winit_windows.rs:43:41
   |
43 |         event_loop: &winit::event_loop::EventLoopWindowTarget<()>,
   |                                         ^^^^^^^^^^^^^^^^^^^^^---- help: remove these generics
   |                                         |
   |                                         expected 0 generic arguments
   |

[daxpedda]

Winit v0.29.10 is out now.
Let me know if something is amiss!

[miketwenty1]

works without patching in winit verison now.