Mouse/pointer not captured when dragging out of the canvas area on web target

[alvinhochun]

When dragging from inside the canvas to outside, the winit window stops receiving mouse events.

Possible fixes:

• When PointerEvent is available, one can use canvas.setPointerCapture on pointerdown to capture the pointer.
• When using the MouseEvent fallback, the mouse* events should be attached to the window and the event handling code has to manually track the mouse capturing state. There is an implementation in kiss3d (web-sys version that can serve as an example.

[ryanisaacg]

Is there a reason the canvas should continue to receive mouse events once the mouse leaves the area?

[alvinhochun]

Is there a reason the canvas should continue to receive mouse events once the mouse leaves the area?

• The window currently does not receive a mouse release event if the mouse is released outside of the canvas, causing the user code to think that the mouse button is stuck.
• This mouse capturing behaviour is beneficial for drag operations like adjusting up/down spinners or performing camera movements due to the increased movement area (though one might argue that using the pointer lock API is more suitable for the task).
• It should for consistency because this is how it behaves on native targets.

[alvinhochun]

Do you have any concerns with fixing this?

[ryanisaacg]

Nope, if it's the behavior on native targets then I'm all for it.