eframe web: only capture clicks/touches when actually over canvas

[lucasmerlin]

• Closes touchend listener on document prevents listening for clicks on dom elements (web) #4752

To test, start the web demo and follow the repro steps from #4752

[emilk]

Have you tested this with scrolling, to make sure we're not confusing coordinate systems? (page_x vs client_x)

[lucasmerlin]

Have you tested this with scrolling, to make sure we're not confusing coordinate systems? (page_x vs client_x)

Seems to work as expected:

Bildschirmaufnahme.2024-07-04.um.11.45.07.mov

I also checked the clientX/Y and elementFromPoint documentation which both state that they take coordinates relative to the viewport.

[emilk]

This is very difficult to parse. Naming intermediates helps

Suggested change

	window()
	.unwrap()
	.document()
	.unwrap()
	.element_from_point(pos.x, pos.y)
	.is_some_and(|element| element.eq(runner.canvas()))
	|| runner
	.egui_ctx()
	.input(|i| i.pointer.any_down() || i.any_touches())
	let document = web_sys::window().unwrap().document().unwrap();
	let hovering_canvas = document
	.element_from_point(pos.x, pos.y)
	.is_some_and(|element| element.eq(runner.canvas()));
	let pointer_down = runner
	.egui_ctx()
	.input(|i| i.pointer.any_down() || i.any_touches())
	is_hovering_canvas || pointer_down

[lucasmerlin]

Much better!