Bug 128534 – 'mouseenter' mouse compat event not fired when listeners for touch events

• Status: RESOLVED
• Resolution: FIXED
• Component: UI Events

[Patrick H. Lauke]

Not sure if it's a bug or a "feature", but in any case it's a strange inconsistency and I'd like clarification if it's intended behavior or not: it seems that "mouseenter" mouse compatibility event is only fired if there are no touch* events also being listened to.

on iOS/Safari, go to http://patrickhlauke.github.io/touch/tests/event-listener_mouse-only.html and tap the test button. This page only shows the mouse events, and the sequence of events for a clean tap are usually:

mousenter > mouseover > mousemove > mousedown > mouseup > click

now, on http://patrickhlauke.github.io/touch/tests/event-listener_all-no-timings.html doing the same clean tap results in:

touchstart > touchend > mouseover >  mousemove > mousedown > mouseup > click

Note that "mouseenter" is absent in this case. The only difference in the scripts here is that the second example also listens for touch events (as well as pointer events, with and without MS prefix, but surely that shouldn't have any effect).

[Benjamin Poulain]

That looks like a input event bug. Next time you can CC me on Twitter too :)

Can I attach the two files to the bug for future reference?

[Patrick H. Lauke]

Created attachment 223834 [details]
Event test for touch, pointer, MSPointer, mouse events

[Patrick H. Lauke]

Created attachment 223835 [details]
Event test just for mouse events

[Patrick H. Lauke]

Cheers Ben. I assume you're @awfulben ?

I made the two tests self-contained (stuck the styles directly in there) and attached them.

[Patrick H. Lauke]

Created attachment 223836 [details]
iOS/Safari when zoomed out - no mouseenter fired on "all events" test

[Patrick H. Lauke]

Created attachment 223838 [details]
iOS/Safari when zoomed in - mouseenter fired on "all events" test

Just testing this further, some more weirdness which may point towards the cause of the bug: it seems that mouseenter is not fired in my test when Safari is zoomed out. If I pinch-zoom into my test page, mouseenter DOES fire.

[Benjamin Poulain]

(In reply to comment #4)
> Cheers Ben. I assume you're @awfulben ?

I am :)

> I made the two tests self-contained (stuck the styles directly in there) and attached them.

Thanks for attaching the tests.

I can reproduce locally, I will take the bug.

I suspect we changes a hover state when delivering the touch events, and when we generate the synthetic mouse events eventHandler thinks mouseenter was already delivered. Just a wild guess though, I'll find out when I'll have time to debug this.

[Benjamin Poulain]

Created attachment 224159 [details]
Patch

[Andreas Kling]

Comment on attachment 224159 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=224159&action=review

r=me

> Source/WebCore/ChangeLog:8
> +        The code dispatchign mouseenter and mouseleave events was making the assumption that

dispatching

> Source/WebCore/ChangeLog:15
> +        processing of mouse events. The update is done along the events mouseover and mouseout.

along what?

> Source/WebCore/dom/Document.cpp:5873
> +    for (size_t i = 0; i < removeCount; ++i)

range for

> Source/WebCore/page/EventHandler.cpp:2384
> +            RenderElement* oldHoverObj = m_lastElementUnderMouse ? m_lastElementUnderMouse->renderer() : nullptr;
> +            RenderElement* newHoverObj = m_elementUnderMouse ? m_elementUnderMouse->renderer() : nullptr;

I'd call these *Renderer instead of *Obj.

> Source/WebCore/page/EventHandler.cpp:2387
> +            Vector<RefPtr<Element>, 32> leftElementsChain;

This could be Vector<Ref<Element>> since it never contains null pointers.

> Source/WebCore/page/EventHandler.cpp:2400
> +            Vector<RefPtr<Element>, 32> enteredElementsChain;

Ditto.

> Source/WebCore/page/EventHandler.cpp:2415
> +            for (size_t i = 0; i < leftElementsChain.size(); ++i) {

range for

> Source/WebCore/page/EventHandler.cpp:2425
> +            for (size_t i = 0, size = enteredElementsChain.size(); i < size; ++i) {

range for

[Benjamin Poulain]

Committed r164495: <http://trac.webkit.org/changeset/164495>