Bug 163648 – MouseEvent's coordinates should be 0 for simulated clicks

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

[Chris Dumez]

MouseEvent.screenX / screenY should be 0 / 0 for simulated clicks. This is the behavior of Chrome and Firefox.
However, WebKit computes actual screenX / screenY values which requires a synchronous IPC with the UI process.

Demo: https://jsfiddle.net/7nc7ufkh/1/

[Chris Dumez]

https://jsfiddle.net/7nc7ufkh/3/ shows that clientX / clientY are also 0 for simulated clicks in Firefox and Chrome.

[Chris Dumez]

All coordinates (screenX, clientX, x, layerX, offsetX, pageX) are 0 in Firefox and Chrome for simulated clicks. However, they are all populated in Safari.

[Chris Dumez]

Seems to have been caused by <https://trac.webkit.org/changeset/160032>.

[Chris Dumez]

Created attachment 292048 [details]
Patch

[Darin Adler]

Comment on attachment 292048 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=292048&action=review

> Source/WebCore/dom/SimulatedClick.cpp:70
> +        } else if (AXObjectCache::accessibilityEnabled()) {
> +            // We apparently need coordinates when accessibility is enabled (see Bug 76677).
> +            // In other cases, the coordinates will be 0, which matches the behavior of Firefox and Chrome.
> +            // Note that the call to screenRect() causes a synchronous IPC with the UI process.

This really doesn’t make sense. It’s OK to decide that accessibility-driven clicks need to include coordinates to be more like clicks done in other ways, but clicks created by JavaScript on the webpage don’t need them. We should not be checking globally whether accessibility is enabled. Instead we should have that code path pass a different argument or call a different function.

[Chris Dumez]

Created attachment 292049 [details]
Patch

[Chris Dumez]

Created attachment 292052 [details]
Patch

[Darin Adler]

*** Bug 130301 has been marked as a duplicate of this bug. ***

[WebKit Commit Bot]

Comment on attachment 292052 [details]
Patch

Clearing flags on attachment: 292052

Committed r207544: <http://trac.webkit.org/changeset/207544>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Chris Dumez]

Looks like a 4% progression on Speedometer.

[Lucas Forschler]

Mass move bugs into the DOM component.