[GTK] The Previous/Next gesture should handle RTL

• Component: WebKitGTK
• Status: RESOLVED FIXED

[Adrien Plazas]

The Previous/Next gesture (two-fingers horizontal drag) should be inversed on RTL languages, as the newer page should move to/come from the left instead of the right.

This affects GNOME Web: https://gitlab.gnome.org/GNOME/epiphany/issues/820.

[Alice Mikhaylenko]

Hm, it looks like WebKit in general doesn't support at least GtkInspector's text direction override. Scrollbars are still on the right, for example.

[Alice Mikhaylenko]

Nevermind, it seems to be flipped for RTL pages only.

However, `m_webPageProxy.userInterfaceLayoutDirection()` seems to always return LTR direction, which is why it doesn't work.

I wonder if it would work with an actual RTL locale.

Other than that, I need to adjust `ViewGestureController::PendingSwipeTracker::scrollEventGetScrollingDeltas()` and drawing. The pages comes from the correct side, but the order is reversed: the current page is on the bottom when you're going back, and on the top if you're going forward. It should be the other way.

[Alice Mikhaylenko]

Created attachment 372552 [details]
Patch

[EWS Watchlist]

Thanks for the patch. If this patch contains new public API please make sure it follows the guidelines for new WebKit2 GTK+ API. See http://trac.webkit.org/wiki/WebKitGTK/AddingNewWebKit2API

[Michael Catanzaro]

(In reply to Alexander Mikhaylenko from comment #2)
> Nevermind, it seems to be flipped for RTL pages only.
> 
> However, `m_webPageProxy.userInterfaceLayoutDirection()` seems to always
> return LTR direction, which is why it doesn't work.
> 
> I wonder if it would work with an actual RTL locale.

Currently we have this in our PageClientImpl.h:

WebCore::UserInterfaceLayoutDirection userInterfaceLayoutDirection() override { return WebCore::UserInterfaceLayoutDirection::LTR; }

Something like this in our PageClientImpl.cpp would probably suffice:

WebCore::UserInterfaceLayoutDirection PageClientImpl::userInterfaceLayoutDirection()
{
    return gtk_widget_get_direction(m_viewWidget) == GTK_TEXT_DIR_RTL ?
        WebCore::UserInterfaceLayoutDirection::RTL : WebCore::UserInterfaceLayoutDirection::LTR;
}

[Michael Catanzaro]

Next time, I should read your patch *before* wasting time investigating the problem you've already solved. :)

[Michael Catanzaro]

Comment on attachment 372552 [details]
Patch

This could improve a bunch of layout test results. I suppose we'll find out.

[WebKit Commit Bot]

Comment on attachment 372552 [details]
Patch

Clearing flags on attachment: 372552

Committed r246635: <https://trac.webkit.org/changeset/246635>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.