Bug 158655 – Remove positioned descendants when RenderBlock is no longer a containing block.

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[alan]

1. Size the browser window to over 1000px
2. Load http://www.stubhub.com/beyonce-tickets-beyonc--santa-clara-levi-s-stadium-9-17-2016/event/9578810/ (webarchive attached)
3. Size the browser window to trigger narrow layout so that the ticket list moves below the stadium picture.
4. Scroll the tickets

[alan]

rdar://problem/26510032

[alan]

Created attachment 281079 [details]
Patch

[alan]

*** Bug 158656 has been marked as a duplicate of this bug. ***

[alan]

Created attachment 281117 [details]
Patch

[Simon Fraser (smfr)]

Comment on attachment 281117 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=281117&action=review

> Source/WebCore/rendering/RenderBlock.cpp:251
> +    // We are no longer the containing block for fixed descendants.
> +    if (hadTransform && !willHaveTransform) {
> +        removePositionedObjects(nullptr, NewContainingBlock);
> +        return;
> +    }

I assume it's OK to be overly aggressive here in removal, because we'll re-add descendants later anyway? If so, it would be nice to say that in a comment.

> LayoutTests/fast/block/fixed-position-reparent-when-transition-is-removed.html:4
> +<title>This tests that we can re-parent fixed positioned elements properly.</title>

It's not really re-parenting, right?

[alan]

Created attachment 281126 [details]
Patch

[alan]

(In reply to comment #5)
> Comment on attachment 281117 [details]
> Patch
> 
> View in context:
> https://bugs.webkit.org/attachment.cgi?id=281117&action=review
> 
> > Source/WebCore/rendering/RenderBlock.cpp:251
> > +    // We are no longer the containing block for fixed descendants.
> > +    if (hadTransform && !willHaveTransform) {
> > +        removePositionedObjects(nullptr, NewContainingBlock);
> > +        return;
> > +    }
> 
> I assume it's OK to be overly aggressive here in removal, because we'll
> re-add descendants later anyway? If so, it would be nice to say that in a
> comment.
Done.

> 
> > LayoutTests/fast/block/fixed-position-reparent-when-transition-is-removed.html:4
> > +<title>This tests that we can re-parent fixed positioned elements properly.</title>
> 
> It's not really re-parenting, right?
Fixed.

[WebKit Commit Bot]

Comment on attachment 281126 [details]
Patch

Clearing flags on attachment: 281126

Committed r201984: <http://trac.webkit.org/changeset/201984>

[WebKit Commit Bot]

All reviewed patches have been landed.  Closing bug.

[Simon Fraser (smfr)]

Comment on attachment 281126 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=281126&action=review

> LayoutTests/fast/block/fixed-position-reparent-when-transition-is-removed.html:31
> +        newChild.style.positioned = "absolute";

Typo!