REGRESSION: Animations inside RTL multicolumn content is broken

• Component: Layout and Rendering
• Status: RESOLVED DUPLICATE

[Ryosuke Niwa]

When a CSS animation is added to an element inside a RTL multicolumn content,
the accelerated layer is shown at a wrong location.

[Ryosuke Niwa]

Created attachment 235809 [details]
Test case

See how "hello" moves between two locations but it shouldn't.
It should always show up on the right of "world".

[Ryosuke Niwa]

This one appears to be caused by accumulateOffsetTowardsAncestor adding the offset in:

                RenderRegion* region = toRenderMultiColumnFlowThread(parentLayer->renderer()).physicalTranslationFromFlowToRegion(location);
                if (region)
                    location.moveBy(region->topLeftLocation() + -parentLayer->renderBox()->topLeftLocation());

Removing the last two lines here fixes the bug.

It's curious how RenderBoxModelObject::adjustedPositionRelativeToOffsetParent has a very similar code:

                    RenderRegion* region = toRenderMultiColumnFlowThread(curr)->physicalTranslationFromFlowToRegion(referencePoint);
                    if (region)
                        referencePoint.moveBy(region->topLeftLocation());

[Simon Fraser (smfr)]

Isn't this just all RenderLayer content, even without animation? I thought you had an example with opacity.

[Andrei Bucur]

This bug has the same cause as https://bugs.webkit.org/show_bug.cgi?id=135452.

[Ryosuke Niwa]

Confirmed fixed with http://trac.webkit.org/changeset/171882.  Thanks!

*** This bug has been marked as a duplicate of bug 135452 ***