Bug 82059 – Incorrect foreignObject hit test results when overlapping other SVG elements

• Component: SVG
• Status: RESOLVED FIXED

[Florin Malita]

Created attachment 133498 [details]
Blue div clicks are not detected in the overlapping region.

http://code.google.com/p/chromium/issues/detail?id=116908

The generic phased subtree hit testing logic doesn't play nice with FO's stacking context. The FO content is flattened so a HitTestForeground query needs to also check for children background hits, etc.

For the attached example, clicking on the blue div in the overlapping region ends up firing a foreground hit on the underlying red rect.

[Florin Malita]

Created attachment 134135 [details]
Patch

[Nikolas Zimmermann]

Comment on attachment 134135 [details]
Patch

r=me. You're doing all of this from the Foreground phase, due the FOs stacking context. The only renderer that used to care about phases like HitTestFloat or HotTestChildBlockBackgrounds is RenderSVGFo. Now that this dependency is gone, we can completely avoid painting() the whole SVG subtree in non-foreground phases (still exceptions are needed for PaintPhaseSelection I think) - that would save a lot of time! Can you look into this? (Easy approach, early return in RenderSVGRoot::paint if phase is not foreground, then see what tests breaks :-)

[Florin Malita]

(In reply to comment #2)
> we can completely avoid painting() the whole SVG subtree in non-foreground phases (still exceptions are needed for PaintPhaseSelection I think) - that would save a lot of time! Can you look into this? (Easy approach, early return in RenderSVGRoot::paint if phase is not foreground, then see what tests breaks :-)

Sure thing, thanks.

[WebKit Review Bot]

Comment on attachment 134135 [details]
Patch

Clearing flags on attachment: 134135

Committed r112438: <http://trac.webkit.org/changeset/112438>

[WebKit Review Bot]

All reviewed patches have been landed.  Closing bug.