1199417 - PathSkia::ContainsPoint fails for paths with small coordinates

Status: RESOLVED FIXED

(Core :: Graphics, defect)

Description

[Lee Salzman [:lsalzman]]

The main symptoms are the following mochitest failures:

616 INFO TEST-UNEXPECTED-FAIL | dom/svg/test/test_pointer-events-3.xhtml | Top of circle should hit - got [object SVGSVGElement], expected [object SVGCircleElement]
619 INFO TEST-UNEXPECTED-FAIL | dom/svg/test/test_pointer-events-3.xhtml | Left of circle should hit - got [object SVGSVGElement], expected [object SVGCircleElement] 

This is because the SVG circle is created in a very small coordinate system. With (1.5, 1.5) as the center and a radius of 1.

Since the path gets truncated to integer coordinates when it is converted to a region, the path doesn't survive the conversion to a region.

Comment 1

[Lee Salzman [:lsalzman]]

Attachment: scale skia paths up before hit testing to workaround coordinate resolution limits

This employs a similar solution to what Blink and Webkit are currently doing: scale the path up as far as we can within the coordinate precision Skia can support.

I also investigated whether the SkPath::contains() method still had the same problems outlined in bug 831529, and it is so. For now, we're stuck with the current regionizing workaround we have.

Comment 2

[Lee Salzman [:lsalzman]]

Attachment: scale skia paths up before hit testing to workaround coordinate resolution limits

Updated comment to note issue with bug 831259 and why we're still using this particular workaround.

Comment 3

[Lee Salzman [:lsalzman]]

Try run: https://treeherder.mozilla.org/#/jobs?repo=try&revision=518a5a6f5eaa

Comment 4

[Pulsebot]

https://hg.mozilla.org/integration/mozilla-inbound/rev/4931013ed9e9

Comment 5

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/4931013ed9e9