tree e0843dcb556d1ad159f064b02e64dc38780347d1
parent 280e282d2a89ba3b9ff05dd2475d7452b7dccdbe
author senorblanco <senorblanco@chromium.org> 1471470982 -0700
committer Commit bot <commit-bot@chromium.org> 1471470982 -0700

Fix assert caused by floating point error in tessellating path renderer.

In rare cases, floating point error causes the tesselator to add the
same Vertex to more than one Poly on the same side. This was not a big
problem when we were allocating new vertices when constructing Polys,
but after https://codereview.chromium.org/2029243002 it causes more serious
issues, since each Edge can only belong to two Polys, and violating this
condition messes up the linked list of Edges used for left & right Polys
and the associated estimated vertex count.

The fix is to simply let the first Poly win, and skip that vertex for
subsequent Polys. Since this only occurs in cases where vertices are very
close to each other, it should have little visual effect.

This is also exercised by Nebraska-StateSeal.svg.

BUG=skia:5636
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2259493002

Review-Url: https://codereview.chromium.org/2259493002