tree ec172b9ffd6a31e2d89512dd88714136f7557436
parent a225e9be53001a8397344ce1e272a7df2fced499
author liyuqian <liyuqian@google.com> 1478535044 -0800
committer Commit bot <commit-bot@chromium.org> 1478535044 -0800

Combine analytic edges with tolerance

If not, we sometimes would end up with only one edge for a convex path. That
either triggers SkASSERT(count >= 2) failure in debug build or SIGSEGV in
release build. After the change, we should return 0 edges for such a path
because everything is totally combined.

Note that this change also makes the SkAnalyticEdge's CombineVertical function
behave more similarly to SkEdge's CombineVertical function: SkEdge only
compares fFirstY and fLastY which are integer values, which is equivalent to
setting our tolerance to SK_Fixed1 (our current tolerance is 0x100, 1/256 of
SK_Fixed1).  And this is intentional.

BUG=chrome:662914
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2477373002

Review-Url: https://codereview.chromium.org/2477373002