keep SVG arcs axis aligned

Computing the arc width introduces rounding errors that cause the
arc to exceed 1/4 circle and cause integer anchored arcs to start
outside their marks. A round rect may lose convexity as a result.

Check if arcTo() inputs are integers and arc is 90 degrees;
if so, output conics which are axis-aligned on integers as well.

This is triggered when using SVG to represent a round rect.

Possible future enhancements are recorded in bug.skia.org/7383

R=reed@google.com,djsollen@google.com
Change-Id: I6609456fcefabcda6c9560a044533ecb5cda2d31
Reviewed-on: https://skia-review.googlesource.com/79423
Reviewed-by: Derek Sollenberger <djsollen@google.com>
Commit-Queue: Derek Sollenberger <djsollen@google.com>

0 files changed, 0 insertions, 0 deletions