Fix GrAAConvexTessellator to handle cases slightly concave bistectors.
When repeatedly insetting rings we can wind up with bisector vectors
that correspond to a slightly concave ring. This would cause the first
intersection when computing the next ring's inset depth to be outside
the current ring. Instead skip adjacent bisectors that intersect outside
the ring during the search.
Change-Id: I3efab5a9f44966888cfa86715876b7b177950732
Reviewed-on: https://skia-review.googlesource.com/151827
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>
diff --git a/gm/convex_all_line_paths.cpp b/gm/convex_all_line_paths.cpp
index 7dc973e..6d7155d 100644
--- a/gm/convex_all_line_paths.cpp
+++ b/gm/convex_all_line_paths.cpp
@@ -358,6 +358,30 @@
canvas->translate(0.0f, 500.0f);
canvas->drawPath(p2, p);
canvas->restore();
+
+ // Repro for crbug.com/856137. This path previously caused GrAAConvexTessellator to turn
+ // inset rings into outsets when adjacent bisector angles converged outside the previous
+ // ring due to accumulated error.
+ SkPath p3;
+ p3.setFillType(SkPath::kEvenOdd_FillType);
+ p3.moveTo(1184.96f, 982.557f);
+ p3.lineTo(1183.71f, 982.865f);
+ p3.lineTo(1180.99f, 982.734f);
+ p3.lineTo(1178.5f, 981.541f);
+ p3.lineTo(1176.35f, 979.367f);
+ p3.lineTo(1178.94f, 938.854f);
+ p3.lineTo(1181.35f, 936.038f);
+ p3.lineTo(1183.96f, 934.117f);
+ p3.lineTo(1186.67f, 933.195f);
+ p3.lineTo(1189.36f, 933.342f);
+ p3.lineTo(1191.58f, 934.38f);
+ p3.close();
+ canvas->save();
+ SkMatrix m;
+ m.setAll(0.0893210843f, 0, 79.1197586f, 0, 0.0893210843f, 300, 0, 0, 1);
+ canvas->concat(m);
+ canvas->drawPath(p3, p);
+ canvas->restore();
}
}