add more conservative check for wayward divide

When the parallel stroke to the curve can't be computed from
the intersection of the tangent lines, as straight line connects
the two points instead. Allow the intersection to succeed unless
the ratio isn't finite or the contribution of (1 - ratio) isn't
significant.

R=reed@google.com,fmalita@chromium.org
BUG=skia:4603

Review URL: https://codereview.chromium.org/1484873003

1 files changed, 16 insertions, 0 deletions

diff --git a/gm/strokes.cpp b/gm/strokes.cpp
index bd393829e0..aa2db9ccb2 100644
--- a/gm/strokes.cpp
+++ b/gm/strokes.cpp
@@ -193,6 +193,22 @@ private:
     typedef skiagm::GM INHERITED;
 };
 
+DEF_SIMPLE_GM(CubicStroke, canvas, 384, 384) {
+    SkPaint p;
+    p.setAntiAlias(true);
+    p.setStyle(SkPaint::kStroke_Style);
+    p.setStrokeWidth(1.0720f);
+	SkPath path;
+    path.moveTo(-6000,-6000);
+    path.cubicTo(-3500,5500,-500,5500,2500,-6500);
+    canvas->drawPath(path, p);
+    p.setStrokeWidth(1.0721f);
+    canvas->translate(10, 10);
+    canvas->drawPath(path, p);
+    p.setStrokeWidth(1.0722f);
+    canvas->translate(10, 10);
+    canvas->drawPath(path, p);
+}
 
 class Strokes2GM : public skiagm::GM {
     SkPath fPath;