Fallback to moveTo when unable to find the first tangent in cubicTo

tests/PathTest.cpp

Index: tests/PathTest.cpp
diff --git a/tests/PathTest.cpp b/tests/PathTest.cpp
index 3941ad6e183946ff42f86a40434c87c8b5467f02..2719e1fd913dc38f068f9592c75b1d2d3693de4b 100644
--- a/tests/PathTest.cpp
+++ b/tests/PathTest.cpp
@@ -64,6 +64,35 @@ static void test_path_crbug364224() {
     canvas->drawPath(path, paint);
 }
 
+static void make_path_crbugskia2820(SkPath* path, skiatest::Reporter* reporter) {

[reed1, 2014/08/20 14:47:11]

Seems like a brief comment would help. e.g.

/* This path used to generate valgrid/asan warnings in the stroker code. */

[Rémi Piotaix, 2014/08/20 18:18:08]

Done.

+    float rdi =  1./4096.;

[reed1, 2014/08/20 14:47:10]

All of these literals will generate double->float warnings.

[Rémi Piotaix, 2014/08/20 18:18:08]

Done.

+
+    SkPoint orig, p1, p2, p3;
+    orig = SkPoint::Make(1., 1.);
+    p1 = SkPoint::Make(1.-rdi, 1.);
+    p2 = SkPoint::Make(1., 1.+rdi);
+    p3 = SkPoint::Make(2., 2.);
+
+    REPORTER_ASSERT(reporter, SkPath::IsLineDegenerate(orig, p1));

[reed1, 2014/08/20 14:47:10]

I don't see why these checks should be in the test. They seem to be leaking
(current) implementation details outside of the SkPath api.

[Rémi Piotaix, 2014/08/20 18:18:08]

These are assertions on the data (orig+p1-3) used to trigger the bug.
Because the behavior of cubicTo depends on these assertions on the input, it is
meaningful to me to keep them but maybe it is not....

+    REPORTER_ASSERT(reporter, SkPath::IsLineDegenerate(orig, p2));
+    REPORTER_ASSERT(reporter, !SkPath::IsLineDegenerate(p1, p2));
+    REPORTER_ASSERT(reporter, !SkPath::IsLineDegenerate(p2, p3));
+
+    path->reset();
+    path->moveTo(1, 1);
+    path->cubicTo(p1, p2, p3);
+    path->close();
+}
+
+static void test_path_crbugskia2820(skiatest::Reporter* reporter) {//GrContext* context) {
+    SkPath path;
+    make_path_crbugskia2820(&path, reporter);
+
+    SkStrokeRec stroke(SkStrokeRec::kFill_InitStyle);
+    stroke.setStrokeStyle(2 * SK_Scalar1);
+    stroke.applyToPath(&path, path);
+}
+
 static void make_path0(SkPath* path) {
     // from  *  https://code.google.com/p/skia/issues/detail?id=1706
 
@@ -3553,4 +3582,5 @@ DEF_TEST(Paths, reporter) {
     PathTest_Private::TestPathTo(reporter);
     PathRefTest_Private::TestPathRef(reporter);
     test_dump(reporter);
+    test_path_crbugskia2820(reporter);
 }