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

tests/PathTest.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkCanvas.h"
 #include "SkPaint.h"
 #include "SkParse.h"
@@ skipping 46 matching lines @@
     SkAutoTUnref<SkSurface> surface(SkSurface::NewRasterPMColor(84, 88));
     SkCanvas* canvas = surface->getCanvas();
 
     make_path_crbug364224_simplified(&path);
     canvas->drawPath(path, paint);
 
     make_path_crbug364224(&path);
     canvas->drawPath(path, paint);
 }
 
+/**
+ * In debug mode, this path is causing an assertion to fail in
+ * SkPathStroker::preJoinTo() and, in Release, the use of an unitialized value.
+ */
+static void make_path_crbugskia2820(SkPath* path, skiatest::Reporter* reporter) {
+    SkPoint orig, p1, p2, p3;
+    orig = SkPoint::Make(SkIntToScalar(1), SkIntToScalar(1));

[reed1, 2014/08/20 19:07:18]

:)

I find this very hard to read. Looking right below, lines 101.. is very
readable, and does not generate any warnings. I think that patterns is worth
replicating.

[Rémi Piotaix, 2014/08/20 19:21:08]

Done.

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

[reed1, 2014/08/20 19:07:18]

These lines are testing some aspect of IsLineDegenerate, not testing anything
about stroking per-se, as we can always change how we implement stroking. The
only "real" bug here is that we read uninitialized memory, and/or fire an
assert. The purpose of a test is to exercise that, so that we see that neither
of those happen in the future.

[Rémi Piotaix, 2014/08/20 19:21:09]

Done.

+    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(SkIntToScalar(1), SkIntToScalar(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
 
     path->moveTo(146.939f, 1012.84f);
     path->lineTo(181.747f, 1009.18f);
     path->lineTo(182.165f, 1013.16f);
     path->lineTo(147.357f, 1016.82f);
     path->lineTo(146.939f, 1012.84f);
     path->close();
 }
@@ skipping 3469 matching lines @@
     test_addPathMode(reporter, true, true);
     test_extendClosedPath(reporter);
     test_addEmptyPath(reporter, SkPath::kExtend_AddPathMode);
     test_addEmptyPath(reporter, SkPath::kAppend_AddPathMode);
     test_conicTo_special_case(reporter);
     test_get_point(reporter);
     test_contains(reporter);
     PathTest_Private::TestPathTo(reporter);
     PathRefTest_Private::TestPathRef(reporter);
     test_dump(reporter);
+    test_path_crbugskia2820(reporter);
 }