fix cubic/line intersection; add skp tests

tests/PathOpsCubicLineIntersectionTest.cpp

 /*
  * Copyright 2012 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "PathOpsTestCommon.h"
 #include "SkIntersections.h"
 #include "SkPathOpsCubic.h"
 #include "SkPathOpsLine.h"
 #include "SkReduceOrder.h"
 #include "Test.h"
 
-static struct lineCubic {
+struct lineCubic {
     SkDCubic cubic;
     SkDLine line;
-} lineCubicTests[] = {
+};
+
+static lineCubic failLineCubicTests[] = {
+    {{{{37.5273438,-1.44140625}, {37.8736992,-1.69921875}, {38.1640625,-2.140625},
+            {38.3984375,-2.765625}}},
+            {{{40.625,-5.7890625}, {37.7109375,1.3515625}}}},
+};
+
+static const size_t failLineCubicTests_count = SK_ARRAY_COUNT(failLineCubicTests);
+
+static void testFail(skiatest::Reporter* reporter, int iIndex) {
+    const SkDCubic& cubic = failLineCubicTests[iIndex].cubic;
+    SkASSERT(ValidCubic(cubic));
+    const SkDLine& line = failLineCubicTests[iIndex].line;
+    SkASSERT(ValidLine(line));
+    SkReduceOrder reduce1;
+    SkReduceOrder reduce2;
+    int order1 = reduce1.reduce(cubic, SkReduceOrder::kNo_Quadratics);
+    int order2 = reduce2.reduce(line);
+    if (order1 < 4) {
+        SkDebugf("[%d] cubic order=%d\n", iIndex, order1);
+        REPORTER_ASSERT(reporter, 0);
+    }
+    if (order2 < 2) {
+        SkDebugf("[%d] line order=%d\n", iIndex, order2);
+        REPORTER_ASSERT(reporter, 0);
+    }
+    if (order1 == 4 && order2 == 2) {
+        SkIntersections i;
+        int roots = i.intersect(cubic, line);
+        REPORTER_ASSERT(reporter, roots == 0);
+    }
+}
+
+static lineCubic lineCubicTests[] = {
+
     {{{{421, 378}, {421, 380.209137f}, {418.761414f, 382}, {416, 382}}},
             {{{320, 378}, {421, 378.000031f}}}},
 
     {{{{416, 383}, {418.761414f, 383}, {421, 380.761414f}, {421, 378}}},
             {{{320, 378}, {421, 378.000031f}}}},
 
     {{{{154,715}, {151.238571,715}, {149,712.761414}, {149,710}}},
             {{{149,675}, {149,710.001465}}}},
 
     {{{{0,1}, {1,6}, {4,1}, {4,3}}},
@@ skipping 62 matching lines @@
         SkDPoint prevL = line.ptAtT(i[1][0] - 0.0000007);
         SkDebugf("{{%1.9g,%1.9g}, {%1.9g,%1.9g}},\n", prevL.fX, prevL.fY, i.pt(0).fX, i.pt(0).fY);
         SkDPoint nextL = line.ptAtT(i[1][0] + 0.0000007);
         SkDebugf("{{%1.9g,%1.9g}, {%1.9g,%1.9g}},\n", i.pt(0).fX, i.pt(0).fY, nextL.fX, nextL.fY);
         SkDebugf("prevD=%1.9g dist=%1.9g nextD=%1.9g\n", prev.distance(nextL),
                 sect.distance(i.pt(0)), cubic[3].distance(prevL));
 #endif
     }
 }
 
+DEF_TEST(PathOpsFailCubicLineIntersection, reporter) {
+    for (size_t index = 0; index < failLineCubicTests_count; ++index) {
+        int iIndex = static_cast<int>(index);
+        testFail(reporter, iIndex);
+        reporter->bumpTestCount();
+    }
+}
+
 DEF_TEST(PathOpsCubicLineIntersection, reporter) {
     for (size_t index = 0; index < lineCubicTests_count; ++index) {
         int iIndex = static_cast<int>(index);
         testOne(reporter, iIndex);
         reporter->bumpTestCount();
     }
 }
 
 DEF_TEST(PathOpsCubicLineIntersectionOneOff, reporter) {
     int iIndex = 0;
     testOne(reporter, iIndex);
     const SkDCubic& cubic = lineCubicTests[iIndex].cubic;
     const SkDLine& line = lineCubicTests[iIndex].line;
     SkIntersections i;
     i.intersect(cubic, line);
     SkASSERT(i.used() == 1);
 }