Add intersections for path ops

tests/PathOpsCubicLineIntersectionTest.cpp

Index: tests/PathOpsCubicLineIntersectionTest.cpp
===================================================================
--- tests/PathOpsCubicLineIntersectionTest.cpp	(revision 0)
+++ tests/PathOpsCubicLineIntersectionTest.cpp	(revision 0)
@@ -0,0 +1,61 @@
+/*
+ * 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 "SkIntersections.h"
+#include "SkPathOpsCubic.h"
+#include "SkPathOpsLine.h"
+#include "SkReduceOrder.h"
+#include "Test.h"
+
+static struct lineCubic {
+    SkDCubic cubic;
+    SkDLine line;
+} lineCubicTests[] = {
+    {{{{1, 2}, {2, 6}, {2, 0}, {1, 0}}}, {{{1, 0}, {1, 2}}}},
+    {{{{0, 0}, {0, 1}, {0, 1}, {1, 1}}}, {{{0, 1}, {1, 0}}}},
+};
+
+static const size_t lineCubicTests_count = sizeof(lineCubicTests) / sizeof(lineCubicTests[0]);
+
+static void CubicLineIntersectionTest(skiatest::Reporter* reporter) {
+    for (size_t index = 0; index < lineCubicTests_count; ++index) {
+        int iIndex = static_cast<int>(index);
+        const SkDCubic& cubic = lineCubicTests[index].cubic;
+        const SkDLine& line = lineCubicTests[index].line;
+        SkReduceOrder reduce1;
+        SkReduceOrder reduce2;
+        int order1 = reduce1.reduce(cubic, SkReduceOrder::kNo_Quadratics,
+                SkReduceOrder::kFill_Style);
+        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);
+            for (int pt = 0; pt < roots; ++pt) {
+                double tt1 = i[0][pt];
+                SkDPoint xy1 = cubic.xyAtT(tt1);
+                double tt2 = i[1][pt];
+                SkDPoint xy2 = line.xyAtT(tt2);
+                if (!xy1.approximatelyEqual(xy2)) {
+                    SkDebugf("%s [%d,%d] x!= t1=%g (%g,%g) t2=%g (%g,%g)\n",
+                        __FUNCTION__, iIndex, pt, tt1, xy1.fX, xy1.fY, tt2, xy2.fX, xy2.fY);
+                }
+                REPORTER_ASSERT(reporter, xy1.approximatelyEqual(xy2));
+            }
+        }
+    }
+}
+
+#include "TestClassDef.h"
+DEFINE_TESTCLASS("PathOpsCubicLineIntersection", CubicLineIntersectionTestClass, \
+        CubicLineIntersectionTest)