Add intersections for path ops

tests/PathOpsQuadLineIntersectionTest.cpp

Index: tests/PathOpsQuadLineIntersectionTest.cpp
===================================================================
--- tests/PathOpsQuadLineIntersectionTest.cpp	(revision 0)
+++ tests/PathOpsQuadLineIntersectionTest.cpp	(revision 0)
@@ -0,0 +1,132 @@
+/*
+ * 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 "PathOpsExtendedTest.h"
+#include "SkIntersections.h"
+#include "SkPathOpsLine.h"
+#include "SkPathOpsQuad.h"
+#include "SkReduceOrder.h"
+#include "Test.h"
+
+static struct lineQuad {
+    SkDQuad quad;
+    SkDLine line;
+    int result;
+    SkDPoint expected[2];
+} lineQuadTests[] = {
+    //        quad                    line                  results
+    {{{{1, 1}, {2, 1}, {0, 2}}}, {{{0, 0}, {1, 1}}},  1,  {{1, 1}        }},
+    {{{{0, 0}, {1, 1}, {3, 1}}}, {{{0, 0}, {3, 1}}},  2,  {{0, 0}, {3, 1}}},
+    {{{{2, 0}, {1, 1}, {2, 2}}}, {{{0, 0}, {0, 2}}},  0                   },
+    {{{{4, 0}, {0, 1}, {4, 2}}}, {{{3, 1}, {4, 1}}},  0,                  },
+    {{{{0, 0}, {0, 1}, {1, 1}}}, {{{0, 1}, {1, 0}}},  1,  {{.25, .75}    }},
+};
+
+static size_t lineQuadTests_count = sizeof(lineQuadTests) / sizeof(lineQuadTests[0]);
+
+static int doIntersect(SkIntersections& intersections, const SkDQuad& quad, const SkDLine& line,
+                       bool& flipped) {
+    int result;
+    flipped = false;
+    if (line[0].fX == line[1].fX) {
+        double top = line[0].fY;
+        double bottom = line[1].fY;
+        flipped = top > bottom;
+        if (flipped) {
+            SkTSwap<double>(top, bottom);
+        }
+        result = intersections.vertical(quad, top, bottom, line[0].fX, flipped);
+    } else if (line[0].fY == line[1].fY) {
+        double left = line[0].fX;
+        double right = line[1].fX;
+        flipped = left > right;
+        if (flipped) {
+            SkTSwap<double>(left, right);
+        }
+        result = intersections.horizontal(quad, left, right, line[0].fY, flipped);
+    } else {
+        intersections.intersect(quad, line);
+        result = intersections.used();
+    }
+    return result;
+}
+
+static struct oneLineQuad {
+    SkDQuad quad;
+    SkDLine line;
+} oneOffs[] = {
+    {{{{369.848602, 145.680267}, {382.360413, 121.298294}, {406.207703, 121.298294}}},
+        {{{406.207703, 121.298294}, {348.781738, 123.864815}}}}
+    };
+
+static size_t oneOffs_count = sizeof(oneOffs) / sizeof(oneOffs[0]);
+
+static void testOneOffs(skiatest::Reporter* reporter) {
+    SkIntersections intersections;
+    bool flipped = false;
+    for (size_t index = 0; index < oneOffs_count; ++index) {
+        const SkDQuad& quad = oneOffs[index].quad;
+        const SkDLine& line = oneOffs[index].line;
+        int result = doIntersect(intersections, quad, line, flipped);
+        for (int inner = 0; inner < result; ++inner) {
+            double quadT = intersections[0][inner];
+            SkDPoint quadXY = quad.xyAtT(quadT);
+            double lineT = intersections[1][inner];
+            SkDPoint lineXY = line.xyAtT(lineT);
+            REPORTER_ASSERT(reporter, quadXY.approximatelyEqual(lineXY));
+        }
+    }
+}
+
+static void TestQuadLineIntersection(skiatest::Reporter* reporter) {
+    testOneOffs(reporter);
+    for (size_t index = 0; index < lineQuadTests_count; ++index) {
+        int iIndex = static_cast<int>(index);
+        const SkDQuad& quad = lineQuadTests[index].quad;
+        const SkDLine& line = lineQuadTests[index].line;
+        SkReduceOrder reducer1, reducer2;
+        int order1 = reducer1.reduce(quad, SkReduceOrder::kFill_Style);
+        int order2 = reducer2.reduce(line);
+        if (order1 < 3) {
+            SkDebugf("%s [%d] quad order=%d\n", __FUNCTION__, iIndex, order1);
+            REPORTER_ASSERT(reporter, 0);
+        }
+        if (order2 < 2) {
+            SkDebugf("%s [%d] line order=%d\n", __FUNCTION__, iIndex, order2);
+            REPORTER_ASSERT(reporter, 0);
+        }
+        SkIntersections intersections;
+        bool flipped = false;
+        int result = doIntersect(intersections, quad, line, flipped);
+        REPORTER_ASSERT(reporter, result == lineQuadTests[index].result);
+        if (!intersections.used() > 0) {
+            continue;
+        }
+        for (int pt = 0; pt < result; ++pt) {
+            double tt1 = intersections[0][pt];
+            REPORTER_ASSERT(reporter, tt1 >= 0 && tt1 <= 1);
+            SkDPoint t1 = quad.xyAtT(tt1);
+            double tt2 = intersections[1][pt];
+            REPORTER_ASSERT(reporter, tt2 >= 0 && tt2 <= 1);
+            SkDPoint t2 = line.xyAtT(tt2);
+            if (!t1.approximatelyEqual(t2)) {
+                SkDebugf("%s [%d,%d] x!= t1=%1.9g (%1.9g,%1.9g) t2=%1.9g (%1.9g,%1.9g)\n",
+                    __FUNCTION__, iIndex, pt, tt1, t1.fX, t1.fY, tt2, t2.fX, t2.fY);
+                REPORTER_ASSERT(reporter, 0);
+            }
+            if (!t1.approximatelyEqual(lineQuadTests[index].expected[0])
+                    && (lineQuadTests[index].result == 1
+                    || !t1.approximatelyEqual(lineQuadTests[index].expected[1]))) {
+                SkDebugf("%s t1=(%1.9g,%1.9g)\n", __FUNCTION__, t1.fX, t1.fY);
+                REPORTER_ASSERT(reporter, 0);
+            }
+        }
+    }
+}
+
+#include "TestClassDef.h"
+DEFINE_TESTCLASS("PathOpsQuadLineIntersection", QuadLineIntersectionTestClass, \
+        TestQuadLineIntersection)