quad and conic do not intersect

src/pathops/SkPathOpsQuad.cpp

Index: src/pathops/SkPathOpsQuad.cpp
diff --git a/src/pathops/SkPathOpsQuad.cpp b/src/pathops/SkPathOpsQuad.cpp
index dafa3f5b7588cbebbcb64465fb527526d1efba5b..ab1ba05c5691646c010a2677c2a0b79c50da6174 100644
--- a/src/pathops/SkPathOpsQuad.cpp
+++ b/src/pathops/SkPathOpsQuad.cpp
@@ -10,6 +10,28 @@
 #include "SkPathOpsCurve.h"
 #include "SkPathOpsQuad.h"
 
+// from blackpawn.com/texts/pointinpoly
+static bool pointInTriangle(const SkDPoint fPts[3], const SkDPoint& test) {
+    SkDVector v0 = fPts[2] - fPts[0];
+    SkDVector v1 = fPts[1] - fPts[0];
+    SkDVector v2 = test - fPts[0];
+    double dot00 = v0.dot(v0);
+    double dot01 = v0.dot(v1);
+    double dot02 = v0.dot(v2);
+    double dot11 = v1.dot(v1);
+    double dot12 = v1.dot(v2);
+    // Compute barycentric coordinates
+    double invDenom = 1 / (dot00 * dot11 - dot01 * dot01);
+    double u = (dot11 * dot02 - dot01 * dot12) * invDenom;
+    double v = (dot00 * dot12 - dot01 * dot02) * invDenom;
+    // Check if point is in triangle
+    return u >= 0 && v >= 0 && u + v < 1;
+}
+
+static bool matchesEnd(const SkDPoint fPts[3], const SkDPoint& test) {
+    return fPts[0] == test || fPts[2] == test;
+}
+
 /* started with at_most_end_pts_in_common from SkDQuadIntersection.cpp */
 // Do a quick reject by rotating all points relative to a line formed by
 // a pair of one quad's points. If the 2nd quad's points
@@ -44,6 +66,14 @@ bool SkDQuad::hullIntersects(const SkDQuad& q2, bool* isLinear) const {
             return false;
         }
     }
+    if (linear && !matchesEnd(fPts, q2.fPts[0]) && !matchesEnd(fPts, q2.fPts[2])) {
+        // if the end point of the opposite quad is inside the hull that is nearly a line,
+        // then representing the quad as a line may cause the intersection to be missed.
+        // Check to see if the endpoint is in the triangle.
+        if (pointInTriangle(fPts, q2.fPts[0]) || pointInTriangle(fPts, q2.fPts[2])) {
+            linear = false;
+        }
+    }
     *isLinear = linear;
     return true;
 }