Use conics for round joins and caps

src/core/SkGeometry.cpp

 /*
  * Copyright 2006 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkGeometry.h"
 #include "SkMatrix.h"
 
@@ skipping 1594 matching lines @@
 
     int conicCount = quadrant;
     for (int i = 0; i < conicCount; ++i) {
         dst[i].set(&quadrantPts[i * 2], quadrantWeight);
     }
 
     // Now compute any remaing (sub-90-degree) arc for the last conic
     const SkPoint finalP = { x, y };
     const SkPoint& lastQ = quadrantPts[quadrant * 2];  // will already be a unit-vector
     const SkScalar dot = SkVector::DotProduct(lastQ, finalP);
-    SkASSERT(0 <= dot && dot <= SK_Scalar1);
+    SkASSERT(0 <= dot && dot <= SK_Scalar1 + SK_ScalarNearlyZero);
 
     if (dot < 1 - SK_ScalarNearlyZero) {
         SkVector offCurve = { lastQ.x() + x, lastQ.y() + y };
         // compute the bisector vector, and then rescale to be the off-curve point.
         // we compute its length from cos(theta/2) = length / 1, using half-angle identity we get
         // length = sqrt(2 / (1 + cos(theta)). We already have cos() when to computed the dot.
         // This is nice, since our computed weight is cos(theta/2) as well!
         //
         const SkScalar cosThetaOver2 = SkScalarSqrt((1 + dot) / 2);
         offCurve.setLength(SkScalarInvert(cosThetaOver2));
         dst[conicCount].set(lastQ, offCurve, finalP, cosThetaOver2);
         conicCount += 1;
     }
 
     // now handle counter-clockwise and the initial unitStart rotation
     SkMatrix    matrix;
     matrix.setSinCos(uStart.fY, uStart.fX);
     if (dir == kCCW_SkRotationDirection) {
         matrix.preScale(SK_Scalar1, -SK_Scalar1);
     }
     if (userMatrix) {
         matrix.postConcat(*userMatrix);
     }
     for (int i = 0; i < conicCount; ++i) {
         matrix.mapPoints(dst[i].fPts, 3);
     }
     return conicCount;
 }