path ops near exact

src/pathops/SkPathOpsQuad.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 "SkIntersections.h"
 #include "SkLineParameters.h"
 #include "SkPathOpsCubic.h"
 #include "SkPathOpsQuad.h"
@@ skipping 146 matching lines @@
 
 SkDVector SkDQuad::dxdyAtT(double t) const {
     double a = t - 1;
     double b = 1 - 2 * t;
     double c = t;
     SkDVector result = { a * fPts[0].fX + b * fPts[1].fX + c * fPts[2].fX,
             a * fPts[0].fY + b * fPts[1].fY + c * fPts[2].fY };
     return result;
 }
 
+// OPTIMIZE: assert if caller passes in t == 0 / t == 1 ?
 SkDPoint SkDQuad::xyAtT(double t) const {
     double one_t = 1 - t;
     double a = one_t * one_t;
     double b = 2 * one_t * t;
     double c = t * t;
     SkDPoint result = { a * fPts[0].fX + b * fPts[1].fX + c * fPts[2].fX,
             a * fPts[0].fY + b * fPts[1].fY + c * fPts[2].fY };
     return result;
 }
 
@@ skipping 149 matching lines @@
  * c =             C
  */
 void SkDQuad::SetABC(const double* quad, double* a, double* b, double* c) {
     *a = quad[0];      // a = A
     *b = 2 * quad[2];  // b =     2*B
     *c = quad[4];      // c =             C
     *b -= *c;          // b =     2*B -   C
     *a -= *b;          // a = A - 2*B +   C
     *b -= *c;          // b =     2*B - 2*C
 }