Move gpu conic calculations to GrPathUtils

src/gpu/GrPathUtils.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "GrPathUtils.h"
 
 #include "GrPoint.h"
@@ skipping 257 matching lines @@
             fM[0] = m.get(SkMatrix::kMScaleX);
             fM[1] = m.get(SkMatrix::kMSkewX);
             fM[2] = m.get(SkMatrix::kMTransX);
             fM[3] = m.get(SkMatrix::kMSkewY);
             fM[4] = m.get(SkMatrix::kMScaleY);
             fM[5] = m.get(SkMatrix::kMTransY);
         }
     }
 }
 
+////////////////////////////////////////////////////////////////////////////////
+
+// k = (y2 - y0, x0 - x2, (x2 - x0)*y0 - (y2 - y0)*x0 )
+// l = (2*w * (y1 - y0), 2*w * (x0 - x1), 2*w * (x1*y0 - x0*y1))
+// m = (2*w * (y2 - y1), 2*w * (x1 - x2), 2*w * (x2*y1 - x1*y2))
+void GrPathUtils::getConicKLM(const SkPoint p[3], const SkScalar weight, SkScalar klm[9]) {
+    const SkScalar w2 = 2.f * weight;
+    klm[0] = p[2].fY - p[0].fY;
+    klm[1] = p[0].fX - p[2].fX;
+    klm[2] = (p[2].fX - p[0].fX) * p[0].fY - (p[2].fY - p[0].fY) * p[0].fX;
+
+    klm[3] = w2 * (p[1].fY - p[0].fY);
+    klm[4] = w2 * (p[0].fX - p[1].fX);
+    klm[5] = w2 * (p[1].fX * p[0].fY - p[0].fX * p[1].fY);
+
+    klm[6] = w2 * (p[2].fY - p[1].fY);
+    klm[7] = w2 * (p[1].fX - p[2].fX);
+    klm[8] = w2 * (p[2].fX * p[1].fY - p[1].fX * p[2].fY);
+
+    // scale the max absolute value of coeffs to 10
+    SkScalar scale = 0.f;
+    for (int i = 0; i < 9; ++i) {
+       scale = SkMaxScalar(scale, SkScalarAbs(klm[i]));
+    }
+    SkASSERT(scale > 0.f);
+    scale = 10.f / scale;
+    for (int i = 0; i < 9; ++i) {
+        klm[i] *= scale;
+    }
+}
+
+////////////////////////////////////////////////////////////////////////////////
+
 namespace {
 
 // a is the first control point of the cubic.
 // ab is the vector from a to the second control point.
 // dc is the vector from the fourth to the third control point.
 // d is the fourth control point.
 // p is the candidate quadratic control point.
 // this assumes that the cubic doesn't inflect and is simple
 bool is_point_within_cubic_tangents(const SkPoint& a,
                                     const SkVector& ab,
@@ skipping 510 matching lines @@
         set_loop_klm(d, controlK, controlL, controlM);
     } else if (kCusp_CubicType == cType) {
         SkASSERT(0.f == d[0]);
         set_cusp_klm(d, controlK, controlL, controlM);
     } else if (kQuadratic_CubicType == cType) {
         set_quadratic_klm(d, controlK, controlL, controlM);
     }
 
     calc_cubic_klm(p, controlK, controlL, controlM, klm, &klm[3], &klm[6]);
 }