use pathops utils to improve precision of cubic chopping in scan converter

src/core/SkEdgeClipper.cpp

 
 /*
  * Copyright 2009 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 "SkEdgeClipper.h"
@@ skipping 249 matching lines @@
         }
         if (delta < TOLERANCE) {
             break;
         }
     }
     *t = mid;
 //    SkDebugf("-- evalCubicAt %d delta %g\n", i, eval_cubic_coeff(A, B, C, D, *t));
     return true;
 }
 
+#if 0
 static bool chopMonoCubicAtY(SkPoint pts[4], SkScalar y, SkScalar* t) {
     return chopMonoCubicAt(pts[0].fY, pts[1].fY, pts[2].fY, pts[3].fY, y, t);
 }
+#endif
 
 static bool chopMonoCubicAtX(SkPoint pts[4], SkScalar x, SkScalar* t) {
     return chopMonoCubicAt(pts[0].fX, pts[1].fX, pts[2].fX, pts[3].fX, x, t);
 }
 
 // Modify pts[] in place so that it is clipped in Y to the clip rect
 static void chop_cubic_in_Y(SkPoint pts[4], const SkRect& clip) {
 
     // are we partially above
     if (pts[0].fY < clip.fTop) {
+        SkPoint tmp[7];
+#if 0
         SkScalar t;
         if (chopMonoCubicAtY(pts, clip.fTop, &t)) {
-            SkPoint tmp[7];
             SkChopCubicAt(pts, tmp, t);
-
+#else
+        if (SkChopMonoCubicAtY(pts, clip.fTop, tmp)) {
+#endif
             // tmp[3, 4, 5].fY should all be to the below clip.fTop.
             // Since we can't trust the numerics of
             // the chopper, we force those conditions now
             tmp[3].fY = clip.fTop;
             clamp_ge(tmp[4].fY, clip.fTop);
-            clamp_ge(tmp[5].fY, clip.fTop);
+     //       clamp_ge(tmp[5].fY, clip.fTop);
 
             pts[0] = tmp[3];
             pts[1] = tmp[4];
             pts[2] = tmp[5];
         } else {
             // if chopMonoCubicAtY failed, then we may have hit inexact numerics
             // so we just clamp against the top
             for (int i = 0; i < 4; i++) {
                 clamp_ge(pts[i].fY, clip.fTop);
             }
         }
     }
 
     // are we partially below
     if (pts[3].fY > clip.fBottom) {
+        SkPoint tmp[7];
+#if 0
         SkScalar t;
         if (chopMonoCubicAtY(pts, clip.fBottom, &t)) {
-            SkPoint tmp[7];
             SkChopCubicAt(pts, tmp, t);
+#else
+        if (SkChopMonoCubicAtY(pts, clip.fBottom, tmp)) {
+#endif
             tmp[3].fY = clip.fBottom;
             clamp_le(tmp[2].fY, clip.fBottom);
 
             pts[1] = tmp[1];
             pts[2] = tmp[2];
             pts[3] = tmp[3];
         } else {
             // if chopMonoCubicAtY failed, then we may have hit inexact numerics
             // so we just clamp against the bottom
             for (int i = 0; i < 4; i++) {
@@ skipping 203 matching lines @@
         assert_monotonic(&pts[0].fY, count);
     }
 }
 
 void sk_assert_monotonic_x(const SkPoint pts[], int count) {
     if (count > 1) {
         assert_monotonic(&pts[0].fX, count);
     }
 }
 #endif