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 207 matching lines @@
     }
 
     *fCurrVerb = SkPath::kDone_Verb;
     fCurrPoint = fPoints;
     fCurrVerb = fVerbs;
     return SkPath::kDone_Verb != fVerbs[0];
 }
 
 ///////////////////////////////////////////////////////////////////////////////
 
+#ifdef SK_SUPPORT_LEGACY_CUBIC_CHOPPER
 static SkScalar eval_cubic_coeff(SkScalar A, SkScalar B, SkScalar C,
                                  SkScalar D, SkScalar t) {
     return SkScalarMulAdd(SkScalarMulAdd(SkScalarMulAdd(A, t, B), t, C), t, D);
 }
 
 /*  Given 4 cubic points (either Xs or Ys), and a target X or Y, compute the
     t value such that cubic(t) = target
  */
 static bool chopMonoCubicAt(SkScalar c0, SkScalar c1, SkScalar c2, SkScalar c3,
                            SkScalar target, SkScalar* t) {
@@ skipping 29 matching lines @@
     return true;
 }
 
 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);
 }
 
 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);
 }
+#endif
 
 // 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];
+#ifdef SK_SUPPORT_LEGACY_CUBIC_CHOPPER
         SkScalar t;
         if (chopMonoCubicAtY(pts, clip.fTop, &t)) {
-            SkPoint tmp[7];
             SkChopCubicAt(pts, tmp, t);
-
-            // tmp[3, 4, 5].fY should all be to the below clip.fTop.
+#else
+        if (SkChopMonoCubicAtY(pts, clip.fTop, tmp)) {
+#endif
+            // tmp[3, 4].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);
+#ifdef SK_SUPPORT_LEGACY_CUBIC_CHOPPER
             clamp_ge(tmp[5].fY, clip.fTop);
+#endif
 
             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];
+#ifdef SK_SUPPORT_LEGACY_CUBIC_CHOPPER
         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 30 matching lines @@
     }
     if (pts[0].fX >= clip.fRight) {  // wholly to the right
         if (!this->canCullToTheRight()) {
             this->appendVLine(clip.fRight, pts[0].fY, pts[3].fY, reverse);
         }
         return;
     }
 
     // are we partially to the left
     if (pts[0].fX < clip.fLeft) {
+        SkPoint tmp[7];
+#ifdef SK_SUPPORT_LEGACY_CUBIC_CHOPPER
         SkScalar t;
         if (chopMonoCubicAtX(pts, clip.fLeft, &t)) {
-            SkPoint tmp[7];
             SkChopCubicAt(pts, tmp, t);
+#else
+        if (SkChopMonoCubicAtX(pts, clip.fLeft, tmp)) {
+#endif
             this->appendVLine(clip.fLeft, tmp[0].fY, tmp[3].fY, reverse);
 
-            // tmp[3, 4, 5].fX should all be to the right of clip.fLeft.
+            // tmp[3, 4].fX should all be to the right of clip.fLeft.
             // Since we can't trust the numerics of
             // the chopper, we force those conditions now
             tmp[3].fX = clip.fLeft;
             clamp_ge(tmp[4].fX, clip.fLeft);
+#ifdef SK_SUPPORT_LEGACY_CUBIC_CHOPPER
             clamp_ge(tmp[5].fX, clip.fLeft);
+#endif
 
             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 left
             this->appendVLine(clip.fLeft, pts[0].fY, pts[3].fY, reverse);
             return;
         }
     }
 
     // are we partially to the right
     if (pts[3].fX > clip.fRight) {
+        SkPoint tmp[7];
+#ifdef SK_SUPPORT_LEGACY_CUBIC_CHOPPER
         SkScalar t;
         if (chopMonoCubicAtX(pts, clip.fRight, &t)) {
-            SkPoint tmp[7];
             SkChopCubicAt(pts, tmp, t);
+#else
+        if (SkChopMonoCubicAtX(pts, clip.fRight, tmp)) {
+#endif
             tmp[3].fX = clip.fRight;
             clamp_le(tmp[2].fX, clip.fRight);
+#ifdef SK_SUPPORT_LEGACY_CUBIC_CHOPPER
             clamp_le(tmp[1].fX, clip.fRight);
+#endif
 
             this->appendCubic(tmp, reverse);
             this->appendVLine(clip.fRight, tmp[3].fY, tmp[6].fY, reverse);
         } else {
             // if chopMonoCubicAtX failed, then we may have hit inexact numerics
             // so we just clamp against the right
             this->appendVLine(clip.fRight, pts[0].fY, pts[3].fY, reverse);
         }
     } else {    // wholly inside the clip
         this->appendCubic(pts, reverse);
@@ skipping 120 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