Rewriting path writer

src/pathops/SkPathOpsCurve.cpp

 /*
  * Copyright 2015 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 #include "SkPathOpsBounds.h"
 #include "SkPathOpsRect.h"
 #include "SkPathOpsCurve.h"
 
@@ skipping 70 matching lines @@
 
 void SkDCurve::setQuadBounds(const SkPoint curve[3], SkScalar ,
         double tStart, double tEnd, SkPathOpsBounds* bounds) {
     SkDQuad dCurve;
     dCurve.set(curve);
     SkDRect dRect;
     dRect.setBounds(dCurve, fQuad, tStart, tEnd);
     bounds->set(SkDoubleToScalar(dRect.fLeft), SkDoubleToScalar(dRect.fTop),
             SkDoubleToScalar(dRect.fRight), SkDoubleToScalar(dRect.fBottom));
 }
+
+void SkDCurveSweep::setCurveHullSweep(SkPath::Verb verb) {
+    fOrdered = true;
+    fSweep[0] = fCurve[1] - fCurve[0];
+    if (SkPath::kLine_Verb == verb) {
+        fSweep[1] = fSweep[0];
+        fIsCurve = false;
+        return;
+    }
+    fSweep[1] = fCurve[2] - fCurve[0];
+    // OPTIMIZE: I do the following float check a lot -- probably need a
+    // central place for this val-is-small-compared-to-curve check
+    double maxVal = 0;
+    for (int index = 0; index < SkPathOpsVerbToPoints(verb); ++index) {
+        maxVal = SkTMax(maxVal, SkTMax(SkTAbs(fCurve[index].fX),
+                SkTAbs(fCurve[index].fY)));
+    }
+    {
+        if (SkPath::kCubic_Verb != verb) {
+            if (roughly_zero_when_compared_to(fSweep[0].fX, maxVal)
+                    && roughly_zero_when_compared_to(fSweep[0].fY, maxVal)) {
+                fSweep[0] = fSweep[1];
+            }
+            goto setIsCurve;
+        }
+        SkDVector thirdSweep = fCurve[3] - fCurve[0];
+        if (fSweep[0].fX == 0 && fSweep[0].fY == 0) {
+            fSweep[0] = fSweep[1];
+            fSweep[1] = thirdSweep;
+            if (roughly_zero_when_compared_to(fSweep[0].fX, maxVal)
+                    && roughly_zero_when_compared_to(fSweep[0].fY, maxVal)) {
+                fSweep[0] = fSweep[1];
+                fCurve[1] = fCurve[3];
+            }
+            goto setIsCurve;
+        }
+        double s1x3 = fSweep[0].crossCheck(thirdSweep);
+        double s3x2 = thirdSweep.crossCheck(fSweep[1]);
+        if (s1x3 * s3x2 >= 0) {  // if third vector is on or between first two vectors
+            goto setIsCurve;
+        }
+        double s2x1 = fSweep[1].crossCheck(fSweep[0]);
+        // FIXME: If the sweep of the cubic is greater than 180 degrees, we're in trouble
+        // probably such wide sweeps should be artificially subdivided earlier so that never happens
+        SkASSERT(s1x3 * s2x1 < 0 || s1x3 * s3x2 < 0);
+        if (s3x2 * s2x1 < 0) {
+            SkASSERT(s2x1 * s1x3 > 0);
+            fSweep[0] = fSweep[1];
+            fOrdered = false;
+        }
+        fSweep[1] = thirdSweep;
+    }
+setIsCurve:
+    fIsCurve = fSweep[0].crossCheck(fSweep[1]) != 0;
+}