Revert 386ba54 and 4ab47e0 : perf debug assert.

src/utils/SkCurveMeasure.cpp

Index: src/utils/SkCurveMeasure.cpp
diff --git a/src/utils/SkCurveMeasure.cpp b/src/utils/SkCurveMeasure.cpp
index 2a74a49c22e6fd41d1541bdcbe3ad1b37422285a..fc2aa84faa119558d5dce1c30f6bdd826c3eb890 100644
--- a/src/utils/SkCurveMeasure.cpp
+++ b/src/utils/SkCurveMeasure.cpp
@@ -6,66 +6,10 @@
  */
 
 #include "SkCurveMeasure.h"
-#include "SkGeometry.h"
 
 // for abs
 #include <cmath>
 
-#define UNIMPLEMENTED SkDEBUGF(("%s:%d unimplemented\n", __FILE__, __LINE__))
-
-/// Used inside SkCurveMeasure::getTime's Newton's iteration
-static inline SkPoint evaluate(const SkPoint pts[4], SkSegType segType,
-                               SkScalar t) {
-    SkPoint pos;
-    switch (segType) {
-        case kQuad_SegType:
-            pos = SkEvalQuadAt(pts, t);
-            break;
-        case kLine_SegType:
-            pos = SkPoint::Make(SkScalarInterp(pts[0].x(), pts[1].x(), t),
-                                SkScalarInterp(pts[0].y(), pts[1].y(), t));
-            break;
-        case kCubic_SegType:
-            SkEvalCubicAt(pts, t, &pos, nullptr, nullptr);
-            break;
-        case kConic_SegType: {
-            SkConic conic(pts, pts[3].x());
-            conic.evalAt(t, &pos);
-        }
-            break;
-        default:
-            UNIMPLEMENTED;
-    }
-
-    return pos;
-}
-
-/// Used inside SkCurveMeasure::getTime's Newton's iteration
-static inline SkVector evaluateDerivative(const SkPoint pts[4],
-                                          SkSegType segType, SkScalar t) {
-    SkVector tan;
-    switch (segType) {
-        case kQuad_SegType:
-            tan = SkEvalQuadTangentAt(pts, t);
-            break;
-        case kLine_SegType:
-            tan = pts[1] - pts[0];
-            break;
-        case kCubic_SegType:
-            SkEvalCubicAt(pts, t, nullptr, &tan, nullptr);
-            break;
-        case kConic_SegType: {
-            SkConic conic(pts, pts[3].x());
-            conic.evalAt(t, nullptr, &tan);
-        }
-            break;
-        default:
-            UNIMPLEMENTED;
-    }
-
-    return tan;
-}
-/// Used in ArcLengthIntegrator::computeLength
 static inline Sk8f evaluateDerivativeLength(const Sk8f& ts,
                                             const Sk8f (&xCoeff)[3],
                                             const Sk8f (&yCoeff)[3],
@@ -77,15 +21,18 @@ static inline Sk8f evaluateDerivativeLength(const Sk8f& ts,
             x = xCoeff[0]*ts + xCoeff[1];
             y = yCoeff[0]*ts + yCoeff[1];
             break;
+        case kLine_SegType:
+            SkDebugf("Unimplemented");
+            break;
         case kCubic_SegType:
             x = (xCoeff[0]*ts + xCoeff[1])*ts + xCoeff[2];
             y = (yCoeff[0]*ts + yCoeff[1])*ts + yCoeff[2];
             break;
         case kConic_SegType:
-            UNIMPLEMENTED;
+            SkDebugf("Unimplemented");
             break;
         default:
-            UNIMPLEMENTED;
+            SkDebugf("Unimplemented");
     }
 
     x = x * x;
@@ -93,7 +40,6 @@ static inline Sk8f evaluateDerivativeLength(const Sk8f& ts,
 
     return (x + y).sqrt();
 }
-
 ArcLengthIntegrator::ArcLengthIntegrator(const SkPoint* pts, SkSegType segType)
     : fSegType(segType) {
     switch (fSegType) {
@@ -113,6 +59,9 @@ ArcLengthIntegrator::ArcLengthIntegrator(const SkPoint* pts, SkSegType segType)
             yCoeff[1] = Sk8f(2.0f*(By - Ay));
         }
             break;
+        case kLine_SegType:
+            SkDEBUGF(("Unimplemented"));
+            break;
         case kCubic_SegType:
         {
             float Ax = pts[0].x();
@@ -124,7 +73,6 @@ ArcLengthIntegrator::ArcLengthIntegrator(const SkPoint* pts, SkSegType segType)
             float Cy = pts[2].y();
             float Dy = pts[3].y();
 
-            // precompute coefficients for derivative
             xCoeff[0] = Sk8f(3.0f*(-Ax + 3.0f*(Bx - Cx) + Dx));
             xCoeff[1] = Sk8f(3.0f*(2.0f*(Ax - 2.0f*Bx + Cx)));
             xCoeff[2] = Sk8f(3.0f*(-Ax + Bx));
@@ -135,10 +83,10 @@ ArcLengthIntegrator::ArcLengthIntegrator(const SkPoint* pts, SkSegType segType)
         }
             break;
         case kConic_SegType:
-            UNIMPLEMENTED;
+            SkDEBUGF(("Unimplemented"));
             break;
         default:
-            UNIMPLEMENTED;
+            SkDEBUGF(("Unimplemented"));
     }
 }
 
@@ -169,9 +117,7 @@ SkCurveMeasure::SkCurveMeasure(const SkPoint* pts, SkSegType segType)
             }
             break;
         case SkSegType::kLine_SegType:
-            fPts[0] = pts[0];
-            fPts[1] = pts[1];
-            fLength = (fPts[1] - fPts[0]).length();
+            SkDebugf("Unimplemented");
             break;
         case SkSegType::kCubic_SegType:
             for (size_t i = 0; i < 4; i++) {
@@ -179,17 +125,13 @@ SkCurveMeasure::SkCurveMeasure(const SkPoint* pts, SkSegType segType)
             }
             break;
         case SkSegType::kConic_SegType:
-            for (size_t i = 0; i < 4; i++) {
-                fPts[i] = pts[i];
-            }
+            SkDebugf("Unimplemented");
             break;
         default:
-            UNIMPLEMENTED;
+            SkDEBUGF(("Unimplemented"));
             break;
     }
-    if (kLine_SegType != segType) {
-        fIntegrator = ArcLengthIntegrator(fPts, fSegType);
-    }
+    fIntegrator = ArcLengthIntegrator(fPts, fSegType);
 }
 
 SkScalar SkCurveMeasure::getLength() {
@@ -218,9 +160,6 @@ SkScalar SkCurveMeasure::getTime(SkScalar targetLength) {
     if (SkScalarNearlyEqual(targetLength, currentLength)) {
         return 1.0f;
     }
-    if (kLine_SegType == fSegType) {
-        return targetLength / currentLength;
-    }
 
     // initial estimate of t is percentage of total length
     SkScalar currentT = targetLength / currentLength;
@@ -260,8 +199,9 @@ SkScalar SkCurveMeasure::getTime(SkScalar targetLength) {
 
         prevT = currentT;
         if (iterations < kNewtonIters) {
+            // TODO(hstern) switch here on curve type.
             // This is just newton's formula.
-            SkScalar dt = evaluateDerivative(fPts, fSegType, currentT).length();
+            SkScalar dt = evaluateQuadDerivative(currentT).length();
             newT = currentT - (lengthDiff / dt);
 
             // If newT is out of bounds, bisect inside newton.
@@ -278,7 +218,7 @@ SkScalar SkCurveMeasure::getTime(SkScalar targetLength) {
             newT = (minT + maxT) * 0.5f;
         } else {
             SkDEBUGF(("%.7f %.7f didn't get close enough after bisection.\n",
-                      currentT, currentLength));
+                     currentT, currentLength));
             break;
         }
         currentT = newT;
@@ -295,16 +235,52 @@ SkScalar SkCurveMeasure::getTime(SkScalar targetLength) {
 }
 
 void SkCurveMeasure::getPosTanTime(SkScalar targetLength, SkPoint* pos,
-                                   SkVector* tan, SkScalar* time) {
+                               SkVector* tan, SkScalar* time) {
     SkScalar t = getTime(targetLength);
 
     if (time) {
         *time = t;
     }
     if (pos) {
-        *pos = evaluate(fPts, fSegType, t);
+        // TODO(hstern) switch here on curve type.
+        *pos = evaluateQuad(t);
     }
     if (tan) {
-        *tan = evaluateDerivative(fPts, fSegType, t);
+        // TODO(hstern) switch here on curve type.
+        *tan = evaluateQuadDerivative(t);
     }
 }
+
+// this is why I feel that the ArcLengthIntegrator should be combined
+// with some sort of evaluator that caches the constants computed from the
+// control points. this is basically the same code in ArcLengthIntegrator
+SkPoint SkCurveMeasure::evaluateQuad(SkScalar t) {
+    SkScalar ti = 1.0f - t;
+
+    SkScalar Ax = fPts[0].x();
+    SkScalar Bx = fPts[1].x();
+    SkScalar Cx = fPts[2].x();
+    SkScalar Ay = fPts[0].y();
+    SkScalar By = fPts[1].y();
+    SkScalar Cy = fPts[2].y();
+
+    SkScalar x = Ax*ti*ti + 2.0f*Bx*t*ti + Cx*t*t;
+    SkScalar y = Ay*ti*ti + 2.0f*By*t*ti + Cy*t*t;
+    return SkPoint::Make(x, y);
+}
+
+SkVector SkCurveMeasure::evaluateQuadDerivative(SkScalar t) {
+    SkScalar Ax = fPts[0].x();
+    SkScalar Bx = fPts[1].x();
+    SkScalar Cx = fPts[2].x();
+    SkScalar Ay = fPts[0].y();
+    SkScalar By = fPts[1].y();
+    SkScalar Cy = fPts[2].y();
+
+    SkScalar A2BCx = 2.0f*(Ax - 2*Bx + Cx);
+    SkScalar A2BCy = 2.0f*(Ay - 2*By + Cy);
+    SkScalar ABx = 2.0f*(Bx - Ax);
+    SkScalar ABy = 2.0f*(By - Ay);
+
+    return SkPoint::Make(A2BCx*t + ABx, A2BCy*t + ABy);
+}