Revert of Generate Signed Distance Field directly from vector path (patchset #23 id:440001 of https://codereview.chromium.org/1643143002/ )

Reason for revert:
Seems to have caused lot of test bots to fail.
Eg:
https://luci-milo.appspot.com/swarming/task/332e3b427135f010

Original issue's description:
> Generate Signed Distance Field directly from vector path
>
> Add SkGenerateDistanceFieldFromPath API to generate signed distance field directly from SkPath.
>
> BUG=skia:
> GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1643143002
>
> Committed: https://skia.googlesource.com/skia/+/4de97a64e8829323a7070b623411d9f9ddb0cd0f
> Committed: https://skia.googlesource.com/skia/+/e8f0a7b986f1e5583c9bc162efcdd92fd6430549
> Committed: https://skia.googlesource.com/skia/+/67c7c81a82b6351e9fbbf235084d7120162d9268
> Review-Url: https://codereview.chromium.org/1643143002
> Committed: https://skia.googlesource.com/skia/+/64b70b096ac20833d9737758a4bd5f2a51078bc4

TBR=bsalomon@google.com,jvanverth@google.com,mtklein@google.com,wasim.abbas@arm.com,caryclark@google.com,reed@google.com,egdaniel@google.com,joel.liang@arm.com
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review-Url: https://codereview.chromium.org/2580373002

1 files changed, 0 insertions, 849 deletions

diff --git a/src/gpu/GrDistanceFieldGenFromVector.cpp b/src/gpu/GrDistanceFieldGenFromVector.cpp
deleted file mode 100644
index 0874616f93..0000000000
--- a/src/gpu/GrDistanceFieldGenFromVector.cpp
+++ /dev/null
@@ -1,849 +0,0 @@
-/*
- * Copyright 2016 ARM Ltd.
- *
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#include "GrDistanceFieldGenFromVector.h"
-#include "SkPoint.h"
-#include "SkGeometry.h"
-#include "SkPathOps.h"
-#include "GrPathUtils.h"
-#include "GrConfig.h"
-
-/**
- * If a scanline (a row of texel) cross from the kRight_SegSide
- * of a segment to the kLeft_SegSide, the winding score should
- * add 1.
- * And winding score should subtract 1 if the scanline cross
- * from kLeft_SegSide to kRight_SegSide.
- * Always return kNA_SegSide if the scanline does not cross over
- * the segment. Winding score should be zero in this case.
- * You can get the winding number for each texel of the scanline
- * by adding the winding score from left to right.
- * Assuming we always start from outside, so the winding number
- * should always start from zero.
- *      ________         ________
- *     |        |       |        |
- * ...R|L......L|R.....L|R......R|L..... <= Scanline & side of segment
- *     |+1      |-1     |-1      |+1     <= Winding score
- *   0 |   1    ^   0   ^  -1    |0      <= Winding number
- *     |________|       |________|
- *
- * .......NA................NA..........
- *         0                 0
- */
-enum SegSide {
-    kLeft_SegSide  = -1,
-    kOn_SegSide    =  0,
-    kRight_SegSide =  1,
-    kNA_SegSide    =  2,
-};
-
-struct DFData {
-    float fDistSq;            // distance squared to nearest (so far) edge
-    int   fDeltaWindingScore; // +1 or -1 whenever a scanline cross over a segment
-};
-
-///////////////////////////////////////////////////////////////////////////////
-
-/*
- * Type definition for double precision DPoint and DAffineMatrix
- */
-
-// Point with double precision
-struct DPoint {
-    double fX, fY;
-
-    static DPoint Make(double x, double y) {
-        DPoint pt;
-        pt.set(x, y);
-        return pt;
-    }
-
-    double x() const { return fX; }
-    double y() const { return fY; }
-
-    void set(double x, double y) { fX = x; fY = y; }
-
-    /** Returns the euclidian distance from (0,0) to (x,y)
-    */
-    static double Length(double x, double y) {
-        return sqrt(x * x + y * y);
-    }
-
-    /** Returns the euclidian distance between a and b
-    */
-    static double Distance(const DPoint& a, const DPoint& b) {
-        return Length(a.fX - b.fX, a.fY - b.fY);
-    }
-
-    double distanceToSqd(const DPoint& pt) const {
-        double dx = fX - pt.fX;
-        double dy = fY - pt.fY;
-        return dx * dx + dy * dy;
-    }
-};
-
-// Matrix with double precision for affine transformation.
-// We don't store row 3 because its always (0, 0, 1).
-class DAffineMatrix {
-public:
-    double operator[](int index) const {
-        SkASSERT((unsigned)index < 6);
-        return fMat[index];
-    }
-
-    double& operator[](int index) {
-        SkASSERT((unsigned)index < 6);
-        return fMat[index];
-    }
-
-    void setAffine(double m11, double m12, double m13,
-                   double m21, double m22, double m23) {
-        fMat[0] = m11;
-        fMat[1] = m12;
-        fMat[2] = m13;
-        fMat[3] = m21;
-        fMat[4] = m22;
-        fMat[5] = m23;
-    }
-
-    /** Set the matrix to identity
-    */
-    void reset() {
-        fMat[0] = fMat[4] = 1.0;
-        fMat[1] = fMat[3] =
-        fMat[2] = fMat[5] = 0.0;
-    }
-
-    // alias for reset()
-    void setIdentity() { this->reset(); }
-
-    DPoint mapPoint(const SkPoint& src) const {
-        DPoint pt = DPoint::Make(src.x(), src.y());
-        return this->mapPoint(pt);
-    }
-
-    DPoint mapPoint(const DPoint& src) const {
-        return DPoint::Make(fMat[0] * src.x() + fMat[1] * src.y() + fMat[2],
-                            fMat[3] * src.x() + fMat[4] * src.y() + fMat[5]);
-    }
-private:
-    double fMat[6];
-};
-
-///////////////////////////////////////////////////////////////////////////////
-
-static const double kClose = (SK_Scalar1 / 16.0);
-static const double kCloseSqd = SkScalarMul(kClose, kClose);
-static const double kNearlyZero = (SK_Scalar1 / (1 << 18));
-static const double kTangentTolerance = (SK_Scalar1 / (1 << 11));
-static const float  kConicTolerance = 0.25f;
-
-static inline bool between_closed_open(double a, double b, double c,
-                                       double tolerance = 0.0,
-                                       bool xformToleranceToX = false) {
-    SkASSERT(tolerance >= 0.0);
-    double tolB = tolerance;
-    double tolC = tolerance;
-
-    if (xformToleranceToX) {
-        // Canonical space is y = x^2 and the derivative of x^2 is 2x.
-        // So the slope of the tangent line at point (x, x^2) is 2x.
-        //
-        //                          /|
-        //  sqrt(2x * 2x + 1 * 1)  / | 2x
-        //                        /__|
-        //                         1
-        tolB = tolerance / sqrt(4.0 * b * b + 1.0);
-        tolC = tolerance / sqrt(4.0 * c * c + 1.0);
-    }
-    return b < c ? (a >= b - tolB && a < c - tolC) :
-                   (a >= c - tolC && a < b - tolB);
-}
-
-static inline bool between_closed(double a, double b, double c,
-                                  double tolerance = 0.0,
-                                  bool xformToleranceToX = false) {
-    SkASSERT(tolerance >= 0.0);
-    double tolB = tolerance;
-    double tolC = tolerance;
-
-    if (xformToleranceToX) {
-        tolB = tolerance / sqrt(4.0 * b * b + 1.0);
-        tolC = tolerance / sqrt(4.0 * c * c + 1.0);
-    }
-    return b < c ? (a >= b - tolB && a <= c + tolC) :
-                   (a >= c - tolC && a <= b + tolB);
-}
-
-static inline bool nearly_zero(double x, double tolerance = kNearlyZero) {
-    SkASSERT(tolerance >= 0.0);
-    return fabs(x) <= tolerance;
-}
-
-static inline bool nearly_equal(double x, double y,
-                                double tolerance = kNearlyZero,
-                                bool xformToleranceToX = false) {
-    SkASSERT(tolerance >= 0.0);
-    if (xformToleranceToX) {
-        tolerance = tolerance / sqrt(4.0 * y * y + 1.0);
-    }
-    return fabs(x - y) <= tolerance;
-}
-
-static inline double sign_of(const double &val) {
-    return (val < 0.0) ? -1.0 : 1.0;
-}
-
-static bool is_colinear(const SkPoint pts[3]) {
-    return nearly_zero((pts[1].y() - pts[0].y()) * (pts[1].x() - pts[2].x()) -
-                       (pts[1].y() - pts[2].y()) * (pts[1].x() - pts[0].x()), kCloseSqd);
-}
-
-class PathSegment {
-public:
-    enum {
-        // These enum values are assumed in member functions below.
-        kLine = 0,
-        kQuad = 1,
-    } fType;
-
-    // line uses 2 pts, quad uses 3 pts
-    SkPoint fPts[3];
-
-    DPoint  fP0T, fP2T;
-    DAffineMatrix fXformMatrix;
-    double fScalingFactor;
-    double fScalingFactorSqd;
-    double fNearlyZeroScaled;
-    double fTangentTolScaledSqd;
-    SkRect  fBoundingBox;
-
-    void init();
-
-    int countPoints() {
-        GR_STATIC_ASSERT(0 == kLine && 1 == kQuad);
-        return fType + 2;
-    }
-
-    const SkPoint& endPt() const {
-        GR_STATIC_ASSERT(0 == kLine && 1 == kQuad);
-        return fPts[fType + 1];
-    }
-};
-
-typedef SkTArray<PathSegment, true> PathSegmentArray;
-
-void PathSegment::init() {
-    const DPoint p0 = DPoint::Make(fPts[0].x(), fPts[0].y());
-    const DPoint p2 = DPoint::Make(this->endPt().x(), this->endPt().y());
-    const double p0x = p0.x();
-    const double p0y = p0.y();
-    const double p2x = p2.x();
-    const double p2y = p2.y();
-
-    fBoundingBox.set(fPts[0], this->endPt());
-
-    if (fType == PathSegment::kLine) {
-        fScalingFactorSqd = fScalingFactor = 1.0;
-        double hypotenuse = DPoint::Distance(p0, p2);
-
-        const double cosTheta = (p2x - p0x) / hypotenuse;
-        const double sinTheta = (p2y - p0y) / hypotenuse;
-
-        fXformMatrix.setAffine(
-            cosTheta, sinTheta, -(cosTheta * p0x) - (sinTheta * p0y),
-            -sinTheta, cosTheta, (sinTheta * p0x) - (cosTheta * p0y)
-        );
-    } else {
-        SkASSERT(fType == PathSegment::kQuad);
-
-        // Calculate bounding box
-        const SkPoint _P1mP0 = fPts[1] - fPts[0];
-        SkPoint t = _P1mP0 - fPts[2] + fPts[1];
-        t.fX = _P1mP0.x() / t.x();
-        t.fY = _P1mP0.y() / t.y();
-        t.fX = SkScalarClampMax(t.x(), 1.0);
-        t.fY = SkScalarClampMax(t.y(), 1.0);
-        t.fX = _P1mP0.x() * t.x();
-        t.fY = _P1mP0.y() * t.y();
-        const SkPoint m = fPts[0] + t;
-        fBoundingBox.growToInclude(&m, 1);
-
-        const double p1x = fPts[1].x();
-        const double p1y = fPts[1].y();
-
-        const double p0xSqd = p0x * p0x;
-        const double p0ySqd = p0y * p0y;
-        const double p2xSqd = p2x * p2x;
-        const double p2ySqd = p2y * p2y;
-        const double p1xSqd = p1x * p1x;
-        const double p1ySqd = p1y * p1y;
-
-        const double p01xProd = p0x * p1x;
-        const double p02xProd = p0x * p2x;
-        const double b12xProd = p1x * p2x;
-        const double p01yProd = p0y * p1y;
-        const double p02yProd = p0y * p2y;
-        const double b12yProd = p1y * p2y;
-
-        const double sqrtA = p0y - (2.0 * p1y) + p2y;
-        const double a = sqrtA * sqrtA;
-        const double h = -1.0 * (p0y - (2.0 * p1y) + p2y) * (p0x - (2.0 * p1x) + p2x);
-        const double sqrtB = p0x - (2.0 * p1x) + p2x;
-        const double b = sqrtB * sqrtB;
-        const double c = (p0xSqd * p2ySqd) - (4.0 * p01xProd * b12yProd)
-                - (2.0 * p02xProd * p02yProd) + (4.0 * p02xProd * p1ySqd)
-                + (4.0 * p1xSqd * p02yProd) - (4.0 * b12xProd * p01yProd)
-                + (p2xSqd * p0ySqd);
-        const double g = (p0x * p02yProd) - (2.0 * p0x * p1ySqd)
-                + (2.0 * p0x * b12yProd) - (p0x * p2ySqd)
-                + (2.0 * p1x * p01yProd) - (4.0 * p1x * p02yProd)
-                + (2.0 * p1x * b12yProd) - (p2x * p0ySqd)
-                + (2.0 * p2x * p01yProd) + (p2x * p02yProd)
-                - (2.0 * p2x * p1ySqd);
-        const double f = -((p0xSqd * p2y) - (2.0 * p01xProd * p1y)
-                - (2.0 * p01xProd * p2y) - (p02xProd * p0y)
-                + (4.0 * p02xProd * p1y) - (p02xProd * p2y)
-                + (2.0 * p1xSqd * p0y) + (2.0 * p1xSqd * p2y)
-                - (2.0 * b12xProd * p0y) - (2.0 * b12xProd * p1y)
-                + (p2xSqd * p0y));
-
-        const double cosTheta = sqrt(a / (a + b));
-        const double sinTheta = -1.0 * sign_of((a + b) * h) * sqrt(b / (a + b));
-
-        const double gDef = cosTheta * g - sinTheta * f;
-        const double fDef = sinTheta * g + cosTheta * f;
-
-
-        const double x0 = gDef / (a + b);
-        const double y0 = (1.0 / (2.0 * fDef)) * (c - (gDef * gDef / (a + b)));
-
-
-        const double lambda = -1.0 * ((a + b) / (2.0 * fDef));
-        fScalingFactor = fabs(1.0 / lambda);
-        fScalingFactorSqd = fScalingFactor * fScalingFactor;
-
-        const double lambda_cosTheta = lambda * cosTheta;
-        const double lambda_sinTheta = lambda * sinTheta;
-
-        fXformMatrix.setAffine(
-            lambda_cosTheta, -lambda_sinTheta, lambda * x0,
-            lambda_sinTheta, lambda_cosTheta, lambda * y0
-        );
-    }
-
-    fNearlyZeroScaled = kNearlyZero / fScalingFactor;
-    fTangentTolScaledSqd = kTangentTolerance * kTangentTolerance / fScalingFactorSqd;
-
-    fP0T = fXformMatrix.mapPoint(p0);
-    fP2T = fXformMatrix.mapPoint(p2);
-}
-
-static void init_distances(DFData* data, int size) {
-    DFData* currData = data;
-
-    for (int i = 0; i < size; ++i) {
-        // init distance to "far away"
-        currData->fDistSq = SK_DistanceFieldMagnitude * SK_DistanceFieldMagnitude;
-        currData->fDeltaWindingScore = 0;
-        ++currData;
-    }
-}
-
-static inline void add_line_to_segment(const SkPoint pts[2],
-                                       PathSegmentArray* segments) {
-    segments->push_back();
-    segments->back().fType = PathSegment::kLine;
-    segments->back().fPts[0] = pts[0];
-    segments->back().fPts[1] = pts[1];
-
-    segments->back().init();
-}
-
-static inline void add_quad_segment(const SkPoint pts[3],
-                                    PathSegmentArray* segments) {
-    if (pts[0].distanceToSqd(pts[1]) < kCloseSqd ||
-        pts[1].distanceToSqd(pts[2]) < kCloseSqd ||
-        is_colinear(pts)) {
-        if (pts[0] != pts[2]) {
-            SkPoint line_pts[2];
-            line_pts[0] = pts[0];
-            line_pts[1] = pts[2];
-            add_line_to_segment(line_pts, segments);
-        }
-    } else {
-        segments->push_back();
-        segments->back().fType = PathSegment::kQuad;
-        segments->back().fPts[0] = pts[0];
-        segments->back().fPts[1] = pts[1];
-        segments->back().fPts[2] = pts[2];
-
-        segments->back().init();
-    }
-}
-
-static inline void add_cubic_segments(const SkPoint pts[4],
-                                      PathSegmentArray* segments) {
-    SkSTArray<15, SkPoint, true> quads;
-    GrPathUtils::convertCubicToQuads(pts, SK_Scalar1, &quads);
-    int count = quads.count();
-    for (int q = 0; q < count; q += 3) {
-        add_quad_segment(&quads[q], segments);
-    }
-}
-
-static float calculate_nearest_point_for_quad(
-                const PathSegment& segment,
-                const DPoint &xFormPt) {
-    static const float kThird = 0.33333333333f;
-    static const float kTwentySeventh = 0.037037037f;
-
-    const float a = 0.5f - (float)xFormPt.y();
-    const float b = -0.5f * (float)xFormPt.x();
-
-    const float a3 = a * a * a;
-    const float b2 = b * b;
-
-    const float c = (b2 * 0.25f) + (a3 * kTwentySeventh);
-
-    if (c >= 0.f) {
-        const float sqrtC = sqrt(c);
-        const float result = (float)cbrt((-b * 0.5f) + sqrtC) + (float)cbrt((-b * 0.5f) - sqrtC);
-        return result;
-    } else {
-        const float cosPhi = (float)sqrt((b2 * 0.25f) * (-27.f / a3)) * ((b > 0) ? -1.f : 1.f);
-        const float phi = (float)acos(cosPhi);
-        float result;
-        if (xFormPt.x() > 0.f) {
-            result = 2.f * (float)sqrt(-a * kThird) * (float)cos(phi * kThird);
-            if (!between_closed(result, segment.fP0T.x(), segment.fP2T.x())) {
-                result = 2.f * (float)sqrt(-a * kThird) * (float)cos((phi * kThird) + (SK_ScalarPI * 2.f * kThird));
-            }
-        } else {
-            result = 2.f * (float)sqrt(-a * kThird) * (float)cos((phi * kThird) + (SK_ScalarPI * 2.f * kThird));
-            if (!between_closed(result, segment.fP0T.x(), segment.fP2T.x())) {
-                result = 2.f * (float)sqrt(-a * kThird) * (float)cos(phi * kThird);
-            }
-        }
-        return result;
-    }
-}
-
-// This structure contains some intermediate values shared by the same row.
-// It is used to calculate segment side of a quadratic bezier.
-struct RowData {
-    // The intersection type of a scanline and y = x * x parabola in canonical space.
-    enum IntersectionType {
-        kNoIntersection,
-        kVerticalLine,
-        kTangentLine,
-        kTwoPointsIntersect
-    } fIntersectionType;
-
-    // The direction of the quadratic segment/scanline in the canonical space.
-    //  1: The quadratic segment/scanline going from negative x-axis to positive x-axis.
-    //  0: The scanline is a vertical line in the canonical space.
-    // -1: The quadratic segment/scanline going from positive x-axis to negative x-axis.
-    int fQuadXDirection;
-    int fScanlineXDirection;
-
-    // The y-value(equal to x*x) of intersection point for the kVerticalLine intersection type.
-    double fYAtIntersection;
-
-    // The x-value for two intersection points.
-    double fXAtIntersection1;
-    double fXAtIntersection2;
-};
-
-void precomputation_for_row(
-            RowData *rowData,
-            const PathSegment& segment,
-            const SkPoint& pointLeft,
-            const SkPoint& pointRight
-            ) {
-    if (segment.fType != PathSegment::kQuad) {
-        return;
-    }
-
-    const DPoint& xFormPtLeft = segment.fXformMatrix.mapPoint(pointLeft);
-    const DPoint& xFormPtRight = segment.fXformMatrix.mapPoint(pointRight);;
-
-    rowData->fQuadXDirection = (int)sign_of(segment.fP2T.x() - segment.fP0T.x());
-    rowData->fScanlineXDirection = (int)sign_of(xFormPtRight.x() - xFormPtLeft.x());
-
-    const double x1 = xFormPtLeft.x();
-    const double y1 = xFormPtLeft.y();
-    const double x2 = xFormPtRight.x();
-    const double y2 = xFormPtRight.y();
-
-    if (nearly_equal(x1, x2, segment.fNearlyZeroScaled, true)) {
-        rowData->fIntersectionType = RowData::kVerticalLine;
-        rowData->fYAtIntersection = x1 * x1;
-        rowData->fScanlineXDirection = 0;
-        return;
-    }
-
-    // Line y = mx + b
-    const double m = (y2 - y1) / (x2 - x1);
-    const double b = -m * x1 + y1;
-
-    const double m2 = m * m;
-    const double c = m2 + 4.0 * b;
-
-    const double tol = 4.0 * segment.fTangentTolScaledSqd / (m2 + 1.0);
-
-    // Check if the scanline is the tangent line of the curve,
-    // and the curve start or end at the same y-coordinate of the scanline
-    if ((rowData->fScanlineXDirection == 1 &&
-         (segment.fPts[0].y() == pointLeft.y() ||
-         segment.fPts[2].y() == pointLeft.y())) &&
-         nearly_zero(c, tol)) {
-        rowData->fIntersectionType = RowData::kTangentLine;
-        rowData->fXAtIntersection1 = m / 2.0;
-        rowData->fXAtIntersection2 = m / 2.0;
-    } else if (c <= 0.0) {
-        rowData->fIntersectionType = RowData::kNoIntersection;
-        return;
-    } else {
-        rowData->fIntersectionType = RowData::kTwoPointsIntersect;
-        const double d = sqrt(c);
-        rowData->fXAtIntersection1 = (m + d) / 2.0;
-        rowData->fXAtIntersection2 = (m - d) / 2.0;
-    }
-}
-
-SegSide calculate_side_of_quad(
-            const PathSegment& segment,
-            const SkPoint& point,
-            const DPoint& xFormPt,
-            const RowData& rowData) {
-    SegSide side = kNA_SegSide;
-
-    if (RowData::kVerticalLine == rowData.fIntersectionType) {
-        side = (SegSide)(int)(sign_of(xFormPt.y() - rowData.fYAtIntersection) * rowData.fQuadXDirection);
-    }
-    else if (RowData::kTwoPointsIntersect == rowData.fIntersectionType) {
-        const double p1 = rowData.fXAtIntersection1;
-        const double p2 = rowData.fXAtIntersection2;
-
-        int signP1 = (int)sign_of(p1 - xFormPt.x());
-        bool includeP1 = true;
-        bool includeP2 = true;
-
-        if (rowData.fScanlineXDirection == 1) {
-            if ((rowData.fQuadXDirection == -1 && segment.fPts[0].y() <= point.y() &&
-                 nearly_equal(segment.fP0T.x(), p1, segment.fNearlyZeroScaled, true)) ||
-                 (rowData.fQuadXDirection == 1 && segment.fPts[2].y() <= point.y() &&
-                 nearly_equal(segment.fP2T.x(), p1, segment.fNearlyZeroScaled, true))) {
-                includeP1 = false;
-            }
-            if ((rowData.fQuadXDirection == -1 && segment.fPts[2].y() <= point.y() &&
-                 nearly_equal(segment.fP2T.x(), p2, segment.fNearlyZeroScaled, true)) ||
-                 (rowData.fQuadXDirection == 1 && segment.fPts[0].y() <= point.y() &&
-                 nearly_equal(segment.fP0T.x(), p2, segment.fNearlyZeroScaled, true))) {
-                includeP2 = false;
-            }
-        }
-
-        if (includeP1 && between_closed(p1, segment.fP0T.x(), segment.fP2T.x(),
-                                        segment.fNearlyZeroScaled, true)) {
-            side = (SegSide)(signP1 * rowData.fQuadXDirection);
-        }
-        if (includeP2 && between_closed(p2, segment.fP0T.x(), segment.fP2T.x(),
-                                        segment.fNearlyZeroScaled, true)) {
-            int signP2 = (int)sign_of(p2 - xFormPt.x());
-            if (side == kNA_SegSide || signP2 == 1) {
-                side = (SegSide)(-signP2 * rowData.fQuadXDirection);
-            }
-        }
-    } else if (RowData::kTangentLine == rowData.fIntersectionType) {
-        // The scanline is the tangent line of current quadratic segment.
-
-        const double p = rowData.fXAtIntersection1;
-        int signP = (int)sign_of(p - xFormPt.x());
-        if (rowData.fScanlineXDirection == 1) {
-            // The path start or end at the tangent point.
-            if (segment.fPts[0].y() == point.y()) {
-                side = (SegSide)(signP);
-            } else if (segment.fPts[2].y() == point.y()) {
-                side = (SegSide)(-signP);
-            }
-        }
-    }
-
-    return side;
-}
-
-static float distance_to_segment(const SkPoint& point,
-                                 const PathSegment& segment,
-                                 const RowData& rowData,
-                                 SegSide* side) {
-    SkASSERT(side);
-
-    const DPoint xformPt = segment.fXformMatrix.mapPoint(point);
-
-    if (segment.fType == PathSegment::kLine) {
-        float result = SK_DistanceFieldPad * SK_DistanceFieldPad;
-
-        if (between_closed(xformPt.x(), segment.fP0T.x(), segment.fP2T.x())) {
-            result = (float)(xformPt.y() * xformPt.y());
-        } else if (xformPt.x() < segment.fP0T.x()) {
-            result = (float)(xformPt.x() * xformPt.x() + xformPt.y() * xformPt.y());
-        } else {
-            result = (float)((xformPt.x() - segment.fP2T.x()) * (xformPt.x() - segment.fP2T.x())
-                     + xformPt.y() * xformPt.y());
-        }
-
-        if (between_closed_open(point.y(), segment.fBoundingBox.top(),
-                                segment.fBoundingBox.bottom())) {
-            *side = (SegSide)(int)sign_of(xformPt.y());
-        } else {
-            *side = kNA_SegSide;
-        }
-        return result;
-    } else {
-        SkASSERT(segment.fType == PathSegment::kQuad);
-
-        const float nearestPoint = calculate_nearest_point_for_quad(segment, xformPt);
-
-        float dist;
-
-        if (between_closed(nearestPoint, segment.fP0T.x(), segment.fP2T.x())) {
-            DPoint x = DPoint::Make(nearestPoint, nearestPoint * nearestPoint);
-            dist = (float)xformPt.distanceToSqd(x);
-        } else {
-            const float distToB0T = (float)xformPt.distanceToSqd(segment.fP0T);
-            const float distToB2T = (float)xformPt.distanceToSqd(segment.fP2T);
-
-            if (distToB0T < distToB2T) {
-                dist = distToB0T;
-            } else {
-                dist = distToB2T;
-            }
-        }
-
-        if (between_closed_open(point.y(), segment.fBoundingBox.top(),
-                                segment.fBoundingBox.bottom())) {
-            *side = calculate_side_of_quad(segment, point, xformPt, rowData);
-        } else {
-            *side = kNA_SegSide;
-        }
-
-        return (float)(dist * segment.fScalingFactorSqd);
-    }
-}
-
-static void calculate_distance_field_data(PathSegmentArray* segments,
-                                          DFData* dataPtr,
-                                          int width, int height) {
-    int count = segments->count();
-    for (int a = 0; a < count; ++a) {
-        PathSegment& segment = (*segments)[a];
-        const SkRect& segBB = segment.fBoundingBox.makeOutset(
-                                SK_DistanceFieldPad, SK_DistanceFieldPad);
-        int startColumn = (int)segBB.left();
-        int endColumn = SkScalarCeilToInt(segBB.right());
-
-        int startRow = (int)segBB.top();
-        int endRow = SkScalarCeilToInt(segBB.bottom());
-
-        SkASSERT((startColumn >= 0) && "StartColumn < 0!");
-        SkASSERT((endColumn <= width) && "endColumn > width!");
-        SkASSERT((startRow >= 0) && "StartRow < 0!");
-        SkASSERT((endRow <= height) && "EndRow > height!");
-
-        for (int row = startRow; row < endRow; ++row) {
-            SegSide prevSide = kNA_SegSide;
-            const float pY = row + 0.5f;
-            RowData rowData;
-
-            const SkPoint pointLeft = SkPoint::Make((SkScalar)startColumn, pY);
-            const SkPoint pointRight = SkPoint::Make((SkScalar)endColumn, pY);
-
-            if (between_closed_open(pY, segment.fBoundingBox.top(),
-                                    segment.fBoundingBox.bottom())) {
-                precomputation_for_row(&rowData, segment, pointLeft, pointRight);
-            }
-
-            for (int col = startColumn; col < endColumn; ++col) {
-                int idx = (row * width) + col;
-
-                const float pX = col + 0.5f;
-                const SkPoint point = SkPoint::Make(pX, pY);
-
-                const float distSq = dataPtr[idx].fDistSq;
-                int dilation = distSq < 1.5 * 1.5 ? 1 :
-                               distSq < 2.5 * 2.5 ? 2 :
-                               distSq < 3.5 * 3.5 ? 3 : SK_DistanceFieldPad;
-                if (dilation > SK_DistanceFieldPad) {
-                    dilation = SK_DistanceFieldPad;
-                }
-
-                // Optimisation for not calculating some points.
-                if (dilation != SK_DistanceFieldPad && !segment.fBoundingBox.roundOut()
-                    .makeOutset(dilation, dilation).contains(col, row)) {
-                    continue;
-                }
-
-                SegSide side = kNA_SegSide;
-                int     deltaWindingScore = 0;
-                float   currDistSq = distance_to_segment(point, segment, rowData, &side);
-                if (prevSide == kLeft_SegSide && side == kRight_SegSide) {
-                    deltaWindingScore = -1;
-                } else if (prevSide == kRight_SegSide && side == kLeft_SegSide) {
-                    deltaWindingScore = 1;
-                }
-
-                prevSide = side;
-
-                if (currDistSq < distSq) {
-                    dataPtr[idx].fDistSq = currDistSq;
-                }
-
-                dataPtr[idx].fDeltaWindingScore += deltaWindingScore;
-            }
-        }
-    }
-}
-
-template <int distanceMagnitude>
-static unsigned char pack_distance_field_val(float dist) {
-    // The distance field is constructed as unsigned char values, so that the zero value is at 128,
-    // Beside 128, we have 128 values in range [0, 128), but only 127 values in range (128, 255].
-    // So we multiply distanceMagnitude by 127/128 at the latter range to avoid overflow.
-    dist = SkScalarPin(-dist, -distanceMagnitude, distanceMagnitude * 127.0f / 128.0f);
-
-    // Scale into the positive range for unsigned distance.
-    dist += distanceMagnitude;
-
-    // Scale into unsigned char range.
-    // Round to place negative and positive values as equally as possible around 128
-    // (which represents zero).
-    return (unsigned char)SkScalarRoundToInt(dist / (2 * distanceMagnitude) * 256.0f);
-}
-
-bool GrGenerateDistanceFieldFromPath(unsigned char* distanceField,
-                                     const SkPath& path, const SkMatrix& drawMatrix,
-                                     int width, int height, size_t rowBytes) {
-    SkASSERT(distanceField);
-
-    SkPath simplifiedPath;
-    SkPath workingPath;
-    if (Simplify(path, &simplifiedPath)) {
-        workingPath = simplifiedPath;
-    } else {
-        workingPath = path;
-    }
-
-    if (!IsDistanceFieldSupportedFillType(workingPath.getFillType())) {
-        return false;
-    }
-
-    workingPath.transform(drawMatrix);
-
-    // translate path to offset (SK_DistanceFieldPad, SK_DistanceFieldPad)
-    SkMatrix dfMatrix;
-    dfMatrix.setTranslate(SK_DistanceFieldPad, SK_DistanceFieldPad);
-    workingPath.transform(dfMatrix);
-
-    // create temp data
-    size_t dataSize = width * height * sizeof(DFData);
-    SkAutoSMalloc<1024> dfStorage(dataSize);
-    DFData* dataPtr = (DFData*) dfStorage.get();
-
-    // create initial distance data
-    init_distances(dataPtr, width * height);
-
-    SkPath::Iter iter(workingPath, true);
-    SkSTArray<15, PathSegment, true> segments;
-
-    for (;;) {
-        SkPoint pts[4];
-        SkPath::Verb verb = iter.next(pts);
-        switch (verb) {
-            case SkPath::kMove_Verb:
-                break;
-            case SkPath::kLine_Verb: {
-                add_line_to_segment(pts, &segments);
-                break;
-            }
-            case SkPath::kQuad_Verb:
-                add_quad_segment(pts, &segments);
-                break;
-            case SkPath::kConic_Verb: {
-                SkScalar weight = iter.conicWeight();
-                SkAutoConicToQuads converter;
-                const SkPoint* quadPts = converter.computeQuads(pts, weight, kConicTolerance);
-                for (int i = 0; i < converter.countQuads(); ++i) {
-                    add_quad_segment(quadPts + 2*i, &segments);
-                }
-                break;
-            }
-            case SkPath::kCubic_Verb: {
-                add_cubic_segments(pts, &segments);
-                break;
-            };
-            default:
-                break;
-        }
-        if (verb == SkPath::kDone_Verb) {
-            break;
-        }
-    }
-
-    calculate_distance_field_data(&segments, dataPtr, width, height);
-
-    for (int row = 0; row < height; ++row) {
-        int windingNumber = 0; // Winding number start from zero for each scanline
-        for (int col = 0; col < width; ++col) {
-            int idx = (row * width) + col;
-            windingNumber += dataPtr[idx].fDeltaWindingScore;
-
-            enum DFSign {
-                kInside = -1,
-                kOutside = 1
-            } dfSign;
-
-            if (workingPath.getFillType() == SkPath::kWinding_FillType) {
-                dfSign = windingNumber ? kInside : kOutside;
-            } else if (workingPath.getFillType() == SkPath::kInverseWinding_FillType) {
-                dfSign = windingNumber ? kOutside : kInside;
-            } else if (workingPath.getFillType() == SkPath::kEvenOdd_FillType) {
-                dfSign = (windingNumber % 2) ? kInside : kOutside;
-            } else {
-                SkASSERT(workingPath.getFillType() == SkPath::kInverseEvenOdd_FillType);
-                dfSign = (windingNumber % 2) ? kOutside : kInside;
-            }
-
-            // The winding number at the end of a scanline should be zero.
-            // SkASSERT(((col != width - 1) || (windingNumber == 0)) &&
-            //         "Winding number should be zero at the end of a scan line.");
-            // Fallback to use SkPath::contains to determine the sign of pixel instead of assertion.
-            if (col == width - 1 && windingNumber != 0) {
-                for (int col = 0; col < width; ++col) {
-                    int idx = (row * width) + col;
-                    dfSign = workingPath.contains(col + 0.5, row + 0.5) ? kInside : kOutside;
-                    const float miniDist = sqrt(dataPtr[idx].fDistSq);
-                    const float dist = dfSign * miniDist;
-
-                    unsigned char pixelVal = pack_distance_field_val<SK_DistanceFieldMagnitude>(dist);
-
-                    distanceField[(row * rowBytes) + col] = pixelVal;
-                }
-                continue;
-            }
-
-            const float miniDist = sqrt(dataPtr[idx].fDistSq);
-            const float dist = dfSign * miniDist;
-
-            unsigned char pixelVal = pack_distance_field_val<SK_DistanceFieldMagnitude>(dist);
-
-            distanceField[(row * rowBytes) + col] = pixelVal;
-        }
-    }
-    return true;
-}