Public Types
enum	{ kLine = 0 , kQuad = 1 }

Public Member Functions
void	init ()

int	countPoints ()

const SkPoint &	endPt () const

Public Attributes
enum PathSegment:: { ... }	fType

SkPoint	fPts [3]

DPoint	fP0T

DPoint	fP2T

DAffineMatrix	fXformMatrix

double	fScalingFactor

double	fScalingFactorSqd

double	fNearlyZeroScaled

double	fTangentTolScaledSqd

SkRect	fBoundingBox

Detailed Description

Definition at line 198 of file GrDistanceFieldGenFromVector.cpp.

Member Enumeration Documentation

◆ anonymous enum

anonymous enum

Enumerator
kLine
kQuad

Definition at line 200 of file GrDistanceFieldGenFromVector.cpp.

         {
        // These enum values are assumed in member functions below.
        kLine = 0,
        kQuad = 1,
    } fType;

Member Function Documentation

◆ countPoints()

int PathSegment::countPoints ( )

inline

Definition at line 219 of file GrDistanceFieldGenFromVector.cpp.

                      {
        static_assert(0 == kLine && 1 == kQuad);
        return fType + 2;
    }

◆ endPt()

const SkPoint & PathSegment::endPt ( ) const

inline

Definition at line 224 of file GrDistanceFieldGenFromVector.cpp.

                                 {
        static_assert(0 == kLine && 1 == kQuad);
        return fPts[fType + 1];
    }

◆ init()

void PathSegment::init ( )

Definition at line 232 of file GrDistanceFieldGenFromVector.cpp.

                       {
    const DPoint p0 = { fPts[0].fX, fPts[0].fY };
    const DPoint p2 = { this->endPt().fX, this->endPt().fY };
    const double p0x = p0.fX;
    const double p0y = p0.fY;
    const double p2x = p2.fX;
    const double p2y = p2.fY;
 
    fBoundingBox.set(fPts[0], this->endPt());
 
    if (fType == PathSegment::kLine) {
        fScalingFactorSqd = fScalingFactor = 1.0;
        double hypotenuse = p0.distance(p2);
        if (SkTAbs(hypotenuse) < 1.0e-100) {
            fXformMatrix.reset();
        } else {
            const double cosTheta = (p2x - p0x) / hypotenuse;
            const double sinTheta = (p2y - p0y) / hypotenuse;
 
            // rotates the segment to the x-axis, with p0 at the origin
            fXformMatrix.setAffine(
                cosTheta, sinTheta, -(cosTheta * p0x) - (sinTheta * p0y),
                -sinTheta, cosTheta, (sinTheta * p0x) - (cosTheta * p0y)
            );
        }
    } else {
        SkASSERT(fType == PathSegment::kQuad);
 
        // Calculate bounding box
        const SkPoint m = fPts[0]*0.25f + fPts[1]*0.5f + fPts[2]*0.25f; // midpoint of curve
        SkRectPriv::GrowToInclude(&fBoundingBox, m);
 
        const double p1x = fPts[1].fX;
        const double p1y = fPts[1].fY;
 
        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;
 
        // calculate quadratic params
        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;
 
        // transforms to lie on a canonical y = x^2 parabola
        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);
}