public override void AddToPath(GraphicsPath graphicsPath)
{
if (this.Start == this.End)
{
return;
}
if (this.RadiusX == 0.0f && this.RadiusY == 0.0f)
{
graphicsPath.AddLine(this.Start, this.End);
return;
}
double sinPhi = Math.Sin(this.Angle * SvgArcSegment.RadiansPerDegree);
double cosPhi = Math.Cos(this.Angle * SvgArcSegment.RadiansPerDegree);
double x1dash = cosPhi * (this.Start.X - this.End.X) / 2.0 + sinPhi * (this.Start.Y - this.End.Y) / 2.0;
double y1dash = -sinPhi * (this.Start.X - this.End.X) / 2.0 + cosPhi * (this.Start.Y - this.End.Y) / 2.0;
double root;
double numerator = this.RadiusX * this.RadiusX * this.RadiusY * this.RadiusY - this.RadiusX * this.RadiusX * y1dash * y1dash - this.RadiusY * this.RadiusY * x1dash * x1dash;
float rx = this.RadiusX;
float ry = this.RadiusY;
if (numerator < 0.0)
{
float s = (float)Math.Sqrt(1.0 - numerator / (this.RadiusX * this.RadiusX * this.RadiusY * this.RadiusY));
rx *= s;
ry *= s;
root = 0.0;
}
else
{
root = ((this.Size == SvgArcSize.Large && this.Sweep == SvgArcSweep.Positive) || (this.Size == SvgArcSize.Small && this.Sweep == SvgArcSweep.Negative) ? -1.0 : 1.0) * Math.Sqrt(numerator / (this.RadiusX * this.RadiusX * y1dash * y1dash + this.RadiusY * this.RadiusY * x1dash * x1dash));
}
double cxdash = root * rx * y1dash / ry;
double cydash = -root * ry * x1dash / rx;
double cx = cosPhi * cxdash - sinPhi * cydash + (this.Start.X + this.End.X) / 2.0;
double cy = sinPhi * cxdash + cosPhi * cydash + (this.Start.Y + this.End.Y) / 2.0;
double theta1 = SvgArcSegment.CalculateVectorAngle(1.0, 0.0, (x1dash - cxdash) / rx, (y1dash - cydash) / ry);
double dtheta = SvgArcSegment.CalculateVectorAngle((x1dash - cxdash) / rx, (y1dash - cydash) / ry, (-x1dash - cxdash) / rx, (-y1dash - cydash) / ry);
if (this.Sweep == SvgArcSweep.Negative && dtheta > 0)
{
dtheta -= 2.0 * Math.PI;
}
else if (this.Sweep == SvgArcSweep.Positive && dtheta < 0)
{
dtheta += 2.0 * Math.PI;
}
int segments = (int)Math.Ceiling((double)Math.Abs(dtheta / (Math.PI / 2.0)));
double delta = dtheta / segments;
double t = 8.0 / 3.0 * Math.Sin(delta / 4.0) * Math.Sin(delta / 4.0) / Math.Sin(delta / 2.0);
double startX = this.Start.X;
double startY = this.Start.Y;
for (int i = 0; i < segments; ++i)
{
double cosTheta1 = Math.Cos(theta1);
double sinTheta1 = Math.Sin(theta1);
double theta2 = theta1 + delta;
double cosTheta2 = Math.Cos(theta2);
double sinTheta2 = Math.Sin(theta2);
double endpointX = cosPhi * rx * cosTheta2 - sinPhi * ry * sinTheta2 + cx;
double endpointY = sinPhi * rx * cosTheta2 + cosPhi * ry * sinTheta2 + cy;
double dx1 = t * (-cosPhi * rx * sinTheta1 - sinPhi * ry * cosTheta1);
double dy1 = t * (-sinPhi * rx * sinTheta1 + cosPhi * ry * cosTheta1);
double dxe = t * (cosPhi * rx * sinTheta2 + sinPhi * ry * cosTheta2);
double dye = t * (sinPhi * rx * sinTheta2 - cosPhi * ry * cosTheta2);
graphicsPath.AddBezier((float)startX, (float)startY, (float)(startX + dx1), (float)(startY + dy1),
(float)(endpointX + dxe), (float)(endpointY + dye), (float)endpointX, (float)endpointY);
theta1 = theta2;
startX = (float)endpointX;
startY = (float)endpointY;
}
}
